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Effects of Changing Water and Nitrogen Inputs on a Mojave Desert Ecosystem.

DE2008920615

Publication Date	2007
Personal Author	Smith, S. D.; Nowak, R. S.; Fenstermaker, L. F.; Young, M. H.
Page Count	37
Abstract	In order to anticipate the effects of global change on ecosystem function, it is essential that predictive relationships be established linking ecosystem function to global change scenarios. The Mojave Desert is of considerable interest with respect to global change. It contains the driest habitats in North America, and thus most closely approximates the world's great arid deserts. In order to examine the effects of climate and land use changes, in 2001 we established a long-term manipulative global change experiment, called the Mojave Global Change Facility. Manipulations in this study include the potential effects of (1) increased summer rainfall (75 mm over three discrete 25 mm events), (2) increased nitrogen deposition (10 and 40 kg ha-1), and (3) the disturbance of biological N-fixing crusts . Questions addressed under this grant shared the common hypothesis that plant and ecosystem performance will positively respond to the augmentation of the most limiting resources to plant growth in the Mojave Desert, e.g., water and nitrogen. Specific hypotheses include (1) increased summer rainfall will significantly increase plant production through an alleviation of moisture stress in the dry summer months, (2) N-deposition will increase plant production in this N-limited system, particularly in wet years or in concert with added summer rain, and (3) biological crust disturbance will gradually decrease bio-available N, with concomitant long-term reductions in photosynthesis and ANPP. Individual plant and ecosystem responses to global change may be regulated by biogeochemical processes and natural weather variability, and changes in plant and ecosystem processes may occur rapidly, may occur only after a time lag, or may not occur at all.
Keywords	Climates Deserts Ecosystems Environmental effects Global aspects Deposition Disturbances Hypothesis Land use Moisture Neutron probes Nitrogen Photosynthesis Plant growth Productivity Rain Remote sensing Soils Weather
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Nevada Univ. System, Las Vegas.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200816
Contract Number	DE-FG03-02ER63361

Effects of Changing Water and Nitrogen Inputs on a Mojave Desert Ecosystem.

Effects of Changing Water and Nitrogen Inputs on a Mojave Desert Ecosystem.
DE2008920615

Publication Date	2007
Personal Author	Smith, S. D.; Nowak, R. S.; Fenstermaker, L. F.; Young, M. H.
Page Count	37
Abstract	In order to anticipate the effects of global change on ecosystem function, it is essential that predictive relationships be established linking ecosystem function to global change scenarios. The Mojave Desert is of considerable interest with respect to global change. It contains the driest habitats in North America, and thus most closely approximates the world's great arid deserts. In order to examine the effects of climate and land use changes, in 2001 we established a long-term manipulative global change experiment, called the Mojave Global Change Facility. Manipulations in this study include the potential effects of (1) increased summer rainfall (75 mm over three discrete 25 mm events), (2) increased nitrogen deposition (10 and 40 kg ha-1), and (3) the disturbance of biological N-fixing crusts . Questions addressed under this grant shared the common hypothesis that plant and ecosystem performance will positively respond to the augmentation of the most limiting resources to plant growth in the Mojave Desert, e.g., water and nitrogen. Specific hypotheses include (1) increased summer rainfall will significantly increase plant production through an alleviation of moisture stress in the dry summer months, (2) N-deposition will increase plant production in this N-limited system, particularly in wet years or in concert with added summer rain, and (3) biological crust disturbance will gradually decrease bio-available N, with concomitant long-term reductions in photosynthesis and ANPP. Individual plant and ecosystem responses to global change may be regulated by biogeochemical processes and natural weather variability, and changes in plant and ecosystem processes may occur rapidly, may occur only after a time lag, or may not occur at all.
Keywords	Climates Deserts Ecosystems Environmental effects Global aspects Deposition Disturbances Hypothesis Land use Moisture Neutron probes Nitrogen Photosynthesis Plant growth Productivity Rain Remote sensing Soils Weather
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Nevada Univ. System, Las Vegas.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200816
Contract Number	DE-FG03-02ER63361