PARENT SESSION
Oral Session 4: Biodiversity I: Communities and Function.
Presiding: C Holzapfel and D Ellsworth
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room B 110.

Defining plant functional types by their potential effects on ecosystem properties.

Comas, L^*,1, Skinner, R¹, Goslee, S¹, Sanderson, M, ¹ USDA-ARS, University Park, PA

ABSTRACT- Interest in defining plant functional groups quantitatively by their ecosystem effects has been increasing as ecologists strive to understand plant communities from a functional perspective. We measured plant physiological, morphological, and seasonal growth traits in order to define plant functional types by traits having direct effects on the productivity and resilience of temperate grazed grasslands. Traits such as relative growth rate, shoot productivity under drought and low N, root distribution, leaf area index, shoot density, and seasonal plant performance, were measured under a recurring cutting regime in a combination of greenhouse and field studies. Measured traits were used to divide 23 common grazing land species from three broad categories (grass, legume, forb) into functional groups. We examined the ability of plant physiological and morphological traits assessed in the greenhouse to explain seasonal growth patterns and competitive ability of plants in the field. In general, the fastest growing species were most affected by water and nitrogen availability. Plants with higher leaf to stem ratios had the fastest re-growth rates following cutting and were most competitive against weeds. Defining plant functional types for temperate grazed grasslands is the first step in investigating the effects of plant functional diversity on productivity and resilience of these systems.

Key words: plant growth strategies, plant biodiversity, functional diversity