Impacts of temperature and precipitation on the abundance and role of Bromus tectorum within a Montana sagebrush-steppe community.
The invasive species Bromus tectorum (downy brome or B. tectorum) is arguable the most destructive invasive species within the sagebrush-steppe communities of the American west. Given the proper conditions B. tectorum can form monocultures in previously uninvaded native sagebrush-steppe vegetation. This dominance can affect every aspect of the ecosystem from the hydrology and nutrient cycling to community diversity and composition. Most notably, however, is B. tectorum’ impact on an ecosystem’s fire regime; by introducing an abnormal fuel load, B. tectorum can greatly increase fire length, severity, and return interval. This change to the sagebrush-steppe fire regime has created conditions that are favorable for further B. tectorum invasion, thereby creating a positive feedback between fire and B. tectorum.
It has been shown that B. tectorum dominance and the positive feedback between fire and B. tectorum are constrained by climate to the Great Basin and areas of similar climate. However, climate models project change across the west, thereby affecting the range of suitable climate for not only B. tectorum dominance but also of the feedback between B. tectorum and fire. Therefore, using small scale climate manipulations and prescribed burns in the field, my research focus is on how climate change will impact B. tectorum’s presence and role within southwestern Montana’s sagebrush steppe communities. Specifically, will warmer and drier summer conditions create conditions favorable for the expanded presence of B. tectorum in SW. Montana and, similarly, will these conditions promote the establishment of the positive feedback between fire and B. tectorum in SW. Montana.
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