bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial and Temporal Variation in the Ant Occupants of a Facultative Ant‐Plant1
Authors: Alonso Leeanne E. 
Published: March 2006

ABSTRACTStriking 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

ABSTRACTDespite 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

ABSTRACTTo 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

ABSTRACTWe 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

RESUMÉUne 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

ABSTRACTThe 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

ABSTRACTThere 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

ABSTRACTI 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

ABSTRACTBetween 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

ABSTRACTAn 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

ABSTRACTLong‐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

ABSTRACTSeasonal 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

ABSTRACTIn 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

ABSTRACTThis 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

ABSTRACTTwo 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.