PARENT SESSION
Thursday, August 10, 5:00-6:30 pm
Poster Session 23 - Arid and semi-arid ecosystems: deserts, grasslands, shrublands, and savannas
Exhibit Hall, Ballroom Level, Cook Convention Center
Plant cover as related to groundwater depth in Owens Valley, CA.
Mata-Gonzalez, Ricardo*,1, McLendon, Terry1, Martin, David2, Trlica, M3, Pearce, Robert4, 1 MWH Americas, Inc., Fort Collins, CO2 Los Angeles Department of Water and Power, Bishop, CA3 Colorado State University, Fort Collins, CO4 Natural Resources Conservation Service (NRCS-USDA), Bishop, CA
ABSTRACT- The Owens Valley, CA receives limited precipitation (13-17 cm annually) but has extensive areas with shallow water tables that can be a source of water for vegetation. Despite its suggested importance, the relationship between depth to water (DTW) and plant cover in this area has not been adequately documented. Previous studies have mostly estimated DTW and plant cover. We conducted an extensive study measuring DTW and plant cover at the same locations throughout the Owens Valley to elucidate the relationship between these two variables. We evaluated plant cover along 67 transects within eight major plant communities on sites with shallow water tables. Along these transects, we measured DTW at 820 augered wells and recorded changes in micro-topography. Overall, DTW ranged from 0.3 to 4.0 m, averaging 1.8 m and plant cover ranged from 0% to 198%, averaging 46%. Correlation analyses indicated that the relationship between DTW and plant cover was weak (R=0.23) and that DTW was a poor predictor of plant cover (R2=0.06). Average DTW varied for individual species (Juncus balticus, 1.2 m, Distichlis spicata, 1.3 m, Leymus triticoides, 1.6 m, Atriplex torreyi, 1.7 m, Chrysothamnus nauseosus, 2.0 m, Sporobolus airoides, 2.1 m, Sarcobatus vermiculatus, 2.1 m, and Artemisia tridentata, 2.3 m). For each species, however, the relationship between DTW and cover was weak (R<0.20), indicating that although species may thrive under certain DTW levels, the range of DTW they may inhabit is significantly large. We conclude that the relationship between DTW and plant cover is complex and that DTW as a single factor is a poor predictor of vegetation cover.
Key words: arid grassland/shrubland, groundwater, plant cover