Man versus rat: A comparison of two traditional seeding methods to seeding done by Dipodomys ordii (Ord's kangaroo rat)

Great Basin sagebrush communities are becoming increasingly threatened by reduced perennial grass cover and diversity and invasion by non-native annual grasses.  Many of these landscapes are targeted for ecological restoration where seed application is a viable management strategy.  In suitable topography drill seeding is an effective method for restoration, but in sites with challenging topography and in wilderness areas aerial broadcasting has been a widely used alternative that has met with mixed results. At the same time, these semiarid environments are home to many rodent species who can potentially contribute to plant recruitment through seed caching. We tested these traditional seeding techniques to seeding done by Dipodomys ordii (Ord’s kangaroo rat), a common granivorous rodent in the semiarid West using two native and commonly seeded restoration seeds, Achnatherum hymenoides (Indian ricegrass) and Pseudoroegneria spicata (Bluebunch wheatgrass).  For both grass species, drilling was significantly more effective (P≤.0001) than either broadcasting or caching, based on the number of individuals establishing.  However, broadcasting was not significantly more effective than caching, pointing to the potential use of caching animals in restoration in areas where drilling is inappropriate or impossible.  In some cases, where shrub structure remains intact but diversity is reduced, land managers might be able to increase species diversity by incorporating strategies to facilitate dispersal by rodents. The application of such rodent mediated autogenic approach is discussed.