Restorationists often hope and expect that wildlife will increase in abundance and diversity when “native” habitats are restored, but this assumption has not been well-investigated for most wildlife species, particularly in grasslands, and even more so in the Central Valley of California. From 2014 to 2015 I conducted a rather ambitious spatiotemporally replicated natural experiment investigating wildlife responses to grassland restoration in the Central Valley. One component of this experiment was to monitor rodent, snake, and raptor activity in paired restored and unrestored (exotic invaded) grasslands at four locations across Yolo and Sacramento counties. Last night I submitted the results of this to the international Journal of Applied Ecology, in which I shared our results for these three trophic levels (plus vegetation!) and their interactions via structural equation modeling.
Journal review and publication is often a long and drawn-out process, so until the paper is officially published, here is the abstract and citation information, and if you have any questions I would be happy to answer them!
Preferred (temporary) citation: Wolf KM, Whalen MA, Bourbour R, Baldwin R. In Review. Rodent, snake, and raptor activity in restored perennial native grasslands is lower than in unrestored exotic annual grasslands. Journal of Applied Ecology.
- In California’s Central Valley, 98% of native grasslands have been destroyed or degraded due to invasion, farming, and development. Grassland restoration is often assumed to provide improved wildlife habitat, ostensibly increasing the abundance and diversity of at least some native wildlife species relative to unrestored, invaded annual grasslands.
- We compared rodent, snake and raptor activity and species richness at paired unrestored and restored grasslands across four locations using trapping and observational surveys in up to four seasons per guild from 2014–2015. Restored treatments were planted with native perennial grasses 13–24 years prior to study initiation but were partially re-invaded by Mediterranean annual grasses and forbs. Unrestored treatments contained similar non-native plant species assemblages as restored treatments, but did not contain any native grass.
- Rodent, snake and raptor activity was generally higher in unrestored relative to restored treatments. For rodents, the non-native Mus musculus (house mouse) showed the greatest disparity in abundance, while greater raptor and snake abundance was likely in response to greater rodent abundance.
- Within treatments, species-specific rodent responses were related to structure of physical vegetation. In particular, the native deer mouse (Peromyscus maniculatus) was associated with more bare ground and shorter vegetation, while the house mouse was associated with less bare ground and taller vegetation, regardless of treatment type. Substantial changes in rodent species composition resulted over short periods of time (< 3 months) after unplanned manipulation of vegetation structure via livestock grazing.
- Synthesis and applications: Our results reveal that while grassland restoration may promote some persistence of native plant communities, restoration may not be beneficial to higher trophic levels, and in fact may reduce habitat value for some native predators in Mediterranean grasslands. Changes in vegetation structure can strongly impact wildlife species composition, suggesting a more nuanced approach is required for the restoration of desired wildlife communities.
exotic species; habitat management; herpetofauna; native species; restoration; vegetation management; weed management; wildlife.