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Main pattern found

Herbivores strongly altered the response of plants to climate change, and changes in species richness differed between competition and bipartite communities (see figures below). The main trend found was that plants suffered large declines in species richness when herbivores were absent, in contrary to when herbivores were present. The decline in species richness occurred after the period of climate change, when climate had stabilized. 

Plant response to climate change without and with herbivory. Time in years. Dashed vertical line indicates end of climate change at year 300. Black line gives global species richness; blue, green and red shows species richness in polar, temperate and tropical regions, respectively. Subplots show different scenarios of genetic variance and dispersal.

Additional explanation to the figures: Increased species richness in a region indicates that immigration has occurred, that is, species not initially present in the particular region have been established in the region. Declining species richness in a region indicates that emmigration has occurred, that is, movement out of the region of species intially present in the region, and /or local extinctions of species. 

Effect of dispersal and genetic variance

Genetic variance and dispersal were of primarily of importance for plants when herbivores were not present. Low genetic variance led to more severe declines in species richness than high genetic variance. Dispersal rate was mainly of importance determining the rate of the early increase in species richness in the polar and temperate regions, as well as the later decline in species richness in these regions. The different response of plants in the different communities indicates that the additional interactions present with included herbivory reduced the impact of dispersal rate and genetic variance. 

More results...

...can be found in the thesis, which can be downloaded (see left menu)! Additional results found in the thesis are for example figures revealing species densities and possible extinctions, which in the figure above might be concealed by immigrating species. Also, you will find a more detailed explanation of the figure showed above. 

Responsible for this page: Agneta Johansson
Last updated: 06/01/14