Comparative Mediterranean vegetation dynamics

Role of Evolutionary History in Determining Vegetation Dynamics: A Comparative Study of Mediterranean Ecosystems in California and in Israel
José M. Grünzweig, Yohay Carmel and Curtis H. Flather1
1Rocky Mountain Research Station, USDA Forest Service
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Global change models assume that ecosystems in climatically similar regions are structurally and functionally similar, and model parameters can be extrapolated from one ecosystem to another. This hypothesis was approved for important ecosystem traits, but was not tested for vegetation dynamics. We are testing the hypothesis that growth rate and response to various disturbances would be similar in two climatically similar regions, in Israel and California. We conduct a mutual transplant experiment, in which species that occupy ecologically-similar niches in Israel and California are planted in experimental plots, under the same controlled conditions, enabling optimal growth. Seeds will be germinated and then seedlings will be grown within established facilities in both countries. During the pilot study, germination, seedling establishment, and seedling survival will be monitored during two years. In a follow-up study, saplings will be exposed to various disturbances, namely simulated grazing, cutting and fire. Growth rate and regeneration strategies following these disturbances will be monitored. This study has three major goals:

  • The pilot study will test the hypothesis that ecologically similar species in climatically similar regions would have similar growth rate under optimal conditions.
  • The follow up study will provide a test of the hypothesis that vegetation in climatically similar regions responds similarly to disturbance.
  • An assessment of the relative contributions of evolutionary history, soil, and other local environmental conditions in determining species response to disturbance. The answer to this question is of basic ecological interest. It  also has important practical implications for constructing realistic management programs in both California and Israel, as exemplified above.