Common Gardens For All Your Climate Change Needs
A guest post from PLOS Ecology Reporting Fellows, Caitlin McDonough MacKenzie & Daniel E. Winkler, on research from the Ecological Society of America Scientific Meeting in Ft. Lauderdale, Florida, August 7-11, 2016.
Experimental gardens are an old-school methodology. In perhaps the best known example in the 1930s and 1940s Clausen, Keck, and Hiesey transplanted Potentilla glandulosa across their range in the Sierras to explore the roles of environment and genetics played in determining growth form. Clausen, Keck, and Hiesey’s classic methodology of reciprocal transplanting has a contemporary application in climate change studies, whereby researchers relocate a plant (or seed) from its home and current climate to a transplant garden and new (and perhaps future) climate. Seven decades later, the Ecological Society of America’s 2016 Annual Meeting features experimental gardens that include species ranging from alpine forbs to douglas fir trees to a dune-loving annual—collected along latitudinal, elevation, and habitat gradients.
Nicole Rafferty opened the Climate Change: Ranges & Phenology I session presenting her research on patterns of bumblebee visitation at the Rocky Mountain Biological Laboratory. As a part of this project, she installed a reciprocal transplant experiment with seeds from three elevations planted at 12 plots per elevation site. She wanted to test how alpine plant-pollinator relationships might change as plant communities experience new microclimates (for example, if a species is transplanted to a warmer site at a lower elevation). Unfortunately, the first year of this study coincided with a dry summer and low germination rates — as a result, in 2016 she switched to seedlings. In her 2015 seed study, the glacier lily seeds from mid-elevation had the lowest success in the transplants, suggesting that mid-elevation might be a barrier to plant migrations upslope for this species.
Range shifts and phenological are also on the minds of researchers at the U.S. Forest Service. This time with an applied focus aimed at aiding land managers who will likely need to develop strategies to make Forest Service lands more resilient to climate change impacts. Sheel Bansal at the U.S. Forest Service’s Pacific Northwest Research Station and colleagues carried out a large-scale common garden study aptly named the Douglas-fire Seed-Source Movement trial. Their experiment used seeds from 60 sources throughout the species range in Washington, Oregon, and California and grew trees from each of the sources in 9 climatically-divergent field sites and also used artificial freeze experiments to test the impacts of changing environmental queues on Douglas fir cold hardiness and associated genetic linkages.
They found strong differences in cold hardiness, with minimum winter temperatures and fall frosts as major predictors of cold hardiness based on seed source. Their results have important implications for the ability of species to shift their ranges by tracking climate envelopes, and further extend to land management efforts to maintain healthy forests experiencing future climates.
In the Great Lakes region, Elizabeth LaRue from the Emery Lab at the University of Colorado Boulder used a common garden to explore dispersal traits in American sea rocket (Cakile edentula var. lacustris). She knew that dispersal traits like pericarp, or seed wall, thickness and wet mass varied across the Cakile edentula range, but it was unclear if the variability was caused by environmental or genetic differences. Collecting seeds from across the range, and growing them together in a common garden isolated the role of genetic differences and revealed lower dispersal traits at the range edges. This data was used to inform species distribution models with different scenarios for starting dispersal genetics for Cakile edentula under climate change.
Kennedy Rubert-Nason in the Department of Entomology at the University of Wisconsin-Madison and his colleagues looked at the role of vernal freezes in determining aspen phenology and growth. They planted 6 aspen genotypes into common gardens at varying temperatures and examined a number of biological responses.
The number of days it took aspen to break bud accelerated in trees that experienced freeze-damage. Freeze-damaged trees were also stunted in their second year of growth when they experienced a freeze event during their first year. Defense compounds were also dramatically impacted, potentially indicating the negative effects of freeze events and the associated ability of the trees to defend against herbivores during their most vulnerable life stage. Their study nicely highlights the importance of the timing of environmental queues in dictating species susceptibility to a changing climate.
Caitlin McDonough MacKenzie is a PhD candidate in the Primack Lab in the Biology Department at Boston University. She spends her field seasons in Acadia National Park, Maine studying leaf out and flowering phenology and patterns of historical species loss across plant communities. Her field methods include three ridge transects that are conveniently located adjacent to beautiful running trails and carriage roads. Away from Acadia’s granite ridges, she’s interested in underutilized sources of historical ecology data including herbarium specimens, field notebooks, photographs, and old floras; the potential for citizen science in phenology research; and the intersection of science and policy. (Follow Caitlin on Twitter @CaitlinInMaine)
Daniel Winkler is a PhD candidate at the University of California, Irvine and a recent National Park Service Young Leader in Climate Change. Daniel is a plant ecophysiologist interested in invasive species, evolutionary ecology, and climate change impacts on native communities in “extreme” environments. His field sites include much of the desert southwest, alpine regions of Colorado, the subalpine forests of Baja California, and the tundra of northern Japan. All of Daniel’s research focuses on climate change impacts on native systems, with an emphasis on parks and protected areas. You can follow him on Twitter @DanielEWinkler, his research on Facebook at www.facebook.com/GeoMustard/, or find more information on his website at www.winklerde.com.