bluuebunny/crossref_metadata_2025 huggingface dataset:
The Contribution of Ant‐Plant Protection Studies to Our Understanding of Mutualism1
Authors: Bronstein Judith L.
Published: March 2006

One common class of ant‐plant mutualism involves ants that defend plants from natural enemies in return for food and sometimes shelter. Studies of these interactions have played a major role in shaping our broad understanding of mutualism. Their central contribution has come via their development of approaches to measuring the benefits, costs, and net outcomes of mutualism, and their explicit consideration of variability in all of these phenomena. Current research on these interactions is suggesting ecological and evolutionary hypotheses that may be applicable to many other forms of mutualism. It is also generating comparative data for testing the few general theories about mutualism that currently exist.
Density Patterns ofPiperAnt‐Plants and Associated Arthropods: Top‐Predator Trophic Cascades in a Terrestrial System?1
Authors: Letourneau D. K. , Dyer L. A.
Published: March 2006

Top‐predator (fourth‐trophic‐level) controlled trophic cascades are thought to be uncommon in terrestrial systems, but actual quantitative tests and comparisons of bottom‐up and top‐down forces in systems with more than three linear trophic levels are rare. Here, we describe the density patterns of the arthropod community associated withPiperant‐plants in Costa Rican wet forests. Consumers in this community comprise a complex, interacting web of herbivores, predaceous ants, and predators of ants. Although the hollow stems and petioles of thePiperplants provide some protection to resident ants from predation, specializedDipoenaspiders andPhyllobaenusbeetles exploitPheidoleants inhabitingPiperplants. We report abundance patterns of plants, ants and predators in four forests. These patterns of abundance are consistent with predictions of top‐down cascades across four trophic levels when the top predators are effective (beetles). We discuss how top‐down and bottom‐up forces may interact in systems with less effective top predators (spiders).
Interactions between Fungus‐Growing Ants (Attini), Fruits and Seeds in Cerrado Vegetation in Southeast Brazil1
Authors: Leal Inara R. , Oliveira Paulo S.
Published: March 2006

We surveyed the material collected for fungus culturing by attine ants in the cerrado vegetation of southeast Brazil. Six genera of the so‐called lower attines (Cyphomyrmex, Mycetarotes, Mycocepurus, Myrmicocrypta, SericomyrmexandTrachymyrmex) collect a wide variety of plant material as fungal substrate. Plant diaspores of nonmyrmecochorous species comprise a large portion of the items brought to the nest, especially in the rainy season. Removal experiments using fruits of selected plant species revealed that attine ants (including the leaf‐cuttersAttaandAcromyrmex) not only actively clean the seeds (remove fruit pulp), but also carry them up to 12 m in the cerrado. Germination tests showed that removal of fruit pulp by attine ants increases germination rate inOcotea pulchella(Lauraceae),Prunus sellowii(Rosaceae),Ouratea spectabilis(Ochnaceae),Rapanea umbellata(Myrsinaceae) andPsychotria stachyoides(Rubiaceae). ForP. stachyoides, however, ants had no effect on germination if seeds had already passed the digestive tract of birds. Aril removal by attines also increases germination success ofCopaifera langsdorffii(Leguminosae) andVirola sebifera(Myristicaceae) seeds. The results indicate that attine‐fruit/seed interactions are particularly conspicuous in the cerrado, suggesting that fungus‐growing ants may play a relevant role in fruit/seed biology in this vegetation type. Potential ant‐derived benefits to diaspores of nonmyrmecochorous plants in the cerrado would include secondary seed dispersion and/or increased germination success by ant‐handled seeds.
Geographical and Seasonal Variation in the Richness of Ant‐Plant Interactions in México1
Authors: Rico‐Gray Victor , García‐Franco José G. , Palacios‐Rios Mónica , íz‐Castelazo Cecilia , Parra‐Tabla Victor , Navarro Jorge A.
Published: March 2006

The richness and seasonal variation of ant‐plant interactions were compared in four habitats in México: lowland tropical dry forest (La Mancha, Veracruz), coastal sand dune matorral (San Benito, Yucatán), semiarid highland vegetation (Zapotitlán, Puebla), and lower montane humid forest (Xalapa, Veracruz). The effects of temperature and precipitation on the seasonal distribution of the number of ant‐plant interactions differed among habitats. The general linear models fitted to the ant‐plant interaction curves explained 78.8 percent of the variation for La Mancha, 80.1 percent for Zapotitlán, 18 percent for San Benito, and 29.5 percent for Xalapa. Even though rainfall is low in Zapotitlán and San Benito, minimum temperature was the most important factor accounting for the seasonal distribution and low number of interactions. At La Mancha, with milder minimum temperatures and higher water availability, temperature alone did not account for the seasonal distribution and number of interactions, whereas the effect of the precipitation × temperature interaction was highly significant. Xalapa exhibits the lowest temperatures and the highest precipitation, but the role of these factors was only marginal. We suggest that the vegetation at Xalapa, a mixture of tropical and temperate floristic elements, constrains ant‐plant interactions due to a limited presence of nectaries. Also, ants are less abundant in cool and relatively aseasonal habitats. The other habitats have tropical floristic elements that are abundant and frequently have nectar‐producing structures. We report considerable variation among habitats in the number and seasonal distribution of ant‐plant interactions, and suggest that it is due to the effect of variation in environmental parameters, the richness of plants with nectaries in the vegetation, and habitat heterogeneity.
Spatial and Temporal Variation in the Ant Occupants of a Facultative Ant‐Plant1
Authors: Alonso Leeanne E.
Published: March 2006

Striking variation in ant occupation of a facultative ant‐plant,Conostegia setosa(Melastomataceae), was found at three scales: local spatial, geographic, and temporal.C. setosaprovides housing for ants and grows in groups of stems (clones). The ant occupants of 14C. setosaclones were censused four times over a 14‐mo period at the La Selva Biological Station, Costa Rica, and twice over a 9‐mo period at the Nusagandi Station, Panama. Twelve facultative ant species occupiedC. setosastems at La Selva, compared to six facultative and one obligate species at Nusagandi. Occupancy (as % of stems ever occupied/clone) was higher at Nusagandi (median = 89%) compared to La Selva (65%). Occupancy varied among clones at La Selva but not at Nusagandi.C. setosaclones differed between sites, with larger clones and more small stems/clone at La Selva. Occupancy was influenced by clone structure; larger clones contained more ant species at both sites and had lower occupancy at La Selva. Occupancy was highest in larger stems and lowest in small stems at both sites. Temporally, percent occupation/clone did not differ among censuses at either site, but overall occupancy was lower in the dry season at La Selva. Turnover in ant occupants was higher at La Selva than at Nusagandi. The variation observed in this study is likely due to a number of factors, including differences between sites in plant population structure and history, differences between and within sites in ant faunas and their nesting requirements, and changes over space and time in microclimatic variables. Such high variation at multiple scales draws attention to the importance of long‐term comparative studies of facultative animal‐plant interactions.
Species Richness, Spatial Variation, and Abundance of the Soil Seed Bank of a Secondary Tropical Rain Forest1
Authors: Butler Brett J. , Chazdon Robin L.
Published: March 2006

Despite the importance of the soil seed bank in tropical forest regeneration, little is known about spatial variability in species composition and abundance of seeds stored in the soil. To develop sampling methods for comparative studies, we examined species richness, spatial variation, and abundance of germinants from the soil seed bank in a 16 year old secondary, tropical wet forest at La Selva Biological Station, Costa Rica. Surface soil (10 cm deep, 4.7 cm diameter) was collected at the intersection points of a gridded 1 ha plot (10 × 10‐m grid, 121 samples) and in a nested 100 m2 subplot (2 × 2‐m grid, 36 samples). The 1 ha plot had a density of 4535 seeds/m2 with 34 species observed. Based on a series of 100 randomized species accumulation curves, a Michaelis‐Menten fit predicted a mean species richness of 36.3 species; the number of observed species was close to the predicted asymptote. A nonparametric, first‐order jackknife species richness estimator predicted a species richness of 37.0 species. Eighty‐five and 95 percent of the observed species richness is contained, on average, within 41 and 74 pooled samples, respectively. Within the 100 m2 nested subplot, a density of 5476 seeds/m2 was observed, comprising 26 species with an estimated species richness (Michaelis‐Menten fit) of 29.1 species. The jackknife species richness estimator predicted a species richness of 36.7 species. For species richness and abundance of both plots, spatial autocorrelation statistics (Moran's I) were not significantly different from zero at lag distances from 2 to 100 m, indicating a random distribution at these spatial scales. For this site, accurate estimates of species composition depend upon the number of samples collected as well as the spatial distribution of sampling effort. Many small samples distributed over a large area provide greater accuracy and precision for estimating species richness of the soil seed bank.
Long‐Term Effects of Forest Regrowth and Selective Logging on the Seed Bank of Tropical Forests in NE Costa Rica1.
Authors: Dupuy Juan M. , Chazdon Robin L.
Published: March 2006

To investigate long‐term effects of land use on the soil seed bank, we compared the abundance/density, species richness, life form distribution, and species composition of seeds stored in the soil of four 15–20 yr‐old second‐growth stands, two old‐growth stands, and two previously selectively‐logged stands in the Caribbean lowlands of Costa Rica. Surface soil (10 cm deep, 4.7 cm diameter) was collected at 10 m intervals along three 120–160 m long transects in each stand (44–48 soil cores, 22–24 combined seed bank samples per site). Seed density was highest but variable in second‐growth stands (8331–14535 seeds/m2), low and homogeneous in old‐growth stands (2258–2659 seeds/m2), and intermediate and highly variable in selectively‐logged stands (1165–6854 seeds/m2), which also had contrasting logging intensities. Species richness was strongly dependent on seed density, but showed less variation. Life form distribution did not differ statistically among or within land‐use categories. In each stand, herbs‐forbs, shrubs, and vines dominated the seed bank (> 75% of the species richness and abundance), whereas trees were a minor component (< 20% of the species richness and < 5% of the abundance) and were predominandy early successional. Shrubs and vines were most abundant in second‐growth stands where regrowth vegetation was repeatedly cut before abandonment, whereas grasses and sedges were most abundant in the only forest stand that was completely surrounded by pastures. In terms of species composition, old‐growth stands were more similar to selectively‐logged stands than to second‐growth stands, but across stands, selectively‐logged forests were most distinct from the other two forest types. An inventory of the standing woody vegetation in each site showed little representation of the woody taxa found in the seed bank. We discuss these results in the context of the main factors that have been postulated to influence the abundance, life form, and species composition of tropical forest seed banks, and explore the role of the latter during intermediate phases of tropical forest succession and regeneration.
Typhoon Disturbance and Stand‐level Damage Patterns at a Subtropical Forest in Taiwan1
Authors: Mabry Catherine M. , Hamburg Steven P. , Lin Teng‐Chiu , Horng Fu‐Wen , King Hen‐Biau , Hsia Yue‐Joe
Published: March 2006

We examined the typhoon wind disturbance regime of the Fu‐Shan Experimental Forest in northeastern Taiwan. Mean number of typhoons passing within 200 kilometers of Taipei (40 kilometers from the site) was 1.4 per year. Category 4 and 5 typhoons, which are intense enough to uproot large numbers of trees, occurred every 8.3 and 12.5 years respectively, although it is likely that some category 4 and 5 typhoons did not produce extensive blowdowns at Fu‐Shan because the area of maximum winds missed the study site. Uprooting was more common than snapped boles; the most common damage to trees, however, was probably defoliation, although this damage was not quantified in the current study. Thirty‐five percent of wind‐damaged trees were associated with a gap. Six percent of the land area was in gaps. Canopy turnover time was calculated at 175 years when all gaps ≤ 9 years old were included in the calculation, but the time decreased when older gaps were excluded from the calculation. Turnover time was somewhat higher than calculated for other tropical forests. Because turnover time increases as the percent of land in gaps decreases, the short life span of gaps at Fu‐Shan probably contributed to our higher calculated time. Probability of being damaged was not related to tree species identity, and only a few species of trees were found regenerating in gaps. Principal Components Analysis indicated that damaged trees varied largely in treefall orientation and aspect; gaps varied primarily in aspect and in gap size.
Caractérisation d'une Mosaïque Forestière et de sa Dynamique en Forêt Tropicale Humide Sempervirente1
Authors: Riéra Bernard , Pélissier Raphaël , Houllier François
Published: March 2006

RESUMÉ

Une typologie des unités de la mosaïs forestière (quadrats de 5 × 5 m) d'un transect de forêt naturelle de Guyane française (0,78 ha) est proposée à partir de I'analyse de la distribution en trois classes de diamètre des arbres ≥5 cm DBH. Elle permet d'identifier neuf types structuraux élémentaries qui s'organisent en une séquence de stades de développement potentiels correspondant à la colonisation des ouvertures, puis au remplissage progressif de I'espace vertical divisé en trois strates. A partir de relevés réalisés à 10 ans d'intervalle (1981 et 1991), la matrice de transition, qui résume les flux de quadrats d'un type vers un autre entre les deux inventaires, permet de discuter de l'évolution de la mosaïque forestière.
The Polarization of Light in a Tropical Rain Forest1
Authors: Shashar N. , Cronin T. W. , Wolff L. B. , Condon M. A.
Published: March 2006

The light environment within forests presents complex patterns of brightness and spectral distribution of light. The polarized light field is no less complex. Using an imaging polarized light analyzer, we examined the natural fields of linearly polarized light in the tropical rain forest of Guatopo National Park, Venezuela. We found that the celestial polarization pattern remains visible underneath the forest canopy, although cloud and fog coverage may diffuse the light and reduce the polarization signal. We characterized several distinct light environments, each having a characteristic polarized light field. Furthermore, objects throughout the forest reflect light that is polarized in a predictable fashion depending upon the material, structure, and orientation of the reflecting surface. As a consequence of these patterns in the distribution of polarized light, some functions of polarization vision, such as navigation, must be limited to the spaces exposed to several extended portions of the sky, while others, such as remote sensing of surface orientation, object detection, and breaking of camouflage would be useful throughout the forest. The polarization of light adds another dimension to the complexity of the rain forest photic environment.
Tree Mortality and Collecting Botanical Vouchers in Tropical Forests1
Authors: Phillips O. L. , Nuñez V. P. , Timaná M. E.
Published: March 2006

There is growing concern about the potential impact of reseatchers on tropical forest ecology, but few data. The aim of this paper is to examine the effects of collecting botanical specimens from tropical forest trees on their subsequent survivorship, using mortality data from plots in Amazonian Peru that were established in 1989 and reinventoried in 1994. In total, 2017 trees were originally tagged and collections were made from 948 trees. Making voucher collections always involved using unsterilized telescopic plant collecting poles to cut representative small branches, and sometimes also involved using iron‐spiked tree‐climbing gear to gain access to the canopy. Annual mortality in the four plots averaged 1.99 percent. Among the whole population of dicotyledenous trees, there was no detectable difference between the mortality rate of collected trees (1.96%) and noncollected trees (2.29%). We conclude that in spite of the physical damage caused to collected trees, collecting voucher specimens from tropical moist forest trees may not affect their survivorship, at least in the short‐term. Further studies are needed to fully evaluate the potential impacts of research activities on petmanent forest plots in the tropics.
Interspecific Territoriality by a Rufous‐Tailed Hummingbird (Amazilia tzacatl): Effects of Intruder Size and Resource Value1
Authors: Dearborn Donald C.
Published: March 2006

I studied two aspects of interspecific territoriality in a Costa Rican nectarivorous bird, the rufous‐tailed hummingbird (Amazilia tzacatl). First, I examined variation in the response of the territory holder to four species of intruding hummingbirds by quantifying the proportion of intruders chased from the territory. This measure of territory defense varied significantly among species of intruders and was negatively related to the intruding species’body mass, possibly due to potential costs associated with becoming involved in escalated contests with larger individuals. Second, I tested for an effect of resource manipulation on territory defense. I increased the resource value of the territory by injecting extant natural flowers with artificial sucrose solution. While the frequency of territorial intrusions did not change, the proportion of intruders chased by the territory holder increased. Apparently, nectar supplementation changed the territory holder's perception of resource value but had little impact on the intruders’perception.
Emergence, Echolocation, Diet and Foraging Behavior of Molossus ater (Chiroptera: Molossidae)1
Authors: Fenton M. B. , Rautenbach I. L. , Rydell J. , Arita H. T. , Ortega J. , Bouchard S. , Hovorka M. D. , Lim B. , Odgren E. , Portfors C. V. , Scully W. M. , Syme D. M. , Vonhof M. J.
Published: March 2006

Between 4 and 16 January 1996, during a period of cool weather, we studied the emergence and foraging behavior of Molossus ater at a site near Akumal, in the Yucatan Peninsula in Mexico. The bats, a colony of at least 32 individuals, roosted in a north‐facing cinder block wall, and emerged about sunset. Emerging bats were usually clustered in time, while those returning usually were not. Radio‐tracking revealed that the bats foraged for short periods (mean 26.8 min) and captures of returning individuals indicated that 27 of 28 had fed, taking, on average, 4.4 g of insects, mainly hydrophilid beetles. On some nights, few or none of the radio‐tagged bats emerged from the roost. Calculations concerning the costs of flight and roosting show that they were more than covered by the energy intake the bats achieved. Molossus ater have high aspect ratio (8.3–9.1) wings and high wing‐loadings of 17.55–24.15 N/m2. When searching for prey, these bats produce long (12.3 ms), narrowband(3.8 kHz), echolocation calls that sweep from 27.6–23.8 kHz. Energy was not limiting for these bats at the time of our study.
Wood Volume, Foliar Chemical Composition, and Soil Nitrogen Turn Over of Metrosideros polymorpha (Myrtaceae) Stands on a Slope of Mount Haleakala, Hawaii1
Authors: Kitayama Kanehiro , Raitio Hannu , Mueller‐Dombois Dieter , Schuur Edward A. G.
Published: March 2006

An earlier study suggested that soils on the windward slope of Mount Haleakala are excessively waterlogged at low altitudes but become better drained upslope. We analyzed altitudinal changes in soil N turn over, vegetation mass, and foliar chemical composition of the dominant canopy species, Metrosideros polymorpha (Myrtaceae), on this slope. The basal areas and DBH2× height (an index for volume) of woody species ≥2 m in height increased with altitude (as opposed to a general trend elsewhere), peaked at 1800 m elev., and abruptly declined above this altitude. Foliar N and P concentrations of Metrosideros showed a similar altitudinal trend with DBH2× height values. Foliar Fe and Al concentrations steadily increased downslope, but were low again at 450 m, the lowest altitude, contrary to expectation based on waterlogging. Toxic forms of Fe and Al may retard root penetration in waterlogged soils and thus the uptake of these elements. The net N mineralization rate for topsoils incubated in situ was 78.6 μg/g/20d at 1800 m elev., while small amounts of N were immobilized at 450, 1200 and 2200 m elev. The net N mineralization rates of the topsoils, which were air‐dried to their permanent wilting points and incubated at 26°C, were greater than those of the wet samples at 26°C, only for the lowest altitude. Conversely, the net N mineralization rates of the topsoils which were kept wet and incubated at the higher temperature of 26°C were greater (P < 0.1) than those of the in situ wet samples only for 1800 m elev. The rates were the same for 450 and 2200 m elev. where the soils were waterlogged and very dry, respectively; thus, N turn over was more strongly limited by moisture than by temperature in these cases. Nutrient availability improved with altitude up to 1800 m elev. in association with the moisture gradient, and appeared to be responsible for the observed pattern in vegetation mass.
A Flood Plain Palm Forest in the Luquillo Mountains of Puerto Rico Five Years After Hurricane Hugo1
Authors: Frangi Jorge L. , Lugo Ariel E.
Published: March 2006

Long‐term studies are needed to understand the dynamics of tropical forests, particularly those subject to periodic disturbances such as hurricanes. We studied a flood plain Prestoea montana palm forest in the Luquillo Mountains of Puerto Rico over a 15‐yr period (1980–1995), which included the passage of Hurricane Hugo in September 1989. The passage of the hurricane caused the dominant species to become more dominant and created low instantaneous tree mortality (1% of stems) and reductions in tree biomass (‐16 Mg/ha/yr) and density, although not in basal area. Five years after the hurricane, the palm flood plain forest had exceeded its prehurricane aboveground tree biomass, tree density, and basal area. Aboveground tree biomass accumulated at a rate of 9.2 Mg/ha/yr, 76 percent of which was due to palms. Before the hurricane this rate was on the order of 3 Mg/ha/yr. Forest floor litter decreased to prehurricane levels (6.7 Mg/ha), within 5 yr, mostly due to the disappearance of woody litter. Thirteen tree species not represented in the canopy entered the forest by regeneration, and 2 species suffered almost 20 percent/yr mortality over a 5‐yr period after the storm (floodplain average of 2%/yr). Delayed tree mortality was twice as high as instantaneous tree mortality after the storm and affected dicotyledonous trees more than it did palms. Regencration of dicotyledonous trees, palms, and tree ferns was influenced by a combination of factors including hydroperiod, light, and space. Redundancy Data Analysis showed that the area near the river channel was the most favorable for plant regeneration. Palm regeneration was higher in locations with longer hydroperiods, while regeneration of dicotyledonous trees was higher in areas with low risk of flooding. This study shows how a periodic disturbance provides long‐term opportunities for species invasions and long‐term ecosystem response at the patch scale of < 1 ha.
Seasonal Foliage Changes in the Eastern Amazon Basin Detected from Landsat Thematic Mapper Satellite Images1
Authors: Bohlman Stephanie A. , Adams John B. , Smith Milton O. , Peterson David L.
Published: March 2006

Seasonal changes in tropical forests are difficult to measure from the ground, especially in areas of high species diversity and low phenological synchrony. Satellite images, which integrate individual tree canopies and cover a large spatial extent, facilitate tests for stand‐level canopy phenology. Variability in near‐infrated radiance (TM bands 4 and 5) of several distinct vegetation types was used to detect seasonal changes in a series of three Landsat Thematic Mapper (TM) images from the wet season to the dry season in Marabá, Brazil (eastern Amazon basin). Despite different atmospheric and instrumental conditions among the images, spectral changes were distinguishable. A phenological process (leaf aging, leaf drop, water stress) was determined from the spectral changes for each vegetation type. Changes in the spectral properties suggest that during the dry season, upland terra firme forest increased the rate of leaf exchange and some riparian vegetation was deciduous. Terra firme forest that had been altered by penetration of fires from nearby pastures increased in leaf biomass over a 14‐month period. This study shows that a time series of images can provide information on temporal changes in primary vegetation and guide field studies to investigate seasonal changes that may not be detectable from the ground.
Frugivory and Seed Dispersal by Four Species of Primates in Madagascar's Eastern Rain Forest1
Authors: Dew J. Lawrence , Wright Patricia
Published: March 2006

In the unique faunal assemblage of the Malagasy rain forest, lemurs appear to play particularly important roles as seed‐dispersing frugivores. A three‐month study of feeding ecology and seed dispersal by four species of lemurs in Madagascar's eastern rain forest found that three species, Eulemur rubriventer, Eulemur fulvus, and Varecia variegata were seed dispersers, and the fourth, Propithecus diadema, was a seed predator. In germination trials, seeds passed by lemurs sprouted significantly faster and in greater numbers than those not passed by lemurs. Analysis of fruit morphologies of 69 local plant taxa producing fleshy fruits during the study period found that these fruits fell into two well‐defined color categories that correlated significantly with fruit size. Seventy seven percent of fleshy fruits greater than 10 mm in diameter were colored green, brown, tan, purplish, or black, while all fruits less than 10 mm in diameter were colored red, yellow, orange, pink, blue, or white. Three introduced exotic plant species provided exceptions to this pattern, producing fruits which were larger than 10 mm and pink or orange. Fruits chosen by the primates in this study were usually larger than 10 mm in diameter and were in nearly all cases colored green, brown, tan, purplish, red, or some combination of these colors. Morphological traits shared by fruits of multiple plant taxa in the diets of seed‐dispersing lemurs suggest possible coevolved relationships between Malagasy rain forest plants and lemurs.
Thrips Cross‐Pollination ofPopowia pisocarpa(Annonaceae) in a Lowland Dipterocarp Forest in Sarawak1
Authors: Momose Kuniyasu , Nagamitsu Teruyoshi , Inoue Tamiji
Published: March 2006

This paper reports thrips (Thysanoptera) cross‐pollination in the primitive angiosperm,Popowia pisocarpa(Annonaceae), in lowland rain forest of Sarawak, Malaysia. Flowers ofP. pisocarpahave a tiny pollination chamber (3–4 mm in depth) with the entrance almost closed by the disk‐shaped stigmatic heads, allowing only small insects to enter. Experiments showed that thrips were effective pollinators and flowers ofP. pisocarpawere self‐incompatible. Seed set was limited by pollen. Clumped adult trees had higher seed‐set than more distant individuals (>5 m from nearest flowering neighbor), indicating limited inter‐tree movement by thrips.
Home Range and Movement Patterns of White‐lipped Peccary (Tayassu pecari) Herds in the Northern Brazilian Amazon1
Authors: Fragoso José M. V.
Published: March 2006

Two white‐lipped peccary (Tayassu pecari) herds were radio‐tracked for 5 and 13 mo, respectively, on Maracá Island Ecological Reserve, Roraima, Brazil. Home range size was 109.6 km2 for the larger herd (130 animals) and 21.8 km2 for the smaller herd (53 animals). Neither herd migrated or moved nomadically during the study period. The herd with the longer observation period increased its home range size during the flooded season by including new sites not used in the nonflooded season and continuing to use the nonflooded season sites. This pattern of simultancously using distinct seasonal ranges also occurred between the rainy and dry periods and the herd regularly and predictably returned to favored feeding sites. Population declines and disappearances in this study and others may have been caused by in situ mortality rather than by long‐distance movements.
Structure and Composition of One Hectare of Central Amazonian Terra Firme Forest1
Authors: Milliken William
Published: March 2006

The trees, vines, and stranglers ≥10 cm in diameter in 1 ha of terra firme forest in Amazonas State, Brazil, were measured and identified. The plot contained 645 trees representing 201 species, 95 genera, and 34 families (basal area ca 31 m2); 16 vines representing 14 species, 13 genera, and 8 families; and 1 strangler. The dominant families of trees present were the Leguminosae (sensu latu), Lecythidaceae, Sapotaceae, Burseraceae, and Moraceae; the dominant species were Clathrotropis macrocarpa (Leguminosae), Eschweilera coriacea (Lecythidaceae), and Protium hebetatum (Burseraceae). In terms of structure, diversity, and floristic composition, this plot is reasonably typical of the terra firme forests in the central Amazon, as far as this diverse biota can be typified.
Growth and Reproduction in Forest Trees of the Cactus Opuntia excelsa1
Authors: Bullock Stephen H. , Martijena Nora E.
Published: March 2006

In southwestern México, the number of new cladodes on Opuntia excelsa was a skewed bell‐shaped function of size (“size” being the number of cladodes persisting from previous years). Fruit number was a sigmoidal function of size, but the number of seeds per fruit was independent of number of fruits per plant. The curves for production of new cladodes and of fruits both showed maximum increase for plants with 150–350 cladodes, when the crowns were reaching or in the canopy. New cladode production declined at about the size where reproduction plateaued; we suggest this was due to limitation of crown dimensions by mechanical and physiological factors.
The Fecundity, Seed, and Seedling Ecology of the Edible PalmEuterpe edulisin Southeastern Brazil1
Authors: Matos D. M. Silva , Watkinson A. R.
Published: March 2006

Euterpe edulisflowers at the beginning of the wet season and fruits over an extended period during the end of the wet season and the dry season. Reproductive plants produced an average ofca1500 fruits within a season. Five species of birds belonging to the family Turdidae were observed to feed on and disperse the fruits. Most seeds fell directly to the ground, where there was some subsequent local dispersal by water. The dispersion of seeds was highly clumped with most seeds being found in close proximity to adult plants; the distance of dispersal could be described by a negative power curve. Germination was higher on wetter soils. The probability of seedlings advancing to the next size class within a year was inversely related to the density of seedlings, and occurred optimally atca4 m from adult plants. The latter observation indicates that the survival and growth of seedlings are suppressed in the immediate vicinity of conspecific adults.
An Advantage of Large Seed Size: Tolerating Rather than Succumbing to Seed Predators1
Authors: Mack Andrew L.
Published: March 2006

Although large seeds might be more attractive and apparent to seed predators, large seed size could enable tolerance of seed predators. If seeds are large enough to sustain damage that would kill smaller seeds yet still produce viable seedlings, investment above the minimum by the maternal plant could be advantageous. I tested this hypothesis by removing 0–80 percent of the cotyledons of four large‐seeded (4–180 g) tree species from Papua New Guinea and monitoring germination and seedling growth for eight months. All species showed little negative effect on seedling size with up to 50 percent removal of cotyledons and the larger species showed a less serious effect on growth than smaller‐seeded species above 50 percent removal. Large‐seeded species clearly have more than the minimum‐required cotyledonary reserves. Observations of viable seedlings with heavily damaged cotyledons suggest that these species withstand attack by rodents and beetles by virtue of their large size.
Dictyostelid Cellular Slime Molds in Canopy Soils of Tropical Forests1
Authors: Stephenson Steven L. , Landolt John C.
Published: March 2006

The occurrence and distribution of dictyostelid cellular slime molds (CSM) in the mantle of dead organic matter (literally a “canopy soil”) at the bases of large epiphytes were studied in the Luquillo Experimental Forest of north‐eastern Puerto Rico. CSM were isolated from 18 of 50 samples collected from this microhabitat, and four different species were recovered. Dictyostelium purpureum was the single most abundant species and represented almost half (48%) of all clones isolated during the study. Total densities (clones/g) averaged only 38 in the five forest types examined, but densities > 75 were recorded for two forest types. Relative abundance of CSM in canopy soils of the five forest types followed the same general pattern displayed by these organisms in forest floor litter, but a particular species was not necessarily common to both microhabitats in a given forest type.
Soil Characteristics and Vegetation Structure in a Heavily Deteriorated Mangrove Forest in the Caribbean Coast of Colombia
Authors: Cardona Pablo , Botero Leonor
Published: March 2006

Mass mortality and biomass of mangrove trees are related to soil factors in the Caribbean Coast of Colombia. Soil properties measured were particle size distribution, bulk density, organic matter, total nitrogen, total phosphorus, pH, redox potential, salinity, and extractable nitrogen (NO2, NO3, NH4) and phosphorus (PO4). Sampling was performed at three locations along two 50 m transects at each site. Soil nutrient concentrations of either exchangeable nitrogen or phosphorus were comparable to other reported values. Redox potentials (Eh) were variable probably due to microtopographic conditions and to the amount of water and organic matter present in the soil. Hydrogen potentials (pH) are within the range reported as normal for mangrove soils. Locations with highest biomass had an average soil salinity of 35 with a range of 20 to 53. Sites with dead or dwarfed vegetation had an average soil salinity of 74 and minimum and maximum values observed were 52 and 100 respectively. Statistical analysis exhibited temporal and spatial differences in soil salinity and suggest that this parameter is most correlated to the development and distribution of mangrove vegetation in the area indicating that basal area and biomass volume are inversely correlated with soil salinity.
Cannibalistic Interactions Resulting from Indiscriminate Predatory Behavior in Tadpoles of Poison Frogs (Anura: Dendrobatidae)1
Authors: Caldwell Janalee P. , de Araújo Maria Carmozina
Published: March 2006

Poison frogs in the genusDendrobateshave very small clutch sizes (2–6 eggs among species for which there are data) and typically transport their tadpoles singly to small phytotelmata, such as bromeliad tanks, leaf axils, fallen fruit capsules, and treeholes. Tadpoles of many species are predaceous, consuming larvae of insects that use the same microhabitat for breeding, such as giant damselflies and mosquitoes. Previous studies and observations on the behavior of poison frog tadpoles led us to question whether tadpoles might be cannibalistic. We studied a population ofDendrobates castaneoticusin lowland rainforest in Pará, Brazil; additional data were collected onDendrobates auratusin Nicaragua. At the study site in Brazil, we established a grid of 40 Brazil nut capsules, the microhabitat used byD. castaneoticusfor tadpole deposition. Of 42 tadpoles deposited during the 55 days of the study, 20 were killed or died; 16 of these were presumably killed by conspecific tadpoles. Growth rate and time to metamorphosis was higher among tadpoles that consumed three or more tadpoles or relatively large larvae of the mosquitoTrichoprosopon digitatum, a colonist of newly opened Brazil nut capsules. We propose that selection has favored the development of predatory behavior in poison frog tadpoles primarily as a mechanism to eliminate predators from the small phytotelmata in which they develop and that cannibalism is a secondary outcome of this behavior. Predatory behavior also provides tadpoles with a source of food, which is frequently limited in these microhabitats. Additional studies of the biology of tadpoles of other species ofDendrobatesare needed to determine the evolution of predatory and cannibalistic behavior in the clade.
Patterns of Genetic Population Differentiation in Four Species of Amazonian Frogs: A Test of the Riverine Barrier Hypothesis1
Authors: Gascon Claude , Lougheed Stephen C. , Bogart James P.
Published: March 2006

Patterns and levels of allozyme variation among populations of Amazonian frogs were used to test the riverine barrier hypothesis of species differentiation. Two frog species were sampled from each of the two main forest habitats on both banks of the Juruá River in the southwestern Brazilian Amazon Basin at various points along its course to contrast different barrier strengths.Scarthyla ostinodactylaandScinax rubrawere sampled from flooded forest (varzea), andPhysalaemus petersiandEpipedobates femoralisfrom non‐flooded forest (terra firme). All species showed high levels of within‐population genetic variation. Average Nei's (1978) and Rogers’ (1972) genetic distances between sampled sites for all species were high indicating substantial among‐population differentiation. The observation of low gene flow between sampled sites within species was further substantiated with Slatkin's (1993) M̂ analyses. Randomization tests suggested that there was some population structure at a few assayed polymorphic loci that was consistent with the riverine barrier hypothesis. However, it was apparent from the raw allozyme frequency data that these results were largely driven by substantial differentiation at one or a few collecting localities rather than by basin‐wide patterns of riverine differentiation. Phenograms using genetic distance matrices supported this interpretation. Patterns of geographic variation are probably more consistent with the idea of this region being a zone of secondary contact.
Biology of the Mongoose (Herpestes javanicus) in a Rain Forest of Puerto Rico1
Authors: Vilella Francisco J.
Published: March 2006

Ecological aspects of the mongoose (Herpestes javanicus) were studied in the Luquillo Mountains, a rain forest region in eastern Puerto Rico. Information was obtained by removal trapping of mongoose from grids placed in tree plantations, colorado and tabonuco forests. Trapping efficiency was two mongoose per 100 trap‐days, suggesting mongoose abundance is low in wet montane forests of Puerto Rico. Sex ratio was biased (2.6:1) in favor of males. Body masses of male mongoose inhabiting rain forests of the Luquillo Mountains were larger than those in dry forests at Guánica (P < 0.0001). Stomach contents from 18 mongoose were examined, animal matter comprised 75 percent of the total food items encountered. Of these, 33 percent were from vertebrates. The food items most frequently encountered were lizards (Anolis spp.), centipedes (Scolopendra spp.), and cockroaches (Blatellidae).
Abundance and Distribution of Native and Alien Grasses in a “Cerrado” (Brazilian Savanna) Biological Reserve1
Authors: Pivello V. R. , Carvalho V. M. C. , Lopes P. F. , Peccinini A. A. , Rosso S.
Published: March 2006

Several species of African grasses brought to Brazil as cattle forage have spread widely, outcompeting native herb species. The open forms of Brazilian savanna (“campo cerrado” and “campo sujo”) are the most affected by such invasions, because their structure is open, permitting enough sunlight into the lower strata. The invasion of alien forage grasses occurs in almost every cerrado nature reserve. This study was carried out in the “Cerrado de Hmas Biological Reserve”, Pirassununga, São Paulo State, Brazil, with the following objectives: (a) to compare the abundance of native and alien grass species; (b) to verify the importance of such alien grasses in the community; (c) to identity distribution patterns for the alien grass species in a gradient from the edge (highly disturbed) to the center (less disturbed) of the reserve; and (d) to explore the distribution of native and alien grasses in the search for possible competitive interactions. Using the “point method,” a total of 260 points was sampled and 52 species were recorded. The four most frequent species (FA = absolute frequency) were two native (Echinolaena inflexa [Poir.J Chase [FA = 38.85%] and Diandrostachya chrysotrix [Nees] Jacues Felix [FA = 15.38%]) and two alien African species (Melinis minutiflora Beauv. [FA = 33.08%] and Brachiaria decumbens Stapf [FA = 13.85%]). M. minutiflora and E. inflexa had higher values of absolute vigor (67.69 and 59.62%, respectively), relative vigor (28.16 and 24.80%, respectively), and cover (100.77 and 98.47, respectively), indicating higher biomasses and densities and their dominance in the community. B. decumbens presented the highest number of contacts per point, showing the highest stratification. To detect possible edge–center distribution gradients, correspondence analysis was done, initially using all the recorded species and subsequently only the four more frequent grasses, with similar results: (a) the alien grasses, especially M. minutiflora, did not show a distinct distribution gradient from edge to center, but occurred over the whole reserve; (b) no distinct ecotonal band around the reserve (edge–belt) was detected, the whole reserve seeming to be “ecotonal”; and (c) E. inflexa and M. minutiflora showed similar phytosociological patterns, and spatial distribution; association between these two species was statistically significant.
Litter Interception on Astrocaryum mexicanum Liebm. (Palmae) in a Tropical Rain Forest1
Authors: Alvarez‐Sánchez J. , Guevara S.
Published: March 2006

The goal of this study was to quantify litter interception onAstrocaryum mexicanumLiebm., an abundant and efficient litter–capturing palm. The study was done in a forest at Los Tuxtlas, Veracruz, on the Gulf of Mexico coast. Palms were randomly selected and total litter retention was quantified by determining dry weight over two years. Litter interception by palms was 4.4 and 27.1 Mg/ha/yr for the first and second years, respectively, and accounted for 47.9 and 239.4 percent of the reported annual litterfall in the same area. Results showed that litter interception by plants is related to litterfall and should therefore be added to total litterfall in order to calculate the net primary productivity.
Root Architecture and Root:Shoot Allocation of Shrubs and Saplings in Two Lowland Tropical Forests: Implications for Life‐Form Composition1
Authors: Becker Peter , Sharbini Norhartini , Yahya Razali
Published: March 2006

Entire root systems of saplings of five canopy species and of six shrub and treelet species growing in lowland mixed dipterocarp forest at Andulau, Brunei were excavated and measured. Referring to a prior study at Gigante, Panama, two‐way, fixed‐factor ANOVAs were used to compare life–forms and sites. Rooting depth and the proportion of root surface area in the upper 20 cm of soil did not differ significantly between life‐forms because some treelets/shrubs at Andulau were deep‐rooted; all saplings studied were deep‐rooted. The root:leaf area ratios of both saplings and treelets/ shrubs at Andulau were significantly higher than those at Gigante. We attribute this strong difference to the lower soil content of available nutrients at Andulau where rainfall shortage is less severe and regular than at Gigante. Available data on life‐form composition and mortality rates in large plots are consistent with our proposal that shallow‐rooted shrubs and treelets are more vulnerable to drought than deep‐rooted life‐forms. We suggest that future studies of water use partitioning, wood anatomy, leaf morphology, and associations with neighboring plants would benefit from an explicit examination of their relation to rooting depth.
Growth Ecology of Carapa nicaraguensis Aublet. (Meliaceae): Implications for Natural Forest Management1
Authors: Webb Edward L.
Published: March 2006

The probability of achieving a sustainable tropical logging operation is increased if the growth of surviving trees is maximized after logging. This research examined the growth ecology of seedlings and trees of the Neotropical timber species, Carapa nicaraguensis (Meliaceae). Shadehouse experiments, field plantings, and growth rate analyses tested the hypothesis that Carapa seedlings and trees experience higher growth rates in high light levels (recently formed logging gaps or logged forest plots) than in low light levels (old logging gaps or undisturbed forest plots). Consistently poor seedling growth rates under low light conditions suggest that seedlings establishing in newly formed gaps will be more successful than those establishing in building‐phase gaps. Thus, the first year after logging is a critical time for gap recolonization by Carapa, and seed casting into gaps after logging is recommended. Growth of Carapa trees was significantly faster in logged forest than in undisturbed forest, and was positively associated with light availability. The results provide evidence that harvest models can be both diameter‐ and illumination‐based. Crown illumination was not significantly higher in logged forest than in undisturbed forest, indicating that the illumination scale for this study was not sensitive enough to detect increases in light availability brought about by selective logging. Potential silvicul‐tural methods (particularly poison‐girdling) that maintain adequate forest light levels in Carapa swamps without significantly altering long‐term tree diversity or allowing invasion of secondary species should be explored.