My current research examines the links between species coexistence mechanisms and the mechanisms underlying the relationship between biodiversity and ecosystem productivity. The following are two examples of my research projects and interests.
(1) Are species- or community-specific plant-soil microbe feedbacks a dominant mechanism underlying the biodiversity-productivity relationship in grasslands? It has been predicted that the accumulation of pathogens diminishes productivity over time in monocultures, and that formation of positive relationships between plants and microbes increases productivity over time in high diversity plant mixtures. I am conducting greenhouse experiments utilizing the soil communities from the Cedar Creek long-term biodiversity experiment to assess whether these plant-soil feedbacks alone, or in concert with nutrient feedbacks, can lead to overyielding.
(2) How does warming affect the relationship between biodiversity and productivity? Within the biodiversity and climate (BAC) experiment at Cedar Creek, I am looking at how plant communities shift their rooting depth distributions in response to planted diversity and experimental warming treatments. In particular, I am investigating how shifts in water availability and nitrogen dynamics may drive these shifts in plant communities, and drive changes in above and below ground productivity in grasslands.
CONTACT
jcowles@umn.edu
218-343-1519
SELECTED PUBLICATIONS
Clark CM, Bai Y, Bowman WD, Cowles JM, Fenn ME, Gilliam FS, Phoenix GK, Siddique I, Stevens CJ, Sverdrup HU, Throop HL. Nitrogen Deposition and Terrestrial Biodiversity.- In: Levin, S.A.(ed.), Encyclopedia of biodiversity. Academic Press, 2013.