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