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A comparison of carbon cycling between native perennial and non-native annual grass communities in northern coastal California.

Laura Elizabeth. Koteen University of California, Berkeley. 2009

Dissertation Abstracts International 71-06B.

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  • 題名:
    A comparison of carbon cycling between native perennial and non-native annual grass communities in northern coastal California.
  • 著者: Laura Elizabeth. Koteen
  • University of California, Berkeley.
  • 主題: Biology, Ecology; Climate Change
  • 所屬期刊: Dissertation Abstracts International 71-06B.
  • 描述: Grassland ecosystems of California have undergone dramatic changes, resulting in the almost complete replacement of native perennial grasses by non-native annuals across millions of hectares of grassland habitat. This research investigates the effects of this community shift on the carbon cycle in grassland ecosystems at two sites in northern coastal California. The broader goal is to understand how changes to California's grasslands have affected global climate through shifting the balance of carbon storage between terrestrial stocks and the atmosphere. To compare the processes that govern carbon exchange before and after annual grass invasion, we made use of coastal research sites where native vegetation is found growing adjacent to locations that have undergone exotic invasion. In research plots of each vegetation type, we monitored carbon pools and fluxes, including whole plant productivity, root and litter decay rates and soil respiration, as well as soil climatic controls on these processes.
    Although seemingly subtle, the shift in California grassland communities from native perennial to non-native annual grass dominance has had profound consequences for ecosystem biogeochemical cycles. Our findings indicate that soil carbon storage is significantly greater in regions dominated by native perennial grass communities in both study locations, and among all species considered. Across both study sites, we found that non-native grass invasion has resulted in the transfer of from 3 to 6 tons of carbon per hectare from the soil to the atmosphere. A soil density fractionation and a radiocarbon analysis also revealed this carbon to be more recalcitrant in native grass dominated locations. The primary plant traits that explain why soil carbon losses follow annual grass invasion are differences between annual and perennial grasses in belowground productivity and in the traits that govern soil respiration. Perennial grasses exceed annuals in belowground productivity by a large margin most years. The deeper root system and dense aboveground morphology of perennial grasses relative to annuals also affects the distribution of soil moisture within the soil profile, impacting rates of soil respiration. We also found that perennial and annual grasses exhibit different growth and soil respiratory responses to interannual precipitation variability. If annual precipitation were to change as a result of global climate change, so might the balance of productivity and soil respiration, resulting in different trajectories of soil organic matter accumulation and loss.
  • 出版者: Thesis (Ph.D.)--University of California, Berkeley, 2009.
  • 建立日期: 2009
  • 格式: 293 p..
  • 語言: 英文
  • 識別號: ISBN9781124037219
  • 資源來源: NUTN ALEPH
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