The Escalante River: Sustaining hard-won restoration in a warmer and drier future
Michael L. Scott1, 2
1Coordinating Committee, Escalante River Watershed Partnership, Escalante, UT
2Adjunct Faculty, Department of Geosciences, Colorado State University, Fort Collins, CO
The Escalante River channel and floodplain have a six-thousand-year history of dramatic ecological state changes associated with arroyo cut and fill cycles, driven largely by shifts in climate. Within this broader context, a recent and widespread invasion of the non-native tree, Russian olive, along the Escalante River, altered geomorphic and ecological processes as well as aesthetic qualities. Embedded within a landscape of intricate complexity and world class beauty, the Escalante River attracts visitors from across the globe. Thus, the Russian olive invasion prompted an ambitious, decade-long restoration effort by Grand Staircase Escalante Partners and the Escalante River Watershed Partnership, to remove established Russian olive, prevent re-invasion, and thus restore channel and floodplain processes that sustain native riparian vegetation. There is evidence suggesting exponential expansion of Russian olive along the Escalante was triggered by floods, which ushered in an extended, regional wet period. Given the climate-sensitivity of large-scale geomorphic processes and possible climate connections to plant invasions, on-going and predicted climate warming are concerning to local resource managers and human communities. Local historical climate records show a steady average annual temperature increase of +1.7o C, beginning in the 1970s, compared against the 100-year average, with no obvious trends in precipitation over the same period. Further, downscaled model projections for the watershed predict an additional 1.7o C increase in average annual temperature with no significant change in precipitation within the next 20 years; with or without attempts to mitigate CO2 emissions. Such changes raise questions on how well conservation objectives and tactics in the Escalante watershed are adapted to projected warmer and drier conditions. Specific questions in this regard include: 1) how are large-scale channel and floodplain processes likely to change? 2) will non-native plant invasion processes change or escalate? 3) with increasing water scarcity, how do we balance human community needs against those of water-dependent ecosystems?