Spatial pattern and dynamics of experimental plant communities

Peter Stoll , Deborah Vogt, Daniel Prati

There is strong theoretical evidence that the spatial pattern is an important factor controlling the species dynamics of plant communities. The emerging conclusion is that intraspecific aggregation promotes coexistence by slowing down competitive exclusion. Whereas local interactions contribute to interspecific segregation, limited seed dispersal contributes to aggregation at two hierarchical levels: species within communities and genetically related individuals (e.g. siblings) within populations.
However, especially for plant communities explicit experimental tests of the predictions from spatially-explicit models are largely missing. We conducted a pilot study using different spatial patterns (random vs. aggregated) in an experimental community of four annual plant species (Stoll & Prati 2001). The results showed that weaker competitors increased their fitness while superior competitors were more suppressed when grown in the neighborhood of conspecifics. This pilot study builds the starting point for the present project which is aimed to increase our basic understanding in population and community ecology of plants.

manipulate the spatial pattern, i.e. the relative frequency of inter- vs. intraspecific contacts and
contrast the performance of genetically related with unrelated individuals.

Growth, survival and fitness (seed output) of individuals will be monitored with methods from plant population biology. The basic goal is to see whether or not the spatial pattern and genetic make-up change community composition by altering individual performance and therefore population dynamics. It is anticipated that results will also help to implement better informed management practices (e.g. restoring species rich communities) and contribute to recently renewed interests in alternative ecological mechanisms (e.g. positive interactions, co-operation, hierarchical organization and multi-level selection) which play potentially underestimated roles in structuring plant communities.

Keywords: biodiversity - spatial ecology

Publications

Vogt DR, Murrell DJ & Stoll P (2010) — Testing spatial theories of plant coexistence: No consistent differences in intra- and interspecific interaction distances — American Naturalist 175: 73–84

Wassmuth BE, Stoll P, Tscharntke T & Thies C (2009) — Spatial aggregation facilitates coexistence and diversity of wild plant species in field margins — Perspectives in Plant Ecology Evolution and Systematics 11: 127–135

Monzeglio U & Stoll P (2008) — Effects of spatial pattern and relatedness in an experimental plant community — Evolutionary Ecology 22: 723–741

Monzeglio U & Stoll P (2005) — Spatial patterns and species performances in experimental plant communities — Oecologia 145: 619–628

Stoll P & Prati D (2001) — Intraspecific aggregation alters competitive interactions in experimental plant communities — Ecology 82: 319–327

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