Dr. Jesse Bellemare, Smith College
Friday, September 27, 2013 at 1:10pm
Thompson Biology, 112 59 Lab Campus Dr, Williamstown, MA 01267
Biology Department Colloquium
"Climate Change and Plant Conservation in the Forests of Eastern North America"
Climate change will be a top threat to biodiversity in coming decades. Species with small ranges, i.e. endemics, may be at increased risk of extinction, as unsuitable conditions may develop rapidly across the entirety of their ranges. Human-assisted colonization or "managed relocation" has been proposed as one option to avoid extinctions by facilitating species in tracking suitable conditions poleward. In this research we conducted a biogeographic GIS analysis to document where small-ranged endemic species are concentrated in the forests of eastern North America and how these distribution and diversity patterns might relate to past climate change and the threats posed by modern, anthropogenic climate change. We found that endemic forest plants are highly concentrated in the Southeast US, but largely absent from areas near and north of the boundary of the last glacial maximum in the Northeast and upper Midwest. The patterns detected suggest that many small-ranged species' distributions are still impacted by past climate change and that they might be slow to respond to modern challenges. In parallel to the GIS study, we also launched an on-the-ground experiment testing the feasibility of northward managed relocation with one of the small-ranged endemics investigated in the biogeographic analysis, Umbrella-leaf (Diphylleia cymosa, Berberidaceae). This forest herb is endemic to high elevation forests in the southern Appalachian Mountains of western North Carolina. In Fall 2008, we established a ~1000 km transect of seed sowing sites from 3 locations within the species' native range to 5 apparently suitable, but unoccupied, sites outside the range in the Mid-Atlantic and Northeast US. Germination in 2009 was relatively high overall (44%) and did not differ significantly within vs. beyond the species' range (40% vs. 46%). Survival from the seedling to juvenile stage (2009-2010) was significantly higher inside vs. outside the range (63% vs. 30%), possibly due to increased herbivory beyond the native range. However, 2010-13 survival rates have been comparable inside vs. outside the range as juveniles have become established. Growth rates of experimental plants outside the native range have been higher than those within the range, despite increased herbivory, and sexual reproduction is possible in 2014. Overall, these results suggest that the distributions of many small-ranged forest plants may still be recovering from past climate change and that assisted colonization could be an option for some endemic species threatened by modern climate change.
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