PARENT SESSION
Poster Session #54: Plant Ecology: Communities.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Effects of invading young sagebrush (Artemisia rothrockii) on an herbaceous meadow in the eastern Sierra Nevada.

Darrouzet-Nardi, Anthony^*,1, D'Antonio, Carla¹, Berlow, Eric^1,2, ¹ University of California, Berkeley² University of California, San Diego

ABSTRACT- We hypothesized that when young sagebrush shrubs (Artemisia rothrockii) invade herbaceous meadows, they modify the physical conditions of the meadow to the disadvantage of resident species, thereby resulting in further sagebrush expansion. To test this hypothesis, we found areas where fronts of sagebrush were beginning to invade Bullfrog Meadow (Golden Trout Wilderness in the Eastern Sierra Nevada) and manually removed young sagebrush plants. We compared soil moisture and nitrogen, herbaceous biomass and percent ground cover of shrubs and herbs between removal plots and nearby 'control' areas. There was no difference between the treatments until late August, when plots with removed sagebrush began to show higher moisture levels than plots with intact sagebrush. This suggests that young sagebrush plants put water stress on the meadow. We also examined the rates of photosynthesis and transpiration in the herbs and the sagebrush to see how these processes might affect the soil moisture in the meadow. These data suggested that, as sagebrush seedlings grew, there would be a size threshold where they were using enough water to desiccate sections of the meadow to the detriment of the herbs growing there.

KEY WORDS: Artemisia rothrockii, invasion ecology, water relations, montane meadows