An Ecohydrological Framework for Riparian Restoration and Southwestern Willow Flycatcher Recovery Planning and Prioritization
Bruce Orr1*, Glen Leverich2, Tom Dudley3, James Hatten4, Matt Johnson5, Kevin Hultine6
1 Stillwater Sciences, Berkeley, California
2 Stillwater Sciences, Portland, Oregon
3 University of California, Santa Barbara, California
4 U.S. Geological Survey
5 Northern Arizona University
6 Desert Botanical Garden, Phoenix, Arizona
With the upsurge of river restoration and floodplain management projects being implemented across North America and elsewhere, it is valuable to incorporate informed, science-based project designs during the planning phases to ensure long-term success of these much-needed efforts. This is especially true in highly dynamic systems, such as the large, flashy rivers in the arid Southwest that do not fit the “classic” textbook river model and, thus, demand consideration of regionally specific conditions. We have developed a ecohydrological riparian restoration planning approach for systems in the arid and semi-arid regions of the Western United States that links the key physical attributes of a river and its watershed—such as climate, hydrology, and geomorphology—with the ecological responses of vegetation, birds, and other wildlife to those conditions. This integrative approach provides a functional framework for increasing our ability to implement successful restoration by using our understanding of key ecosystem linkages to identify appropriate and feasible restoration approaches, including both passive and active revegetation, and suitable locations for river-floodplain conservation and riparian restoration actions. We applied this approach in two ongoing restoration efforts in the Southwest that were initiated primarily to enhance and restore habitat for the endangered southwestern willow flycatcher (Empidonax traillii extimus) (SWFL) and other native species of interest. The overarching goals of the restoration planning and implementation projects on the Virgin River (UT, AZ, NV) and the upper Gila River (AZ) were to: (1) prepare for observed (Virgin) and anticipated (Gila) alterations to the existing riparian system following colonization by the tamarisk beetle (Diorhabda elongata complex) introduced for the biological control of tamarisk (Tamarix spp.); (2) support recovery of native riparian habitat through active (e.g. replanting of native species) and passive revegetation (where natural or managed hydrology is suitable for natural recruitment of native woody riparian plants) to promote local increases in SWFL population size; (3) facilitate implementation of a comprehensive approach toward riparian restoration by a collaborative group of stakeholders, resource managers, and scientists; and (4) provide recommendations to be incorporated into the restoration plans developed by local stakeholders, such as the Clark County Desert Conservation Program (Virgin) and Gila Watershed Partnership (Gila). This approach has widespread applicability to the SWFL conservation plan and associated habitat restoration currently being developed by USDA-APHIS. We propose to develop a decision support tool that would link key aspects of our ecohydrological framework, including the rangewide results of a satellite model of SWFL habitat suitability, with key elements from the SWFL Recovery Plan dealing with metapopulation viability. This type of decision support tool has the potential to assist APHIS and others with assessment and prioritization of habitat restoration actions most likely to promote persistence and recovery of SWFL populations.