Document: MAR-3-34-75

Changes in plant community patterns under elements of global change.

SEBASTIA, M.* ^1,2, V.GRACIA ¹ and S.DUAIGUES ¹

Centre Tecnologic Forestal de Catalunya. Solsona. Spain ¹
Universitat de Lleida. 25198 Lleida. Spain ²

Abstract:
Using the reciprocal transplanting technique, we assessed changes in the patterns of productivity, diversity, plant composition and functional types in subalpine meadows from the Pyrenees under elements of Global Change. We transplanted 60 intact 40 by 40 by 20 cm monoliths from the meadows to the lowland; 60 additional monoliths remained in their original habitat. In the lowland, there was a temperature rise of about 10C, a reduction in water input of about 50%, and a small increase of CO₂. There was a significant increase in plant biomass in the lowland compared to the subalpine. However, this increase was not homogeneously distributed among all the species. Although the six most abundant species were the same in both sites, they ranked differently, and, in the lowland, they broadened the differences in biomass among them; as a general pattern, the dicot species augmented proportionally more than the grasses. Plant composition, species richness and diversity varied more strongly because of intra-seasonal temporal changes than the transplanting treatment, but an episodic drought by the end of the growth season in the lowland decreased significantly plant diversity. Changes in the dominance of the species during the first growth season can have significant impacts in the trajectory of the system through time, with increases of dominance, decreases in plant diversity, and species extinctions, although the inertia of the community prevents some in the first year. These effects could be aggravated by punctual episodes of extreme events.

Keywords: Productuvity, Plant Diversity, Functional Types, Plant Composition, Temperature raise, Drought

This abstract is being presented at: 10:15 AM in session:
Oral Session #43: Plant Community Responses to Climate Change.