Climate Change in Arid Lands: Effects on Soil Biota and Ecosystem Processes Deborah A. Neher University of Vermont Jayne Belnap USGS - Southwest Biological Research Center Cheryl Kuske Los Alamos National Laboratory Thank you to B. Darby, D. Housman, S. Johnson and DOE PER
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Climate Change in Arid Lands: Effects on Soil Biota and Ecosystem Processes
Climate Change in Arid Lands: Effects on Soil Biota and Ecosystem Processes. Deborah A. Neher University of Vermont. Jayne Belnap USGS - Southwest Biological Research Center. Cheryl Kuske Los Alamos National Laboratory. Thank you to B. Darby, D. Housman, S. Johnson and DOE PER. - PowerPoint PPT Presentation
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Climate Change in Arid Lands: Effects on Soil Biota and Ecosystem Processes
Deborah A. NeherUniversity of Vermont
Jayne BelnapUSGS - Southwest Biological Research Center
Cheryl KuskeLos Alamos National Laboratory
Thank you to B. Darby, D. Housman, S. Johnson and DOE PER
Average increased soil warming: surface +2.9oC, 5cm +2.7oC, 15cm +2.5oC% of 24 hr period with additional warming of >0oC and <5oC: 78, 81, 93%% of nighttime hrs with additional warming of >0oC and <5oC: 92, 82, 93%
HypothesesBiological soil crusts (BSC’s):
• H1: Increased temperature and summer precipitation will alter species composition, abundance, activity times and physiological functioning of BSC’s. This will reduce C and N inputs into soils. Increasing both temperature and precipitation will have a greater effect than either factor alone.
Subsurface soil biota:• H2: Increased temperature and summer precipitation will alter
the species composition, abundance, activity times, and physiological functioning of subsurface soil biota due to their dependence on C and N inputs from BSC’s, as well as direct effects of altered temperature and precipitation on their physiological functioning. Increasing both temperature and precipitation will have a greater effect than either factor alone.
Soil processes & vascular plants:• H3: Alterations in the species composition, abundance, activity
times, and physiological functioning of soil biota will affect soil processes and vascular plant performance.
Field Measurements• Air & soil temp, humidity, precipitation, wind, & net radiation• Soil water at three depths• CO2 flux in warmed and control plots• Crust cover, composition & pigments• Photosynthesis & Fv/Fm• Nitrogen (total, fixation, mineralization, isotopes)• Soil bacteria biomass & metabolism• Photosynthetic and N cycling bacterial abundance/composition• Soil fauna composition & abundance• Soil chemistry (nutrients, texture, OM, decomposition)• Soil enzymes
Baseline:
No significant difference in photosynthesis, Fv/Fm, N fixation, bacterial biomass, or faunal abundance
25Control flux IR flux Control temperature IR temperature
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Winter C loss greater in warmed vs. control plots
Abundance of late-winter soil fauna similar across treatments except for amoebae
Drydown Experiment• Single drying events of 10, 20, 30(typical), and 120 min.
• Soil faunal abundance similar across drying treatments, but < controls.• N - fixing ability (nifH mRNA) declined slowly in dried soils. • Total RNA content and ammonia-oxidizing ability similar across treatments. • Soil crust Fv/Fm and pigments similar across treatments.
0%
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2006 Drydown Experiment - Fauna
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Nematodes Amoebae
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Experimental field study of the interactive effects of extremes (temperature and precipitation) on ecosystem function and diversity (including genetic diversity) in drylands.