Abstract
Aims
The direct effects of atmospheric and climatic change factors�atmospheric [CO2], air temperature, and changes in precipitation�can shape plant community composition and alter ecosystem function, but it is essential to understand how these factors interact to make better predictions about how ecosystem may respond to change. We investigated the direct and interactive effects of [CO2], warming, and altered soil moisture in open-top chambers enclosing a constructed old-field community to test how the these factors shape plant communities.
Materials and methods
The experimental facility in Oak Ridge, Tennessee, USA made use of 4-m diameter open-top chambers and rain shelters to manipulate [CO2] (ambient, ambient + 300 ppm), air temperature (ambient, ambient + 3.5 C), and soil moisture (wet, dry). The plant communities within the chambers comprised seven common old-field species, including grasses, forbs, and legumes. We tracked foliar cover for each species and calculated community richness, evenness, and diversity from 2003-2005.
Important findings
This work resulted in three main results: 1) warming had species-specific effects on foliar cover that varied through time and were altered by soil moisture treatments; 2) [CO2] had little effect on individual species or the community; 3) diversity, evenness, and richness were influenced most by soil moisture, primarily reflecting the response of one dominant species. This experiment demonstrated that individualistic species responses to atmospheric and climatic change can alter community composition, and plant community response should be an important component of analyses of terrestrial ecosystem response. Prediction of plant community changes will remain difficult, however, given the occurrence of interactions between factors and the changes in response through time.
