Prescribed cattle grazing as a tool for native prairie management: Lessons from the Tualatin River basin, Oregon

P rairie and oak ( Quercus spp.) savanna are important disturbance-dependent habitats in the Willamette Valley–Puget Trough–Georgia Basin ecoregion (WPG). Estimates of previous extent and current cover of prairie habitat suggest that between 2% and 10% of presettlement prairie remains (Dunwiddie and Bakker 2011; Vesely and Rosenberg 2010; Intertwine Alliance 2013). Previous to Euro-American settlement, Native Americans burned prairies to discourage encroachment of trees and shrubs, maintain habitat for grazing ungulates, and increase productivity and diversity of herbaceous plant species. Due to conversion to agriculture, land development, invasion by nonnative vegetation, reduction in elk ( Cervus canadensis ) numbers, and fire exclusion, native prairie and savanna have declined dramatically in this ecoregion. Several state and regional species of concern are reliant on prairie and savanna habitats (ODFW 2016; Altman 2011), and restoration of prairies remains a top priority for agencies and organizations with a conservation mission. The focus on prairie and savanna conservation in the WPG ecoregion over the past several decades has led to the development of many prairie-oak focused partnerships, emerging science and management practices, and increased protection and restoration of these habitats (Dunwiddie and Bakker 2011; Stanley et al. 2011; Intertwine Alliance 2013). Land managers of these properties are tasked with…