Document: MIC-3-64-9

Restoring dry meadow ecosystems using threshold and alternative state concepts: Aboveground vegetation response.

WRIGHT, J.M.* ^1,2 and J.C.CHAMBERS ^1,2

University of Nevada, Reno, NV 89503, USA ¹
USDA Forest Service Rocky Mountain Research Station. ²

Abstract:
Riparian corridors in central Nevada have high economic and ecological value. Degradation of riparian dry meadows (overgrazing, fire suppression, and stream incision) lowers water table levels and facilitates encroachment and dominance by Artemisia tridentata. Restoring A. tridentata sites to dry meadows is possible where water table dependent thresholds have not been exceeded. Two ecosystem types, dry meadows and A. tridentata tridentata/Elymus cinereus, trough drainageways, characterize the apparent alternative stable states for these systems and were used to evaluate restoration of sagebrush-dominated sites to dry meadows. The study (1997-1999) used a paired-plot approach on sites with high, intermediate or low water tables. One plot received a restoration treatmentburning then reseeding with native grasses and forbs. Not-burned plots served as the control. Species composition and aboveground biomass were measured in undershrub and interspace microsites of both plots and used to assess treatment response. In general, biomass progressively increased from 1997 to 1999 on burned plots, but controls showed little change. Effects of burning were microsite specific, with undershrub microsites exhibiting lower biomass than interspaces the first and sometimes second year after burning. By 1999 biomass was as high or higher in interspace microsites. Seedling establishment was low and species composition was determined largely by pre-burn vegetation. Sites with high and intermediate water tables had greater abundance of perennial dry meadow species, Leymus triticoides, Poa pratensis, and Leymus cinereus, and responded favorably to the burn. Sites with low water tables were dominated by annual forbs, Nicotiana attenuata, Chenopodium album, and Descurainia pinnata, that increased after the burn. Results suggest restoring sagebrush-dominated areas to the dry meadow alternative stable state is practical when thresholds governing water table depth are not exceeded.

Keywords: alternative stable states, riparian, restoration, threshold

This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS