Tamarisk and river restoration along the San Pedro and Gila Rivers
This article is part of a larger document. View the larger document here.Abstract
The abundance of tamarisk (Tamarix ramosissima and related species) along the San Pedro and Gila River flood plains varies with differences in stream flow regimes. Tamarisk abundance, relative to Fremont cottonwood and Goodding willow, is greater at sites with more intermittent stream flows and deeper and more fluctuating ground-water levels. Tamarisk abundance is further increased below Coolidge Dam, where both flood and low flow patterns have been altered. Shifts from cottonwood-willow to tamarisk parallel other changes in the riparian community: as rivers are dewatered and flood regimes altered, species diversity and landscape heterogeneity decline. Tamarisk dominance can be seen as an indicator, rather than a cause, of riparian degradation, reflecting changes in the physical processes that shape riparian plant communities. Restoration strategies should focus on identifying and alleviating these underlying environmental stressors to produce long-lasting results.