SMITHSONIAN CONTRIBUTIONS TO BOTANY NUMBER 48 

Growth and Population Dynamics 

of Espeletia (Compositae) 

in the Venezuelan Andes 

Alan P. Smith 

SMITHSONIAN INSTITUTION PRESS 

City of Washington 

1981 
ABSTRACT 

Smith, Alan P. Growth and Population Dynamics of Espeletia (Compositae) 

in the Venezuelan Andes. Smithsonian Contributions to Botany, number 48, 45 

pages, 19 figures, 20 tables, 1981.-Espeletia (Compositae, Heliantheae) is a 

major component of alpine and subalpine plant communities in the Venezuelan Andes. A detailed analysis of population dynamics was undertaken for 

Espeletia species representing the arborescent, caulescent rosette, and acaulescent rosette forms. Mortality, growth, and reproduction were recorded during 

a 15-month period for E. schultzii, and E. lutescens (caulescent rosette species), 

E. fzoccosa and E. atropurpurea (acaulescent rosette species), and E. humbertii (an 

arborescent species of treeline forests). Espeletia floccosa is obligately semelparous; all other study species are iteroparous. Microenvironmental variables 

were measured at all sites. 

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded 

in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: Leaf clearing from the 

katsura tree Cercidiphyllum japonicum Siebold and Zuccarini. 

Library of Congress Cataloging in Publication Data vv 

Smith,'Alan P.- 

Growth and DoDulation dvnamics of EsDeletia ComDositae) in the Venezuelan Andes. \I 

(Srnithsonian' cbntributions to botany ;'no. 48) 

Bibliography: p. 

1. Espeletia. 2. Growth (Plants) 3. Plant populations-Andes. 4. Plant populations-venezuela. 5. Alpine flora-Andes. 6. Alpine flora-Venezuela. 7. Botany-Andes-Ecology. 8. Botany-Venezuela-Ecology. I. Title. 11. Series. 

QKl.S2747 no. 48 [QK495.C74] 581s 81-607061 [583'.55] AACR2 
Contents 

Introduction ................... .............................. 

Acknowledgments ................................ 

General Methods ....... ...................................... 

Research Design ................................................... 

Plot Design ........................................................ 

Environmental Measurements ..................................... 

The Phramo Environment ............... ..................... 

Studies of Juveniles .................................................. 

Recruitment .............................. ...................... 

Size Class Distribution ........................................... 

Growth ....................... ............................. 

Mortality ......................................... 

Size Class Distribution ............................................. 

Growth ............................................................ 

Rosette Turnover Time ........................................... 

Mortality .......................................................... 

Reproductive Phenology ........................................... 

......... 

Studies of Adults ................ ............................ 

Effects of Slope Aspect on Growth and Population Density ........ 

Experimental Study of Growth .............................. 

Discussion .......................... ............................. 

Relationship between Growth Form and Population Dynamics .... 

Population Control and Stability .................................. 

Summary: Tables ................................ 

Appendix: Tables .................... ............................. 

Literature Cited .................................................... 

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111 

Growth and Population Dynamics 

of Espeletia (Compositae) 

in the Venezuelan Andes 

Alan P. Smith 

Introduction 

The presence of perennial caulescent rosette 

plants differentiates many high elevation ecosystems in the tropics from alpine comunities of the 

temperate latitudes (Cuatrecasas, 1968; see also 

Figure 1). Such plants are characterized by rosettes of large leaves supported by unbranched or 

little-branched stems. Immature leaves form a 

dense bud around the apical meristem. Dead 

leaves are often persistent, forming a thick cylinder around the stem. This form has evolved independently in the alpine regions of the East 

Africa (Senecio, Carduus and Lobelia), South America (Puya and Espeletia), Hawaii (Argyroxiphium), 

New Guinea (Cyathea), and the Canary Islands 

(Echium), but is absent in extra-tropical alpine 

regions. It is therefore assumed that the form is 

an adaptive response to tropical alpine environments (Hedberg, 1964; Mabberly, 1973). Ecological studies of these plants may help us understand plant forms characteristic of high tropical 

mount ains. 

The giant rosette form is particularly well 

suited for studies of plant population biology: 

plants are small enough to make thorough growth 

measurements feasible, yet large enough to permit 

precise measurements; the rosette form permits 

Alan P. Smith, Smithsontan Tropical Research Institute, Post Office 

Box 2072, Balboa, Panama. 

accurate description of spatial relationships because each plant’s location can be described as a 

point on an “X-Y” coordinate system, a technique far less appropriate for plants with assymetrical canopies; plants can be easily manipulated for experimental studies; associated plants 

are also small in stature, facilitating characterization of competitive neighborhoods; many giant 

rosette species are abundant, permitting adequate 

replication of measurements. 

This paper describes seasonal variation in 

growth, mortality, and reproduction in relation 

to environment for Espeletia species of contrasting 

growth forms. Long-term studies of year-to-year 

variation in population dynamics are continuing, 

and will be presented in later papers. This research is part of a larger study of convergent 

evolution among tropical alpine giant rosette species of the New and Old World tropics. 

Espeletia (Compositae, Heliantheae) is endemic 

to the Andes of Venezuela, Colombia, and northern Ecuador. The genus probably evolved in 

place from the genus Polymnia, which occurs in 

tropical montane forests (J. Cuatrecasas, pers. 

comm., Mar 1973). At least 90 species are recognized, of which 45 occur in Venezuela (Cuatrecasas, 1954, 1977; Aristeguieta, 1965). The most 

“primitive” member of the genus is probably E. 

nerifolia Sch. Bip., a very widely distributed ar1 
2 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 1.-Study species: .4. E. humbertzi on talus slope at 3500 m: plant is approximately 4 m 

tall; B? E. schulltiz at 3600 m on leeward slope; C. E. schultzii at 4200 m: D. E. schultzii at 3000 

m, showing insect damage to leaves: E, E. jloccosa at 3600 m. an acaulescent, monocarpic 

species: F, E. atropurpurea at La Aguada at 3400 m, an acaulescent, glabrous-leaved species; G, 

E. lutesrens at 4200 m; largest plant is approximately 1.5 m tall: H, longitudinal section of E. 

schultrii plant at 3600 m. 

borescent species of subalpine forests (Cuatrecasas, 1954; Chardon, 1951; Smith and Koch, m to 3600 m in elevation. 

1935). There are 15 other arborescent species, all 

occupying restricted geographical ranges. Arborescent species occur at elevations of about 2600 

The majority of Espeletia species occurs in the 

paramo (alpine and/or subalpine) zone. Most 
NUMBER 48 3 

paamo species have the caulescent rosette growth 

form, but there are also several acaulescent paramo species. Caulescent and acaulescent rosette 

species occur at elevations of about 2700 m to 

4600 m. Nomenclature of Espeletia spp. is that of 

Aristeguieta (1965); for other plants, Vareschi 

(1970) is followed. 

Montane forest tree line occurs between 2700 

m and 3400 m in the Venezuelan Andes around 

Merida, Estado Merida (9’N), depending on exposure and degree of human disturbance. Pockets 

of woodland extend up to 4200 m in sheltered 

valleys and on talus slopes. Forests have been 

eliminated altogether in many areas, so that paramo vegetation merges gradually with manmade 

montane pastures. The upper limit of vascular 

plants occurs at approximately 4800 m, just below 

snowline. 

The Andes began to rise during the Cretaceous, 

reaching their present height during the Pliocene 

and the Pleistocene (Vuillemier, 197 1). Pleistocene glaciations caused fluctuations of climatic 

zones (Van der Hammen, 1968). Glaciers extended downward to approximately 2600 m in 

the Andes around Merida (R. Giegengack, pers. 

comm., Feb 1974). Modern snowline occurs at 

approximately 4850 m and, in Venezuela, apparently is retreating. Anecdotal accounts suggest 

that in the early 20th century snowline occurred 

at approximately 4400 m to 4500 m (R. Giegengack, pers. comm., Feb 1974). 

Sierran “islands” with alpine or subalpine environments were produced as the Andes rose. The 

invasion of these islands by Espeletia-presumably 

by genotypes of arborescent forest species similar 

to E. neriifolia-produced numerous isolated populations. This comparative isolation, combined 

with new selective forces imposed by the paramo 

environment, apparently contributed to extensive 

speciation (Chardon, 195 1; J. Cuatrecasas, pers. 

comm., March 1973). The arborescent type was 

apparently ancestral to the more compact caulescent rosette form, which requires lower energy 

allocation for nonphotosynthetic support tissue 

and provides greater buffering against intense 

diurnal temperature fluctuations (Smith, 1974a, 

1974b, 1979). The arborescent form persists in 

Espeletia species of subalpine forests. A similar 

evolutionary pattern has been proposed for the 

genus Senecio in the East African high mountains 

(Mabberley, 1973). 

Only one previous study has dealt with growth 

and population dynamics of Espeletia. Pannier 

(1969) grew E. schultzii under phytotron conditions. He found that germination percentage was 

increased by wetting and drying cycles, and that 

the degree of seed dormancy varied seasonally. 

Leaf color and amount of leaf pubescence varied 

with the temperature regime under which the 

plants were grown, suggesting a high degree of 

phenotypic plasticity. Pannier recorded mortality 

of E. schultzii seedlings in a 1 m2 plot in the 

paramo at 3600 m. Highest mortality occurred in 

the dry season. Baruch (1972) studied water relations in E. neriiflia under both field and phytotron conditions. He found that increased leaf 

pubescence and density thickness (dry weight per 

cm2 of leaf surface) is correlated with reduced 

transpiration. 

The anatomy of Espeletia has been studied by 

Carlquist (1958), Roth (1973), Weber (1956), and 

Rock (pers. comm., May 1972). Powell and Cuatrecasas (1970) found that 30 Espeletia species all 

had a chromosome number of N= 19. 

Observations on the distribution, growth form, 

and anatomy of certain Afroalpine caulescent 

rosette species (Lobelia spp. and Senecio spp.) were 

made by Cotton (1943), Hauman (1934, 1935), 

and Mabberley (1973), but no quantitative ecological data were collected. Hedberg (1964) and 

Coe (1967) found that nyctinastic leaf movement 

and retention of dead leaves on the stem in these 

species result in maintenance of tissue temperatures above ambient at night. Hedberg (1969) 

found that annual height increase in Senecio keniodendron was approximately 2.5 cm. Studies of the 

population biology of the alpine Senecio species 

were initiated in 1977 and are continuing (Smith, 

unpublished data). Less extensive, but similarly 
4 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

long-term studies of growth, mortality, and recruitment for alpine Cyathea species on Mount 

Wilhelm were initiated in 1975 (Smith, unpublished data). 

Information on within- and between-species 

variation in population dynamics is essential for 

an interpretation of growth form patterns in Espeletia. Data on net growth rate and longevity are 

necessary in order to determine the immediate 

causes of trends in plant height. It is also necessary 

to determine which environmental factors reduce 

growth and reproduction and increase mortality; 

the capacity of the caulescent rosette growth form 

to moderate the effects of these specific factors 

can then be evaluated. 

Knowledge of population dynamics in Espeletia 

is also essential for an understanding of the functioning of alpine and subalpine ecosystems of the 

north tropical Andes, where Espeletia is a dominant component of the community. 

ACKNOWLEDGMENTS-I am grateful to Dr. W. 

D. Billings for his encouragement and advice 

throughout this study. 

Logistical support in Venezuela was kindly 

provided by the Instituto Silvicultura, Facultad 

de Ciencias Forestales, and the Centro de Estudios Forestales de Postgrado, Universidad de 10s 

Andes, Merida; the Instituto Forestal LatinoAmerican0 de Investigaction y Capitacion, Merida; the Herbarium of the Facultad de Ciencias 

Forestales and the Herbarium of the Facultad de 

Farmacia, Universidad de 10s Andes, Merida. 

Dr. Jose Cuatrecasas and Dr. Federico Pannier 

generously provided me with information on the 

ecology and distribution of Espeletia. 

I am grateful to Mrs. Shirley M. Billings for 

much advice and assistance on financial and 

logistical matters, and to David Hanselmann, 

Marilyn Loveless, Zdravko Baruch, Juliana Mulroy, and Sr. Faustino Diaz and his family for 

their cooperation in the field. I thank Drs. Beryl 

B. Simpson and Egbert G. Leigh for useful comments on the manuscript, and Mrs. Arilla H. 

Kourany for editorial assistance. 

Financial support was provided by National 

Science Foundation grants GB 34882 and GB 

35733 to W. D. Billings and GB 28950 to the 

Southeastern Plant Environment Laboratory at 

Duke University, a Duke University Graduate 

School Research Award, a Duke University Dissertation Travel Award, and by the Smithsonian 

Tropical Research Institute. 

General Methods 

RESEARCH DEsIGN.-The research provided (1) 

elevational comparisons within a wide-ranging 

caulescent rosette species (E. schultzii), (2) comparisons within E. schultzii at an intermediate 

elevation along a topographic gradient, and (3) 

comparisons among Espeletia species representing 

different growth forms. All sites were located in 

the Andes near Merida, Estado Merida, Venezuela (Figure 2). 

Elevational Comparisons: Elevat ional comparisons 

for E. schultzii were made among sites at 3000 m 

(Zerpa site), 3600 m (Mucubaji site), and 4200 m 

(Aguila site). Espeletia schultzii is abundant at 3000 

m and 3600 m, growing in dense stands from 

ridge tops to bog edges. At 4200 m, at the upper 

limit of its range, E. schultzzi occurs primarily in 

gently sloping, rocky drainage areas. These three 

sites were all on gentle slopes exposed to the 

prevailing NE winds. The 3000 m and 3600 m 

sites were located on morainal deposits. The 4200 

m site was never glaciated. 

Topographic Comparisons: Comparisons within E. 

schultzii were made along a small morainal ridgebog gradient at 3600 m (Mucubaji). The total 

relief from ridge to bog was about 10 m. Sites 

were located at the base of the slope; on a midslope exposed to the prevailing NE winds; at the 

top of the slope, also exposed to the wind; and on 

a leeward midslope. Some data were also collected on plants growing on the edge of the bog 

(Figure 3). This gradient was in a fenced research 

area referred to as the “upper exclosure.” 

Three other sites at 3600 m were used for 

studies of E. schultzii: (1) a steep xeric slope of a 

terminal moraine north of Laguna Mucubaji

(Figure 2); (2) a gently sloping talus slope at 3600 

m; (3) a series of windward and leeward slopes in 
NUMBER 48 5 

8O50’ N 

KM BELOW 3000M 

ABOVE 4000M 

FIGURE 2.-Map of research sites (numbers = study site numbers given in Appendix (Table A; 

X = locations of government weather stations; triangle = Pic0 Mucunque, 4765 m). 

the “lower exclosure,” a fenced research area 

adjacent to Laguna Mucubaji(Figure 2). 

Interspec@ Comparisons: Espeletia schultzii was 

compared with several other species differing 

from it in growth form. An arborescent species, 

E. humbertii Cuatrecasas, was studied at Laguna 

Negra, approximately 1 km southeast of the Mucubajitopographic site, at 3500 m (Figure 2). 
6 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

L 

WIND 

WEATHER STATION 

FIGURE 3.-Topographic gradient used for study of E. schultzii at 3600 m (numbers = site 

numbers in Appendix Table A). 

Populations were located on a talus slope, in a 

closed forest, and in a treefall in an otherwise 

closed forest. 

A semelparous acaulescent rosette species, E. 

floccosa, was studied at 3600 m (Mucubaji). Populations were small and were located on rocky 

windward slopes, surrounding by E. schuftzii. A 

study plot was established in such a population 

(Mucubaji), approximately 300 m from the main 

topographic site used for E, schultzii and a few 

meters above the E. schuftzii plot located on talus. 

An acaulescent, glabrous-leaved species, E. atropurpurea, was studied at La Aguada, a station on 

the Merid a Teleferico (cable car) at 3400 m. Data 

on this species are presented elsewhere (Baruch 

and Smith, 1979). 

A caulescent rosette species, E. lutescens, similar 

to E. schuftzii but much taller, was studied at 4200 

m (Aguila). It is one of the most widespread 

species at this altitude, occurring from ridge tops 

to the edges of drainage areas and bogs. A plot 

was established in a population of E. lutescens 

adjacent to the E. schultzii plot at 4200 m. 

Descriptions of all sites are summarized in Appendix A. Locations are given in Figure 2. 

PLOT DESIGN.--IO X 10 m plots were used for 

population studies. Height, stem diameter (for 

arborescent species), rosette or crown diameter, 

and distance to nearest adult neighbor of the 

same species were recorded for each Espeletia 

adult within a 10 X 10 m plot. In most cases, 1 

m2 random quadrats, located within the 10 X 10 

m plots, were used to sample juvenile plants. A 

preliminary survey was carried out for each species to find the reproductive adult with the smallest rosette diameter. A reproductive adult was 

defined as any plant with new or old flower stalks. 

This minimum rosette diameter was then used to 

distinguish between adults and juveniles. For E. 

schuftzii this critical diameter is 25 cm, for E. 

fluccosa it is 10 cm, and for E. futescens it is 40 cm. 

For E. humbertii it was not necessary to distinguish 

between adult and juvenile stages: the large plots 

used for surveys of adults were also used for 

complete counts of juveniles, because juvenile 

densities were low at most sites. 

Sampling was initiated on the north edge of a 

given 10 X 10 m plot. The first 120 adults encountered were marked with a metal stake and 

numbered aluminum tag. If there were fewer 

than 120 adults in the plot, the first adults encountered beyond the plot were tagged in order 

to give a uniform sample size from site to site. 

These 120 marked adults were used for measurement of growth and mortality. Dates for surveys 

are given in Appendix Tables C and D. 

Ten I X 1 m quadrats were located at random 

within each 10 X 10 m plot, using coordinates 

from a random number table. Height to highest 

leaf tip, rosette diameter, and distance to nearest 

adult neighbor were recorded for every Espeletia 

juvenile in each quadrat. Each juvenile was 

marked with a numbered plastic pot marker. 

Each marker was located 2 cm upslope from its 

plant, with the marker edges oriented east-west 

to minimize shading. Great care was taken to 

locate all juveniles present, including seedlings 
NUMBER 48 7 

(cotyledon stages). Dates for surveys of juveniles 

are given in Appendix Table E. 

The original research design called for a minimum of two replicate 10 X 10 m plots for each 

site. However, because insufficient time was available during the initial wet season survey, only 

one plot per site was established, each divided 

into two subplots. 

tions of elevational gradients in rainfall and temperature are based primarily on data from Venezuelan government weather stations. These stations are located at 3100 m (Los Plantios), 1 km 

from the 3000 m study site; at 3550 m (Mucubaji), 0.5 km from the main Mucubaji study site; 

at 4095 m (Pic0 del Aguila), 5 km from the 4200 

m study site. These stations are visited daily by 

government personnel. 

Soil moisture, measured gravimetrically, was 

determined periodically for most study sites. 

Cores of soil were extracted from depths of 0-5, 

5-10, and 10-15 cm for several points around 

each study plot. Soil moisture content under 15 

atmospheres pressure was determined in the laboratory for soil from each site, using the methods 

of Richard (1949). 

Weather stations were established at the topographic gradient site in the upper exclosure at 

3600 m (Figure 3). Each station had a white, 

double-roofed, louvered, instrument shelter (Chabot and Billings, 1972) placed at ground level. 

Each shelter contained a Taylor maximum-minimum thermometer. A Bendix-Friez 3-cup anemometer was located at 100 cm above the ground 

adjacent to each shelter. Weather stations were 

serviced weekly from early June 1972 through 

mid-January 1973. 

Percentage cover by vascular plants, moss, lichens, rock, litter, and bare soil was estimated for 

each 1 m2 random quadrat used for surveys of 

juveniles. In addition, vegetation cover was estimated for the area within a 1 cm radius of the 

canopy margin of each juvenile present in the 1 

m2 quadrats. 

A brief microclimatic study was made on a 20' 

NE-facing slope (windward) and the adjacent 20' 

ENVIRONMENTAL MEASUREMENTS.-DeSCripSW-facing slope (leeward) at 3550 m in the lower 

exclosure (Figure 2). The leeward slope at this 

site was far more sheltered from the prevailing 

NE wind than was the leeward slope studied in 

the upper exclosure. The lower exclosure site thus 

provided a clearer demonstration of the effects of 

wind on microclimate. These data were used to 

interpret patterns of flowering phenology on 

windward and leeward slopes. The study was 

carried out in clear weather on 24-25 Mar 1973. 

Measurement sites were located 6-7 m below the 

crest. Distance from ridge crest to base of the NEfacing slope was 13.4 m; distance from crest to 

base of the SW-facing slope was 18.0 m. Air 

temperatures were measured with shaded thermocouples at 50 cm. Wind speed was recorded 

with a hand-held anemometer (Deuta-Werke) at 

1.5 m above the ground. 

For each of seven adult E. schulttii plants on 

each slope, one thermocouple was placed in the 

center of the apical bud, a second in the tissue of 

one of the outermost bud leaves on the north side 

of the bud, and a third in the tissue of a mature 

leaf at a 45' angle on the north side of the rosette. 

The Paramo Environment 

Elevational trends in climate are summarized 

in Table 1. Total annual precipitation decreased 

from the 3100 m site to the 4095 m site. Wet 

season soil moisture levels also decreased with 

increasing elevation (Table 1). Snowfall is rare at 

3550 m, but occurs occasionally at 4200 m in the 

wet season. There are seldom more than few cm 

of accumulation, and this rarely persists for more 

than 24 hours. 

Rainfall is strongly seasonal. The dry season 

generally lasts from December through March or 

April. The transition from wet season to dry 

season, and from dry season to wet season, can be 

very gradual. Rainfall data and other climatic 

variables for Mucubaji (3550 m) are summarized 

in Figure 4. Seasonal precipitation patterns vary 

greatly from year to year. Figure 5 summarizes 

30 years of precipitation data for the months of 
8 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 1 .-Elevational differences in environment at research location (except where noted, data are from Venezuelan government weather stations near Espeletia study 

sites) 

Factors I 3/00m 3550m 4095m 

Mean maximum ternperature, 1972 

Mean minimum temperature, 1972 

Precipitation 

Evaporation, open pan, 

Nov 1970 

Soil moisture' 

1 Aug 1972 

26 Mar 1973 

Wilting percentage 

Vegetation cover' 

Cover by rock 

12.6OC 10.5"C 5.2'C2 

4.2OC 1.9"C l.l°C2 

1304 mm 1118 mm 980 mm 

108mm 78 mm 74mm 

62% 47% 35% 

27% 30% 18% 

18% 18% 11% 

94+2.6% 78+4.0% 38&8.1% 

0% 2+1.0% 37f9.170 

' Data from E. schultrii study plots at 3000 m and 3600 m 

and E. lutescens study plot at 4200 m; soil moisture expressed 

on oven-dry weight basis. 

Temperature data from June 1968-May 1969. 

February (mid dry season) and May (early wet 

season) at Paramo de Mucuchies (41 18 m), located between the 4200 m (Aguila) and 3550 m 

(Mucubaji) research sites. 

Mean monthly temperatures are relatively constant throughout the year. However, the diurnal 

temperature range is greater in the dry season 

than in the wet season (Figure 4). Heavy cloud 

cover and frequent fog, as well as rain and snow, 

are characteristic of the wet season. In the wet 

season, clear weather often occurs early in the 

morning but seldom persists beyond 0900 or 1000 

hours. Completely clear days are common in the 

dry season. Relative humidity can drop to 15% to 

20% at ground level during the dry season but 

often remains near 100% all day in the wet season. 

Wind is nearly continuous during the day in both 

wet and dry seasons. Wind speeds seldom exceeds 

20 mph, except on high mountain peaks. Highest 

wind speeds occur in the wet season. Winds are 

almost entirely from the northeast during the wet 

season, but occasionally shift to the southwest 

during the dry season. Such shifts generally last 

for less than a day. 

The effects of topography on microclimate for 

the primary study site at 3600 m are summarized 

in Table 2. The lowest dry season temperatures 

occurred in the bog, as a result of cold air drainage. Highest dry season temperatures occurred on 

the leeward slope, because this slope was sheltered 

from the wind. Differences between topographic 

sites were greatly reduced during the wet season. 

Short-term data on wind speed and air temperature on a NE-facing (windward) slope and 

the adjacent SW-facing (leeward) slope are summarized in Figure 6. Data on tissue temperatures 

for E. schultzii plants on these slopes are summarized in Figure 7. The slopes were located in the 

lower exclosure at 3550 m (Figure 2). 

Air and plant temperatures early in the morning rose faster on the NE-facing slope than they 

did on the SW-facing slope because the sun hit 

the NE-facing slope first. However, by 1130 hours 

wind speed had increased and the sun was almost 

directly overhead. By this time, plant temperatures for the more sheltered SW-facing had risen 

above those for the NE-facing slope and remained 

higher during the afternoon. Soil moisture measured at a depth of 0-15 cm on 25 March 1973 

was 28.9% on the NE-facing slope and 16.2% on 

the SW-facing slope. 

Needle ice formation occurred at elevations 

above 3000 m on bare soil wherever soil moisture 

was high enough. At 4200 m there were extensive 

areas of bare soil, probably maintained by intense 

frost activity; needle ice occurred on most nights. 

At 3600 m there was extensive cover by moss, 

lichens, and higher plants, and only small patches 

of bare soil a few cm2 in size surrounded by 

vegetation. Needle ice formation was restricted to 

these small areas and occurred only on clear 

nights. Soil frost activity was most intense in the 

early dry season when clear nights were common 

and soil moisture was still high. By mid dry 

season, soil moisture was too low to permit needle 

ice formation except in wet swales and bogs. 

Cattle and horses graze throughout and paramo zone. Cattle were seen at elevations up to 

4600 m. However, grazing was eliminated at 3600 
NUMBER 48 9 

OC 

15 

10 

5 

C 

MM 

250 

20c 

a 2 

d 

z15C 

< a 

1 O( 

5c 

0 1 I 

J' F M' A' ME J' J A 5 0' N D 

MONTH 

FIGURE 4.-Seasonal variation in climate at Mucubaji (3550 m) (data from government weather 

station). Top: A, mean maximum temperature (monthly); B, mean minimum temperature 

(monthly); C, mean number of hours of sunshine per day for each month. Bottom: A, mean 

relative humidity (monthly); B, total mm evaporation per month; C, total precipitation per 

month (mean maximum and mean minimum temperatures were calculated from daily maximum and daily minimum temperatures, recorded with hygrothermographs; hours of sunshine 

recorded with Campbell Stokes sunshine recorder-"sunshine" defined as solar radiation at or 

above intensity of 0.33 cal-'cm-2min-' (Stringer, 1972). 

10 

C W

w 

bO 

< 

. 

4 

2 

1, 

/.R.H. 

I00 

30 

50 

10 

10 

1. 

m (Mucubaji) approximately 15 years ago. There 

was light grazing at 3000 m (Zerpa) and at 4200 

m (Aguila). An attempt was made to enclose the 

study plots at Zerpa and Aguila with barbed 

wire, but the fences were stolen or vandalized. 

However, no cattle or horses were observed feeding on Espeletia and no evidence of such grazing 

was found for any of the species studied. 
10 

100 

42 43 

YEAR 

50 5 60 61 62 t 

FIGURE 5.-Thirty years of precipitation data for February and May, Paamo de Mucuchies, 

41 18 m (data from government weather station; X = missing data). 

Studies of Juveniles 

REcRuITMENT.-The 1 m2 random quadrats 

used for studies of juveniles were resurveyed periodically. New seedlings were marked and measured during each resurvey. Data were collected 

for E. schultzii, E. lutescens, and E. floccosa. Espeletia 

humbertii seedlings were too rare on the talus slope 

site to make studies of seedling dynamics practical. Extensive excavations of young plants indicated that, of all species studied, only E. atropurpurea reproduces vegetatively. Thus, the new 

plants recorded for E. schultzii, E. lutescens, and E. 

floccosa were all derived from seed. 

Elevational Comparisons in E. schultzii: Results 

are summarized in Table 3 and Figure 8. Seedling 

production decreased with increasing elevation. 

New seedlings were relatively common at both 

3000 m and 3600 m. Only two new seedlings were 

recorded during the year at 4200 m. Seedling 

production occurred entirely in the wet season at 

3000 m and 4200 m. At 3600 m, all but four of 

the 91 new seedlings produced during the year 

appeared during the wet season. 

Topographic Comparisons in E. schultzii at 3600 m: 

Seedling production decreased from leeward to 

windward slope sites and from slope base to ridge 

(Table 3). Highest rates of seedling production 

thus occurred in the sites most sheltered from the 

prevailing wind (Table 2). 

Interspecijic Comparisons: Seedling recruitment 

rate was low in E. lutescens (only one new seedling 

was recorded during the year), but was similar to 

that for the adjacent E. schultzii population at 

4200 m (two seedlings). 

Twenty-five new seedlings were recorded for E. 

floccosa during the year. All of these seedlings 

appeared during the wet season. There were only 

five 1 m2 quadrats for E. floccosa versus 10 for 

other species. On a per area basis, the recruitment 

rate for E. floccosa was therefore similar to that for 

E. schultzii on the ridge site at 3600 m (50 seedlings 

per 10 m2 per year). 

The low number of new seedlings recorded for 
NUMBER 48 11 

TABLE 2.-Variation in environment along a topographic gradient at 3600 m (site described 

in Figure 3 and Appendix Table A) 

Midslope Midslope 

Factors Bog Slope base windward Ridge leeward 

Temperature ("C) * 

25 Jun -23 Jul 1972 

Mean maximum 

Mean minimum 

Mean maximum 

Mean minimum 

Soil moisture (% oven-dry 

17 Dec 1972 -14 Jan 1973 

weight) 

24 Ju1 1972 

24 Aug 1972 

2 Jan 1973 

26 Feb 1973 

Wilting percentage 

Mean wind speed (mph) 

Percent of cover 

Vegetation 

Rock 

8 Jun 1972 -14 Jan 1973 

12.8 

1.1 

17.8 

-9.8 

94.5 

109.2 

66.4 

53.4 

24.3 

1.5 

- 

- 

13.3 

1.1 

16.7 

-5.9 

57.0 

54.6 

34.9 

20.0 

17.9 

3.1 

81k5.5 

<1 

13.9 

1.1 

20.0 

-3.6 

51.6 

49.5 

31.0 

20.6 

18.0 

3.6 

78f4.0 

2k1.0 

14.4 

1. I 

19.4 

- 1.8 

54.6 

47.1 

26.7 

20.6 

17.5 

6.4 

72k5.8 

3k1.2 

15.6 

1.1 

23.6 

-5.0 

49.6 

48.9 

28.5 

21.8 

17.6 

2.7 

79k2.6 

0 

* Mean temperatures are based on weekly readings of maximum-minimum thermometers 

both E. schultzii and E. lutescens at 4200 m could 

have been the result, in part, of intense, nightly, 

soil frost activity. Most seedlings are destroyed by 

frost heaving as soon as they germinate and thus 

disappeared too quickly to be recorded during 

the quadrat resurveys. Most of the established 

juvenile plants at 4200 m grow among rocks, or 

are surrounded by vegetation, and are protected 

from soil frost activity. 

Higher rates of seedling recruitment in more 

sheltered sites could have resulted from increased 

seed production, as well as from the direct effects 

of microclimate on germination and establishment. The number of adult plants that flowered 

and the number of flower heads per plant were 

both highest in more sheltered places (Table 15- 

SIZE CLASS DIsTRIBuTIow.-The number of juveniles present in the 1 m2 random quadrats was 

recorded at each site. Height to highest leaf tip 

was then recorded for each plant. These data 

were used to construct size class distributions. 

Size class distributions were based on data from 

the initial survey. 

17). 

Height class intervals were based on a geometric sequence with a common quotient of 2 (0-0.5, 

0.6-1.0, 1.1-2.0, 2.1-4.0 cm, etc.). This sequence 

was used because for the smallest plants a difference in plant height of a few mm was associated 

with major differences in mortality rate, whereas 

for larger plants a difference of several cm had 

little effect. These same height classes were used 

to summarize data on juvenile mortality and 

growth. 

Elevational Comparisons in E. schultzii: Size class 

distributions are shown in Figure 8. The greatest 

number ofjuvenile plants occurred in the smallest 

height classes. At 4200 m there were far fewer 

plants in the smallest size classes than was the 

case at either 3600 m or 3000 m. Total number 

ofjuveniles per 10 m2 was highest at 3000 m and 

lowest at 4200 m (Appendix 'Table B). 

Comparisons within E. schultzii at 3600 m along 

a Topographic Gradient: For the upper exclosure 

sites the number of juveniles decreased from 

smallest to largest height classes (Figure 9). Juvenile density was highest on the slope base site 
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

15 

10 

2 

x 

5 

0 

20 

ov 

10 

0 

J 

I. 

14 16 18 26 8 10 12 14 16 

TIME (HOURS) 

FIGURE 6.-Comparison of microclimate on NE-facing 

(windward) and SW-facing (leeward) slopes at 3550 m: A, 

wind speed: B, air temperature at 50 cm (dotted lines = 

windward slope data). 

and lowest on the ridge. Density was higher on 

the leeward slope than on the windward slope 

(Appendix B). On the xeric slope site at 3550 m, 

the greatest number of juveniles occurred in the 

intermediate size classes, with lowest numbers in 

the smallest classes (Figure 1OA). On the talus 

slope at 3600 m, only threejuveniles, all cotyledon 

stage seedlings, were found (Figure 10B). These 

were located in small pockets of moist organic 

debris. 

Interspecfic Comparisons: Juvenile density in E. 

lutescens was too low to yield a clear pattern of 

size class distribution (Figure 11B). 

In E. j7occosa the greatest number of juveniles 

occurred in intermediate size classes (Figure 11A). 

The only other population showing a similar 

pattern was E. schultzii on the xeric slope at 3550 

m. 

For E. humbertii, young plants were too rare on 

the talus slope site and the closed-canopy forest 

site to yield clear size distribution patterns (Figure 

12A-B). High juvenile densities occurreil only on 

the treefall site within otherwise closed forest 

(Figure 12C). At this site, the number ofjuveniles 

decreased from the smallest to the largest size 

classes. 

For E. floccosa at 3600 m and E. schultzii on the 

xeric slope site at 3600 m, juveniles were concentrated in the intermediate rather than the lowest 

size classes. Both of these populations had shorter 

generation times and fewer large adults than was 

the case in other populations. The relative scarcity of large adults may have resulted in decreased 

competition between adults and juveniles. This 

could lead to an increased probability that newly 

recruited seedlings reach higher size classes. 

GROWTH.-A~~ juveniles of E. schultzii, E. lutescens, and E. floccosa present in the 1 m2 quadrats 

at the initial survey were marked with plastic 

tags. Height, measured to the highest leaf tip, was 

recorded. The surviving plants were remeasured 

one year later. Change in plant height was used 

as a measure of growth. Distance to nearest adult 

of the same species was recorded for each plant. 

Elevational, Topographic, and Interspecific Comparisons: Growth rates are summarized in Figures 8, 

9, and 1 1. Growth was highly variable; there were 

no clear-cut patterns along either altitudinal or 

topographic gradients. Mean annual growth rate 

was negative for E. schultzii on the midslope windward site at 3600 m and for E. lutescens at 4200 

m, indicating that, on the average, juveniles decreased in size during the year. This was the result 

of extensive leaf wilting during the dry season. 

For most plants, leaf regrowth during the next 

wet season was too slow to permit full recovery 

from this wilting. Some juveniles in both populations increased in size, however. 

Growth occurred primarily in the wet season 

for all populations. Wilting of older leaves in the 

dry season caused a reduction in size, even for 

plants that showed a net increase in height over 

the entire year. 

For E. schultzii at 3000 m, annual height growth 

increased with increasing initial plant height (rxy 
NUMBER 48 13 

"C 

4( 

3 

2 

1 

"C 

3 

2 

1 

A 

B 

1 . a 1 1 . a I ,,,,,,, 14 16 18 20 8 10 12 14 16 

TIME (HOURS) 

FIGURE 7.-Comparison of E. schulttzz tissue temperatures on windward NE-facing (dotted line) 

slope and leeward SW-facing (solid line) slope at 3550 m: A, bud core temperature: B, mature 

leaf temperature (vertical lines represent 95% confidence intervals). 
14 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABL~ 3 -Seedling production at various tirnts of )ear (each figure = 

number of nen seedlings in ten I-rn2 quadrats (five quadrats for E. /%ccocai 

a[ the end of given time period: dates for all surveys given in Appendix 

Tables C-E) 

and sills season season season season in onr I 1972 1972-3 1973 1973 jrarE irhiil/~ri 

3000 ni 

3h00 m 

blope base 

\2 indnard slope 

Ridge 

Leeward slope 

-1200 m 

E Jlorcusa 

3600 rn 

E luiescens 

4200 rn 

51 0 0 71 125 

I16 3 0 7 I26 

81 4 0 3 91 

45 1 0 4 50 

137 1 0 ‘4 162 

1 0 0 0 1 

23 0 0 1 ? 5 

0 0 0 I I 

= 0.340; P<O.Ol). This same relationship was 

found for E. schultzii on the leeward slope site at 

3600 m (rxy = 0.225; P<O.O5). However, for E. 

schultziz on the windward slope site at 3600 m, 

annual height growth decreased with increasing 

initial plant height (rxy = -0.451; P<0.005). This 

was also the case for E. lutescens at 4200 m (rxy = 

-0.709; Pt0.003). For other populations, there 

was no significant correlation between annual 

height growth and initial plant height. 

Nearest Neighbor Effts: Annual height growth 

of juveniles increased with decreasing nearest 

neighbor distance for E. schultrii at 3000 m and 

for E. floccosa at 3600 m (Table 4). Adults could 

shelter juveniles from wind and intense insolation. 

They might also inhibit interspecific competitors. 

However, adults simply may occupy the most 

favorable microsite. In any case, the closer a 

juvenile was to an adult, the more nearly optimal 

its own microsite would be. Increased intraspecific competition close to the adult might be 

outweighed by these effects. 

Effects of Vegetation: No significant correlations 

were found between juvenile growth and vegetation cover (Table 5). Experimental studies 

strongly suggest that vegetation reduces juvenile 

growth (manuscript in preparation). 

MoRTALITY.-The 1 m2 quadrats were resurveyed periodically to determine the numbers of 

marked juveniles that had died since the last 

‘“I 

68 5d 92% 22 72 

~ 

A AHG= 2.0 

.~ 

12 

28 

20 

= I P AHG= 0.3 

U 0 

- 5c56 

-I 

\ 

29 

1% 

00 

2 -7 

IC AHG = 2.0 

25 k 

0.25 0.75 1.5 30 6.0 12.0 24.0 

HEIGHT CLASSES (CM) 

FIGURE 8.-Altitudinal variation in population structure and 

dynamics for E. schultrzz juveniles: A, 3000 m: B, 3600 m; C, 

4200 m (juvenile = plant with rosette diameter of less than 

25 cm; AHG = annual height growth (cm); bar = number 

ofjuveniles found in each height class; top number = percent 

of mortality in one year; lower number = percent of height 

increase in one year). 

survey. Newly recruited seedlings were marked 

during the resurvey. Subsequent mortality rates 

for these new seedlings were compared with mortality of previously established juveniles. Distance 

to nearest adult of the same species and percentage of cover by vegetation in the plant’s immediate vicinity were recorded for each marked 

plant. 

Eleuational Comparisons in E. schultzii: For juve- 
NUMBER 48 15 

100 

AHG.I.2 AH G = - 0.3 

' 200 

v) 

75 

50 

25 

AHG= 0.7 

c,": t D 

AHG.0.4 

70 60 

10 6 

- 

0.25 0.75 1.5 30 6.0 120 XOOB ~n 15 3.0 60 1x1 MC 

HEIGHT CLASSES (CM) 

FIGURE 9.-Topographic variation in population structure 

and dynamics for E. schultrii juveniles at 3600 m: A, ridge; 

B, midslope windward: C, slope base; D, midslope leeward 

(juvenile = plant with rosette diameter of less than 25 cm; 

AHG = annual height growth (cm); bar = number of 

juveniles: top number = percent mortality in one year: lower 

number = height increase in one year). 

niles present at the initial survey, there was a 

slight decrease in annual mortality rate from 3000 

m to 3600 m, and a large decrease from 3600 m 

to 4200 m for midslope windward sites (Table 6). 

At 3000 m, 87% of all mortality occurred during 

the dry season, compared with 64% at 3600 m 

(Table 6). At 4200 m, only four deaths occurred 

during the year, too few to accurately estimate 

seasonal trends. 

Mortality rates for each size class are shown in 

Figure 8. Mortality decreased with increasing 

plant size for the midslope windward sites at 3000 

m and 3600 m (cf. Hett, 1971; Sarukhan and 

Harper, 1973). For both sites, there was a negative 

N 75, 

A 

B 

OB 

0.25 0.75 1.5 3.0 6.0 12.0 24.0 

HEIGHT CLASSES (CM 

FIGURE 10.--Size class distributions of E. schultrzz juveniles 

at 3600 m: A, xeric slope; B, talus slope (juvenile = plant 

with rosette diameter of less than 25 cm). 

linear relationship between percent mortality in 

each size class and the natural log of the median 

value (in cm) for each height class (Figure 13). 

The regression of mortality rate against plant size 

was not statistically significant for E. schultziz at 

4200 m. However, mean initial height for juveniles that died was significantly lower than mean 

initial height for juveniles that survived one year 

(0.7 cm versus 3.8 cm; P<O.O2). 

Topographic Comparisons zn E. schultzii at 3600 m: 

Annual mortality rate ofjuveniles decreased from 

slope base to ridge (Table 6). Annual mortality 

rate on the leeward slope (58%) was similar to 

that on the windward slope (54%). 

The proportion of total mortality that occurred 

during the dry season was greater on the slope 

base site than on the ridge, and was greater on 

the leeward slope than on the windward slope 

(Table 6). With the exception of the ridge site, 

mortality was always greatest during the dry 

season. 

For all four topographic sites, mortality de- 
16 

100 0 - 130 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

AHG=2.0 cm 

A 

v) 

W 

1 

z 

W 

> 

3 

- 

AHG= -1.2 cm 

B 

25 t 0 

HEIGHT CLASSES (CM) 

FICCRE 11 .-Population structure and dynamics for juveniles: A, E. Joccosa at 3600 m: B, E. lutescens at 4200 m (for 

E. Joccosajuvenile = plant with rosette diameter of less than 

15 cm. for E. lutescens juvenile = plant with rosette diameter 

of less than 40 cm; AHG = annual height growth (cm). bar 

=juveniles, top number = percent mortality in one year; 

lower number = height increase in one year). 

creased with increasing plant size (Figure 9). 

There were negative linear relationships between 

percent mortality in each size class and the natural log of the median value for each size class 

(Figure 13). For the midslope leeward site, the 

apparent sigmoidal relationship between these 

two variables (Figure 13, middle) was not statistically significant; a polynomial regression was 

not significiantly better then a linear regression. 

Interspecfic Comparisons: Annual mortality rate 

for E. floccosa juveniles at 3600 m was 4970. The 

proportion of total annual mortality that occurred during the dry season was higher for E. 

floccosa (98%) than for any other population studied (Table 6). Mortality rates for each class are 

given in Figure 11A. The relationship between 

percent mortality in each size class and the natural log of the median value for each size class 

was linear (Figure 13). The apparent sigmoidal 

(u 

E 25 

0 

Lo 

\ 

cu 

- 

0 

E 

0 25 

0 - 

\ 

0 

175 

N 

E 1% 

0 

Ln 

\ 125 

cn 

I- 103 

Z 

J 

a 75 

a 

50 

25 

0 

C 

&WA I 1-11 

60 103 140 180 220 260 300 340 

HEIGHT CLASSES ( CM) 

FIGURE 12.-Population structures for E. humbertii at 3500 

m: A, talus slope (plants/ljO m2); B, closed forest (plants/ 

100 m2): C, treefall (plants/50 m2) (growth rate for talus 

slope population = 4.2 cm/year based on 50 marked plants, 

all over 75 cm in height: growth data not recorded for other 

populations; solid bar = reproductives: striped bar = prereproductives). 

relationship between these two variables was not 

statistically significant. 

In E. lutescens at 4200 m, only two of the marked 

juveniles died (Table 6), making a detailed analysis of mortality impossible. 

Comparisons between Newly Recruited and Previously 

Established Juveniles: The figures for juvenile mortality discussed so far have been based on those 

sets of juveniles present in the quadrats during 

the initial survey in mid wet season, 1972. These 

quadrats were resurveyed in early December 1972 
NUMBER 48 17 

E. schultrii 

3600 rn 

3000 m 

Slope base 

Ridge 

Midslope leeward 

Midslope windward 

4200 m 

E. froccosa 

3600 m 

E. lutescens 

4200 m 

TABLE 4.-Distance to nearest adult neighbor in relation to juvenile growth, mortality, and 

initial height (juvenile and adult always of same species) 

-0.077 29.3 42.1*** 

0.023 0.136 -0.024 -0.323** 42.3 44.1*** 

0.100 0.024 0.509*** 0.415*** 67.6 34.9*** 

0.034 0.225* 0.0 12 -0.026 32.7 28.5* 

-0.046 0.291 0.042 -0.268 43.4 17.8*** 

-0.394* 0.000 0.152 0.392* 29.5 33.8 

-0.182 -0.709* * * 0.359 0.427t - - 

-0.276** 0.340** -0.114 

-0.118 -0.45 1 *** -0.085 -0.133 49.7 49.9 

Species 

and sits 

Initial height us. Height Height nearest neighbor 

nearest initial All Survivors neighbor distance 

neigh bar height juveniles only 

rxY TXY TXY rxY 

growth us. growth us. Mean nearest 

Survivors Mortalities 

TABLE 5.-Effects of vegetation on juveniles (vegetation cover measured in immediate 

vicinity of each juvenile) 

Species 

and sites 

Initial height us. 

Height vegetation cover (%) 

growth us. vegetal ion Vegetation cover (%) All Survivors 

cover juveniles only 

rxY Survivors Mortalities r,, r*Y 

E. schultzii 

3000 m 

3600 m 

Slope base 

Midslope windward 

Ridge 

Midslope leeward 

4200 rn 

E. froccosa 

3600 m 

E. lu tescens 

4200 rn 

-0.01 1 

-0.069 

-0.2481- 

-0.070 

0.086 

0.21 1 

0.222 

0.100 

83.9 

59.9 

73.0 

62.6 

53.8 

42.2 

84.5 

69.3** 

47.2* 

48.0*** 

42.3** 

26.1*** 

38.5** 

6 1 .O*** 

0.299* * * 

0.23 7* * 

0.336*** 

0.303** 

0.367* * * 

0.346t 

0.102 

0.045 

-0.077 

0.357** 

0.329* 

0.320** 

0.326*** 

0.504* 

0.220 

-0.065 

* P<O.O5 ** Pc0.01 *** Pc0.005 t PeO.1 

(wet season-dry season transition), and seedlings 

that had appeared since the initial survey were 

marked and measured. Mortality during the following dry season was, in general, much greater 

than mortality for juveniles already present at the 

time of the initial survey (Table 7). The only 

exception to this trend occurred in E. schultzii at 

4200 m. In this case, however, only two newly 

recruited seedlings were present, making a meaningful analysis impossible. 

Nearest Neighbor Effects: For E. schultzii at 3000 

m, mean distance to nearest conspecific adult 

neighbor was significantly lower forjuveniles that 

survived one year than for those that died. This 
18 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 6.--Seedling mortality for seedlings present in initial survey (wet season, 1972) (survey 

dates summarized in Appendix Table E) 

Species 

and sites 

Percent of all mortality occurring New Total 

seedlings seedlings 

Initial Percent Wet Dry Wet present present 

number mortality season season season at final at final 

seedlings in I year 1972 1972-3 1973 suruey surztey 

E. schultrii 

3000 m 

3600 m 

Slope base 

Midslope windward 

Ridge 

Midslope leeward 

4200 m 

E. jloccosa 

3600 m* 

E. lutescens 

4200 m 

178 

314 

134 

118 

197 

29 

82 

21 

60.7 

79.3 

53.7 

33.0 

57.7 

13.8 

48.8 

9.5 

8.3 

20.5 

29.2 

43.6 

17.9 

25.0 

0 

50.0 

87.0 

79.1 

63.9 

48.7 

78.8 

75.0 

97.5 

50.0 

4.7 

0.4 

6.9 

7.7 

3.3 

0 

2.5 

0 

73 

19 

17 

13 

29 

2 

2 

1 

143 

84 

79 

92 

164 

27 

44 

20 

* Number of seedlings per 5 m2, rather than 10 m2, 

same relationship was found for E. schultzii at 

3600 m on the slope base plot and for E. floccosa 

at 3600 m. 

On the ridge and leeward slope plots at 3600 

m, surviving juveniles of E. schultzii had a greater 

mean nearest neighbor distance than did mortalities. Dry season soil moisture levels for those two 

plots were the lowest recorded at this site. Competition between adults and juveniles for water 

could have outweighed any moderating effects of 

the adults on microenvironment on these plots. 

Effects of Vegetation: At all sites, vegetation cover 

around juveniles that survived one year was 

greater than cover around those that died. With 

the exception of the E. floccosa and E. lutescens 

populations, initial plant height was positively 

correlated with vegetation cover (Table 5). Mortality rate decreases as juvenile height increases 

(Table 5). Mortality rates were therefore lower in 

sites with higher vegetation cover, in part because 

the size of juveniles was greater. 

Herbivory: Herbivory on juveniles was rare. Insect damage to leaves was noted in two of the 

marked E. schultzii juveniles at 3000 m (1% of all 

juveniles at this site) and in three marked E. 

lutescensjuveniles at 4200 m (14% of all juveniles). 

The damage was caused by beetle larvae burrowing in the apical buds. However, these plants 

survived. No herbivory on juveniles was recorded 

at other sites. Elimination of juveniles by grazers 

apparently is not a major factor. At all sites, 

marked juveniles that died could always be located and showed no signs of insect damage. 

Discussion: Data on juvenile mortality in Espeletia suggest two general patterns: (1) the probability of mortality decreases as plant size increases, and (2) the probability of mortality is 

greatest in the dry season. Potentially, these two 

patterns could result in several kinds of selection 

on Espeletia populations: (1) selection on adult 

stages for production of larger numbers of seedlings, increasing the probability that some will 

survive despite high mortality rates; (2) selection 

on juvenile stages for rapid growth rates, reducing 

the duration of the most vulnerable stage in the 

life cycle; and (3) selection on juvenile stages for 

physiological and/or morphological adaptations 

that confer protection against environmental extremes of the dry season. Further studies will be 

required to determine the relative importance of 

such selective pressures in various Espeletia populations. 

The positive correlation of juvenile size with 

vegetation cover within 1 cm of the rosette margin 
NUMBER 48 19 

-2 -I 0 I 23 

IN HEIGHT (CM) 

FIGURE 13.-Relationships between seedling height class and 

percent mortality in each height class during one year. Top: 

E. floccosa at 3600 m (y = 72.2 - 30.5 lnX, r = -0.939). 

Middle: A, slope base E. schuitzii plot at 3600 m (y = 65.3 - 20.9 lnX, r = -0.977); B, midslope leeward E. schultzii plot 

at 3600 m (y = 45.5 - 37.4 lnX, r = -0.903); C, ridge plot 

for E. schuitziz at 3600 m (y = 30.1 - 34.0 lnX, r = 

-0.976) Bottom: A, E. schultzii at 3000 m (y = 64.1 - 20.1 

lnX, r = -0.941); B, E. schultzii at 3600 m, midslope 

windward plot (y = 50.1 - 18.6 lnX, r = -0.985). 

TABL~ 7.-Dry season mortality (December 1972 to Aprll 197.3) for 

seedlings presenc at inltial survey (wet season, 1972). and for ieedlmqs 

produced after initial survey, bur before December 1972 (survey dates 

summarized in Appendix Table EI 

Species 

and silrs 

E. schullril 

3000 m 

3600 m 

Slope base 

LVindward slope 

ridge 

Leeward slope 

4200 m 

E. floccosa 

3600 m 

E. lulescens 

4200 m 

.Vumber o/ .Vumber uJ 

inilia1 new 

seedlings reedlings 

presenl ,Morlaliy presenl mortal it^ 

Dec I972 (''4) nrc 1972 ('0 

163 .57,7 5 4 96 3 

2 50 78.8 I16 94.0 

9 i 68 7 84 89.3 

67 28.4 45 82.2 

262 55.3 137 97.1 

28 10 7 1 0 

82 47 6 23 87 0 

20 5 0 0 0 

is probably an inevitable consequence of increase 

in rosette diameter. Nonvegetated patches at 

most sites typically cover only a few square centimeters. A very small juvenile within such a 

patch could be free of vegetation in its immediate 

vicinity. As the rosette expands, it will outgrow 

the bare site. As a result, large juveniles will 

seldom be free vegetation. 

Studies of Adults 

SIZE CLASS DISTRIBUTION.-~ize class distributions are based on height data for adults within 

each study plot. Plant height was measured to 

the base of the apical bud in all species except E. 

floccosa. In E. floccosa, height was measured to the 

highest leaf tip because the apical bud was poorly 

defined. Annual height growth was recorded for 

120 adults in most study plots. Size class distributions can be transposed into very approximate 

adult age class distributions by using these annual 

height growth data as conversion factors. However, such approximations must be interpreted 

with care because rate of height growth for adults 

is probably correlated with initial plant height: 

rate of leaf expansion is positively correlated with 

plant height in many populations, and plant 

height growth and leaf expansion rates are closely 

related in caulescent rosette plants. A more de- 
20 

tailed analysis of height-age relationships will be 

presented in a later paper. 

Elezational Comparisons within E. schultzii: The 

4200 m population had fewer plants in small size 

classes than did populations at 3000 m and 3600 

m. However, considering similar topographic 

sites, the tallest and hence oldest plants occurred 

at highest elevations. Mean adult height, calculated for 120 plants at each elevation, was 23.8 

cm at 3000 m, 26.0 cm at 3600 m, and 29.6 cm at 

4200 m. These means are significantly different 

from each other (P<O.Ol) according to the F test 

and least significant range test (Sokal and Rohlf, 

1969). This relationship is discussed in detail in 

Smith (1980). 

Topographic Comparisons in E. schultzii at 3600 m: 

Maximum height and hence maximum age were 

greatest on the slope base site and lowest on the 

ridge (Figure 15). Mean plant height decreased 

from slope base to ridge and from windward slope 

to leeward slope. 

On the xeric slope site at 3550 m, high adult 

mortality apparently resulted in a very young 

population, with no plants in the larger size 

classes (Figure 16‘4). On the talus slope site at 

3600 m, there were comparatively few small 

plants, but maximum plant height was nearly 

one meter (Figure 16B). Mortality data were not 

collected for the talus slope population. However, 

wet season leaf expansion rates were similar for 

the two populations, suggesting that differential 

mortality, rather than differential growth, may 

be largely responsible for these two contrasting 

size class distribution patterns. 

Interspecqic Comparisons: Small size in E. floccosa 

(Figure 17A) combined with rapid height growth 

suggest that it may have the shortest generation 

time of the species studied. The largest plants 

measured in 1972 flowered and died in late 1975 

(see “Reproductive Phenology”, page 3 1). 

The largest E. lutescens adults at 4200 m were 

160 to 170 cm tall (Figure 17B). It is possible that 

these plants were at least 100 years old, because 

annual height increase was 1.5 cm at this site. 

Mean rate of branch elongation in E. humbertii on 

the talus slope at 3500 m was 4.2 cm per year. 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

50 

AHG = 2.0 

M H = 23.8 

A 

- 

3 

4 3 

B AHG= 1.2 

MH = 26.0 

AHG= 1.1 

MH=29.6 

C 

10 20 30 40 50 60 70 80 

HEIGHT CLASSES (CM) 

FIGURE 14.-Altitudinal variation in population structure 

and dynamics for E. ~chulttzz adults on midslope windward 

sites: A. 3000 rn; B, 3600 rn: C, 4200 m (adult = plant with 

rosette diameter of 25 crn or greater; AHG = annual height 

growth (crn); MH = mean height; solid bar = reproductives; 

striped bar = prereproductives; number on bar = percent 

mortality in one year). 

Using this rate to convert height to approximate 

age, it appears that the tallest individuals may 

have been at least 70 to 80 years old (Figure 18). 

GRowTH.-Growth in adults was measured in 

two ways. First, annual increase in height was 

recorded for the 120 marked adults in each plot. 

Techniques are given in the preceeding section. 

The second measure of growth was rate of leaf 

expansion. Fifty of the 120 marked adults were 

randomly selected for these measurements. The 
NUMBER 48 21 

I 

AHG.I.1 1 B AHG.1.2 

MH = 26.0 t MH = 20.0 

I75 

v) 

AHG.1.2 - D 

MH= 31.6 

- 

- 

0 

AHG= 1.1 

MH.21 .O 

10P3040x)6070 102030405060 

HEIGHT CLASSES (CM) 

FIG~JRE 1.5-Topographic variation in population structure 

and dynamics for E. schultrii adults at 3600 m: A, ridge; B, 

midslope windward; C, slope base; D, midslope leeward 

(adult = plant with rosette diameter of 25 cm or greater; 

solid bar = reproductives; striped bar = prereproductives; 

number on bar = percent mortality in one year). 

oldest leaves in the apical bud were marked on 

the tip with indelible ink (Nursery Marker, Horta 

Craft Corporation), and the number of leaves 

expanding from the bud during the next 4 to 6 

weeks was recorded. This procedure was carried 

out in the wet and dry seasons and in a wet 

season-dry season transition period, providing a 

measure of the seasonality of growth. In E.floccosa 

there was no clear differentiation between bud 

leaves and rosette leaves. Thus, leaf expansion 

rates could not be determined accurately for this 

species. 

Two plants could produce the same number of 

leaves per unit time yet produce very different 

A 8 */e 

MH = 13.1 cm 

LEAVES / WEEK 1.6 

E 

\ 

16 

2o 33 

-I I 

50 751 

25 t 

B 

MH ~31.6 cm 

LEAVES / WEEK = 1.5 

0 

10 20 30 40 50 60 70 80 90 

HEIGHT CLASSES (cm) 

FIGURE 16.-Population structure and dynamics for E. schultrzz adults at 3600 m: on A, xeric slope: B, talus slope (adult 

= plant with rosette diamter of 25 cm or greater; rate of leaf 

production measured during the wet season; solid bar = 

reproductives; striped bar = prereproductives; number on 

bar = percent mortality in one year; MH = mean height). 

amounts of leaf tissue, since leaf size varied 

greatly from plant to plant. Therefore, for each 

of the 50 plants at each site, the outline of the 

outermost mature leaf was traced in situ, and the 

area of the outlines determined with a planimeter. 

In converting from number of leaves expanded 

per unit time to leaf area produced per unit time, 

the number of leaves was multiplied by this area. 

Leaf area produced per unit time was converted to dry weight of leaf tissue produced per 

unit time. To do this, mature leaves from 50 

additional plants were collected at each site. Each 

leaf was traced and the area determined with a 
22 

AHG = 4.5 cm 

MH = 25.8 cm 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

75t- 0 2 

J 

3 HEIGHT CLASSES (cm) 

a 50 

AHG= 1.5 cm 

MH.60.9 cm 

I.Imm-- 

15 35 55 75 95 115 135 155 175 

HEIGHT CLASSES (cm) 

FIGURE 17.-Population structure and dynamics for adults: 

A. E. floccosa at 3600 m; B, E. lutescens at 4200 m (E. floccosa 

adult = plant with rosette diameter of 15 cm or greater; E. 

lutescens adult =.plant with rosette diameter of 40 cm or 

greater: .4HG = annual height growth (cm); MH = mean 

height; solid bar = reproductives; striped bar = prereproductives: number on bar = percent mortality in one year). 

FIGURE 18.-Effect of flooding on E. schultzii in a swale at 

3600 m; A, June 1972; B, March 1973. 

planimeter. Oven-dry weight was determined for 

each leaf and dry weight per unit surface was 

calculated. Dry weight per unit surface area was 

regressed against total area per leaf. If there was 

a significant correlation at a given site, the resulting regression line was used to determine dry 

weight per surface area for each intensively studied plant. If there was no correlation, the mean 

figure for dry weight per unit leaf area was used. 

The figure for grams dry weight per cm2 of leaf 

surface was multiplied by the figure for leaf area 

produced per week by each plant. 

Growth was highly seasonal at most sites. A 

quantitative index was developed to express this 

seasonality. For each plant, the rate of leaf expansion during the dry season was divided by the 

rate of expansion during the wet season. The 

results for all plants at a given site were then 

summed and averaged, and the resulting mean 

multiplied by 100. Seasonality (S) is calculated 

by 

n n. 

2 ”’ x 100 

i Wi s= 

n 

where S is seasonality, Di is rate of leaf production 

for the ith individual in the dry season, W. , is ’ rate 

of leaf expansion for the ith individual in the wet 

season, and n is the number of individuals. 

Altitudinal Trends within E. schultzii: Seasonality 

decreased with increasing elevation for midslope 

windward sites (Table 8) because dry season 

growth rates increased with increasing elevation, 

and for the same sites in the wet season, growth 

rates decreased with increasing elevation. 
NUMBER 48 23 

TABLE 8.-Growth rates and seasonality (dry season growth rate as percentage of wet season 

growth rate) (dates for sampling periods given in Appendix Tables C-E; see page 22 for 

definition of “seasonality”) 

Species 

and sztes 

Wet to dry season transit iov Dry season Wet season ~ Leaves/ Grams/ 

Lvs/week Gmlweek Lus/week Gmlweek Lvs/week Gm/week year year Seasonality 

E. schultriz 

3000 rn 

3600 rn 

Bog edge 

Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 rn 

E. lutescenh 

E. humbertii* 

3.5k0.18 5.4f0.48 1.OfO.09 1.6k0.21 3.2f0.18 5.4k0.43 

- 

2.6f0.2 1 

2.2f0.12 

1.9f0.12 

2.0f0.12 

1.6f0.11 

1.2fO.11 

0.1 fO.0 1 

- 

5.2f0.83 

4.0f0.37 

3.5f0.42 

3.6k0.46 

3.9f0.40 

4.4f0.67 

0.3f0.05 

1.1 fO.09 

1.4k0.12 

1.1 fO.09 

1.4f0.11 

0.8f0.09 

1.3f0.12 

1 .OfO. 14 

0.1 k0.02 

1.9f0.24 

2.6k0.43 

2.1f0.26 

2.5f0.32 

1.4f0.20 

3.0k0.36 

3.4f0.81 

0.3f0.05 

2.6f0.17 

3.0f0.29 

2.4f0.18 

2.0f0.15 

2.0f0.16 

1.3f0.12 

1.6f0.19 

0.4f0.04 

4.6f0.54 

6.1f 1.05 

4.4f0.49 

3.6f0.48 

3.6f0.54 

3.2k0.38 

5.7f0.84 

0.9k0.12 

125 210 

- 

119 236 

96 177 

88 163 

81 146 

72 172 

64 231 

10 25 

28.2f2.6 

44.8k3.6 

50.8k5.5 

55.0f6.1 

74.235.3 

43.9k4.4 

92.4f 1 1.1 

68.4f 15.0 

34.3f7.1 

* Leaf expansion recorded for single leaf rosettes, rather than for whole trees. 

Decreasing vegetation cover with increasing 

altitude might result in decreasing interspecific 

competition for water in the dry season, causing 

reduced seasonality. Decreased intraspecific competition could also be a factor. At 3000 m, there 

was a significant positive correlation between 

nearest neighbor distance and growth rate in the 

dry season (rxy = 0.491), but a weaker correlation 

during the wet season (rxy = 0.272) (Table lo), 

suggesting that the plants at this site were competing for water. No such correlations were found 

at higher elevations. Frequency of juvenile plants 

of E. schultzii decreases with increasing elevation. 

Competitive effects of juveniles on adults would 

therefore decrease, further improving dry season 

growth at 4200 m. Leaf pubescence increases with 

increasing elevation in E. schultzii (Z. Baruch, 

pers. comm., Nov 1973). This might result in 

greater buffering against drought stress, reducing 

seasonality of growth. 

Topographic Trends in E. schultzii at 3600 m: 

Seasonality decreased from bog edge to ridge and 

from leeward slope to windward. This trend occurred despite the fact that the ridge and windward slope sites both had lower soil moisture 

levels than did the bog edge and both were more 

exposed to the prevailing wind than was the 

leeward slope. 

Greater seasonality of growth for the bog edge 

plants could be related to rapid leaf senescence 

and resulting decrease in total leaf surface area 

during the dry season. Reduction in dry season 

leaf number on the bog edge site was far greater 

than on the midslope site (Table 9). This reduction was due to wilting of the outermost rosette 

leaves. Rates of dry season leaf expansion were 

the same for the bog edge and midslope plants. 

Windward and leeward halves of each rosette 

were distinguished when leaves were counted in 

the early dry season. For the bog edge there was 

no significant difference between number of 

leaves in the two rosette halves. For midslope 

plants, however, the mean number of leaves in 

the leeward rosette halves was 30.6 versus 24.9 for 

the windward halves. These means were significantly different (PCO.005). The midslope site was 

subject to far stronger winds than was the bog 

edge site. In the wet season, there was no significant difference between mean leaf number in the 

leeward and windward rosette halves for the 

midslope plants. Rosette halves were not sampled 

separately when the bog edge plants were resurveyed. 

Greatest total wilting occurred on the bog edge 

despite greater wind-related wilting on the midslope site. It is unlikely that the wilting was 
SMITHSONIAN CONTRIBUTIONS TO BOTANY 24 

TABLE 9.-Number of leaves per rosette and leaf expansion rates for E. schulttii at 3600 m (50 

adult plants measured at each site) 

Sites and seasons 

I LPaoes/rosette, Leaues/rosette, 

dry season dry season x I00 x 100 

Leaoesl Leaveslrosette, Leaves/ Leaves/rosette, 

I rosette wet season week wet season 

Midslope windward 

Wet season 

Dry season 

Wet season 

Drv season 

Bog edge 

68k16.1 

55+ 4.3 

60+ 4.4 

34+ 2.5 

81.6% 

57.0% 

2.4kO. 18 

1.1 kO.09 

2.620.17 

1. I kO.09 

55.0% 

44.8% 

related to soil moisture. On 2 January 1973, soil 

moisture on the bog edge was 46%, versus 3 1% on 

the midslope windward site. Mean minimum 

temperatures in the dry season were much lower 

in the bog (and hence on the bog edge) than on 

the midslope site. Greater leaf wilting on the bog 

edge might have been related to an interaction of 

(1) freezing stress and (2) drought stress due to 

rapid heating of leaves early in the morning 

when, because of cold stem and roots, water 

transport to leaves is inefficient. Presumably, this 

second factor would be more important on the 

bog edge than on the midslope site because of 

lower stem and root temperatures imposed by dry 

season cold air drainage. 

The difference in seasonality between the leeward and the windward slopes might have been 

the result of (1) greater adult density on the 

leeward slope, leading to greater dry season competition for water (199 adults per 100 m2 on the 

leeward slope versus 122 on the midslope windward site); (2) higher dry season mean maximum 

temperature on the leeward slope, possibly resulting in greater dry season evapotranspiration; (3) 

slightly lower dry season soil moisture levels on 

the leeward slope. 

There was a significant positive correlation 

between seasonality and distance to nearest adult 

neighbor on the midslope leeward site (Table 10). 

With increasing distance between an adult plant 

and its nearest adult neighbor, growth became 

progressively less seasonal. This suggests that 

some form of intraspecific interference may be 

controlling seasonality at this site. 

There was a significant negative correlation 

between seasonality and distance to nearest 

neighbor on the midslope windward side. Thus, 

growth becomes progressively more seasonal with 

increasing distance between an adult plant and 

its nearest adult neighbor. There is probably a 

sheltering effect on one plant by another on the 

gently sloping windward site, reducing wind-induced drought stress. This would be most important for short plants located on the leeward sides 

of taller plants. On steeper windward sites, such 

as the ridge plot, an adult located on the windward (downslope) side of a second plant might 

provide little or no shelter, even if taller than the 

second plant. 

Further studies will be required to determine 

the causes of these patterns in seasonality. However, the data do suggest that there is strong 

intraspecific control over seasonality within local 

populations and that the nature of this control 

changes qualitatively with change of topography. 

Interspecif2c Comparisons: Growth in E. lutescens 

was more seasonal than growth in the adjacent 

E. schultzii population (Table 8). Espeletia schultzii 

at 4200 m was restricted to shallow swales that 

received runoff from the surrounding paramo 

during the wet season. The E. schulttii population 

studied was on ground 1 to 3 dm lower than the 

adjacent E. lutescens population. Soil moisture, 

measured on 26 Mar 1973, at 0-10 cm was 20% 

for the E. schulttii plot versus 16% for the E. 

lutescens plot. Percentage moisture content under 

15 atmospheres pressure (laboratory determina- 
NUMBER 48 25 

TABLE 10.-Correlations of nearest neighbor distance with adult leaf production (g/week) and 

with seasonality of leaf production 

Species 

and sites 

Glweek versus nearest neighbor 

Seasonalip cersus 

Dry season Wet season nearest neighbor 

TXY rxr TXY 

E. schultrii 

3000 m 

3600 m Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 m 

E. lutescens 

4200 m 

E. humbertii 

3500 m 

0.49 1 PCO.00 1 0.272 PCO.1 0.214 PCO.05 

0.268 PCO.l 0.145 -0.036 

-0.222 -0.100 -0.278 PCO.05 

-0.219 -0.259 -0.108 

-0.04 1 0.163 -0.174 

-0.117 -0.168 0.384 PCO.01 

-0.209 

0.171 

-0.126 0.31 1 

0.182 0.057 

tion) was 14% for the E. schulttii plot and 11% for 

the E. lutescens plot. Vegetation cover was slightly 

lower on the E. schultzii plot (2928.6% versus 

38+8.1%), and percentage cover by bare rock was 

higher (5528.7% versus 3829.1%). 

Height growth in E. floccosa at 3600 m was 

faster than in any other species studied. This 

species generally grows on rocky, windward 

slopes-sites where both vegetation cover and 

density of E. schulttii are generally lowest. Fast 

growth, occupation of apparently unfavorable 

sites, short generation time, and semelparous reproduction are characters often attributed to “rselected” species (Gadgil and Solbrig, 1972). 

The growth rates for E. humbertii (Table 8) were 

much lower than for other species because rate of 

leaf expansion was recorded for a single leaf 

rosette, rather than for the entire crown. With the 

exception of unbranched saplings, crowns were 

made up of many leaf rosettes located on branch 

apices. Number of rosettes per tree ranged from 

1 to 46, with a mean of 10k2.4. There was no 

significant correlation between the total number 

of rosettes making up a given tree crown and the 

growth rate measured for one of these rosettes. 

Overall growth rate for a given tree will therefore 

be proportional to the number of rosettes making 

up the crown. 

Growth was highly seasonal in E. humbertii (Table 8). The leaves on several trees growing on a 

rock outcrop at Laguna Negra showed signs of 

wilting toward the end of the dry season. Crosssections of E. humbertii trunks showed distinct 

growth rings, providing further evidence of seasonal growth. 

For E. humbertii no significant correlations were 

found between growth rate and distance to nearest neighbor or between seasonality and distance 

to nearest neighbor (Table 10). However, there 

were significant positive correlations between 

nearest neighbor distance and plant size (Table 

1 I), suggesting that interference of some sort has 

occurred in the past. There was a weak positive 

correlation between basal stem diameter and 

nearest neighbor distance for the 50 trees used for 

growth studies. These plants were scattered 

throughout the talus population, from the bottom 

to the top of the slope (a distance of about 30 m). 

For the plants occurring in plot 1, near the base 

of the slope, there was no correlation. For the 

plants occurring in plot 2, near the top of the 

slope, there was a strong positive correlation. 

In both the closed forest plot and the treefall 

site, there were positive correlations between 

plant size and nearest neighbor distance. The 

seedlings in the treefall produced dense cover 

several dm above ground level. Both sites therefore had essentially closed canopies. Competition 

for light as well as for water and nutrients could 

have enforced the observed spacing patterns at 

these sites. 
26 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 1 1.-Correlation of distance to nearest conspecific 

adult with adult plant height 

Species 

and sites 

E. schultrii 

3000 m 

3600 m 

Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 m 

E. Joccosa 

3600 m 

E. lutescms 

4200 m 

E. humbertii* 

Talus plot 1 

Talus plot 2 

50 growth-study 

plants 

Closed forest 

Forest treefall 

Mean Height us. 

distance nearest 

to nearest neighbor 

neighbor distance 

(cm ) (TXY) 

7.2k 2.5 

18.32 3.5 

25.92 1.8 

15.4k 3.1 

9.4k 1.5 

24.52 5.1 

12.0k 3.1 

22.12 4.0 

108.1k18.8 

98.6222.1 

91.5k16.4 

62. 12 10.9 

18.92 1.8 

TABLE 12.-Time required for complete replacement of 

rosette leaves (turnover time) (leaf expansion rates not measured in E. flOccosa) 

Species 

and sites 

0.104 

0.055 

0.146 

0.280 P<O.O1 

0.078 

-0.103 

-0.103 

0.04 1 

E. schultrii 

3000 m 

3600 m 

Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 m 

E. lutescens 

4200 m 

E. humbertii‘ 

3500 m 

0.262 

0.515 PCO.01 

0.248 PCO.1 

0.416 PCO.01 

0.190 PCO.01 

* With exception of treefall plot, all E. humbertii analyses 

carried out for basal stem diameters, rather than height. 

Plant heights used for treefall plot. 

ROSETTE TURNOVER TrME.-short-term measurements of leaf expansion were used to estimate 

total number of leaves expanded in one year 

(Table 8). Wet season, dry season, and transitional periods were each assumed to make up 

one-third of the year. For each plant, the number 

of rosette leaves present during the wet season of 

1973 was then divided by the estimated number 

of leaves expanded during the year, to provide an 

estimate of the time required to renew an entire 

complement of rosette leaves. 

For E. schultzii, turnover time increased with 

increasing elevation because leaf production rates 

decreased (Table 12). Slow rate of leaf replacement might in part explain the upper elevational 

limit of E. schultrii: above 4200 m leaf damage 

and senescence might occur more rapidly than 

leaf growth. At 4200 m, turnover time was greater 

for E. lutescens than for E. schultzii. This was due 

Mean Leaves/ 

Number number of rosette 

leaves/ leaves/ Leaves/ 

year rosette’ year 

125 70.5k 4.80 0.56 

119 74.62 6.60 0.63 

96 68.0k16.10 0.71 

88 66.3k 5.40 0.75 

81 58.92 4.90 0.74 

72 77.92 6.10 1.08 

64 95.52 7.90 1.49 

10 13.42 0.93 1.34 

’ Per leaf rosette, not per tree. 

Mid-wet season, 1973. 

in part to a slower rate of leaf expansion in E. 

lutescens, but also resulted from a larger number 

of leaves per rosette. Long turnover time for the 

E. humbertii population on talus was due to the 

low rate of leaf expansion. This slow expansion 

rate might have resulted in part from the large 

energy input required for maintenance and 

growth of an arborescent support system. 

MORTALITY.-Data on adult mortality during 

one year were based on death of marked plants 

at each study site (Figures 14-16; also see “EXperimental Study of Growth”). Mortality rates 

were very low. Many qualitative observations on 

adult mortality were made and these provide 

information on seasonal, altitudinal, and topographic patterns. 

Flooding: For E. schultzii, high wet season mortality was observed in several swales at 3000 m 

and 3600 m. These swales were apparently subject to flooding only during periods of extremely 

intense rainfall. Rainfall during the month of 

May 1972 was the highest recorded for this month 

during 30 years of measurements (Figure 5). The 

preceding dry season also had unusually heavy 

rainfall. In May 1972, at both 3000 m and 3600 

m, a number of swales had standing water for 
NUMBER 48 27 

several days. Flooding recurred periodically during June. These swales had populations of E. 

schultzii with adults up to 40 or 50 cm tall. In late 

May and early June, these plants began to wilt. 

In one typical swale at 3600 m (Figure 18), all 

seedlings and adults had died by the end of the 

wet season. These plants had evidently become 

established in the swales during a long period of 

more moderate rainfall. High dry season rainfall 

then resulted in extensive soil flooding, killing the 

plants. 

Local distribution patterns of E. schultzii along 

certain moisture gradients apparently undergo 

long-term fluctuations-gradual expansion into 

swales during drier periods and rapid contraction 

during extreme wet periods. This pattern would 

be well developed in those few swales that, because of topography, receive heavy flooding only 

during extreme wet years. For most swale-upland 

ecotones, annual flooding presumably eliminates 

any seedlings that germinate in the swale. 

No wet season mortality was observed in E. 

schultzii at 4200 m. At this elevation, E. schultzii 

populations were largely restricted to drainage 

areas that often had running water during heavy 

wet season rains. However, the soil in these areas 

was extremely rocky so that drainage might be 

sufficient to prevent flooding of roots. At this site, 

populations of E. schultzii did not occur in swales 

that retained standing water. 

Drought and Temperature Stress: At 3600 m, dry 

season mortality was common in three habitats: 

(1) xeric slopes; (2) valley floors and other frost 

pocket sites; and (3) edges of bogs and wet 

meadows, with or without cold-air drainage. 

Extensive dry-season mortality in E. schultzii 

occurred on a steep, S-facing slope located on a 

terminal moraine above Laguna Mucubaji (Figure 16A). Soil moisture measured on 26 February 

1973 at 0-15 cm was 5.8%. Wilting percentage 

(percent moisture content under - 15 atmospheres pressure) was 10.6%. This was the only 

site studied for which soil moisture dropped below 

the wilting range. On the same date, soil moisture 

for the midslope windward plot at 3600 m was 

20.6%. Wilting percentage for this site was 18.0%. 

There was a positive linear correlation between 

height class and mortality rate (r = 0.977, 

P<0.05). No other population showed a significant correlation between adult size and mortality 

rate. Mean nearest neighbor distance for survivors 

was not significantly different from that for mortalities. It appears that adult mortality at this site 

is comparatively low during moderate dry seasons, permitting survival of older, taller individuals. During occasional severe droughts, however, 

these taller plants may be more susceptible to 

drought stress than shorter adults both because 

of greater wind exposure and because of greater 

stem resistence to water transport (cf. Zimmerman and Brown, 197 1). Espeletia stems may store 

water (Smith, 1979) but very severe droughts may 

deplete this, eliminating this beneficial aspect of 

greater stem height. 

Mortality was common among E. schultzii 

adults on the floor of a large morainal valley at 

3600 m. This area received extensive cold-air 

drainage. 

Extensive E. schultzii mortality was commonly 

observed on the edges of sloping wet meadows. 

These sites are not frost pockets. The meadow 

edges were flooded during the intense rainfall of 

May 1972. It is hypothesized that this flooding, 

though less extensive than in swales and not 

sufficient to cause immediate death, was sufficient 

to cause some initially nonlethal root die-back. 

Reduced efficiency of water uptake might then 

have caused mortality. 

Fire: Paramo fires can cause adult mortality in 

the dry season. One such fire was observed at 

3200 m (Laguna Victoria). The burned site was 

on a gentle NE-facing slope. Of 137 adult E. 

schultzii plants in a 10 X 10 m sample plot, 55% 

had been killed by the fire. Damage appeared to 

have taken two forms. For plants 1-2 dm tall, the 

apical meristem seemed to have been burned. In 

taller plants, mortality occurred if the dead leaves 

retained around the stem had been burned off 

and the stem itself had been burned. 

Herbivory: Insect damage to leaves was extensive 

in E. schultzii at 3000 m and below, but was much 

less common at 3600 m and 4200 m during 1972- 
28 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

1973 (Table 13). Longer-term data suggest that 

elevational trends are extremely variable from 

year to year (Smith, ms. in prep.). Insect larvae 

(unidentified) burrowed in the apical bud. Mature click beetles (Elateridae) were observed feeding on bud leaves, on some plants. They consumed all leaf tissue except the midvein. No 

insects were observed feeding on mature leaves. 

Insect damage could not be linked directly to 

mortality, but it is possible that the larvae may 

occasionally burrow through the apical meristem, 

causing death. Reduced photosynthetic area due 

to predation could reduce competitive ability and 

fruit production. 

Leaf herbivory was more common in the E. 

lutescens population than in the adjacent E. schulttiz population at 4200 m. No mortality was 

recorded for the research plants of E. lutescens that 

had been subject to predation. However, there 

was an area that appeared to have been the site 

of extensive insect-related mortality approximately 200 m upslope from the E. lutescens study 

plot. The area was approximately one hectare in 

size. Near the center of the area there were many 

fallen dead stems of E. lutescens and no live adults. 

Further out from the center there were E. lutescens 

plants that appeared to have died more recently; 

they were still standing. Toward the edge of the 

area were many E. lutescens plants in which a 

large portion of the rosette leaves had been eliminated, apparently through larval herbivory. The 

apical buds of many of these plants were inspected and all had insect larvae burrowing in 

them. Beyond these heavily attacked plants, E. 

lutescens plants with moderate levels of herbivory 

were found. This pattern suggests that a longterm buildup of insects may be resulting in a very 

local elimination of E. lutescens over an area of 

several hundred meters. Reduced seed production, combined with naturally low probability of 

seedling establishment at this elevation, will make 

reestablishment of the population a slow process. 

Leafhoppers (Homoptera) attacked the mature 

and immature leaves of E. atropurpurea, E. humbertii, and E. neriifolia. Every plant inspected had at 

least a few damaged leaves. These three species 

lack pubescence on their upper leaf surfaces. Levin (1973) has suggested that, in many plants, leaf 

pubescence may provide protection against leaf 

herbivory. However, other factors such as toxin 

production and nutrient levels could also be involved. 

Semelparity: The only clear-cut mortality pattern noted for E.floccosa adults was that associated 

with flowering. If plants live to reproduce, death 

occurs immediately after fruiting. Flowering occurs in the early to mid wet season, so adult 

mortality is also concentrated in this period. Several hundred dead plants with flower stalks were 

observed at Mucubaji. None of these showed 

TABLE 13.-Number of adult plants in study plots that had insect-damaged leaves 

Species 

and sites 

Number of plants 

damaged in 1973 

that were also 

Wet season 1972 Wet season 1973 damaged in 1972 Total 

Plants Percent Plants Percent Plants Percent Plants Percent 

E. schultzii 

3000 m 

3600 m 

Slope base 

Windward 

Ridge 

Leeward 

4200 m 

E. lutescens 

E. floccosa 

103 86 

2 2 

11 9 

1 1 

16 13 

7 6 

30 25 

9 8 

105 

12 

16 

8 

30 

0 

29 

13 

90 

10 

14 

7 

25 

0 

27 

11 

96 

1 

2 

0 

6 

0 

17 

5 

83 

1 

2 

0 

5 

0 

16 

4 

112 

13 

25 

9 

40 

7 

42 

17 

93 

11 

21 

8 

33 

6 

35 

12 
NUMBER 48 

evidence of resprouting. No live adults with 

flower stalks were observed. 

Effects of Man: Harvesting of Espeletia plants for 

medicinal and other uses may have a significant 

impact on some species. Espeletia weddellii, an 

acaulescent herbaceous species, is collected for 

use as a cure for respiratory diseases (Faustino 

Diaz, pers. comm., June 1973). This species is 

never abundant, so that such collecting could 

cause local extinction. Its present scarcity might 

be the result. in part, from past collecting. Roots 

of E. schultzzi are reportedly used in the manufacture of local butter and E. schultziz leaves are 

used to package the butter. 

The branches of E. humbertii and E. neriifolia are 

collected and the resin extracted for use as incense 

in churches. Cutting of subalpine forests is rapidly 

reducing population size in these arborescent species. 

Intense agriculture in the main valley of the 

Rio Chama, between Mucuchies and Mucubaji, 

has resulted in almost complete elimination of 

Espeletia (both arborescent and rosette species) 

below 3400 m, although Espeletia does occur in 

less heavily used side valleys. 

REPRODUCTIVE PHExoLocY.-For each species, 

the number of individuals in each plot that flowered during the field research period was recorded. A more detailed study of reproductive 

biology was carried out for E. schultziz at 3600 m. 

Flower and fruit production were recorded 

monthly for 100 E. schultzii plants on the floor of 

a sheltered morainal valley and for 100 plants on 

a windy ridge 140 m above the valley floor. The 

plants studied were the first reproductive adults 

(adults in flower or which had flowered in the 

past) encountered along a line transect at each 

site. In addition, flowering of E. schultzii was 

recorded on a series of seven low ridges at 3600 

m. The ridges had NE-facing (windward) and 

SW-facing (leeward) slopes, with relief of 3 to 5 

m. For each ridge, one line transect was run across 

the SW-facing slope and a second along the adjacent NE-facing slope. The transects were located 2 m below the ridge crests. Presence or 

absence of flower buds, flowers, and fruit 

29 

(achenes) was recorded for the first 100 reproductive adults along each transect. The 14 transects 

were run in October 1972 and were resurveyed in 

November 1972. 

A comparison of flowering on the windward 

and leeward sides of E. schultzii plants was made 

at Mucubaji (3600 m). The research site was on 

the crest of a terminal moraine immediately west 

of Laguna Mucubaji. This site received the full 

force of the prevailing NE winds. The number of 

flower stalks, and flower stalk length, was recorded for the NE-facing (windward) and SWfacing (leeward) halv s of each rosett

plants were studied. All plants had completed 

flowering and had set fruit. 

Flower and fruiting heads were collected from 

50 E. schultzii plants at 3000, 3600, and 4200 m. 

The fruiting heads w ere collected just before fruit 

dispersal began and were taken from the same 

plants from which flower heads were obtained. 

Fruiting heads generally remained tightly closed 

until just before the fruit were dispersed. Number 

of ray (male) and disc (female) flowers were 

recorded for the flower heads. Number of achenes 

and number of insect larvae were recorded for 

each fruiting head. 

Mature fruit were collected from 50 plants at 

the same three sites. Fruit size and weight per 

whole fruit were recorded. Fruit were cut open to 

determine the proportion of apparently normal 

fruit that were hollow. 

A detailed study of pollen flow and seed dispersal was made, and will be reported elsewhere 

(Teeri and Smith, unpublished data). 

Eleuational Comparisons of Flowering Phenology in 

E. schultzii: At 3000 m and 3600 m, flowering 

was concentrated in the wet season and the wet 

season-dry season transition period (Table 14). 

Fruit production and dispersal at these sites began 

during the wet season and continued throughout 

the dry season and into the next wet season. 

However, most fruit had already been dispersed 

by the beginning of the next wet season. Germination at all sites generally began with the onset 

of the wet season rains. 

At 4200 m, E. schultzii produced flowers and 
30 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

E. schultzii 

3000 m 

3600 m 

Slope base 

Ridge 

Midslope leeward 

Midslope windward 

4200 m 

E. lutescens 

4200 m 

E. floccosa 

3600 m 

E. humbertii 

3500 ma 

TABLE 14.-Number of plants that flowered within each 100 m' study plot (figures in 

parentheses = number of flowering plants as percentage of all adults in plots) 

10 (9.7) 29 (28.2) 0 9 (9.1) 

5 (5.2) 4 (4.2) 0 11 (11.7) 

13 (11.2)' 0 0 5 (4.4) 

26 (21.7) 0 0 7 (3.5)d 

0 7 (8.1) 0 0 

0 0 0 0 

12 (9.8) 0 0 5 (4.1) 

3 (3.8) 19 (23.8) 10 (12.5) 29 (36.3) 

Not recorded 21 (42.0) 0 10 (20.0) 

Species 

and sites 

Plants Plants Plants Plants with 

in 1972 flowering flowering jlowers or buds 

with 1971 in 1972 in 1972-73 by mid-wet season seedheads wet season dry season I 973b 

fruit throughout the year. Here E. schufttii populations were generally restricted to rocky drainage 

areas that received runoff from the surrounding 

areas. This aseasonality in flowering was associated with aseasonality of growth as well (Table 

8). Possible explanations for this lack of seasonality were discussed in an earlier section. 

At 4200 m, flower heads produced during the 

dry season frequently were killed by frost during 

clear cold nights. Generally, only expanded flower 

heads were killed; flower buds were seldom damaged. At 3600 m (Mucubaji) frost damage to 

flower heads was observed occasionally in the few 

plants producing flowers in late December 1972, 

at the end of the flowering season. Such damage 

was observed again for the few plants coming 

into flower in April and May 1973, at the beginning of the 1973 flowering season. The damage 

occurred during several periods of unusually low 

rainfall, when clear cold nights were more common. It was most pronounced on the floor of a 

large morainal valley (see Smith, 1980). 

No population of E. schultzii was found in 

which all reproductive adults were in flower during a given wet season. Some plants flowered 

during both wet seasons (1972 and 1973), but 

many other plants flowered in only one. Many 

plants that had flowered during past years did 

not flower during the period of this study. 

Topographic Comparison of Flowering Phenology in 

E. schultzii at 3600 m: Flowering occurred first on 

leeward slopes and valley floors and last on exposed ridges and windward slopes. The proportion of all reproductive adults that flowered at 

any given time also decreased from leeward to 

windward slopes and from valley floors to ridge 

tops (Figure 19). Plants that did flower on ridge 

tops produced fewer flower heads than plants on 

the valley floor (Table 15). 

Table 16 summarizes data on flowering on a 

series of NE-facing (windward) and SW-facing 

(leeward) slopes. On 1 October 1972, 31 plants 

on the SW-facing slopes were in fruit (24.2% of 

all plants that flowered during the year), whereas 

only one plant (4.9% of all plants which flowered 

during the year) had come into fruit on the NE- 
NUMBER 48 31 

MM 

200 

60. 

............................................... ...... * ........................ *** .,........ 40. 

% 

1972 

FIGURE 19.-Top: Monthly precipitation at Mucubaji (3550 m). Bottom: Flower and fruit 

production in E. schultzii at 3600 m (A = percent of plants in flower on valley floor; B = 

percent of plants in fruit on valley floor; C = percent of plants in flower, windy ridge, 140 m 

above valley floor). 

TABLE 15.-Mean number of flower heads per flowering 

plant for E. schultzii, recorded at five sites within a morainal 

valley at 3600 m (relief was 140 m) 

Site 

East moraine 

Ridge top 

Midslope leeward 

Valley floor 

West moraine 

Midslope windward 

Ridee toD 

Number of 

jlower head3 

43.6f10.48 

88.2f19.74 

169.9k33.03 

45.9f 8.95 

39.8k 14.60 

TABLE 16.-Flowering on NE-facing (windward) and SWfacing (leeward) slopes at 3600 m (figures = number of 

flowering or fruiting plants per 100 adults sampled at each 

of seven sites; each figure = mean of seven sites) 

Sites and 

stages I 1 Oct 1972 18 Nov 1972 

NE-facing slopes 

Flower buds only 

In flower 

Seed heads only 

Flower buds only 

In flower 

Seed heads only 

SW-facing slopes 

l.Of0.69 0 

1.6k0.48 0.4f0.79 

0.1f0.14 3.6f 1.43 

3.3k0.81 0 

10.7f 1.91 1.7f0.68 

4.4f1.19 17.3f2.12 

facing slope. Of 700 plants monitored on the NEfacing slope, only 17 flowered in 1972 versus 128 

on the SW-facing slopes. Environmental differences between windward (NE-facing) and leeward (NW-facing) slopes are discussed elsewhere 

(Figure 6, 7). 

Within-Plant Eflects of Wind in E. schultzii at 

3600 m: The mean number of windward flower 

stalks was 1.6fO.4; the mean number of leeward 

flower stalks was 3.3f0.5. These means are significantly different (PC0.005). The windward 

stalks were shorter than the leeward stalks 

(70.9k1.3 cm versus 82.3k1.4, cm). Shorter stalks 

on the windward sides of plants might have resulted from greater mechanical stimulation by 

wind, resulting in inhibition of elongation (Jaffe, 

1980). Flower bud initiation, however, takes place 

inside the apical bud. The windward side of each 

plant was presumably cooler than the leeward, or 

suffered more drought stress, perhaps resulting in 

differential rates of flower bud formation. 

Interspecijic Comparisons of Flowering Phenology: 

The E. lutescens population at 4200 m flowered in 

the late wet season and wet season-dry season 

transition period of 1972, but did not flower in 

1973. No recent E. lutescens flower stalks were 

found in the early wet season of 1972, suggesting 
32 

that flowering probably did not occur during 

1971. Flowering occurred again during 1975; no 

flowering occurred in 1976 or 1977. These observations suggest that E. lutescens flowering occurs 

less than once a year, but that it may occur 

synchron!>usly within the population. 

No flowering occurred in the E. Joccosa plot 

during 1972- 1973, although widely scattered individuals did flower in several populations at 

3600 m during the wet season. Extensive flowering occurred in all populations observed in 1975. 

Only very scattered flowering occurred in 1976 

and 1977. All plants that flowered died after fruit 

maturation. 

Flowering in E. humbertii populations at 3600 

m was concentrated in the wet season. Flowering 

occurred in 1972 and 1973. In the early wet 

season of 1972, stalks with fruit were still present, 

suggesting that flowering also occurred in 1971. 

During any given flowering period only a portion 

of all reproductive-age plants actually produced 

flowers. 

Fruit Size: Data on flower and fruit production 

in E. schultzii, E. floccosa, and E. humbertii are 

summarized in Table 17. The most consistent 

trend was an increase in E. schultzii fruit weight 

with increased elevation. Larger fruit contain 

either more endosperm or larger embryos. The 

thickness of the achene wall did not appear to 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

vary with elevation. Larger fruit could produce 

more vigorous, rapidly growing, seedlings. At 

4200 m this would increase the probability of 

seedling establishment during periods of low soil 

frost activity. It would also facilitate seedling 

growth in a rocky substrate or in dense mats of 

vegetation-habitats conferring protection from 

frost heaving. 

Size-spec$c Reproduction: Number of flower 

stalks was recorded for 121 reproductive E. schultzii plants of known size on a valley floor site at 

3600 m (Mucubaji). Number of stalks (y) was 

linearly correlated with plant height (x) (y = 3.94 

+ 0.13 x, r = 0.34, P<O.Ol). 

Number of flower heads was recorded for 73 

reproductive E. froccosa plants on a windward 

slope at 3600 m (Mucubaji). Rosette height was 

measured shortly before flowering began. Number of flower heads (y) was linearly correlated 

with plant height (x) (y = 7.54 X - 105.8, r = 

0.59, PC0.05). 

Hybridization: Putative hybrids between E. schultzii and E. weddellii (an acaulescent herbaceous 

species) were common wherever the two species 

occurred together in large numbers. Both species 

are insect-pollinated and have conspicuous yellow 

influorescences. 

A putative hybrid between E. schultzii and E. 

humbertii was found at 3500 m, on the edge of a 

TABLE 17.-Flower and seed production 

Species 

and sites 

E. schultzii 

3000 m 

3600 

4200 m 

E. floccosa 

E. humbertii 

Number 

disc 

(male) 

flowers 

per head 

Number 

ray Cfemale) Number 

flowers fruits 

per head per head' 

Percent 

hollow 

fmit2 

101f7.7 

102k6.7 

92f6.3 

- 

- 

82f2.8 75k4.6 

83k4.6 71k4.3 

87k4.4 86k4.2 

- 32k3.5 

- 16k1.4 

32 

32 

67 

- 

- 

Percent 

fruiting 

heads 

with 

insect 

larvae 

36 

58 

12 

100 

48 

Number 

flower 

heads per 

plant3 

104k3 1.7 

(see Table 15) 

74k 4.3 

656k105.3 

Dry weight 

Dry weight (s) Per 

per fruit flower 

(mg) stalk 

0.3f0.02 23.2f1.19 

0.4+0.034 16.9f0.67 

0.8-+0.05 19.4f0.93 

1.2f0.08 28.4k5.00 

l.5-+0.10 35.6k4.91 

Number of fruit that appeared undamaged. 

Percent based on number of seeds that appeared undamaged. 

Number of heads per plant produced during the entire year. 

The difference between mean seed weights for E. schultzii at 3000 m and 3600 m is weakly significant (PCO. 1); differenc 

between 3600 m and 4200 m means is highly significant (P<O.OOl). 
NUMBER 48 33 

talus slope near Laguna Negra. The hybrid was 

completely intermediate in leaf shape, leaf pubescence, apical bud structure, stem form, and 

flower stalk form. The flower stalks were old and 

badly weathered, with no flower or seed heads 

remaining. The putative hybrid plant was located 

on the edge of an E. humbertii population where 

E. humbertii plants were intermixed with E. schultzii plants. Inflorescences in E. humbertii are yellowish-white and smaller than those of E. schultzii, 

but both are insect-pollinated. 

The occurrence of apparent hybrids between 

arborescent and caulescent rosette species and 

between caulescent and acaulescent species suggests that, despite great differences in growth 

form, the species are closely related. Barrett Rock 

(pers. comm., May 1972) found that there are no 

fundamental differences between arborescent, 

caulescent rosette, and acaulescent rosette Espeletia species with respect to the anatomy of the 

stem. He found that the anatomy of acaulescent 

rosette species such as E. weddellii closely resembles that of seedlings in the caulescent rosette and 

arborescent species. 

EFFECTS OF SLOPE ASPECT ON GROWTH AND 

POPULATION DENSITY.-A special study was done 

to determine the effects of slope aspect on population density and adult growth rates in E. schultzii at 3550 m. The study was carried out in the 

lower exclosure, adjacent to Laguna Mucubaji. 

Leeward slopes at this site were far more sheltered 

from the prevailing NE winds than was the leeward slope studied at the upper exclosure. The 

lower exclosure thus provided a clearer demonstration of the effects of wind. 

The slopes were located on a series of small 

terminal moraines (Figure 2). Slope angles varied 

from 15' to 20". Relief varied from 10 to 20 m. 

Four NE-facing (windward) slopes were compared with the adjacent WNW-facing slope. A 

24-m transect was run along each slope, 2 m 

below the ridge crest. On the largest NE-SW 

slope system, with approximately 20 m of relief, 

two parallel transects located 2 m and 4 m below 

the crest were used. At 3 m intervals along each 

transect, the point-centered quarter method (Cottam, et al., 1953) was used to determine adult 

density. Transect data were converted to number 

of adults per hectare. 

Growth rates were measured for plants on a 

20" NE-facing slope and the adjacent 20' SWfacing slope at 3550 m. Fifty adults on each slope 

were marked with metal stakes and numbered 

aluminum tags. The plants were located from 4 

to 7 m below the ridge crest. In the dry season 

and again in the wet season the tips of the outermost bud leaves were marked with indelible 

ink. After several weeks the leaves that had expanded were counted. Dates for measurements 

are summarized in Appendix Tables C-E. 

Wind speeds were measured at each of the 

transect sites with a Deuta-Werke hand-held anemometer at 1.5 m above the ground. Readings 

were taken between 1500 and 1515 hours on 28 

July 1973. Each slope was visited twice and the 

readings averaged. These wind speed data are in 

agreement with those taken at the same sites on 

other days. 

More intensive studies were not carried out at 

this site because it was susceptible to vandalism 

by visitors. 

Adult Density: Data on E. schultzii adult density, 

along with data on wind speed for various slope 

types at 3550 m, are shown in Table 18. Mean 

adult density for the four NE-facing slopes was 

49.5% of that on the four adjacent SW-facing 

slopes. This suggests that the prevailing NE wind 

may create a less favorable environment for E. 

schultzii on windward slopes. 

Adult density on the ESE-facing slope was 

26.3% of that on the WNW-facing slope-a 

greater difference than between the NE- and SWTABLE 18.-Number of E. schultzii adults (per hectare) and 

wind speed (rnph) in relation to slope aspect 

Slope aspect I Adults Wind speed 

NE-facing 

SW-facing 

ESE-facing 

WNW-facing 

NE/SW X 100 

ESE/WNW X 100 

14,690 16.3 

29,680 4.1 

(49.5%) (397.6%) 

5,730 12.0 

2 1 .830 8.5 

(26.3%) (141.2%) 
34 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

Leaves per week 

Wet season 

Dry season 

Seasonali t v 

facing slopes. However, wind speed on the ESEfacing slope was only about 1.4 times that on the 

WNW-facing slope-a smaller difference than 

between the NE- and SW-facing slopes. One 

possible explanation for this apparent discrepancy is that the ESE-facing slope faces more 

directly into the rising sun than does the NEfacing slope. As suggested earlier, rapid heating 

of leaves when soil, roots, and stem are still near 

freezing could result in early morning drought 

stress (cf. Mayland, 1972). All the slopes studied 

had similar slope angles and all were located on 

the same system of terminal moraines. Thus, 

differences in slope angle and substrate probably 

were not involved. 

It was shown earlier that the proportion of 

adult plants flowering on NE-facing slopes was 

lower than on SW-facing slopes. It is thus possible 

that low population density on NE-facing slopes 

could result, at least in part, from lower seed 

input. No comparison of NE-facing and ESEfacing slopes were made with respect to flowering. 

Growth: Data on growth of E. schultzii plants on 

a NE-facing slope and the adjacent SW-facing 

slope are present in Table 19. Microclimatic data 

for these same slopes are given in Figures 6 and 

7. 

Growth was faster in the SW-facing slope 

plants and was also less seasonal. Because soil 

moisture was highest on the NE-facing slope 

(28.9% versus 16.2%, measured on 25 March 

1973), soil moisture was apparently not the cause 

of this effect. It is possible that more rapid heating 

2.7k0.15 3.8+0.23* 

1.8f0.15 2.9f0.25* 

68*5% 77+6% 

TABLE 19.--Growth rates (leaves per week) and seasonality 

(dry season growth as percentage of wet season growth) for 

E. schultzii adults on a windward (NE-facing) slope and 

adjacent leeward (SW-facing) slope at 3550 rn 

Windward Leeward 

slope slope Parameter 

* Mean for leeward slope significantly greater than mean 

for windward slope, PC0.05. 

of leaves might have caused some early morning 

drought stress in the NE-facing slope plants. 

However, this effect would probably not be a 

major factor in the wet season. Dew formation on 

E. schultzii leaves is greater in the wet season; in 

the mornings, it seldom evaporates completely 

before the sun is obscured by fog or clouds, 

making drought stress unlikely. Because growth 

differences between the slopes persisted in the wet 

season, it is probable that other factors, such as 

wind-induced leaf water stress and wind-cooling, 

may be acting. Tissue temperatures were lower 

on the NE-facing slope (Figure 7) perhaps resulting in lower metabolic rates. On the midslope 

windward plot at the topographic gradient, it was 

found that there was greater wilting of leaves on 

the windward halves of rosettes than on leeward 

sides. The effect was observed only in the dry 

season, however. 

Leaf width was measured for a single mature 

leaf from each of the 50 marked plants on each 

slope. Leaf width for the NE-facing slope plants 

was 3.2 cm versus 3.9 cm for the SW-facing slope 

plants. These means were significantly different 

(P< 0.001). Narrow leaves could be interpreted 

as a response to wind-related drought areas 

(Parkhurst and Loucks, 1972). No attempt was 

made to determine if this leaf width difference 

was genetically based. 

Comparisons of the upper and lower exclosures 

with respect to E. schultzii growth and population 

density suggest that small differences in aspect 

and topography can have major effects on these 

parameters. Population density in the upper exclosure was estimated using the 100 m2 plots as 

samples. Population density was 19,900 adults 

per hectare on the leeward slope and 12,200 on 

the windward slope. The windward-leeward ratio 

was 61% versus 50% on the lower exclosure. The 

upper exclosure is located on the crest of a large 

morainal system that may partially shelter the 

lower exclosure from the prevailing wind. 

Leaf expansion rates on the windward slopes 

in the upper exclosure were significantly greater 

than on the leeward slope (Table 8; PCO.01, 

according to the F test). This is the reverse of the 
NUMBER 48 

Plants 

Grarns/leaf’ 

Leaves/week 

Grams/week’ 

35 

12 10 8 

1.67 1.25 1.03 P<0.0l2 

3.15 3.32 2.79 Not tested 

5.28 4.12 2.68 P<0.052 

trend in the lower exclosure. The leeward slope 

in the upper exclosure was less sheltered from the 

prevailing wind than was the leeward slope in the 

lower exclosure. Greater exposure may have interacted with greater intraspecific competition 

caused by high adult density, resulting in reduced 

growth rates on the leeward slope. 

Although adult growth rates in the upper exclosure are higher on the windward slope, seedling recruitment rates and juvenile growth rates 

are higher on the leeward slope (Tables 3, 6; 

Figure 9). As pointed out earlier (Table 16), rates 

of seed production are lower on windward slopes. 

Annual juvenile mortality rates were similar on 

the two slopes (Table 6). Adult mortality rates 

after one year were too low to permit meaningful 

comparisons. These data suggest that control of 

population density at this site might occur largely 

in the seedling stage. 

Experimental Study of Growth 

Experimental and descriptive studies of Espeletia adults suggest that inter- and intraspecific 

competition for water may be a major factor 

controlling growth. However, these results do not 

eliminate the possibility that plants may also 

compete for nutrients. An experiment was designed to determine if lack of nutrients can limit 

growth in E. schultzii adults. Further studies will 

be required to determine if competition for nutrients is actually occurring. 

Thirty-two pairs of E. schultzii adults were selected at 3600 m. Fertilizer was applied to one of 

the members of each pair (500 g per m2, 10% N, 

10% Pz05 and 1510 Kz). Leaf expansion rate was 

recorded before and after application. Before application of fertilizer, no significant difference in 

leaf expansion was found. After application, leaf 

expansion in the experimental plants was slightly 

higher than in the control plants (P<O.l), suggesting the possibility that lack of mineral nutrients could limit growth. 

Comparisons of elevational populations of E. 

schultzii in the field indicated that growth rate 

varies with elevation (Table 8). However, these 

data do not permit discrimination between genetically controlled growth rate differences and 

differences imposed directly by elevational variation in environment. Plants were therefore 

grown in a controlled phytotron environment 

(17OC day, 11°C night; 16hr photoperiod) from 

seed collected at 2800 m, 3550 m, and 4100 m. 

After three years, growth rate (grams dry weight 

of leaves per plant per week) was measured over 

a 3-month period (Table 20). These rates are 

similar to those recorded for the windward slope 

populations at 3000 m, 3600 m, and 4200 m 

during the wet season (Table 8). This suggests 

that there are genetically based differences between the three populations with respect to plant 

growth rates. However, field rates for the dry 

season increased with increasing elevation. As 

suggested earlier (see “Studies of Adults: 

Growth”), dry season growth patterns may be 

controlled primarily by inter- and intraspecific 

competition, both of which decrease with increasing elevation (Smith, 1980). Experimental studies 

of population control will be presented elsewhere 

(Smith, 1980; ms. in prep.). 

Discussion 

RELATIONSHIP BETWEEN GROWTH FORM AND 

POPULATION DYNAMICS.-TWO aspects of growth 

form in Espeletia must be considered in the context 

of population dynamics: (1) the presence of both 

caulescent and acaulescent forms, and (2) the 

increase in plant height, both within and between 

TABLE 20.-Growth rates for phytotron-grown E. schulkii 

adults 

Seed source 

2800 m 3550 m 4/00 m 

Parameter 

Oven-dry weight. 

Mean for 3550 m significantly different from both mean 

for 2800 rn and for 4100 rn, according to F test and least 

significant range test (Sokal and Rohlf, 1969). 
36 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

species, with increasing elevation. Data on population dynamics provide information on the 

types of life histories that produce plants of characteristic size and shape, and also suggest possible 

explanations for the evolution of the life histories 

themselves. 

Major patterns in plant height are correlated 

primarily with generation time. Comparing E. 

schultzii populations on midslope windward sites 

at 3000 m, 3600 m, and 4200 m shows both 

maximum and mean adult height increased with 

increasing elevation. However, annual rate of 

height growth decreased from 3000 m to 3600 m, 

and did not change significantly from 3600 m to 

4200 m. Thus, increase in height with increasing 

altitude is apparently the result of greater life 

span. 

Mean height in the E. lutescens population at 

4200 m was twice that of the adjacent E. schultzii 

population. Annual rates of height growth were 

not significantly different in the two populations, 

suggesting much longer generation time in E. 

lutescens. 

Very long-term data on mortality and growth 

will be required to determine if these populations 

have reached stable age distributions. However, 

the presence of dead adults of all sizes in these 

populations suggests that they could be in equilibrium, such that the differences between them 

with respect to plant height will be maintained. 

The acaulescent habit in E. floccosa at 3600 m 

is associated with very short generation time. This 

species appears to reach age of first reproduction 

more quickly than any other species measured, 

and dies after flowering. In a second acaulescent 

species investigated, E. atropurpurea, a similar pattern was observed. In this species, however, new 

rosettes sprout from the old rosette base (see 

Baruch and Smith, 1979). 

The tallest Espeletia plants occur in arborescent 

species such as E. humbertii and E. nertiifolia. In E. 

humbertii, apparent generation time is probably 

comparable to that in E. lutescens at 4200 m. 

However, rate of shoot elongation is greater than 

for any other population studied. Size increase in 

E.floccosa rosettes, although similarly rapid, is due 

almost entirely to production of progressively 

longer leaves rather than to shoot elongation. 

Thus, in E. humbertii, rapid height growth interacts with long generation time to result in tall 

plants. Such a growth pattern might be expected 

in a forest environment where there is strong 

selection for the ability to compete for light. 

Selection for Iteroparity and Semelparity: If rates of 

seedling recruitment are low and/or unpredictable, a population must be composed of individuals that survive and reproduce over a long time 

period to guarantee production of successful offspring (Stearns, 1976; Schaffer, 1974). In the 

absence of such iteroparity, or delayed germination in a portion of the seed, the population 

would go extinct. 

Selection for increased iteroparity could have 

occurred in E. schultzii and E. lutescens at 4200 m. 

Seedling recruitment is lower for these two populations than for any other population studied, 

perhaps because of intense soil frost activity. Apparent generation times are greater than for any 

other paramo population studied. 

Three major growth patterns could be associated with iteroparity in rosette species of Espeletia: 

(1) production of lateral shoots followed by death 

of the parent rosette, as in E. atropurpurea; (2) 

continued growth of the original rosette, with or 

without production of lateral shoots, resulting in 

continued height growth; and (3) continued 

growth of the original rosette, but in a horizontal 

direction, resulting in a prostrate caulescent form. 

The rarity of the first and third patterns, and the 

dominance of the second among paramo species 

of Espeletia suggest that selection for iteroparity, 

if present, may have interacted with selection for 

height growth (cf. Smith, 1980). 

The two populations with shortest apparent 

generation times (E. schultzii at 3000 m and E. 

ji’occosa at 3600 m) both had high seedling recruitment rates. In both populations, juveniles growth 

rates increased and juvenile mortality rates decreased with increasing proximity to adults. This 

“nurse tree” effect could increase the probability 

that an E. schultzii adult that dies is replaced by 

its own progeny, and ought therefore to reduce 
NUMBER 48 37 

intensity of selection for great iteroparity (see 

Smith 1980). 

There might be little selection for continued 

resource allocation to vegetative growth in adults 

if, despite such input, adults generally die early. 

Under these conditions, there should be selection 

for greater allocation of resources to early reproduction. In an expanding population, reproductive value would be increased by such early reproduction (Gadgil and Solbrig, 1972; Schaffer, 

1974). Espeletia floccosa generally occurs on steep, 

rocky, windward slopes. The E. schultzii xeric 

slope population at 3600 m occupies a similar 

site. This is the only E. schultzii population studied 

in which adult mortality was positively correlated 

with size (and, thus, age) (Figure 16A). It also 

had a higher frequency of reproductive plants in 

the smallest size class than did other populations. 

Both trends are consistent with the hypothesis 

that on such sites selection can, at least periodically, favor semelparity and early reproduction. 

Selection for Vegetative Spread: Vegetative spread 

(vegetative “reproduction”) represents a form of 

iteroparity in that it maintains the parent genotype in the population, permitting repeated sexual reproduction. It permits population maintenance in the face of high and unpredictable 

juvenile mortality. Vegetatively spreading plants 

are most frequent in extreme environments where 

the probability of successful sexual reproduction 

is low (Billings and Mooney, 1968; cf. Janzen, 

1977; Cook, 1979; Harper, 1977). 

The occurrence of vegetative spread in E. atropurpurea at 3400 m may be related to this species’ 

great susceptibility to dry season stress. For glabrous-leaved E. atropurpurea plants, dry season 

growth rate (Kcal of leaf tissue per week) was 

only 3% of that in the wet season. Reduced 

growth was combined with severe stunting of dry 

season leaves. For pubescent-leaved E. schultzii 

plants growing in association with E. atropurpurea, 

mean dry season growth rate was 91% of the wet 

season rate and no leaf stunting occurred. Adult 

mortality rate was 5% for E. atropurpurea in the 

dry season. No adults died in the E. schultzii 

population. Data on seedling mortality were not 

collected. The relation between growth and leaf 

pubescence in these two species are discussed in 

more detail elsewhere (Baruch and Smith, 1979). 

These data suggest that the paramo dry season is, 

in effect, more extreme for E. atropurpurea than for 

adjacent plants of E. schultzii. It is possible that 

vegetative spread might represent an evolutionary response to such stress. 

Death of the parent rosette after first flowering-the immediate cause of the acaulescent 

habit in E. atropurpurea-might be selected for if 

it improved survival, growth, and reproduc’tion 

by daughter rosettes. Such mortality might 

release daughter rosettes from apical dominance 

effects of the parent, or might reduce within-clone 

competition. In either case, death of the parent 

rosette would probably increase the reproductive 

value of the clone by (1) increasing the rate of 

vegetative reproduction, and (2) increasing the 

rate of sexual reproduction by reducing time to 

first reproduction in daughter rosettes. 

In this discussion, it has been suggested that 

variation in plant height in Espeletia is due primarily to variation in generation time, the one 

partial exception being E. humbertii, where generation time interacts with rapid height growth 

to produce tall plants. It has also been hypothesized that variation in generation time could be 

explained, in part, by selection for particular life 

history strategies: semelparity, iteroparity, and 

vegetative spread. However, it is possible that 

there has been direct selection for particular 

height growth patterns. That is, at high elevation, 

selection may favor plants capable of growing 

tall; elevation differences in longevity would then 

be an incidental consequence of this selection. 

Finally, it may be that height patterns, particularly intraspecific patterns in E. schultzii, do not 

result directly from elevational differences in selection pressure. Rather, greater adult survivorship at high elevations may result directly from 

less competition or less herbivory. These possibilities are considered in Smith (1980). 

Selection for Growth Fom: The climatic extremes 

of the dry season have a major influence on 

demographic patterns in Espeletia. Juvenile and 
3% SMITHSONIAN CONTRIBUTIONS TO BOTANY 

adult growth is reduced and mortality is increased 

in the dry season. Flowering is generally restricted 

to the wet season; plants that do flower in the dry 

season (primarily E. schultzii at 4200 m) frequently suffer extensive frost damage to flowers. 

If an individual plant possesses adaptations to 

these dry season stresses, such that it matures 

faster, has a lower probability of mortality, and/ 

or has a higher rate of reproduction than other 

members of the population, then, all other factors 

being equal, this individual will contribute more 

progeny to subsequent generations than will others lacking the adaptations. Population growth 

rate will increase and probability of extinction 

will decrease as the proportion of individuals 

possessing such adaptations increases. 

It was hypothesized that the caulescent rosette 

form represents such an adaptation to climatic 

stress. Field studies (Smith, 1974a, 1974b, 1979; 

Baruch and Smith, 1979) demonstrate that apical 

bud structure, leaf pubescence, rosette geometry, 

nyctinastic movement of rosette leaves, stem 

height, and retention of dead leaves on the stem 

all confer protection from the climatic extremes 

of the paramo dry season. 

scriptive data given here, and experimental data 

(Smith, 1980; ms. in prep.), suggest that a wide 

range of environmental stresses acting on E. schultrii populations at worst cause only temporary 

reductions in density. This is due primarily to 

density-dependent control of growth, reproduction, and mortality. In this respect, E. schultzii 

populations are highly stable. For example, extreme reduction in juvenile density without concommitant reduction in adult density might result from extensive frost and pest damage to 

flowers and seed, or from high seedling mortality 

caused by drought or temperature stress. Reduction in juvenile density will increase adult growth 

rate, and may increase adult survivorship. Number of seeds produced per plant is positively correlated with plant size. Seed production will 

therefore increase, increasing the potential for 

seedling recruitment. However, because average 

adult size and adult biomass per unit area are 

POPULATION CONTROL AND STABILITY.-Denow greater than they were before the reduction 

in juvenile density, actual recruitment may remain low until adult mortality occurs. A form of 

feedback inhibition may operate: high juvenile 

density will cause a reduction in seed production 

by adults, followed by reduced recruitment of 

new seedlings, and a gradual decrease in juvenile 

density. 

Similar feedback responses result if adult mortality is increased by predation, interspecific competition, or physical stress without concommitant 

increase in juvenile mortality. Reduction in adult 

density increases juvenile growth, speeding rate 

of replacement of dead adults, and also increases 

growth and seed production in remaining adults, 

speeding recruitment into smallest juvenile size 

classes. 

A decrease in density is likely to persist only if 

all adults and all or most juveniles are killed over 

a large area, perhaps by intense fire or prolonged 

intense insect damage. Seed dispersal over more 

than 3 m to 4 m is rare, because the seeds lack 

adaptations for wind and animal dispersal. Reinvasion would therefore be slow. In the absence 

of abundant cover by Espeletia plants, cover by 

tussock grasses, shrubs, and other associated 

plants will increase. Greater interspecific competition will then further retard reinvasion of the 

site by Espeletia. However, death of all adults and 

all or most juveniles is probably a rare event. 

Morphological buffering against physical stresses, 

and strongly density-dependent population control apparently permit maintenance of dense populations of E. schultzii over a wide range of habitats. 

Summary 

The paramo climate is highly seasonal, with 

lower soil moisture, more intense insolation, 

colder night temperatures, and warmer daytime 

temperatures during the dry season than in the 

wet season. True mean monthly temperatures 

remain nearly constant all year. 

Flowering generally occurs in the wet season 

and wet season-dry season transition period. 
NUMBER 48 39 

Fruit dispersal begins in the wet season and continues throughout the dry season. Germination 

begins in the early wet season. Below 4200 m, 

seedling production is abundant; juveniles were 

common for E. schultzii, E. fzoccosa and, in treefall 

sites, for E. humbertii. Juveniles were uncommon 

at 4200 m, where diurnal needle ice formation 

may eliminate them. 

Juvenile mortality is highest in the dry season. 

For all species, the probability of juvenile mortality decreases as plant size increases. Adult Espeletia plants in some populations appear to shelter juveniles, thus reducing mortality. In other 

populations, mortality is greatest for juveniles in 

close proximity to adults. Insect predation was 

rare in juveniles. 

In some populations, mean yearly juvenile 

height growth was negative due to extensive dry 

season die-back. For E. schultzii at 3000 m and E. 

fzoccosa at 3600 m, growth was greatest for juveniles closest to adults of their own species. 

Growth of adult plants is highly seasonal at 

most sites. Seasonality of growth decreases from 

3000 m to 4200 m for E. schultzii. Intraspecific 

competition was documented on some sites and 

is most pronounced in the dry season. However, 

sheltering of one adult by another may also occur. 

Competition between E. schultzii adults and surrounding vegetation can greatly reduce growth in 

the dry season. Conspecific juveniles can also 

reduce adult growth. Annual growth rate in E. 

schultzii decreases from low to high elevations, 

and from slope bases to ridge tops. Mortality of 

E. schultzii adults can result from drought, fire 

and, in rare cases, flooding. Variation in plant 

height in paramo species is correlated primarily 

with longevity. In E. schultzii, plant height and 

longevity both increased with increasing elevation. The E. lutescens population at 4200 m had a 

greater mean plant height than any other paramo 

population studied, and had the greatest apparent longevity. The acaulescent rosette form in E. 

floccosa at 3600 m was correlated with very short 

generation time: plants reproduced early and 

died after first reproduction. The other acaulescent rosette species, E. atropurpurea, had a similar 

pattern, but new rosettes sprouted from old roset t e bases. 

The species showing greatest iteroparity, E. 

lutescens, occurs on sites where seedling establishment is rare. The semelparous species, E. fzoccosa, 

occurs on sites where adult mortality is greatest 

among the largest size classes, and where seedling 

establishment is comparatively common. 

Population control is strongly density dependent. Reduction in density in one size class results 

in increased growth and/or reproduction among 

remaining plants. Thus, populations rapidly recover from most perturbations. 
Appendix 

Site number, name, 

and location 

1. Zerpa 

Mucubaji 

2. Bog edge 

3. Slope base 

4. Windward slope 

5. Ridge 

6. Leeward slope 

Lower exclosure 

7. Windward slope 

8. Leeward slope 

9. Leeward slope 

10. Windward slope 

1 1. Leeward slope 

12. Windward slope 

13. Windward slope 

14. Leeward slope 

15. Leeward slope 

16. Leeward slope 

17. Xeric slope 

18. Talus slope 

19. E.floccosa plot. 

Laguna Negra 

Talus slope 

Upper exclosure 

20. Plot 1 

21. Plot 2 

22. Closed forest 

23. Treefall 

24. La Aguada 

25. Aguiia 

26. Asuila 

Tables 

TABLE A.-Site characteristics (site locations shown in Figure 2) 

Elevation Slope Aspect Species 

3000 rn 

3600 rn 

3600 m 

3600 rn 

3600 rn 

3600 rn 

3550 rn 

3550 rn 

3550 rn 

3550 m 

3550 rn 

3550 rn 

3550 m 

3550 rn 

3550 rn 

3550 rn 

3550 m 

3600 rn 

3600 rn 

3500 rn 

3500 rn 

3500 rn 

3500 rn 

3400 rn 

4200 rn 

4200 rn 

12' 

20 " 

0' 

13" 

32 " 

15' 

19" 

21' 

21' 

15' 

26" 

26' 

20" 

17' 

20' 

17" 

32" 

10' 

15' 

31' 

29" 

38' 

38" 

26" 

16' 

16' 

40'E 

260'W 

55'E 

55'E 

265'W 

NNB 

ssw 

sw 

NE 

sw 

NE 

"E 

ssw 

ESE 

WNW 

S 

SSE 

SSE 

- 

SSE 

NNW 

sw 

sw 

W 

115'E 

I15'E 

E. schultzii 

E. schultzii 

E. schultrii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultrii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultzii 

E. schultrii 

E. schultzii 

E. floccosa 

E. humbertii 

E. humbertii 

E. humbertii 

E. humbertii 

E. schultzii, 

E. schultzii 

E. lutescens 

E. atropurpurea 

40 
NUMBER 48 

TABLE B.-Plot description 

41 

Species and sites 

E. schultzii 

Mucubaji (3600 m) 

Windward slope 

Leeward slope 

Ridge 

Base of windward 

slope 

Xeric slope 

Talus slope 

Zerpa (3000 m) 

Windward slope 

Aguila (4200 m) 

Windward slope 

La Aguada (3400 m) 

Aguila (4200 m) 

E. lutescens 

Windward slope 

Mucubaji (3600 m) 

E. floccosa 

Rocky slope 

E. humbertii 

Laguna Negra (3500 m) 

Open talus slope 

Plot 1 

Plot 2 

forest 

forest 

Closed Polylepis 

Treefall in Polylepis 

E. atropurpurea 

La Aguada (3400 m) 

Plot size 

Number Number Number 

of adults of marked of marked 

in plot seedlings adults 

10x10 m 

lox 10 m 

10x10 m 

10x10 m 

10x10 m 

20x5 m 

10x10 m 

1OX 10 m 

Plotless 

10x10 m 

20x5 m 

10x15 m 

10x15 m 

10x10 m 

5x10 m 

Plotless 

122 

199 

116 

96 

146 

57 

103 

80 

- 

86 

103 

29 plants total 

45 plants total 

52 plants total 

213 plants total 

257 

456 

172 

440 

167 

3 

298 

34 

- 

23 

105 

- 

120 

120 

120 

120 

120 

- 

120 

120 

50 

120 

120 

50 

45 

52 

- 

50 
42 SMITHSONIAN CONTRIBUTIONS 

TABLE C.-Dates on which bud leaves were marked and counted for measurement of adult leaf 

expansion rates 

Sptcies and site I Dates 

E. schultrii 

3000 m Zerpa 

Descriptive plot 

3550 m Mucubaji 

NE-facing slope 

SW-facing slope 

3600 m Mucubaji 

Bog edge 

Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 m Aguila 

3400 m La Aguada 

E. lutescens 

4200 m 

E. humbertii 

3500 m 

E. atropurpurea 

3400 rn 

9 Oct-9 Dec 72, 15 Feb-16 Mar 72, 24 Jun-5 Aug 73 

27 Mar-25 Apr 73, 24 Jun-28 JuI 73 

27 Mar-25 Apr 73, 24 Jun-28 Ju1 73 

26 Jan-I4 Mar 73, 25 Jun-31 JuI 73 

9 Oct-9 Dec 72, 25 Jan-14 Mar 73, 25 Jun-30 Jul 73 

9 Oct-9 Dec 72, 25 Jan-I4 Mar 73, 25 Jun-30 Ju1 73 

9 Oct-9 Dec 72, 25 Jan-15 Mar 73, 25 Jun-30 Jul 73 

9 Oct-10 Dec 72, 26 Jan-15 Mar 73, 25 Jun-30 JuI 73 

10 Oct-10 Dec 72, 14 Feb-17 Mar 73, 24 Jun-11 Aug 73 

3 Oct 72-14 Jun 73, 14 Jun-20 Jul 73 

10 Oct-10 Dec 72, 14 Feb-17 Mar 73, 24 Jun-11 Aug 73 

9 Oct-16 Dec 72, 29 Jan-28 Mar 73, 2 Jul-1 Aug 73 

3 Oct 72-14 Jun 73, 14 Jun-20 Jul 73 ~ 

TABLE D.-Dates for juvenile mortality and recruitment observations (height measured on 

first and last dates) 

Species and site I Dates 

E. schultrii 

3000 m 

Descriptive plot 

Transplant garden 

Slope base 

Windward slope 

Ridge 

Leeward slope 

Transplant garden 

Adult elimination 

3600 rn 

experiment 

4200 m 

E. lutescens 

4200 m 

E. floccosa 

3600 m 

19 Aug 72, 9 Dec 72, 16 Mar 73, 28 Apr 73, 16 Aug 73 

9 Oct 72, 17 Dec 72, 23 Mar 73, 28 Apr 73, 4 Aug 73 

25 Jun 72, 5 Dec 72, 14 Mar 73, 26 Apr 73, 27 Jun 73 

9 Jun 72, 5 Dec 72, 14 Mar 73, 26 Apr 73, 9 Jun 73 

20 Jun 72, 5 Dec 72, 14 Mar 73, 26 Apr 73, 26 Jun 73 

17 Jul 72, 8 Dec 72, 14 Mar 73, 27 Apr 73, 22 Ju1 73 

8 Oct 72, 16 Dec 72, 22 Mar 73, 28 Apr 73, 5 Aug 73 

21 Oct 72, 22 Mar 73, 29 Apr 73, 7 Aug 73 

7 Aug 72, 10 Dec 72, 17 Mar 73, 29 Apr 73, 18 Aug 73 

7 Aug 72, 10 Dec 72, 17 Mar 73, 29 Apr 73, 18 Aug 73 

6 Aug 72, 13 Dec 72, 28 Mar 73, 29 Apr 73, 3 Aug 73 

TO BOTANY 
NUMBER 48 43 

TABLE E.-Dates for adult height measurements 

Species and site 

E. schultzit 

3000 rn 

3600 rn 

Slope base 

Windward slope 

Ridge 

Leeward slope 

4200 rn 

E. lutescens 

E. floccosa 

Dates 

18 Aug 72, 16 Aug 73 

16 Ju1 72, 17 Jul 73 

5 Jun 72,6 Jun 73 

29 Jun 72, 25 Jun 73 

23 JuI 72, 22 Jul 73 

9 Aug 72, 18 Aug 73 

8 Aug 72, 18 Aug 73 

30 Ju1 72, 3 Aug 73 
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