PARENT SESSION
Friday, August 11, 8:00-11:30 am
COS 104 - Invasive species VII: prevention, control, and models
Ballroom E, Ballroom Level, Cook Convention Center
Presiders: T Langkilde
Fire effects on the invasive tree Chinese Tallow (Triadeca sebifera): an analysis using structural equation modeling.
Anderson, Michael*,1, Grace, James1, Allain, Larry1, 1 National Wetlands Research Center, Lafayette, LA, USA
ABSTRACT- Coastal prairie is a hybrid of coastal wetland and mesic tallgrass prairie and is among the most endangered ecosystems in the United States. An exotic invasive tree, the Chinese Tallow (Triadeca sebifera), threatens to convert what little remains of the coastal prairie into monotypic woodland. This presentation describes an experimental test of the efficacy of fire in controlling Chinese Tallow. Because of the greater capacity for large Tallow trees to survive fire, we hypothesized that there exists a critical tree size, beyond which a community could not be recovered using fire. We evaluated this hypothesis by studying individual responses of trees (n = 378) to prescribed burning at two sites and in two seasons (summer and winter) over a two year period at Brazoria National Wildlife Refuge in Texas. Structural equation modeling was used to understand tree responses to fire in relation to multivariate environmental factors such as soils and elevation that varied between sites and fuel loads surrounding each tree that varied spatially and between seasons. The results demonstrated a strong negative effect of fire on Chinese Tallow, with initial tree height well-correlated with the responses of trees to burning. Study sites had moderate impacts on the results, stemming from variation in fires, fuel properties, or conditions affecting tree growth. Effects of season on initial fuel conditions were deemed coincidental. However, season had an important direct effect on height change by influencing resprouting; trees burned during the dormant season produced resprouts that fared better than trees burned in summer. This study is an example of a multivariate analysis of field experimentation and seeks the development of a general predictive model.
Key words: invasive species, Chinese Tallow (Triadeca sebifera), structural equation modeling (SEM)