ummary 1. Recent studies have documented shifts in habitat associations of single tropical tree species from one life stage to the next. However, the community-level consequences of such shifts have not been investigated, and it is not clear whether they would amplify, neutralize or completely alter habitat structuring during the transitions to the adult community. 2. We compared habitat-driven species assemblages at three life stages (i.e. recruitment, juvenile and reproductive stages) and six censuses for tree and shrub species in a fully censused 50-ha plot of Panamanian lowland forest. Habitat types were determined using multivariate regression trees that group areas with similar species composition (i.e. species assemblages) according to their topographical characteristics. 3. Three topographical variables (a topographical wetness index, slope and elevation) were major determinants of species assemblages. When analysing individuals of all life stages together, we found a distinct and temporally consistent structuring of the plot into four dominant habitat types (low and high plateaus, slope and swamp) which was consistent with previous classifications. Basically, the same habitat structuring emerged for the juvenile communities of individual censuses. However, recruits showed a weak and temporally inconsistent habitat structuring. 4. A notable homogenization in species assemblages occurred during the transition from juvenile to reproductive, through both a reduction in the number of species assemblages (in 3 censuses, one large reproductive assemblage covered 93% of the plot, and in others, an additional slope habitat emerged) and a reduction in the classification error. Overall, habitat structuring became noisier and weaker over the 25 years of the study. 5. Synthesis. Our results suggest that mortality processes during the transition from recruits to juveniles must enhance the signal of habitat structuring. However, during the transition to the reproductive stage, species may have lost the advantage of being in the habitat with which they had become associated, or the quality of habitat changed during their life span because of larger climatic changes. The homogeneous assemblages of the reproductive stage could be interpreted as support for neutral theories, but further research is required to unravel the mechanisms behind these intriguing observations.

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Summary 1.One of the primary goals in community ecology is to determine the relative importance of processes and mechanisms that control biodiversity. Here, we examined habitat-driven species assemblages and species distribution patterns as well as their temporal variations for three life stages of two censuses of a 25-ha mixed dipterocarp forest at Sinharaja (Sri Lanka). 2. Our general objective was to find out whether the species assemblages and associated habitat types changed with life stage, spatial scale and species attributes. We also analyse whether the habitat types were related to certain indicator species. Habitat types were determined with multivariate regression tree analyses driven by topographic variables. 3. We found species assemblages associated with five distinct habitat types that appeared consistently for all life stages of the two censuses. These habitats were related to ridge-valley gradients and a pronounced contrast in south-west versus north-east aspect. Habitat-driven structuring was weak at the recruit stage but strong in the juvenile and adult stages. The species assemblage variance explained by topographic variables for different life stages ranged between 10% for recruits and 23% for juveniles. 4. The species assemblages determined for different spatial scales (10, 20, 50 m) showed similar habitat partitioning, but the variance explained by the topographic variables increased in all life stages with spatial scale. This could be due to the homogenizing effect of topographic variables at the larger scales and unaccounted environmental variation at the smaller scales. The number of indicator species identified in the two censuses was higher in the juvenile stage than in the adult stage, and nearly all indicator species in the adult stage were also indicator species in the juvenile stage. 5. Synthesis. Our study showed that approximately 75% of the variance in local species composition is unexplained. This may be due to spatially structured processes such as dispersal limitation, unaccounted biotic and abiotic environmental variables, and stochastic effects, but only 25% were due to topographic habitat association. Although the pronounced ridge-valley gradient and contrast of south-west versus north-east aspect created consistent habitats, our results suggest that local species assemblages at Sinharaja forest are jointly shaped by neutral and niche processes.

Tiger Panthera tigris populations have declined dramatically in the Terai Arc Landscape (TAL; India and Nepal), and remaining populations are highly fragmented and endangered. As part of a research program to aid tiger management by identifying critical areas for conservation, we aimed to 1) identify the factors which affect the distribution of tigers in the TAL; 2) explore the role of spatial scale in habitat selection; 3) map potentially suitable habitats; and 4) assess the quality of potential corridors linking suitable habitats. We used an approach based on presence and pseudo‐absence data, combining ecological niche factor analysis and generalized linear models. We used an information‐theoretic approach to compare our data on tiger presence with different hypotheses on tiger habitat selection (i.e. protective habitat, prey species, human disturbance), and spatial scales. All hypotheses yielded models with high prediction accuracy (>79%). The most parsimonious model included variables characterizing habitat suitability of the 2 main prey species. More detailed assessment of potentially suitable areas using an extended source‐sink approach suggested that most of the habitats outside the protected areas were attractive sink‐like habitats (i.e. they suffered high levels of human disturbance in otherwise good habitats). Overall, 24% (ca 18 500 km2) of the study area was predicted as suitable (probability cut‐off p>0.5), approximately 7% of which is under protection. Our models showed that protecting the remaining concentrations of tigers requires focusing management efforts on specific areas outside the currently protected areas. These are characterized by good natural suitability; however, they suffer from a high level of human disturbance. Our models underscore the importance of minimizing human disturbances in these areas to avoid that they act as attractive sinks but act as corridors between existing subpopulations.

Aim: Climate change alters the water cycle, potentially affecting the distribution of species. Using an ensemble of species distribution models (SDMs), we predicted changes in distribution of the Asian elephant in South Asia due to increasing climatic variability under warming climate and human pressures. Location: India and Nepal.Methods: We compiled a comprehensive geodatabase of 115 predictor variables, which included climatic, topographic, human pressures and land use, at a resolution | 823 KANAGARAJ et Al.