Native lagomorphs prolong legacy effects limiting restoration of imperiled shrub-steppe communities

Abstract

Over the last +150 years, increases in woody vegetation in drylands and associated declines in herbaceous vegetation have led to widespread interest in reversing this trend. However, the effects of native, noncharismatic herbivores, such as lagomorphs, on these efforts are largely unknown. For 11 years post-treatment, we quantified the effects of native lagomorphs on restoration efforts in sagebrush (Artemisia L.) communities exhibiting legacy effects of past management, including depleted understories and overabundant sagebrush. Reducing sagebrush and seeding perennial grasses was necessary to attain substantial increases in large perennial grass cover and density, but this outcome was realized only with lagomorph exclusion. A small native bunchgrass and perennial forb cover and density increased in all treatments with lagomorph exclusion. This suggests that lagomorphs contribute to the persistence of a depleted understory in areas with increased woody vegetation. In areas where sagebrush was reduced, the cover and density of sagebrush was greater with lagomorph exclusion. This suggests that lagomorphs could hinder sagebrush recovery after disturbances that reduce or eliminate sagebrush. Lagomorph herbivory had a substantial effect on vegetation dynamics and affected the outcome of restoration efforts in these dryland systems. This could reduce livestock forage and alter habitat of wildlife species, potentially affecting their conservation. Lagomorphs and other noncharismatic, native herbivores may facilitate the persistence of depleted understories in areas where woody plants have increased. Results of this study suggests that the potential effects of lagomorph and other native herbivores should be considered and addressed in management, restoration, and conservation plans.