Understanding and Combating the Fire-Enhancing Impact of Non-Native Annuals in Desert Scrub through the Tools of Population and Landscape Ecology.

摘要

This project examined the hypothesis that some of the now dominant and problematic non-native invasive annuals are able to spread into the areas between the shrubs by employing population strategies that sharply contrast with those of native species. This greatly increases the fuel load in the matrix, which has historically produced a natural firebreak between shrubs. Our particular aims were to: (1) gain an understanding of the landscape-scale population dynamics of fire promoting and fire retarding plant species; (2) test the hypothesis that once fire becomes important, naturally formed islands of fertility will break down and a negative feedback will enhance fire even further; (3) apply the results to aid management practices that will help restore the original environmental pattern of islands of fertility in a low-nutrient matrix and therefore prevent future wildfires; and (4) understand the effects of non-native invasive plant species on fire regimes. The results derived from this project s experimental and simulation modeling approaches facilitate a better understanding of the association between annual plants and desert shrubs with respect to key interactions and the development of spatial pattern that may influence fire risk. It also provides insights into the different role the exotic species Schismus arabicus plays in fire spread within the Mojave and Sonora Desert sites. This understanding is a first step in characterizing the interaction of fire and soil disturbance in changing the likelihood of future fire occurrences through the direct influence on the creosote shrub plant community.