Effects of Native and Invasive Plants on Stream Morphology

In the southwest United States, earthen dams are commonly used for management of rivers and streams.  These dams support vegetation growth, and the vegetation in turn adds to the structural stability of the dams.  Two plants frequently found on these dams are the cottonwood tree and the tamarisk shrub.  Tamarisk is an invasive species that poses a threat to native biodiversity.  It concentrates salt at the soil surface so other plants cannot grow, and its roots are more shallow than cottonwood and therefore cannot hold earthen dams together as well.  In this study the survival and growth of tamarisk and cottonwood will be measured, then the plants will be planted on a pointbar at the meander bend of a stream.  The effects of the plants on the sediment flux in the stream will be measured, as well as the number of plants that die or become uprooted after transplating.  This will give researchers some information to compare these two species and learn about the changing plant life in the southwest.  This project is not yet complete, but data collection has ended and analysis has begun.