Grassland Ecosystems Essay

13847 Words May 29th, 2011 56 Pages
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

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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
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The status of these ecosystem components differs among grasslands (Carpenter, 2001; Dellafiore, 2001; Ricketts and Dinerstein, 2001; Seymour and Rowan, 2001), depending on such factors as the degree to which their native species and soil biota are adapted to the current disturbance regime (Mack, 1989; Milchunas and Lauenroth, 1993).

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CHAPTER 1
Grasslands

Stresses and Vulnerabilities Due to Factors Other Than Climate Change
Numerous human disturbances and stresses are causing substantial degradation to the crucial components of grassland ecosystems outlined above (Walker, 1995). These include habitat fragmentation and loss, the spread of invasive species, alteration of fire regimes, and pollution; and all may act alone or synnergistically, leaving grasslands particularly vulnerable to climate change (Walker and Steffen, 1997; Dale et al., 2000).
HABITAT FRAGMENTATION AND LOSS

Throughout the world, grasslands have been degraded by livestock grazing, converted to agriculture and urban centers, and fragmented by roads (Dale et al., 2000).
LIVESTOCK GRAZING:

Livestock grazing is undoubtedly the major land use of the world’s remaining grasslands (IPCC, 2001a), and it is listed as a threat to these systems on all continents except for Antarctica (Richardson et al., 2000; Carpenter, 2001; Dellafiore, 2001; Dinerstein and Louks, 2001; Hobbs, 2001; Ricketts and Dinerstein,

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