Linking ecological processes with spatial andnon-spatial patterns in plant communities

摘要

1. Attempts to infer underlying ecological process from observed patterns in ecology have beenwidespread, but have generally relied on first-order (non-spatial) community characteristics such asthe species abundance distribution (SAD). This measure has become an important test of severaltheories of species coexistence, but has proved unsuccessful in distinguishing between them.2. Spatially explicit data are increasingly available for a range of ecological communities, and analysis methods for these data are well developed. However, relatively little work has investigated thepotential of these data for similar inference about mechanisms of coexistence.3. In this study, we systematically investigate the spatial and non-spatial signals of simulated ecological processes. We include neutral, niche, lottery, Janzen–Connell and heteromyopia models,deriving and comparing first- and second-order measures for the patterns they generate.4. We find that the SAD is unable to distinguish reliably between underlying models, with randomvariation in its shape concealing any systematic differences.5. A new second-order summary measure of spatial structure derived in this paper, in contrast,proves highly sensitive to the type of ecological interaction being modelled, and is robust to randomvariation.6. Synthesis. A simple summary measure of the spatial structure of plant communities is presentedand found to be a more powerful indicator of underlying process in simulated data than a widelyused first-order measure, the SAD. The potential for answering important ecological questionsusing spatial statistics, particularly concerning mechanisms of coexistence in diverse communities,appears to be great.