Ecological Archives E093-137-A8

Anton J. Flügge, Sofia C. Olhede, and David J. Murrell. 2012. The memory of spatial patterns: changes in local abundance and aggregation in a tropical forest. Ecology 93:1540–1549.

Appendix H. Analysis of the relationship between abundance and aggregation in the simulation model.

Our simulation model reproduces the empirical pattern that rare species are on average more aggregated than more common species (see Fig. H1).

Interestingly, the model can produce an abundance–aggregation relationship as found in the empirical data when using a range of mean dispersal distances as has been reported in the literature (Muller-Landau and Hardesty 2005). We note that in our simulation model the dispersal kernel describes the successful establishment of new individuals and so encapsulates both seed dispersal and seedling/sapling establishment, whereas the estimated range of the dispersal kernel concerns only the seed dispersal phase.

Fig. H1. There is a strong correlation of abundance and aggregation of species (top-canopy trees Δ; middle canopy trees O; understory trees ; shrubs *). The green line shows the mean result of 500 runs of the individual-based model (for population sizes of 50, 100, 500, 1000, 2000, 5000, 10000, and 30000) with a mean dispersal distance of 2.8 m, the orange line the respective simulation results for a mean dispersal distance of 30 m, and the blue line for 152 m. The whiskers mark the 10 and 90 percentile of the simulation results. As reported by Muller-Landau and Hardesty (2005) species at BCI have mean dispersal distances between 2.8 m and 152 m, all but two species have Ω0,10,2005 values that simulations with a mean dispersal distance within that range can well explain.

Literature Cited

Muller-Landau, H. C., and B. D. Hardesty, 2005. Seed dispersal of woody plants in tropical forests: concepts, examples and future directions. Pages 267–309 in Burslem, Pinard, and Hartley, editors. Biotic interactions in the Tropics. Cambridge University Press, Cambridge, UK.

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