Spatial structure in ecosystems

Submitted by editor on 21 April 2015.Get the paper!

Ecologists have long been interested in the spatial structure of communities, that is, any non-random spatial organization in the distribution of communities. If communities are spatially structured, sites near each other are compositionally more similar than the more distant sites. Spatial structure in ecological communities reflects organisms` dispersal limitation, mortality, social organization and spatially structured environmental variation (Peres-Neto and Legendre 2010).

In a recent paper “Spatial structure in ecological communities – a quantitative analysis” published in Early View I presented results of a large meta-review about the degree of spatial structure in ecological communities (n=322 data sets). This paper belongs to the sequence of research papers about spatial patterns in ecological communities such as species-area relationships (Drakare et al. 2006), distance decay of community similarity (Soininen et al. 2007a), beta diversity (Soininen et al. 2007b) and species sorting by the environment (Soininen 2014). These recent meta-reviews have increased our knowledge about macroecological patterns in community composition or biodiversity substantially, but most of these have not been able to account properly for the variation in environmental heterogeneity among studies. Here, I asked whether spatial structure in biotic communities varied predictably across organismal traits such as body size, trophic position or dispersal mode and across different types of ecosystems (freshwater, marine and terrestrial ecosystems). I quantified spatial variation as a fraction of community variation that could be explained by spatial variables after controlling for variation in environmental factors.  

I showed that a mean of 11.0% of the variation in community composition was explained by spatial variables after the effect of environmental variables has been accounted for. Across all taxa, spatial component increased with body size suggesting that larger taxa may be more dispersal limited across sites than smaller taxa. Spatial component also increased highly significantly with study extent indicating that dispersal limitation gets stronger with increasing extent. Spatial component was highest among terrestrial taxa and higher in ectotherms than in homoiotherms. Spatial structure was also higher in omnivores than in autotrophs.

These results suggest that the degree of spatial structure is jointly driven by extrinsic factors such as study extent and ecosystem type, and intrinsic factors such as body size, thermoregulation and interactions between body size and dispersal mode. Quantifying the major patterns in the spatial structure of ecological communities is not only an important task for basic research, but it also have important applied implications as sampling campaigns for biomonitoring or conservation programs rely on the knowledge about the degree to which there is natural variation in communities across space. 

 

Reference cited above

 

Drakare, S. et al. 2006. The imprint of the geographical, evolutionary and ecological context on species-area relationships. - Ecol. Lett. 9: 215-227.

Peres-Neto, P.R. and Legendre, P. 2010. Estimating and controlling for spatial structure in the study of ecological communities. - Global Ecol. Biogeogr. 19: 174-184.

Soininen, J. 2014. A quantitative analysis of species sorting across organisms and ecosystems. - Ecology 95: 3284-3292.

Soininen, J. et al. 2007a. The distance decay of similarity in ecological communities. - Ecography 30: 3-12

Soininen, J. et al. 2007b. A multivariate analysis of beta diversity across organisms and environments. - Ecology 88: 2830-2838.

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