PARENT SESSION
Oral Session #80: Plant Ecology .
Presiding: G. Platenkamp
Thursday, August 8. 9:00 AM to 11:30 AM. Grand Ballroom West, Radisson.
Great Plains grasses, shrubs and trees: above- and below-ground functional classification.
Awada, Tala*,1, Wedin, David1, Ding, Xioping1, 1 University of Nebraska-Lincoln, Lincoln, NE
ABSTRACT- Woody species play diverse roles in the Great Plains grassland communities. Some woody species are restricted to unique habitats, some co-exist, while others invade and displace grasses. We examined physiological and morphological traits of both above- and below-ground biomass in 16 woody species and 4 grasses. We classified these species based on a priori classifications: C3 grasses, C4 grasses, conifers, deciduous trees, deciduous shrubs, and nitrogen fixers. Species were grown for two years in the field in pots (20cm in diameter and 96cm high) buried in the ground. Leaf physiological traits included: photosynthesis, stomatal conductance, SLA, WUE, RGR and nitrogen content. At the beginning of September, plants were harvested for total above- and below-ground biomass, and sorted into leaves, aboveground wood (fine, woody) and belowground roots (fine, coarse and woody). Belowground attributes included average root diameter, specific root length (SRL), density and nitrogen content. Anova was performed to test differences in individual traits among species and functional groups. Regression analyses were used to correlate particular traits. Principal component analysis was used to determine the relationships among functional traits across species, and to hypothesize alternative functional group classifications. Woodiness and leaf nitrogen were the dominant aboveground traits separating species. Woodiness and SRL were the belowground traits separating species. Grasses clustered separately from woody species with their belowground traits, however, aboveground, a group of slow growing woody species (ponderosa pine, eastern redcedar and bur oak) clustered with grasses. Cottonwood consistently stood out from other woody species because of its higher growth rate. A priori functional group (nitrogen fixer) appeared to group poorly based on our classification.
KEY WORDS: Great Plains, plant function, grasses, woody vegetation