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Tradeoffs between intra and interspecific distances of individual plants determine the spatial distributions of local plant communities and small‐scale community assembly. Here we use an individual based approach and null model standardization to compare intra‐ and interspecific nearest neighbour distances of plant ramets as well as mean differences in functional trait expression to nearest heterospecifics within local communities of temperate forest understorey plants in northern Poland. We found a general tendency towards clustered intraspecific and segregated interspecific ramet distributions. Spatial distribution patterns of understorey plants differed considerably between two nearby forest sites that mainly differed in the age structure of trees. Individuals of clonal species tended to have significantly smaller intraspecific and larger interspecific nearest neighbour distances than seed dispersing species. Our results indicate a major influence of dominant plant species on the spatial distributions of subdominants. Trait expressions related to plant growth (specific leaf area and leaf mass) and reproduction (seed mass) were significantly segregated in comparison to the spatial distribution of conspecific individuals and less so in comparison to heterospecific individuals. We argue that spatially explicit analyses of plant community assembly need to consider respective distributions of important traits and that the tradeoffs of contrasting trait distributions trigger small scale plant community composition and species distributions. We present a general framework for the analysis of plant community assembly based on the spatial distributions of individual plants and functional traits. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted the importance of higher‐order competitive interactions in stabilizing population dynamics in multi‐species communities. But how does the structure of competitive hierarchies affect population dynamics and extinction processes? We tackled this important question by using spatially explicit simulations of ecological drift (10 species in a homogeneous landscape of 64 patches) in which birth rates were influenced by interspecific competition. Specifically, we examined how transitive (linear pecking orders) and intransitive (pecking orders with loops) competitive hierarchies affected extinction rates and population dynamics in simulated communities through time. In comparison to a pure neutral model, an ecological drift model including transitive competition increased extinction rates, caused synchronous density‐dependent population fluctuations, and generated a white‐noise distribution of population sizes. In contrast, the drift model with intransitive competitive interactions decreased extinctions rates, caused asynchronous (compensatory) density‐dependent population fluctuations, and generated a brown noise distribution of population sizes. We also explored the effect on community stability of more complex patterns of competitive interactions in which pairwise competitive relationships were assigned probabilistically. These probabilistic competition models also generated density‐dependent trajectories and a brown noise distribution of population sizes. However, extinction rates and the degree of population synchrony were comparable to those observed in purely neutral communities. Collectively, our results confirm that intransitive competition has a strong and stabilizing effect on local populations in species‐poor communities. This effect wanes with increasing species richness. Empirical assemblages characterized by brown spectral noise, density‐dependent regulation, and asynchronous (compensatory) population fluctuations may indicate a signature of intransitive competitive interactions. [ABSTRACT FROM AUTHOR]