Submitted to: Ecological Society of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 2003
Publication Date: August 20, 2003
Citation: Comas, L.H., Skinner, R.H., Sanderson, M.A. 2003. Using plant morphology, physiology, and stress response to define plant functional groups in pasture systems [abstract]. Ecological Society of America Proceedings. CDROM. Technical Abstract: Interest in quantitatively defining plant functional groups has been increasing as ecologists strive to understand plant communities from a functional perspective. Plant functional groups in current literature are most often defined qualitatively. We divided 23 common pasture species from three commonly defined functional categories (grass, legume, forb) into eight functional groups using principal component analysis on plant growth responses to low nitrogen (N) and water availability determined in a greenhouse study. Sensitivity of plant biomass to drought explained similar variation between species as rooting depth. Growth of grasses was generally sensitive to N, but grasses could be separated into deep- and shallow-rooted species. Most legumes were drought-sensitive/N-insensitive, but a few were drought-sensitive/N-sensitive and drought-insensitive/N-sensitive. Shallow-rooted, N-insensitive forbs were separated from shallow-rooted/N-sensitive and deep-rooted/N-sensitive forbs. We also collected measurements of plant morphology, architecture, and physiology to determine which traits were best correlated with plant growth responses to low N and water. With the exception of several fast-growing legumes, fast-growing species in general were the most sensitive to N and water availability. Fast-growing species had a greater percentage of their roots at deeper depths at the expense of shoot biomass.