Species–habitat associations in a Sri Lankan dipterocarp forest

Gunatilleke, C. V. S.; Gunatilleke, I. A. U. N.; Esufali, Shameema; Harms, Kyle E.; Ashton, P. Mark S.; Burslem, David F. R. P.; Ashton, Peter S.

doi:10.1017/s0266467406003282

Cited by 138 publications

(164 citation statements)

References 42 publications

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“…However, the results of a homogeneous null model showed that the diversity in the two tropical forests is strongly structured by habitat association (SI Fig. 8), a mechanism not yet included in neutral theory (23,29). This result is in accordance with a recent study (36) that found that Ϸ30% of the species at BCI showed significant affinities to soil nutrient distributions.…”

Section: Discussionsupporting

confidence: 88%

“…The effect of dispersion is important for interpreting and understanding ISAR but can be diagnosed by comparing local densities of the stems of the target species with that of all species in neighborhoods around the stems of the target species [see supporting information (SI) Table 1]. A species may appear to be a diversity accumulator or repeller through habitat association if diversity differs at different habitats [e.g., upper and lower elevation habitats at Sinharaja (23)]. This effect is analogous to the problem of heterogeneous patterns in point-pattern analysis (21,24).…”

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confidence: 99%

“…We applied this framework to data from two fully censused 50-and 25-ha tree plots at Barro Colorado Island (BCI), Panama (26,27), and Sinharaja, Sri Lanka (23,28), respectively. We selected these two sites because they constitute two extremes with respect to habitat association among the Forest Dynamics Plots coordinated within the network of the Centre for Tropical Forest Science (CTFS); the Sinharaja plot shows high specieshabitat associations (23) and the BCI plot shows low specieshabitat associations (29).…”

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confidence: 99%

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How individual species structure diversity in tropical forests

Wiegand

Gunatilleke²,

Gunatilleke³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

113

265

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A persistent challenge in ecology is to explain the high diversity of tree species in tropical forests. Although the role of species characteristics in maintaining tree diversity in tropical forests has been the subject of theory and debate for decades, spatial patterns in local diversity have not been analyzed from the viewpoint of individual species. To measure scale-dependent local diversity structures around individual species, we propose individual speciesarea relationships (ISAR), a spatial statistic that marries common species-area relationships with Ripley's K to measure the expected ␣ diversity in circular neighborhoods with variable radius around an arbitrary individual of a target species. We use ISAR to investigate if and at which spatial scales individual species increase in tropical forests' local diversity (accumulators), decrease local diversity (repellers), or behave neutrally. Our analyses of data from Barro Colorado Island (Panama) and Sinharaja (Sri Lanka) reveal that individual species leave identifiable signatures on spatial diversity, but only on small spatial scales. Most species showed neutral behavior outside neighborhoods of 20 m. At short scales (<20 m), we observed, depending on the forest type, two strongly different roles of species: diversity repellers dominated at Barro Colorado Island and accumulators at Sinharaja. Nevertheless, we find that the two tropical forests lacked any key species structuring species diversity at larger scales, suggesting that ''balanced'' species-species interactions may be a characteristic of these speciesrich forests. We anticipate our analysis method will be a starting point for more powerful investigations of spatial structures in diversity to promote a better understanding of biodiversity in tropical forests.biodiversity ͉ spatial patterns ͉ spatial statistic ͉ species-area relationship S ince the establishment of large permanent sampling plots where all stems Ͼ1 cm in diameter at breast height (dbh) are identified, measured, and mapped (1, 2), substantial progress has been made in explaining the high local diversity of tree species in tropical forests; however, ecologists are still far from having a definitive answer. Several competing hypotheses on processes promoting species coexistence have been developed and tested, but these efforts have yielded contrasting results (3-5). Neutral theory (6-8) suggested that species-specific differences are unimportant for certain community attributes, whereas niche theory outlines the importance of species characteristics and trade-offs (9, 10). It is also clear that species-specific differences affect the spatial distribution of populations (11-16). Surprisingly, although plant-plant interactions should play a major role in structuring tropical forests, the resulting spatial patterns in diversity have not been analyzed from the viewpoint of individual species. However, strong differences in species traits and in species interactions should create clearly identifiable nonrandom spatial structures in diversity...

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Section: Discussionsupporting

confidence: 88%

mentioning

confidence: 99%

mentioning

confidence: 99%

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How individual species structure diversity in tropical forests

Wiegand

Gunatilleke²,

Gunatilleke³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

113

265

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“…The relationships between forest structure and physical environments defined by topography and edaphic factors have not been determined at Yasuni, although soil type and topography may influence disturbance regimes and canopy structure in tropical lowland forests elsewhere (e.g. Gunatilleke et al 2006). The contributions of these interactions to habitat partitioning of Yasuni Myristiaceae awaits further investigation.…”

Section: Discussionmentioning

confidence: 99%

Habitat niche partitioning by 16 species of Myristicaceae in Amazonian Ecuador

et al. 2007

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The distribution and spatial pattern of plants in tropical forests have important implications for how species interact with each other and their environments. In this article we use a large-scale permanent census plot to address if the coexistence of 16 co-occurring species of Myristicaceae is aided by topographic and light gradient niche partitioning. We used a second order spatial pattern analysis based on Ripley's K function to describe species' distributions and associations among species, and a torus translation procedure to test for associations with three topographically defined habitats. A majority of species displayed spatial aggregation and over half had one or more significant habitat associations. Four species were associated with the ridge habitat, four species with slope habitat, and two with valley habitat. Seven other species showed no habitat association. Within each habitat group, species exhibited a variety of distributions in relation to light availability. However, habitat associations were largely unexplained by differential rates of mortality, growth or recruitment over a 5-year interval. We conclude that although in principle partitioning of the topographic and light environments may double or treble the number of species able to coexist, there is no evidence that partitioning of physical habitats can explain the coexistence of all 16 of these closely related species.

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“…Although the importance of edaphic factors in maintaining local diversity has long been recognized (29,30), a thorough, quantitative assessment of the importance of soil resources on tropical tree distributions for entire communities has not been undertaken. Typically, studies have either focused on a small fraction of the tree species in any community (31-33) or related community-wide tree species distributions to topographical variables whose relationships with underlying soil resources are unknown (28,34,35). To test relationships between species distributions and soil resource availability, soil resources and species distributions need to be mapped at high spatial resolution for entire communities in plots large enough to span substantial spatial heterogeneity in soil factors.…”

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confidence: 99%

Soil nutrients influence spatial distributions of tropical tree species

John

Dalling

Harms

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

823

862

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The importance of niche vs. neutral assembly mechanisms in structuring tropical tree communities remains an important unsettled question in community ecology [Bell G (2005) Ecology 86:1757-1770]. There is ample evidence that species distributions are determined by soils and habitat factors at landscape (<10 4 km 2 ) and regional scales. At local scales (<1 km 2 ), however, habitat factors and species distributions show comparable spatial aggregation, making it difficult to disentangle the importance of niche and dispersal processes. In this article, we test soil resource-based niche assembly at a local scale, using species and soil nutrient distributions obtained at high spatial resolution in three diverse neotropical forest plots in Colombia (La Planada), Ecuador (Yasuni), and Panama (Barro Colorado Island). Using spatial distribution maps of >0.5 million individual trees of 1,400 species and 10 essential plant nutrients, we used Monte Carlo simulations of species distributions to test plant-soil associations against null expectations based on dispersal assembly. We found that the spatial distributions of 36 -51% of tree species at these sites show strong associations to soil nutrient distributions. Neutral dispersal assembly cannot account for these plant-soil associations or the observed niche breadths of these species. These results indicate that belowground resource availability plays an important role in the assembly of tropical tree communities at local scales and provide the basis for future investigations on the mechanisms of resource competition among tropical tree species.community assembly ͉ niche differentiation ͉ tropical forest T he high local diversity of tropical tree communities poses a unique challenge for testing niche assembly theories based on resource competition (1). In these species-rich communities, hundreds of tree species can coexist in a single site (2), which renders assessment of the outcome of pairwise competitive interactions intractable. Conversely, the high diversity and relative rarity of most species also means that species seldom encounter each other in ecological neighborhood interactions (3), which suggests that competitive differences among species might not have a predictable effect on community structure. In fact, neutral theories of community assembly assume that there are no competitive differences among species and that ecological communities are assembled by random dispersal. Under neutral community assembly, alpha diversity would be governed by metacommunity diversity and speciation-extinction at macroecological scales (4, 5).Despite the contrasting mechanisms of community assembly proposed by neutral and niche theories, several lines of evidence support each of these perspectives. Tropical tree species differ in their light requirements for regeneration (6) because of a tradeoff between growth rate under high light and survival in the shade (7-9). Seedlings and saplings of different species differ in their resistance to pests, resulting in a frequency-dependent a...

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Species–habitat associations in a Sri Lankan dipterocarp forest

Cited by 138 publications

References 42 publications

How individual species structure diversity in tropical forests

How individual species structure diversity in tropical forests

Habitat niche partitioning by 16 species of Myristicaceae in Amazonian Ecuador

Soil nutrients influence spatial distributions of tropical tree species

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