Abstract
We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.
Highlights
Wildfires have long been a part of the natural and human-altered environments of southern California, USA
Our objectives were: 1) to determine the short-term effects of fire on rodent community structure across four vegetation types, 2) to determine if changes in post-fire community structure were associated with changes in vegetation structure, 3) to determine if individual species responses were predictable based upon habitat preferences and life-history characteristics, and 4) to identify species at risk in consideration of a changing fire regime in southern California
Coastal sage scrub and chaparral fire-impacted plots had 77 % and 46 % reduced shrub and tree cover compared to reference plots, respectively
Summary
Wildfires have long been a part of the natural and human-altered environments of southern California, USA. Native vegetation communities of southern California evolved various survival strategies to adapt to fire (Hanes 1971, Vogl and Schorr 1972, Keeley and Keeley 1981, Zedler et al 1983, Keeley and Fotheringham 2001), large and repeated fires can drastically and permanently alter the habitat, converting diverse chaparral and coastal sage scrub into simple non-native grasslands (Zedler et al 1983, Keeley 2005) These fires can have short- and long-term impacts on animal communities in a region already recognized as being one of the most at risk areas for loss of biodiversity (Mittermeier et al 1997). Half of the protected lands within the MSCP were affected by the fires and some protected habitats were entirely burned
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