Speaker: Dr. David Ackerly (UC Berkeley)
Where: L-GE 110 | When: 1:15 pm “Topography, Species Distributions and Impacts of Climate Change on California Native Plants” Abstract: The structure and composition of plant communities reflect, in part, the climatic tolerances of constituent species. This relationship can be quantified based on the community weighted means (CWM) of species climatic niche values (average or extreme values representing a species geographic distribution across climate gradients). In response to a warming climate, shifts in CWM values may occur by changes in relative abundance of existing species (including local extinction), and by immigration and establishment of new species. In this talk, I will examine the hypothesis that communities on hotter and/or drier sites will face greater dispersal limitation as species adapted to even hotter conditions will not be found within local landscapes. At a local scale (Pepperwood Preserve, Sonoma Co., CA), communities on cooler topographic positions have greater potential for shifts in CWM due to presence of hotter adapted species at low abundance, coupled with nearby seed sources from hotter microclimates. However, scanning the entire California flora, only two tree species adapted to hotter climates are found within 200 km. Similarly, at a regional scale, minimum dispersal distances for arrival of new, hotter adapted species, may be 100s km or more, and are higher for communities at hot or dry margins of the distribution of forests (e.g., around the CA Central Valley). These analyses suggest significant limits to community change based on natural dispersal in communities occupying hot and dry locations within a landscape, and potentially a greater need for assisted migration or restoration initiatives to facilitate vegetation transitions in a warming climate. Photos By: Michael Chung & Arun Dayanandan Comments are closed.
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