bluuebunny/crossref_metadata_2025 huggingface dataset:
Contrasting Growth Rate Patterns in Eighteen Tree Species From a Post‐Hurricane Forest in Nicaragua1
Authors: Vandermeer John , de la Cerda Iñigo Granzow , Boucher Douglas
Published: March 2006

Hurricane Joan struck the Caribbean Coast of Nicaragua in October 1988 causing extensive damage to the lowland rain forest of the zone. Six permanent plots were established in 1990 and the growth rates of all individuals in a total area of 6000 m2 monitored for six years. Eighteen of the species were abundant enough to measure species‐specific growth rates. The post hurricane successional process included a great deal of resprouting of pre‐existing individuals and the current state of the forest includes a low but very dense canopy, suggesting that competition is entering an intensive phase. Specific growth rates between the time of the hurricane and the present thus represent establishment or regenerative growth rates and provide an indication of whether or not distinct regeneration niches exist. Three distinct patterns of growth rate seem apparent, fast‐growing heliophyles (eight species), slow‐growing resprouters (nine species), and vochysia ferruginea, which seems to have a special pattern.
Pollination Biology of Myrrhinium atropurpureum (Myrtaceae): Sweet, Fleshy Petals Attract Frugivorous Birds
Authors: Roitman G. Germán , Montaldo Norberto H. , Medan Diego
Published: March 2006

Myrrhinium atropurpureum has unusual floral characteristics: sweet, juicy petals, long vivid stamens, and absence of nectar and odor. This uncommon syndrome is morphologically and anatomically described. Floral phenology is also described, and censuses of flower visitors are provided. The main pollinators are frugivorous passerine birds, which are attracted by the petals. This type of floral reward is vev uncommon and seems to be restricted, in South America, to Myrrhinium, Feijoa (Myrtaceae) and Calceolaria (Scrophulariaceae). The possible origin of the pollination mechanism is discussed.

Myrrhinium atropurpureum posee caracteres florales inusuales: pétalos dulces y carnosos, estambres exertos y vistosos, y ausencia de néctar y perfume. Este poco común síndrome floral es descrito morfológica y anatómicamente. Se describe la fenología floral y se censaron los visitantes a las flores. Los principales polinizadores son aves frugívoras, que son atraídas por los pétalos. Este tipo de recompensa floral es infrecuente y parece estar restringido, en Sudamérica, a Myrrhinium, Feijoa (Myrtaceae) y Calceolaria (Scrophulariaceae). Se discute el posible origen de este mecanismo de polinización.
Differential Flower Herbivory and Gall Formation on Males and Females of Neea psychotrioides, a Dioecious Tree
Authors: Wolfe Lorne M.
Published: March 2006

The goal of this study was to determine whether there exists intersexual differences in the degree of herbivore attack on a tropical, dioecious tree. Neea pychotrioides is a Costa Rican tree that experiences at least two types of attack on its reproductive structures: flower herbivory and gall formation on inflorescences. Although female trees were more common than males in the two study populations (overall sex ratio = 1.5 females/male), male flowers were more likely to be eaten by lepidopteran larvae. Similarly, inflorescence‐borne, fly‐induced galls were more frequent on males. Ten families of insects from three orders (Diptera, Hymenoptera, Lepidoptera) occupied the galls with varying levels of parasitism and hyperparasitism occurring within. Although the sexes were not significantly different in vegetative size, males had larger floral displays (more inflorescences and larger flowers) that may have acted as attractants to herbivores and gallmakers. The results are consistent with the hypothesis that flower damage and the energetic costs of producing galls exert a greater expense to males, ultimately resulting in death, and over time, a skewing of the sex ratio.
The Diet and Reproductive Schedules of Leptonycteris curasoae curasoae and Glossophaga longirostris elongata (Chiroptera: Glossophaginae) on Curaçao
Authors: Petit Sophie
Published: March 2006

Two bat species, Leptonyrteris curasoae and Glossophaga longirostris, are the principal pollinators of at least two of the three species of columnar cacti that grow on the semiarid island of Curaçao, Netherlands Antilles. I examined the importance of the cacti in the diets of the bats and found that 85–91 percent of their diet samples contained cactus pollen and seeds. At least 43 percent of the samples from each species contained cactus pollen andlor seeds exclusively. Leptonycteris curasoae consumes nectar and pollen of Ceiba pentandra and Agave spp. at the beginning of the dry season and G. longirostris also consumes a few other plant products in the wet season, but both bat species depend nutritionally on cacti. Female bats give birth to one pup per year, and the periods of parturition and lactation in each species correspond to peaks in the reproductive phenology of the two most abundant columnar cactus species. From personal observations and a review of the literature, I determined that bats were unlikely to fly to the mainland to feed, although L. curasoae may do so. I conclude that the interdependence of bats and cacti is suggestive of coevolution, and that columnar cacti are critical for the survival and persistence of nectar‐feeding bats on Curaçao.
Forest Regeneration in Logged and Unlogged Forests of Kibale National Park, Uganda
Authors: Chapman Colin A. , Chapman Lauren J.
Published: March 2006

Processes of forest regeneration in two unlogged areas and in three areas that were logged nearly 25 years ago were quantified in Kibale National Park, Uganda. For forests to recover from logging, one would predict recruitment and growth processes to be accelerated in logged areas relative to unlogged areas, facilitating increased recruitment of trees into the adult size classes. We examined this prediction first by determining the growth of 4733 trees over a 51 to 56 month period and found that growth rates in the most heavily logged area were consistently slower than in the two unlogged areas. In contrast, the lightly logged forest had similar growth rates to unlogged areas in the small size classes, but trees in the 30 to 50 cm DBH size cohort exhibited elevated growth rates relative to the unlogged areas. Mortality was highest in the heavily logged areas, with many deaths occurring when healthy trees were knocked over by neighboring treefalls. We found no difference in the density or species richness of seedlings in the logged and unlogged forests. The number of seedlings that emerged from the disturbed soil (seed bank+seed rain) and initially seed‐free soil (seed rain) was greater in the logged forest than in the unlogged forest. However, sapling density was lower in the heavily logged areas, suggesting that there is a high level of seedling mortality in logged areas. We suggest that the level of canopy opening created during logging, the lack of aggressive colonizing tree species, elephant activity that is concentrated in logged areas, and an aggressive herb community, all combine to delay vegetation recovery in Kibale Forest.
Rhizophora mangle L. Seedling Development into the Sapling Stage across Resource and Stress Gradients in Subtropical Florida1
Authors: Koch Marguerite S.
Published: March 2006

Nutrient, light, salinity, soil redox potentials, and other soil characteristics were determined across a range of mangrove forest heights across the South Florida peninsula encompassing large‐stature trees (> 10 m) on the west coast and dwarf forms (< 1 m) in the southeast Everglades. Relationships were established between abiotic factors and Rhizophora mangle seedling growth rates in four height (cm) classes, 25‐40, > 40‐55, > 55–70, and > 70–85. Light in open canopy gaps was an important determinant of seedling growth. Growth rates in gaps (0.32 ± 0.04 to 1.89 ± 0.18 mm/d) were two‐ to five‐fold greater than adjacent closed canopy forests (0.14 ± 0.01 to 0.40 ± 0.07 mm/d). Among open canopy sites, labile soil phosphorus and soil redox potentials were significantly correlated to growth (P < 0.05; r= 0.98 and 0.89, respectively). Interstitial salinity ranged from 0 to 27 ppt across sites, well below hypersaline conditions. Thus, under low salinity stress and high light availabiliry, soil fertility is proposed to be the dominant factor controlling R. mangle seedling development to a sapling stage (> 85 cm) in South Florida mangrove forests. In addition, soil anoxia is hypothesized to be an important stressor in lagoonal‐bay estuaries and marsh‐mangrove ecotones with minimal tidal exchange.
Observations at a Ficus Tree in Malagasy Humid Forest1
Authors: Goodman Steven M. , Ganzhorn Jörg U. , Wilmé Lucienne
Published: March 2006

Although several authors have recognized that Madagascar has a depauperate frugivore community, little quantitative data is available on this issue. In order to start filling this gap, systematic observations were made at a Ficus tree in the eastern humid forest. Information is presented on the vertebrate species that visited the tree, estimates of total fruit production and proportion consumed by frugivores, and the chemical analysis of the fruits.

Bien que de nombreux auteurs aient reconnu la faible importance des communautés frugivores de Madagascar, peu de données quantitatives sont actuellement disponibles sur cet aspect. Afin de pallier à ce manque, des observations systématiques ont été faites sur un Ficus dans la forêt humide de l'est. Les connaissances apportées concernent les espèces de vertébrés qui ont visité l'arbre, des estimations de la production totale de fruits, des proportions consommés par les frugivores, et des analyses chimiques des fruits.
Seasonal and Spatial Patterns in Ground Foraging Ants in a Rain Forest in the Western Ghats, India1
Authors: Basu Parthiba
Published: March 2006

Seasonal variation and spatial distribution in ground foraging rain forest ants were studied in South Kannada–Kodagu District in Karnataka (India) between 1990 and 1991 by pit‐fall trap sampling. All ant species showed marked seasonality. A total of 31 species were recorded from the primary forest over a period of two years. More species were recorded from the closed canopy forest than from tree fall gaps in primary forest. All ant species showed marked seasonality with fewer species and individuals sampled/plot during the wetter seasons. The numerically dominant species, Pheidole sp., was markedly lower in abundance during the wet seasons. Spatial patterns were also studied during a dry season both in the primary forest and an adjacent logged forest. More species were recorded from the logged forest than the primary forest. Community composition in primary forest was different from that in logged forest. Common species were more ubiquitous than rarer species. Species were distributed bimodally across sampling plots. Probable underlying processes behind these seasonal and spatial patterns have been discussed.
Isozyme Variation in a Tropical Pioneer Tree Species (Cecropia obtusifolia, Moraceae) with High Contents of Secondary Compounds1
Authors: Garay‐Arroyo Adriana , Alvarer‐Buylla Elena R.
Published: March 2006

We define 48 allozyme loci for a tropical pioneer tree species, Cecropia obtusifolia Bertol, which has high contents of secondary compounds. Our goals were to find the effects of extraction procedures on artifacts and variation in resolution of enzyme banding patterns; to explore the relationship among the variation of the loci sampled and the enzymes' molecular structure, metabolic function and substrate; to obtain estimates of the genetic variation in this species at Los Tuxtlas rain forest (México) and to explore the variation of allelic frequencies in six successive life‐history stages of the species.

The resolution of the isozymes bands and the actual banding pattern varied with the type and age of tissue, the collection and storage procedures, the extraction buffer, and other loading and running procedural details. However, artifactual variation was eliminated with a new extraction buffer for species with high contents of secondary compounds.

Of the 26 enzymes resolved for C. obtusifolia, we found that enzymes with a greater number of substrates and an oligomeric quaternary structure tended to be more variable than their counterparts, but the relationship was not statistically significant. The proportion of polymorphic systems varied significantly with the metabolic pathway and the function of the enzymes. Enzymes involved in starch synthesis are significantly more variable (p < 0.05) than all others, except those involved in amino acids metabolism and the proportion of polymorphic enzymes is also significantly associated with the hnction of the enzyme, the hydrolases and isomerases are significantly more variable than lyases and oxidoreductases enzymes.

The percentage of polymorphic loci for C. obtusifolia was estimated at P = 27.1%. The effective number of alleles was estimated at ne = 1.3 and ne = 2.4 for all loci and only polymorphic ones respectively and the average heterozygosity (H) for all 48 loci was estimated at H = 0.05. Allele frequencies varied throughout the life‐cycle of the species, with significant differences for some alleles and loci among some life‐cycle stages. “Tree seeds” allele frequencies differ significantly (P < 0.05) from “rainy dispersed seeds” in 7 of 8 loci and from “soil seeds” in Six of eight loci. Allele frequencies of all three seed categories (“tree seeds”, “rainy dispersed seeds”, and “soil seeds”) differed strongly from established individuals (seedlings, juveniles and adults), while allele frequencies of established individuals are relatively similar to one another. Seedling allele frequencies at most loci were also significantly different from those found in seeds collected from trees, seed‐rain, and soil. Two alleles (at GOT‐2 and FE‐2) were only found in soil seeds and one allele (at LAP‐2) was only found in seedlings.
Disturbance and Seasonal Dynamics of Mycorrhizae in a Tropical Deciduous Forest in Mexico1
Authors: Allen Edith B. , Rincón Emmanuel , Allen Michael F. , Pérez‐Jimenez Alfredo , Huante Pilar
Published: March 2006

Mycorrhizal fungi were sampled in a deciduous tropical forest on the Pacific coast of Mexico during different seasons and in natural treefall gaps and pastures. All 12 plant species sampled in the forest were arbuscular mycorrhizal. The percent root infection and spore production were closely related to the phenology of the plants. Most tree species and all herbaceous species had the highest infection in the summer rainy season, but two species, Opuntia excelsa and Jacquinia pungens, had highest infection in the dry season. Unusually high rainfall during the dry season was associated with increased infection but not increased spore production. Spore density was low for all species at all sample times, except at the beginning of the July 1993 rainy season in, when we observed up to 28 spores/g soil.

The percent cover of shrubs or herbs did not increase in gaps after two years, and we observed no colonizing seedlings. No plant species with cover higher than 2.7 percent occurred exclusively in gaps or forest. The percent mycorrhizal infection did not differ significantly between gaps and forest. Spore counts were as high in the gaps as in the forest in two of the three gaps but lower in the third gap. The lack of significant response of plants in these gaps after two years differed from the rapid response in tropical rainforests. It is likely related to the small size of the gaps and to light infiltration to the forest floor. Pastures were dominated by two species of exotic grasses and one species of mycorrhizal fungus, whereas forests had 15 fungal species. The slow regrowth of vegetation in gaps was not limited by mycorrhizal fungi, since they were still abundant after the treefalls, but recovery in pastures could be affected by low fungal diversity and dominance of grasses.
Microclimate Change and Effect on Fire Following Forest‐Grass Conversion in Seasonally Dry Tropical Woodland1
Authors: Freifelder Rachel R. , Vitousek Peter M. , D'Antonio Carla M.
Published: March 2006

We tested the hypothesis that, where fire has historically been infrequent, wooded areas that have been invaded by grasses and converted to grassland by fire are predisposed to future fire compared to adjacent areas that remain wooded; thus, an initial forest fire may promote future fires. We compared microclimate between a grass‐dominated burned area and a nearby grass‐invaded woodland that has not burned in recent history, both located in the submontane dry forest of Hawaii Volcanoes National Park. The results were used to parameterize BEHAVE, a fire behavior prediction model developed by the USDA Forest Service. The model's predictions include probability of ignition, intensity, rate of spread, and tree mortality. Contrary to expectations, daytime hourly mean temperatures were higher and relative humidity was lower in the woodland site. However, the differences in temperature and humidity were not great enough to affect spread rate or probability of ignition. Wind speeds were substantially greater in the grassland, and this was most important in driving differences in modeled fire spread. Given similar synoptic conditions, a fire started in the grassland can be expected to spread an order of magnitude faster than one started in the woodland.
Tree Regeneration and Species Diversity Following Conventional and Uniform Spacing Methods of Selective Cutting in a Subtropical Humid Forest Reserve1
Authors: Montagnini Florencla , Eibl Beatriz , Szczipanski Lilian , Rios Romàn
Published: March 2006

There are a variety of ways to diminish the negative impacts of forest management for timber on biodiversity. A pilot project using a uniform spacing method of selective cutting was recently implemented in the 5340 ha Guarani Reserve, Misiones, Argentina, to design adequate management schemes for the subtropical forests of the region. Uniform spacing involves moderate timber harvesting and careful selection of remnant trees. In this article we compare tree regeneration in forests experimentally cut by diameter limit and uniform spacing methods. Seedlings of five size classes from 10 cm to 3 m in height were sampled using rectangular nested plots. Three years after cutting, an average of 54,330 and 22,270 seedling/ha (all height classes combined) of commercial and non‐commercial species were found in the forest cut by uniform spacing and by minimum diameter, respectively. In an adjacent uncut forest there were 34,900 seedlings/ha, and in another forest cut by minimum diameters 30 years ago there were 50,000 seedlings/ha, The forest cut by uniform spacing had the highest number of commercial seedlings/ha, with three times as many as the forest cut by minimum diameter three years ago and twice as many as the forest treated by minimum diameters 30 years ago. The forest cut by uniform spacing and the forest treated by minimum diameters 30 years ago had the highest diversity of understory plants other than trees, as well as heterogeneous canopy cover, while the other two forests had a predominance of bamboo in the understory and more open canopy conditions. Although lack of site replication limits interpretation of the results, these early findings suggest that the uniform spacing method can be an ecologically sound forest management option for the region.
Effects of Canopy Gaps, Topography, and Soils on the Distribution of Woody Species in a Central Brazilian Deciduous Dry Forest1
Authors: Oliveira‐Filho Ary T. , Curi Nilton , Vilela Enivanis A. , Carvalho Douglas A.
Published: March 2006

The interrelationships between the distribution of woody species and environmental variables were investigated in an area of deciduous dry forest in Santa Vitöria, central Brazil. This is the first study of a vanishing type of dry forest which grows on base‐rich soils originating from the basalt bedrocks of southern Goiás and western Minas Gerais. A survey of topography, soil properties, canopy gaps and woody plants (≥5 cm diameter at the base of the stem) was conducted in 50–15 × 15 m quadrats. The soils were classified into the following soil series: Hapludolls → Haplustolls → Haplustolls → Ustropepts → Rhodustalfs. This series corresponded to a gradient of increasing elevation and effective soil depth and decreasing slope gradient, soil organic matter and total exchangeable bases. A canonical correspondence analysis and a detrended correspondence analysis indicated that plant species’abundance distribution was significantly correlated with both the relative area of canopy gaps in the quadrats and the soil‐topography gradient. Presumably, the critical factors involved in these two gradients are, respectively, light and ground water regimes. The influence of canopy gaps (i.e., light) was surprising and has not been documented previously for tropical deciduous dry forests.
Hurricane Disturbance, Plant‐Animal Interactions, and the Reproductive Success of a Tropical Shrub1
Authors: Pascarella John B.
Published: March 2006

Hurricane disturbance may have strong effects on plant‐animal interactions important in plant reproductive success. Components of reproductive success (flowering, pollination, seed predation) in the tropical shrub Ardisia escallonioides (Myrsinaceae) were examined from 1991–1994 in four southern Florida populations. Hurricane Andrew struck three of the four populations on 24 August 1992. Hurricane Andrew delayed flowering by two months in 1992. In 1993 and 1994, the three hurricane‐damaged populations had increased flowering and inflorescence production compared to 1991 and 1992, while the undamaged population had no flowering.

Hurricane disturbance had different effects on generalist versus specialist plant‐animal interactions. Species composition and relative abundance of the generalist pollinator community that visits A. escallonioides was similar before and after the hurricane, indicating little effect of the disturbance on this interaction. In contrast, populations of a specialist flower galling moth (Periploca sp., Cosmopterigidae) declined in 1992 following Hurricane Andrew. Although moth populations increased at two of the three sites in 1993, the relative impact of moth predation on seed production was low due to extensive flower production. One moth population suffered local population extirpation for two years, reestablishing itself in November 1994. Hurricane disturbance resulted in a window of opportunity for massive seed production of Ardisia escallonioides in south Florida. Total seed production in 1993 increased twelve to seventy‐three times the 1992 levels. Total seed production declined in 1994, but remained high compared to prehurricane levels.
Effects of Selection Logging on Birds in Northern Belize1
Authors: Whitman Andrew A. , Hagan John M. , Brokaw Nicholas V. L.
Published: March 2006

We compared bird diversity and frequency in selection logged and unlogged forest to determine the effects of recent selection logging on avian biodiversity in a subtropical, moist evergreen forest. We used a combination of mist netting and fixed‐radius point counts to assess bird communities in February and March 1993 in northwestern Belize. Vegetation structure and composition was similar in logged and unlogged forest. The 66 most common species occurred with statistically similar frequency in logged and unlogged forest although 13 species were two times more frequent in intact forest. Numbers of total bird species were similar between logging gaps and the logged forest matrix, and between the logged forest matrix and unlogged forests. A comparison of numbers of species in 26 guilds based on migration strategy, diet, foraging substrate, and height strata also showed them to be similar regardless of logging history. Our results differed from previous studies that reported lower bird species richness and abundance of individual species in logged tropical forests than in unlogged forest. The differences might be explained by the lower logging intensity and/or greater levels of natural disturbance in our study area compared to previous studies.
Environmental Effects of Canopy Gap Formation in High‐Rainfall Mangrove Forests1
Authors: Ewel Katherine C. , Zheng Songfa , Pinzón Zuleika S. , Bourgeois John A.
Published: March 2006

This study investigated the importance of gap formation in mangrove swamps on the island of Kosrae, Federated States of Micronesia, in order to understand better both natural processes of forest development and the effects of harvesting trees for firewood in these wetlands. Measurements were concentrated in seven plots located near four rivers: three in fringe zones and four in basin zones. Each plot was a cluster of five points and covered an area of ca 1.3 ha. From every point in each of the seven plots, the nearest canopy gap ≥10 m2 was located; 25 of the 35 gaps were formed by harvesting. Porewater salinity was significantly higher under the canopy in fringe mangrove forests than in basin mangrove forests. Although gaps were small (mean gap size = 158 m2; median gap size = 92 m2), soil temperatures were significantly higher in gaps of both zones. Soil redox potential was significantly lower and porewater salinity significantly higher in the gaps than under the canopy in the basin zone only. Higher porewater salinity may be attributed to high evaporation rates from the soil and high transpiration rates from trees surrounding gaps. There were significantly more seedlings in gaps than under the canopy only in the fringe zones. Although gap formation alters the soil environment of Kosraean mangrove swamps, high freshwater input may buffer these effects in basin mangrove swamps by reducing porewater salinity. Current harvesting rates do not appear to be changing canopy species composition, but large gaps, especially in mangrove forests in more arid areas, may lead to major changes.
Stand Biomass and Tree Mortality from Permanent Forest Plots on Krakatau, Indonesia, 1989–19951
Authors: Whittaker R. J. , Schmitt S. F. , Jones S. H. , Partomihardjo T. , Bush M. B.
Published: March 2006

Forest closure on the three original Krakatau Islands (Panjang, Rakata, and Sertung) took place ca 1930, about 50 yr after the apparent sterilization of the islands due to volcanic eruptions. Two permanent forest plots were established on each of these islands in 1989. A full enumeration of these plots, of two additional Rakata plots, and of two “mainland”plots from the Ujung Kulon National Park, West Java, was undertaken in 1992. These data provide the first estimates of aboveground biomass from Krakatau. The values reported for Krakatau are below the local West Javan figures, with considerable variation occurring within the islands. In 1992, the fourth Krakatau island, Anak Krakatau, began an eruption sequence which continued through the study period, depositing ash on the study sites of Panjang and Sertung. A further partial survey of these plots in 1994–1995 revealed a significant increase in mortality since the volcanic activity recommenced, with an increase in deaths of larger stems. Although Rakata has not been influenced directly by volcanism, three sites surveyed on Rakata in 1994–1995 have experienced increased tree mortality, in two cases as a consequence of storm damage and in particular, of lightning strikes. Stand dynamics on Krakatau thus appear to be strongly influenced by episodic environmental disturbance with varying degrees of dependence on the volcanic activity of Anak Krakatau.
Seedling and Sprout Response to Slash‐and‐Burn Agriculture in a Tropical Deciduous Forest1
Authors: Miller P. M. , Kauffman J. B.
Published: March 2006

Survival and growth of seedlings and sprouts were assessed in three plots for 16 mo following the slashing and burning of a tropical deciduous forest in Jalisco, Mexico. We encountered a total of 47 species: 21 seedling species and 35 sprout species. Calliandra formosa and Piptadenia flava were the most common seedling species; Bursera arborea, Cordia alliodora, and Piptadenia constricta were the most common sprouts. Colubrina triflora, Diphysa occidentalis, and Cnidoscolus spinosus had limited sprouting ability. Twenty‐six species were represented by one seedling or one sprout. Thirty‐eight percent of the seedlings were tree species, 59 percent were shrub species, and 2 percent were vines species. In contrast, 86 percent of the sprouts were from trees and 13 percent from shrubs. One year after the initial measurements, 29 percent of the seedlings and 13 percent of the sprouts were dead. Each of the seedling means (number of stems/individual, height and diameter of the tallest stem, and elliptical crown area) was significantly smaller (P < 0.05) than that of sprouts at all three measurement periods, but relative growth rates were similar. Total canopy area of seedlings had a larger relative increase than did the canopy area of sprouts. The presence of seedlings increased species diversity compared to calculated diversity excluding seedlings. Timing of fruit dispersal in relation to the date of burning and the high number of Leguminosae species in the forest appeared to favor seedling establishment for some species.
The Potential Impact of Small‐Scale Physical Disturbance on Seedlings in a Papuan Rainforest1
Authors: Mack Andrew L.
Published: March 2006

Physical disturbance, such as falling debris, is an important cause of mortality to rain forest seedlings. I used artificial seedlings to quantify physical disturbance in a rain forest at the Crater Mountain Biological Research Station in Papua New Guinea. Single (N= 418) and clustered artificial seedlings (N= 428) were placed on eight transects spanning varied topography to assess the area's disturbance regime, to test if ground slope affected disturbance, and to test if clustering affected the incidence of damage.

Two transects showed a significant departure from random in the spatial distribution of damaged seedlings within the transect, suggesting that some areas of experience more disturbance than others. Artificial seedlings on level ground experienced damage less often than artificial seedlings on slopes; disturbance increased with ground slope. Artificial seedlings in dry washes experienced the greatest probability of damage. Artificial seedlings in clusters experienced significantly less damage than single ones, suggesting clustered seedlings might be less vulnerable to damage than lone seedlings. The disturbance rate at this site (34.7% damaged in one year) was markedly lower than that measured at the La Selva Biological Reserve in Costa Rica (82.4%).
Sugar Composition of Nectars and Fruits Consumed by Birds and Bats in the Tropics and Subtropics1
Authors: Baker Herbert G. , Baker Irene , Hodges Scott A.
Published: March 2006

Several characteristics of flowers and fruits have been suggested as comprising syndromes of characters that indicate particular classes of pollinators and fruit dispersers. Common phylogenetic history among species, however, may also significantly influence these characters and obscure or enhance perceived patterns of plant syndromes. We analyzed the proportions of glucose, fructose, and sucrose by paper chromatography in the nectar and fruit juice of 525 tropical and subtropical plant species to test whether sugar chemistry was correlated with volant vertebrate pollinator or fruit disperser classes. Samples were taken from Old World and New World species and the calculations kept separate. Kruskal‐Wallis tests of family means showed significant deviations in the percent sucrose content among pollinatorl disperser classes. Mann‐WhitneyU‐tests showed significant differences among nectars of all pollinator classes but fruit juices differed only due to the high sucrose content of megachiropteran dispersed fruits. In addition, sign tests of samples occurring within families showed significant correlations between percentage sucrose content and pollinator/disperser classes. Passerine nectars had low sucrose content. In striking contrast, the nectar of hummingbird flowers had very high sucrose content. The Microchiroptera nectars showed hexose richness with a sucrose content somewhat greater than that of passerine flowers. Megachiroptera flowers showed sucrose‐rich nectars. The results for fruits were comparable to those for nectars. Passerine fruits were hexose dominated, microchiropteran fruits had a sucrose content similar to passerine fruits, and megachiropteran fruits were sucrose‐rich. We speculate on the evolutionary sequence of changes in nectar and fruit juice sugar composition and suggest that future investigations consider the chemistry of other food sources such as pollen and leaves. Only with these additions and other ecological studies can the full interplay of such plant‐animal interactions be anticipated.
The Assemblage of Birds Foraging in Native West Indian Pine (Pinus occidentalis) Forests of the Dominican Republic during the Nonbreeding Season1
Authors: Latta Steven C. , Wunderle Joseph M.
Published: March 2006

We studied avian resource use in a native West Indian pine (Pinus occidentalis) forest in the Cordillera Central of the Dominican Republic during the nonbreeding season. The forest is characterized by a fairly open pine canopy and a dense mixed‐broadleaf and pine understory. We used a principal components analysis of 23 foraging characters for 23 bird species, including foraging height, the proportional use of 5 different foraging methods, 3 horizontal positions and foliage densities, and 11 foraging substrates. Five principal components accounted for 74 percent of the total variance of the assemblage variables and resulted in the delineation of at least 5 foraging guilds. 78 percent of bird species had mean foraging heights of 5.0–10.0 m, corresponding to the region of overlap of pine and broadleaf vegetation. As a result, the diversity of foraging substrates and maneuvers used by birds, rather than foraging height, appears to be the primary means by which birds that exploit this habitat separate ecologically. Migrant wood warblers (Parulinae) are probably able to integrate into the community because of little diet overlap between residents and migrants, and the fairly specialized nature of their largely insectivorous foraging habits. Avian foraging in this habitat may reflect the effects of frequent disturbance such as hurricanes.
The Influence of Temporal Changes in Fruit Availability on Diet Composition and Seed Handling in Blue Monkeys (Cercopithecus mitis doggetti)1
Authors: Kaplin B. A. , Munyaligoga V. , Moermond T. C.
Published: March 2006

We investigated the relation between temporally varying resources, diet composition, and seed‐handling behaviors in a group of blue monkeys (Cercopithecus mitis doggetti) in a tropical montane forest of Rwanda. Changes in diet composition were related to concurrent phenological studies of fruit‐producing trees, and density and abundance of tree resources within the monkey's home range. Fruit composed nearly 50 percent of the diet. Over 50 percent of the fruits eaten had juicy fleshy pulp. Observations of seed handling behavior provided insights into the role of these animals as potential seed dispersal agents. The monkeys moved the seeds of 29 species out of parent canopies by defecating seeds intact and by potentially carrying seeds in cheek pouches and dropping them later. Seeds of 18 species were found intact in fecal piles. Our study showed community‐level phenology patterns did not indicate a decrease in fruit availability during the study period, but an analysis of the preferred fruits consumed by the monkeys showed distinct periods of low fruit availability. The study period included two dry seasons; only one of these produced a period of fruit scarcity for the animals. The animals employed different strategies during times of preferred fruit scarcity. They increased consumption of leaves and other fleshy fruits, and diet diversity increased, or became mainly seed predators and diet diversity decreased. The variable responses of these monkeys to changes in food availability highlights their dietary plasticity and imposes significant variations in their role as potential seed dispersers.
Local and Regional‐Scale Food Web Structure in Nepenthes alata Pitchers1
Authors: Sota T. , Mogi M. , Kato K.
Published: March 2006

TropicalNepenthespitcher plants provide small, isolated aquatic habitats. We examined inter‐pitcher variation in the community structure of the inhabitants ofNepenthes alataBlanco in West Sumatra, focusing on the conditions of the pitchers, bacterial density in the pitcher fluid, density and biomass of metazoan inhabitants, and the frequencies of interspecific encounters. Older pitchers contained more insect carcasses. The bacterial density increased with the age of the pitchers, but decreased in withered pitchers that contained finely decomposed detritus. In live pitchers, the bacterial density, the density, mass and species richness of metazoa, and the number of trophic levels per pitcher were positively correlated with detrital mass, which was correlated with volume of pitcher fluid. The metazoan fauna fromN. alataconsisted of 4 predators and 12 saprophages, among the richest known forNepenthesspecies. However, each individual pitcher harbored a limited numbers of species, owing to (1) the low incidence of many species, and (2) the aggregated distribution and different temporal colonization pattern of major species. Six dipteran taxa (one predator and five saprophages) accounted for the bulk of metazoan inhabitant biomass. Of 48 combinations of predator‐prey encountered, only four occurred frequently (in > 30% of pitchers), which included two predators and three saprophages. Thus, individual pitchers harbored relatively simple communities despite the regional species richness, and only limited kinds of predator‐prey encounters seemed to occur frequently in the regional food web. The local‐scale properties of the subdivided communities presented here provide the basic information for understanding the maintenance of regional species richness and food web complexity.
Before Cattle: A Comparative Floristic Study of Eucalyptus Savanna Grazed by Macropods and Cattle in North Queensland, Australia1
Authors: Fensham R. J. , Skull S. D.
Published: March 2006

Floristic differences between cattle‐grazed and macropod‐grazed sites (protected from domestic stock by enclosure within a Holocene lava flow) were examined in Eucalyptus savanna in north Queensland, Australia. While macropod‐grazed sites have had a lower incidence of fire than the cattle‐grazed sites, it seems probable that grazing impacts per se are the major differences between these treatments. One dominant (Capillipedium parviflorum) and another common (Sehima nervosa) native perennial grass in the macropod‐grazed treatment were not recorded within the cattle‐grazed treatment. There was generally a lower species richness and Shannon‐Weaver diversity of perennial forbs in the cattle‐grazed treatment compared to the macropod‐grazed treatment. There was higher richness, diversity, and abundance of annual grasses in the cattle‐grazed treatment compared to the macropod‐grazed treatment. The relative richness of native and exotic species was not significantly affected by cattle grazing.
Structure of Benthic Diatom Assemblages from a Mangrove Environment in a Mexican Subtropical Lagoon1
Authors: Beltrones David A. Siqueiros , Castrejón Edna Sánchez
Published: March 2006

The taxonomic list and the structure of benthic diatom assemblages occurring in fine sediments (silt and sand) from the mangrove forest of the Balandra lagoon in Baja California Sur, Mexico was determined based on seasonal samplings for one year. Assemblage structure was analyzed using several ecological indices for estimating diversity (H'), dominance (REDI), equitability, and similarity. A total of 230 diatom taxa were identified and include 109 new records for the Baja California peninsula coast. Taxa representative of highly productive and hypersaline environments were common. Assemblages were characterized by a few abundant species and many uncommon or rare taxa. High diatom diversity estimates at all sampling sites during all seasons suggest that diatom assemblages in sediments of the Balandra lagoon represent a quasi‐pristine environment.
Tree Ferns in the Interior and at the Edge of a Mexican Cloud Forest Remnant: Spore Germination and Sporophyte Survival and Establishment1
Authors: Bernabe N. , Williams‐Linera G. , Palacios‐Rios M.
Published: March 2006

The three most common tree fern species in a Mexican montane cloud forest fragment (Alsophila firma, Lophosoria quadripinnata and Sphaeropteris horrida) were selected for laboratory and transplant experiments. The objectives were: (1) to determine the percentage of spore germination and gametophytes producing sporophytes, and (2) to compare early establishment of sporophytes at the edge and in the interior of the forest. Percent spore germination varied between 16 and 86 percent, and the number of gametophytes that produced sporophytes was high (>50%). Survival and growth of sporophytes differed between species and habitats. Survival was greater at the edge than in the forest interior for Lophosoria, but it was similar for Alsophila and Sphaeropteris. Number and length of fronds were higher at the forest edge for individuals of Alsophila and Lophosoria, but not for Sphaeropteris. RGR was higher at the forest edge than in the forest interior for sporophytes of the three species. This study suggests that the forest edge is an appropriate habitat for establishment of Alsophila and Lophosoria, but Sphaeropteris is apparently a forest interior species.
Ecology of Aglaia mackiana (Meliaceae) Seedlings in a New Guinea Rain Forest1
Authors: Mack Andrew L. , Ickes Kalan , Jessen J. Heinrich , Kennedy Brian , Sinclair Ross
Published: March 2006

The large seeds of Aglaia mackiana (Meliaceae) germinate and produce vigorous seedlings under closed canopies or in large gaps. To assess seedling ecology after germination, we measured growth, herbivore damage, and survivorship of seedlings over one year. The sample included shaded seedlings from dispersed seeds, undispersed seeds under parent trees, and seedlings transplanted to gaps. We quantified the light environment using hemispherical canopy photographs taken above seedlings at the beginning and end of the one–year study.

Seedlings transplanted to gaps grew faster and had more leaves, larger total leaf surface area, longer secondary roots, and greater root mass than shaded seedlings. Seedlings in gaps did not differ from shaded seedlings in survivorship or amount of herbivore– and pathogen–caused leaf damage.

The canopy photographs taken one year apart suggest there is a rough equilibrium in closed canopies with slight changes occurring around an average light level. Sites with < 0.06 ISF (a unitless, relative measure of canopy openness or reflected sunlight) tended to remain the same with minor fluctuations toward brighter or darker. Sites with canopy openness > 0.06 ISF tended to close; few gaps grew larger.

Seedlings under parenr trees and seedlings away from parent trees had similar amounts of leaf damage and virtually identical survivorship after 18 months, but seedlings under parent trees had slower growth rates and smaller total leaf surface areas. Dispersal did not strongly benefit seeds via escaping high levels of mortality or comperition around the parent.
Ant‐Homoptera Interactions in a Neotropical Savanna: The Honeydew‐Producing Treehopper,Guayaquila xiphias(Membracidae), and its Associated Ant Fauna onDidymopanax vinosum(Araliaceae)1
Authors: Del‐Claro Kleber , Oliveira Paulo S.
Published: March 2006

We investigate the ant fauna associated with the Neotropical treehopper,Guayaquila xiphias, on shrubs ofDidymopanax vinosumin the cerrado (savanna) of SE Brazil. Treehoppers infested plants at the border of the cerrado almost exclusively and preferably fed near the apical meristem. During the reproductive phase of the host plant, however, the vast majority of the treehoppers aggregated on the inflorescences. We found 21 ant species harvesting honeydew atG. xiphiasaggregations, the most frequent beingCamponotus rufipes, Ectatomma edentatum, C. crassus, andC. renggeri.Such a taxonomic diversity of ants tendingG. xiphiasaggregations in the cerrado is far greater than that reported for any other ant‐homopteran system. Daily turnover of ant species at a given treehopper aggregation was observed on 29 percent (64 out of 222) of theG. xiphiasaggregations recorded onD. vinosumshrubs. Species replacements probably reflect distinct humidity and temperature ranges tolerated by the species, and may ultimately reduce interspecific competition at homopteran aggregations. Since predation and parasitism onG. xiphiascan be severe, and tending ants protect the homopterans against predators and parasitoids, the round‐the‐clock activity by ants atG. xiphiasaggregations is regarded as crucial for the survival of these treehoppers in the cerrado.
Seed Dispersal by Monkeys and the Fate of Dispersed Seeds in a Peruvian Rain Forest1
Authors: Andresen Ellen
Published: March 2006

Primary seed dispersal by two species of monkeys and the effects of rodents and dung beetles on the fate of dispersed seeds are described for a rain forest in southeastern Perú. During the six‐month study period (June–November 1992) spider monkeys (Ateles paniscus) dispersed the seeds of 71 plant species, whereas howler monkeys (Alouatta seniculus) dispersed seeds of 14 species. Spider and howler monkeys also differed greatly in their ranging behavior and defecation patterns, and as a consequence, produced different seed rain patterns. Monkey defecations were visited by 27 species of dung beetles (Scarabaeidae). Dung beetles buried 41 percent of the seeds in the dung, but the number of seeds buried varied greatly, according to seed size. Removal rates of unburied seeds by rodents varied between 63–97 percent after 30 d for 8 plant species. The presence of fecal material increased the percentage of seeds removed by seed predators, but this effect became insignificant with time. Although seed predators found some seeds buried in dung balls (mimicking burial by dung beetles), depth of burial significantly affected the fate of these seeds. Less than 35 percent of Brosimum lactescens seeds buried inside dung balls at a depth of 1 cm remained undiscovered by rodents, whereas at least 75 percent of the seeds escaped rodent detection at a depth of 3 cm and 96 percent escaped at 5 cm. Both dung beetles and rodents greatly affected the fate of seeds dispersed by monkeys. It is thus important to consider postdispersal factors affecting the fate of seeds when assessing the effectiveness of frugivores as seed dispersers.