MAPPING OF COTTONWOOD OCCURRENCE AND RECRUITMENT POST-GRAZING ALONG THE MANCOS RIVER IN MESA VERDE NATIONAL PARK, COLORADO

<span">The Mancos River is the only perennial stream in Mesa Verde National Park and supports the park’s only significant riparian and wetland community along 4.5 miles of Mesa Verde’s eastern boundary. Numerous fires, a past history of 100 years of livestock grazing and current upstream water withdrawals have threatened the health and long term sustainability of the river within the park. To determine the current status of the Mancos River and its potential resiliency in the context of climate change and past and future land use changes riparian tree species were identified, separated by size class and mapped using GPS units. Riparian trees are important for the resiliency of the Mancos River because they provide habitat for a number of species and help to reduce soil erosion and flood damage by dissipating the energy of the river. This vegetation, consisting predominantly of Cottonwood species (Populus), was analyzed using ArcGIS for growth and species patterns in relation to stream and bank geomorphology. After identification the diameter of older growth large trees was recorded, the tree physically tagged and then mapped using a separate protocol for future return study. These large legacy trees were used to help determine current water availability. More than 85 percent of the trees mapped were less than 3m in height showing evidence of recent recruitment. Ultimately the age, density and species composition of more than 20,000 trees will be used as a baseline for future studies and be used to make better informed land-use management decisions such as whether the Mancos River is able to sustain habitat suitable for the successful re-introduction of beavers and other native species forced out in the past.