A Decision Tree to Inform Restoration of Salicaceae Riparian Forests in the Northern Hemisphere
Eduardo GONZÁLEZ1,2*, Vanesa MARTÍNEZ-FERNÁNDEZ3, Patrick B. SHAFROTH4, Anna A. SHER5, Annie L. HENRY6, Virginia GARÓFANO-GÓMEZ7,8, Dov CORENBLIT9
1 Colorado State University, Department of Biology, Fort Collins, CO, USA
2 University of Denver, Department of Biological Sciences, Denver, CO, USA; edusargas@hotmail.com
3 Universidad Politécnica de Madrid, Department of Natural Systems and Resources, Madrid, Spain; vanesa.mfernandez@gmail.com
4 U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO, USA; shafrothp@usgs.gov
5 University of Denver, Department of Biological Sciences, Denver, CO, USA; anna.sher@du.edu
6 University of Denver, Department of Biological Sciences, Denver, CO, USA; annie.henry@du.edu
7 Universitat Politècnica de València, Institut d’Investigació per a la Gestió Integrada de Zones Costaneres (IGIC), València, Spain
8 Université Clermont Auvergne, CNRS, GEOLAB, France; virginiagarofano@gmail.com
9 Université Clermont Auvergne, CNRS, GEOLAB, France; dov.corenblit@uca.fr
The regeneration of foundation riparian shrub and tree species in the Salicaceae family (Populus and Salix spp.) is frequently impaired by human activities. Salicaceae forest restoration has been traditionally approached from a terrestrial perspective that emphasized planting. More recently, floodplain restoration activities have embraced an aquatic perspective, inspired by the emerging philosophy of environmental flows for river management. However, riparian Salicaceae species occur at the interface of both terrestrial and aquatic ecosystems along watercourses, and their regeneration depends on a complex interaction of hydrologic and geomorphic processes that have shaped key life-cycle requirements for seedling establishment. Ultimately, restoration needs to integrate these concepts to succeed. However, the literature reporting restoration actions on Salicaceae regeneration is scattered, and a specific theoretical framework is still missing. We reviewed 105 published experiences in restoration of Salicaceae forests, including 91 projects in 10 world regions throughout their range across the Northern Hemisphere, to construct a decision tree to inform restoration planning through explicit links between the well-studied biophysical requirements of Salicaceae regeneration and 17 specific restoration actions. Planting (in 55% of the projects), land contouring (30%), competing vegetation removal (30%), site selection (26%), and irrigation (24%) were the most common restoration actions. Environmental flows, including induced large pulse flows (8%), managed recessions (13%), base flows (7%) and flow sequencing (11%) were effective restoration actions in less populated areas. With alternative, innovative and feasible approaches that also incorporate human needs, it could be possible to restore Salicaceae riparian forests to better fit their new hydrologic and fluvial geomorphic situation.