海南尖峰岭热带山地雨林林冠层树种功能多样性特征

以海南尖峰岭热带山地雨林3块1 hm²样地为研究对象,利用11个林冠功能性状结合样地地形及林冠乔木树种样地清查数据,分别基于单维性状和多维性状比较物种多度加权对群落功能离散度指数——平均成对距离(MPD)和平均最近类群距离(MNTD)的影响;同时分析林冠层功能丰富度(FRic)与物种丰富度之间的关系,最后利用零模型探讨不同生境类型下标准化效应MPD和MNTD(经过物种多度加权且剔除群落物种丰富度差异影响)的变化,进而评价林冠层群落水平功能多样性格局及其对局域生境异质性的响应.结果表明: 功能性状维度和物种多度对MPD的影响强烈,不同维度功能性状多度加权前后MPD相关性较弱(R=0.359～0.628);但对MNTD的影响相对较弱,不同维度功能性状多度加权前后MNTD相关性较强(R=0.746～0.820);未经物种多度加权的MPD和MNTD均普遍高估了林冠层的功能离散度.林冠层功能丰富度与物种丰富度基本呈指数相关关系(F=128.20;R²=0.632;AIC=97.72;P＜0.001),且功能丰富度很有可能存在一定的物种丰富度阈值.基于不同维度功能性状的林冠层功能多样性格局及其生境响应存在一定的差异性.在生物竞争激烈的低沟生境中,林冠层功能多样性倾向于比预期零模型随机产生的功能多样性高,林冠树种功能性状表现出离散分布;而在其他生境类型中,林冠层功能多样性倾向于接近或低于随机产生的功能多样性,林冠树种功能性状随机或聚集分布.     

Survival, Growth, and Ecosystem Dynamics of Displaced Bromeliads in a Montane Tropical Forest1

Epiphytes generally occupy arboreal perches, which are inherently unstable environments due to periodic windstorms, branch falls, and treefalls. During high wind events, arboreal bromeliads are often knocked from the canopy and deposited on the forest floor. In this study, we used a common epiphytic tank bromeliad, Guzmania berteroniana (R. & S.) Mez, to determine if fallen bromeliads can survive, grow, and reproduce on the forest floor and evaluate the potential impact of adult dispersal on plant and soil nutrient pools. Bromeliads were transplanted to and from tree stems and the forest floor and monitored intensively for six months; survival, growth, and impacts on ecosystem nutrient pools were followed on a subset of plants for 16 months. Six months after transplanting, bromeliad mortality was low (3%), and 19 percent of study individuals had flowered and produced new juvenile shoots. Mortality on the subset of plants followed for 16 months was 14–30 percent. Although survival rates were relatively high in all habitats, bromeliads transplanted to trees grew significantly more root length (x?± SE: 189 ± 43 cm) than those moved to the forest floor (53 ±15 cm) and experienced lower rates of leaf area loss. All transplanted bromeliads rapidly altered the substrate they occupied. Individuals transplanted to and among trees rapidly decreased base cation concentrations but significantly increased P concentrations of their underlying substrate. On the ground, bromeliads increased C, N, and P concentrations within nine months of placement. Our results suggest that in this montane tropical forest, bromeliads respond rapidly to displacement, locally modify their substrates, and can access the resources needed for survival regardless of habitat.     

A new psychodid species from Saban tank bromeliads

A new species of Neotropical Psychodidae, Alepia apexalba sp. nov., is described from dry-forest tank bromeliads in Saba, Netherlands Antilles. Larvae, pupae and adults are described and figured. It is possible to relate larvae and adults because the latter were reared from pupae collected from the bromeliads (Tillandsia utriculata) that also contained larvae. Bromeliads are adapted to intercept canopy litter and throughfall water, and decaying litter is washed into and retained by the leaf bases. It is from this aquatic habitat that the larvae and pupae were collected.     

Fine-scale distributions of carnivores in a logging concession in Sarawak,Malaysian Borneo

Coarse-scale patterns of distribution and abundance of species are the outcome of processes occurring at finer spatial scales, hence the conservation of species depends on understanding their fine-scale ecology. For Bornean carnivores, little is known about fine-scale predictors of species occurrence and it is assumed that the two main threats to wildlife on Borneo, habitat disturbance and hunting, also impact their occurrence. To increase our understanding of the Borneo carnivore community, we deployed 60 cameras in a logging concession in northern Sarawak, Malaysian Borneo, where different landscape covariates, both natural and anthropogenic, were present. We built single-species occupancy models to investigate fine-scale carnivore occupancy. Overall, forest disturbance had a negative effect on Hose’s civet (Diplogale hosei), banded civet (Hemigalus derbyanus) and yellow-throated marten (Martes flavigula). Further, banded civet had greater occupancy probabilities in more remote areas. Logging roads had the most diverse effect on carnivore occupancy, with Hose’s civet and masked palm civet (Paguma larvata) negatively affected by roads, whereas Malay civet (Viverra tangalunga), short-tailed mongoose (Herpestes brachyurus) and leopard cat (Prionailurus bengalensis) showed higher occupancy closer to roads. Canopy height, canopy closure, number of trees with holes (cavities) and distance to nearest village also affected occupancy, though the directions of these effects varied among species. Our results highlight the need to collect often overlooked habitat variables: moss cover and ‘kerangas’ (tropical heath forest) were the most important variables predicting occurrence of Hose’s civet. The preservation of such forest conditions may be crucial for the long-term conservation of this little-known species. Our results confirm that logged forests, when left to regenerate, can host diverse carnivore communities on Borneo, provided less disturbed habitat is available nearby, though human access needs to be controlled. We recommend easy-to-implement forest management strategies including maintaining forest next to logging roads; preserving fruiting trees and trees with cavities, both standing and fallen; and blocks of remote, less disturbed, mid- to high-elevation forest with understorey vegetation.     

The nutrient status of epiphytes and their host trees along an elevational gradient in Costa Rica

Vascular epiphytes are a conspicuous and highly diverse group in tropical wet forests; yet, we understand little about their mineral nutrition across sites. In this study, we examined the mineral nutrition of three dominant vascular epiphyte groups: ferns, orchids, and bromeliads, and their host trees from samples collected along a 2600 m elevational gradient in the tropical wet forests of Costa Rica. We predicted that the mineral nutrition of ferns, orchids, and bromeliads would differ because of their putative differences in nutrient acquisition mechanisms and nutrient sources—atmospherically dependent, foliar feeding bromeliads would have lower nitrogen (N) and phosphorous (P) concentrations and more depleted δ¹⁵N values than those in canopy soil-rooted ferns because canopy soil is higher in available N, and more enriched in δ¹⁵N than the atmospheric sources of precipitation and throughfall. We also predicted that epiphyte foliar chemistry would mirror that of host trees because of the likely contribution of host trees to the nutrient cycle of epiphytes via foliar leaching and litter contributions to canopy soil. In the same vein, we predicted that epiphyte and host tree foliar chemistry would vary with elevation reflecting ecosystem-level nutrients—soil N availability increases and P availability decreases with increasing elevation. Our results confirmed that canopy soil-rooted epiphytes had higher N concentrations than atmospheric epiphytes; however, our predictions were not confirmed with respect to P which did not vary among groups indicating fixed P availability within sites. In addition, foliar δ¹⁵N values did not match our prediction in that canopy soil-rooted as well as atmospheric epiphytes had variable signatures. Discriminant function analysis (DFA) on foliar measurements determined that ferns, orchids, and bromeliads are statistically distinct in mineral nutrition. We also found that P concentrations of ferns and orchids, but not bromeliads, were significantly correlated with those of host trees indicating a possible link in their mineral nutrition’s via canopy soil. Interestingly, we did not find any patterns of epiphyte foliar chemistry with elevation. These data indicate that the mineral nutrition of the studied epiphyte groups are distinct and highly variable within sites and the diverse uptake mechanisms of these epiphyte groups enhance resource partitioning which may be a mechanism for species richness maintenance in tropical forest canopies.     

Effects of Forest Fragmentation on the Abundance of <Emphasis Type="Italic">Colobus angolensis palliatus</Emphasis> in Kenya’s Coastal Forests

We documented the occurrence and abundance patterns of Angola black-and-white colobus (Colobus angolensis palliatus) in 46 coastal forest fragments ranging from 1 ha to >1400 ha in the Kwale District, Kenya. In field surveys conducted in 2001, we also recorded forest spatial, structural, resource, and disturbance characteristics to determine the effects of habitat quality and fragmentation and the factors most critical to the continued survival of the little-known species. We tested 13 hypotheses to explain variation in patch occupancy and abundance patterns of Colobus angolensis palliatus in relation to habitat attributes. Minimal adequate models indicated that the occurrence of colobus in forest fragments is positively associated with fragment area and canopy cover, whereas the density of colobus in occupied fragments is attributable to forest area, the proportion of forest change over the previous 12 yr, and the basal area of 14 major food trees. Large-scale illegal extraction of major colobus food trees in the District for human resource use, in both protected and unprotected forests, together with ongoing forest clearance and modification, are the major threats to Colobus angolensis palliatus in Kenya.     

Nutrients, diversity, and community structure of two phytotelm systems in a lower montane forest, Puerto Rico

1. Bromeliad and heliconia phytotelmata in the same forest area were compared in terms of their animal assemblages, nutrient inputs, and plant architecture. 2. For all major elements, nutrient inputs from canopy‐derived debris and rainfall in bromeliads were significantly lower than those derived from decaying flower parts and plant secretions in heliconia bracts. Bromeliads contained significantly fewer organisms per unit volume of water and unit dry weight of organic matter than did heliconia inflorescences. They also contained a significantly lower animal biomass (199 mg DW from 15 bromeliads, 527 mg DW from 15 heliconia inflorescences). 3. Species richness was independent of abundance, demonstrating that, at least for small container habitats, higher abundance does not necessarily lead to a greater species richness. Communities were remarkably similar in patterns of relative abundance and species richness (23 spp. in bromeliads, 21 spp. in heliconia), probably due to functional similarities in plant architecture, with the two most abundant species comprising 60–62% of the total community. Coefficients of similarity were low because of marked differences in species assemblages. 4. Some taxa were phytotelm generalists but most showed a preference for one particular habitat, indicating differential selection in the choice of oviposition sites and larval development within the forest ecosystem. In common with many island communities, species richness was lower than that reported for these phytotelm habitats in mainland central and south America.     

Effects of Habitat Structure and Adjacent Habitats on Birds in Tropical Rainforest Fragments and Shaded Plantations in the Western Ghats, India

As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are critically examining the role of private lands, habitat fragments, and plantations for conservation. This study in a biodiversity hotspot and endemic bird area, the Western Ghats mountains of India, examined the effects of habitat structure, floristics, and adjacent habitats on bird communities in shade-coffee and cardamom plantations and tropical rainforest fragments. Habitat and birds were sampled in 13 sites: six fragments (three relatively isolated and three with canopy connectivity with adjoining shade-coffee plantations and forests), six plantations differing in canopy tree species composition (five coffee and one cardamom), and one undisturbed primary rainforest control site in the Anamalai hills. Around 3300 detections of 6000 individual birds belonging to 106 species were obtained. The coffee plantations were poorer than rainforest in rainforest bird species, particularly endemic species, but the rustic cardamom plantation with diverse, native rainforest shade trees, had bird species richness and abundance comparable to primary rainforest. Plantations and fragments that adjoined habitats providing greater tree canopy connectivity supported more rainforest and fewer open-forest bird species and individuals than sites that lacked such connectivity. These effects were mediated by strong positive effects of vegetation structure, particularly woody plant variables, cane, and bamboo, on bird community structure. Bird community composition was however positively correlated only to floristic (tree species) composition of sites. The maintenance or restoration of habitat structure and (shade) tree species composition in shade-coffee and cardamom plantations and rainforest fragments can aid in rainforest bird conservation in the regional landscape.     

Comparing Population Patterns to Processes: Abundance and Survival of a Forest Salamander following Habitat Degradation

Habitat degradation resulting from anthropogenic activities poses immediate and prolonged threats to biodiversity, particularly among declining amphibians. Many studies infer amphibian response to habitat degradation by correlating patterns in species occupancy or abundance with environmental effects, often without regard to the demographic processes underlying these patterns. We evaluated how retention of vertical green trees (CANOPY) and coarse woody debris (CWD) influenced terrestrial salamander abundance and apparent survival in recently clearcut forests. Estimated abundance of unmarked salamanders was positively related to CANOPY ( _Canopy  = 0.21 (0.02–1.19; 95% CI), but not CWD ( _CWD  = 0.11 (−0.13–0.35) within 3,600 m² sites, whereas estimated abundance of unmarked salamanders was not related to CANOPY ( _Canopy  = −0.01 (−0.21–0.18) or CWD ( _CWD  = −0.02 (−0.23–0.19) for 9 m² enclosures. In contrast, apparent survival of marked salamanders within our enclosures over 1 month was positively influenced by both CANOPY and CWD retention ( _Canopy  = 0.73 (0.27–1.19; 95% CI) and _CWD  = 1.01 (0.53–1.50). Our results indicate that environmental correlates to abundance are scale dependent reflecting habitat selection processes and organism movements after a habitat disturbance event. Our study also provides a cautionary example of how scientific inference is conditional on the response variable(s), and scale(s) of measure chosen by the investigator, which can have important implications for species conservation and management. Our research highlights the need for joint evaluation of population state variables, such as abundance, and population-level process, such as survival, when assessing anthropogenic impacts on forest biodiversity.     

Laying low: Rugged lowland rainforest preferred by feral cats in the Australian Wet Tropics

Invasive mesopredators are responsible for the decline of many species of native mammals worldwide. Feral cats have been causally linked to multiple extinctions of Australian mammals since European colonization. While feral cats are found throughout Australia, most research has been undertaken in arid habitats, thus there is a limited understanding of feral cat distribution, abundance, and ecology in Australian tropical rainforests. We carried out camera‐trapping surveys at 108 locations across seven study sites, spanning 200 km in the Australian Wet Tropics. Single‐species occupancy analysis was implemented to investigate how environmental factors influence feral cat distribution. Feral cats were detected at a rate of 5.09 photographs/100 days, 11 times higher than previously recorded in the Australian Wet Tropics. The main environmental factors influencing feral cat occupancy were a positive association with terrain ruggedness, a negative association with elevation, and a higher affinity for rainforest than eucalypt forest. These findings were consistent with other studies on feral cat ecology but differed from similar surveys in Australia. Increasingly harsh and consistently wet weather conditions at higher elevations, and improved shelter in topographically complex habitats may drive cat preference for lowland rainforest. Feral cats were positively associated with roads, supporting the theory that roads facilitate access and colonization of feral cats within more remote parts of the rainforest. Higher elevation rainforests with no roads could act as refugia for native prey species within the critical weight range. Regular monitoring of existing roads should be implemented to monitor feral cats, and new linear infrastructure should be limited to prevent encroachment into these areas. This is pertinent as climate change modeling suggests that habitats at higher elevations will become similar to lower elevations, potentially making the environment more suitable for feral cat populations.     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.     

Abundance and composition of forest-dwelling anurans in cashew plantations in a tropical semi-evergreen forest landscape

Plantation crops in tropical human-modified landscapes provide alternative habitats to biodiversity outside protected areas. The Western Ghats of India are home to a mosaic of closely spaced habitats, including forests and agroecosystems. Cashew is a widely grown plantation crop in the northern Western Ghats and is known to provide economic and societal benefits. However, its role as a supplementary habitat for anurans is not well understood. We assessed the factors that influence understorey anuran composition and abundance in cashew plantations, forest edges, and forest interiors in Tillari Conservation Reserve, Maharashtra. Species composition of cashew plantations differed significantly from forests and was positively influenced by understorey and canopy cover. Cashew plantations had a near equal abundance of anurans as that of forest edges and interiors, which could be due to the preponderance of habitat generalists. Understorey positively influenced anuran abundance while ambient temperature had a negative influence. Reduced understorey and low canopy cover represent habitat modifications that occur in cashew plantations. Such structural changes could lead to reduced environmental refuges for anurans, thereby exposing them to large variations in temperature and moisture. Cashew plantations in Tillari Conservation Reserve serve as supplementary habitats for anurans. That said, cashew cultivation practices and markets must be understood before biodiversity-friendly plantation practices are proposed.     

Spatial variation in the strength of mutualism between a jumping spider and a terrestrial bromeliad: Evidence from the stable isotope N

Psecas chapoda, a neotropical jumping spider strictly associated with the terrestrial bromeliad Bromelia balansae in cerrados and semi-deciduous forests in South America, effectively contributes to plant nutrition and growth. In this study, our goal was to investigate if spider density caused spatial variations in the strength of this spider–plant mutualism. We found a positive significant relationship between spider density and δ¹⁵N values for bromeliad leaves in different forest fragments. Open grassland Bromeliads were associated with spiders and had higher δ¹⁵N values compared to forest bromeliads. Although forest bromeliads had no association with spiders their total N concentrations were higher. These results suggest that bromeliad nutrition is likely more litter-based in forests and more spider-based in open grasslands. This study is one of the few to show nutrient provisioning and conditionality in a spider–plant system.     

Proximity is not a proxy for parentage in an animal-dispersed Neotropical canopy palm

We used parentage analysis to estimate seedling recruitment distances and genetic composition of seedling patches centred around reproductive trees of the animal-dispersed Neotropical canopy palm Iriartea deltoidea in two 0.5 ha plots within second-growth forest and one 0.5 ha plot in adjacent old-growth forest at La Selva Biological Field Station in north-eastern Costa Rica. Seedlings were significantly spatially aggregated in all plots, but this pattern was not due to dispersal limitation. More than 70 per cent of seedlings were dispersed at least 50 m from parent trees. Few seedlings were offspring of the closest reproductive trees. Seedling patches observed beneath reproductive trees originate from dozens of parental trees. Observed patterns of seedling distribution and spatial genetic structure are largely determined by the behaviour of vertebrate seed dispersers rather than by spatial proximity to parental trees.     

Effects of disturbance caused by selective timber extraction on fish communities in Sabah, Malaysia

To examine the effects of selective timber extraction on fish communities in Sabah, Malaysia, quantitative samples of fishes were taken from thirteen streams running through undisturbed rainforest or through forest that had been selectively logged 3–18 years previously. Multivariate analysis (canonical discriminant analysis and cluster analysis) indicated that mesohabitats within streams (riffles and pools) and differences in stream size were more important in determining community structure than logging history. Riffles in streams running through logged or undisturbed forest were indistinguishable using relative biomass or abundance data, as were pools from small streams (approximate order 2). Fish communities from pools in larger streams showed some separation in multivariate space corresponding to a complex set of relative changes in abundance and/or biomass between species. However it was difficult to unambiguously assign such changes to logging regime alone. There appeared to be some differences in fish communities between streams in recently-logged (3–7 years) and old-logged (17–18 years) areas related to abundance or biomass of three cyprinids (Garra borneensis, Lobocheilos bo and Osteochilus chini). Only one species, Pangio mariarum, was not found in streams in logged forest, but it was only found at one location in undisturbed forest. A number of other species showed significant differences in abundance or biomass between sites but most of these were only present at some sites and in low abundance. Principal components analysis of habitat data showed that riffle sites were homogeneous whatever their logging history as were pools in unlogged large streams. Pools in logged large streams were significantly more heterogeneous but in a random rather than systematic manner. It is concluded that the type of selective logging practices used locally have low impact on fish communities through mechanisms of persistence and/or rapid recolonisation.     

Complex indirect effects of epiphytic bromeliads on the invertebrate food webs of their support tree

Ecosystem engineers are species that affect others through the provision of habitat rather than consumptive resources. The extent to which ecosystem engineers can indirectly affect entire food webs, however, is poorly understood. Epiphytic tank bromeliads (Bromeliaceae) are ecosystem engineers that are common throughout the Neotropics, and are associated with a variety of predatory arthropods. Here, we examine if bromeliads, by increasing predator densities, indirectly benefit their support tree through reduction in herbivorous insects and leaf damage. We observed and manipulated bromeliad densities in Costa Rican orange orchards, and measured impacts on leaf damage and arboreal and bromeliad invertebrate communities in two different seasons. Our results show that bromeliads are associated with predatory and herbivorous invertebrates but not leaf damage. Bromeliads were correlated with increased densities of their associated predators, especially ants and hunting spiders, but we could not confirm a causal link. Associations with bromeliads changed over time, with seasonal shifts interfering with responses to our manipulations. Bromeliads had a reduced association with predators in the dry season. Moreover, a null association between bromeliads and herbivorous invertebrates in the dry season unexpectedly became positive in the wet season. In summary, we have only limited evidence that bromeliads indirectly promote the top‐down control of arboreal herbivores; instead, our manipulations suggest that bromeliads increase herbivore densities in the wet season. This research suggests that although bromeliads may act as ecosystem engineers, indirectly influencing the invertebrate food web on support trees, their effects are trophically complex and seasonally dependent. Abstract in Spanish is available with online material.     

Habitat Partitioning Among Primates in Maracá Island, Roraima, Northern Brazilian Amazonia

I studied a primate community on a tropical rainforest island, in the northernmost area of the Brazilian Amazonia. While walking through six distinct habitats along a 12-km trail, running toward the center of the island—a remote undisturbed area—I collected data on the use of the different forest types and forest strata by the primate community and the formation of either mixed groups or species assemblages. Five species are present: Cebus olivaceus, C. apella, Saimiri sciureus, Ateles belzubuth, and Alouatta seniculus. They seemed to be habitat generalists, using most habitat types. The five species used the higher strata more significantly, probably because Maracá does not present well-defined forest floors, which could be a result of being located in the transition between the great areas of savannah and the Amazonian seasonally dry forests. The five species all formed some polyspecific associations, which involved sharing the available food resource. Mixed groups were significantly more frequent and therefore possibly more important to Saimiri, which was not the case in relation to the other four species. Assemblages, defined as the presence in the same clumped resource, without coordinated activity, of 3 primate species, were recorded primarily in fruiting fig trees. I suggest that assemblages are impelled by food constraints, forcing cofeeding in large seasonal resources, highlighting the ecological importance of figs to these primates. Linear regression models show that the number of feeding bouts in each habitat type is positively related to the number of fruiting trees exploited, but the density of these fruit trees, diversity of plant species, tree height, and total basal area of each habitat type have no relationship to feeding.     

Canopy and litter ant assemblages share similar climate–species density relationships

Tropical forest canopies house most of the globe''s diversity, yet little is known about global patterns and drivers of canopy diversity. Here, we present models of ant species density, using climate, abundance and habitat (i.e. canopy versus litter) as predictors. Ant species density is positively associated with temperature and precipitation, and negatively (or non-significantly) associated with two metrics of seasonality, precipitation seasonality and temperature range. Ant species density was significantly higher in canopy samples, but this difference disappeared once abundance was considered. Thus, apparent differences in species density between canopy and litter samples are probably owing to differences in abundance–diversity relationships, and not differences in climate–diversity relationships. Thus, it appears that canopy and litter ant assemblages share a common abundance–diversity relationship influenced by similar but not identical climatic drivers.