Grassland Ecosystems
CHAPTER 1: Grasslands
COVER PHOTO CREDITS:
Freshwater and pink coral, Eric Mielbrecht Portage glacier icebergs and Steller sea lions, Lynn Rosentrater Grassland and alpine meadow, Jonathan Gelbard
BUYING TIME: A USER'S MANUAL
15
CHAPTER 1
Grasslands
Grasslands at a Crossroads: Protecting and Enhancing Resilience to Climate Change
Jonathan L. Gelbard, Ph.D. Department of Environmental Science and Policy, University of California, Davis
THE STRUCTURE AND FUNCTION OF the world’s grasslands makes them one of the most vulnerable to global climate change of any terrestrial ecosystem (Sala et al., 2000; IPCC, 2001a). The low-stature of vegetation confers high light availability, leaving many grasslands naturally vulnerable to invasive species (Wagner, 1989), especially following disturbance (Hobbs and Huenneke, 1992). A critical role for fire in maintaining plant community structure in many grassland types leaves them vulnerable to vegetation change should changes to temperatures and precipitation occur that are sufficient to alter biomass and fire frequency. Grasslands are also vulnerable due to human environmental impacts, including conversion to agriculture (both cropland and grazing land) (Dale et al., 2000; Ricketts and Dinerstein, 2001), the introductions and spread of invasive species (Mack et al., 2000; Mooney and Hobbs, 2000), the proliferation of roads (Forman and Alexander, 1998; Forman, 2000), alterations to fire regimes (D’Antonio, 2000; Dale et al. 2000), and pollution that alters soil fertility and rates of plant growth (Schlesinger, 1997; Lejeune and Seastedt, 2001). Combine the above natural and anthropogenic vulnerabilities, and it is apparent that when faced with human-induced global climate change (Schlesinger, 1997; IPCC, 2001b), what remains of the world’s grassland ecosystems as we know them are in trouble (Forseth, 1997).
Fortunately, however, the fate of grassland ecosystems faced with climate change, which has the
COVER PHOTO CREDITS:
Freshwater and pink coral, Eric Mielbrecht Portage glacier icebergs and Steller sea lions, Lynn Rosentrater Grassland and alpine meadow, Jonathan Gelbard
BUYING TIME: A USER'S MANUAL
15
CHAPTER 1
Grasslands
Grasslands at a Crossroads: Protecting and Enhancing Resilience to Climate Change
Jonathan L. Gelbard, Ph.D. Department of Environmental Science and Policy, University of California, Davis
THE STRUCTURE AND FUNCTION OF the world’s grasslands makes them one of the most vulnerable to global climate change of any terrestrial ecosystem (Sala et al., 2000; IPCC, 2001a). The low-stature of vegetation confers high light availability, leaving many grasslands naturally vulnerable to invasive species (Wagner, 1989), especially following disturbance (Hobbs and Huenneke, 1992). A critical role for fire in maintaining plant community structure in many grassland types leaves them vulnerable to vegetation change should changes to temperatures and precipitation occur that are sufficient to alter biomass and fire frequency. Grasslands are also vulnerable due to human environmental impacts, including conversion to agriculture (both cropland and grazing land) (Dale et al., 2000; Ricketts and Dinerstein, 2001), the introductions and spread of invasive species (Mack et al., 2000; Mooney and Hobbs, 2000), the proliferation of roads (Forman and Alexander, 1998; Forman, 2000), alterations to fire regimes (D’Antonio, 2000; Dale et al. 2000), and pollution that alters soil fertility and rates of plant growth (Schlesinger, 1997; Lejeune and Seastedt, 2001). Combine the above natural and anthropogenic vulnerabilities, and it is apparent that when faced with human-induced global climate change (Schlesinger, 1997; IPCC, 2001b), what remains of the world’s grassland ecosystems as we know them are in trouble (Forseth, 1997).
Fortunately, however, the fate of grassland ecosystems faced with climate change, which has the