Abstract
Increasing pressures from land use coupled with future changes in climate will present unique challenges for California’s protected areas. We assessed the potential for future land use conversion on land surrounding existing protected areas in California’s twelve ecoregions, utilizing annual, spatially explicit (250 m) scenario projections of land use for 2006–2100 based on the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios to examine future changes in development, agriculture, and logging. We calculated a conversion threat index (CTI) for each unprotected pixel, combining land use conversion potential with proximity to protected area boundaries, in order to identify ecoregions and protected areas at greatest potential risk of proximal land conversion. Our results indicate that California’s Coast Range ecoregion had the highest CTI with competition for extractive logging placing the greatest demand on land in close proximity to existing protected areas. For more permanent land use conversions into agriculture and developed uses, our CTI results indicate that protected areas in the Central California Valley and Oak Woodlands are most vulnerable. Overall, the Eastern Cascades, Central California Valley, and Oak Woodlands ecoregions had the lowest areal percent of protected lands and highest conversion threat values. With limited resources and time, rapid, landscape-level analysis of potential land use threats can help quickly identify areas with higher conversion probability of future land use and potential changes to both habitat and potential ecosystem reserves. Given the broad range of future uncertainties, LULC projections are a useful tool allowing land managers to visualize alternative landscape futures, improve planning, and optimize management practices.
Highlights
In this century, human land use will likely present a greater threat to biodiversity than climate change (Dale 1997; Sala et al 2000)
Our results indicate that California’s Coast Range ecoregion had the highest conversion threat index (CTI) with competition for extractive logging placing the greatest demand on land in close proximity to existing protected areas
The lowest percentage of protected land area was in the Central California Valley (3.2 %)
Summary
Human land use will likely present a greater threat to biodiversity than climate change (Dale 1997; Sala et al 2000). Changes in land use and land cover (LULC) have been linked to habitat loss (Soule 2001; Seabloom et al 2002), species extinction (Davies et al 2006), changes in species diversity (Rittenhouse et al 2012), declines in water (Foley et al 2005) and air quality (Romero et al 1999; Ross et al 2006), carbon dioxide emissions (Houghton and Hackler 2001), and climate change at regional and global scales (Bonan 1997; Pielke et al 2002; Lawrence and Chase 2010; Pitman et al 2011). Continued land use change is expected in coming decades, as human demand for food, fiber, energy, and urban development continue to grow with increasing population. In California, competition between land use and land preservation is already high and will only intensify in coming decades
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