Struwe, Lena , Hatfield, Colleen A. .
A new method using parsimony to study vegetation patterns and biocomplexity in a spatial context.
Understanding patterns and processes leading to particular species distributions have always been a challenge in ecological studies. These distributions can be strongly linked to environmental and historical factors, as well as spatial relationships among areas. Common methods to study comparative species composition among areas are cluster analysis and ordinations, but these do not allow subsequent evaluation of individual species. Also, these methods do not take the actual spatial relationships into account. In this new approach, based on the parsimony criteria commonly used in evolutionary systematics, patterns found in species composition are evaluated within the spatial context of a branched stream network. A total of 177 higher plant species were sampled in 58 plots in a 12 km long, 3rd order river system in northern New Jersey, USA. Species patterns were analyzed using parsimony, and also parsimoniously mapped onto the actual river topology. The resulting parsimony tree shows some strong similarities to the actual topology, and widespread species appear to retain the spatial structure the best. To track the correlation between environment and species distribution, 11 variables were assessed from the same 58 plots. Interestingly enough, changes in overall species distribution are not strongly correlated with environmental change. Instead, spatial proximity and history might explain a larger portion of the found distribution patterns. This method allows us further evaluate specific species, groups of species (e.g., based on life history, invasiveness), or environmental variables (e.g., disturbance, vegetation type, soil characteristics) in detail and look for correlations. In summary, our approach using a systematic method to answer ecological questions enables scientists to extract the relationships between the community, species, and environment simultaneously in a defined spatial context. Such complex relationships are increasingly important to understand patterns related to invasive species distributions, restoration potential, species response to environmental change, and sustainability of ecosystems.
1 - Rutgers University, Ecology, Evolution, & Natural Resources, 14 College Farm Rd, New Brunswick, New Jersey, 08901, USA
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 8:30 AM