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Still waiting for fertilization effects on soil respiration and root respiration. SUNY-ESF Kikang Bae (kbae02@syr.edu). Introduction. Soil respiration is a major flux of carbon to the atmosphere. Nutrient additions to forest soils can affect soil respiration. The global carbon cycle.
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Still waiting for fertilization effects on soil respiration and root respiration SUNY-ESF Kikang Bae (kbae02@syr.edu)
Introduction • Soil respiration is a major flux of carbon to the atmosphere. • Nutrient additions to forest soils canaffect soil respiration. The global carbon cycle http://sitemaker.umich.edu/section2group4/the_link__human_influences_on_storm_intensity
Introduction • Ways nutrient addition affects soil respiration: • Altering root activity • Altering microbial activity • Change above- and below- ground carbon production • Soil respiration will increase or decrease after nutrient addition? photosynthesis aboveground respiration CO2 CO2 CO2 CO2 soil respiration root + microbial respiration
Objectives • To determine effects of nutrient additions on soil respiration and root respiration between forest ages • To understand which component (root or microbial) causes changing soil respiration, if there is a change at all • To know which nutrients (N, P, N+P) have the greatest effect on soil respiration in our stands.
Hypothesis Soil respiration (root/microbial respiration) Adding nutrients (N, P, N+P) Forest age
Hypothesis Bartlett Hubbard Brook Jeffers Brook Age: P = 0.11 Site: P = 0.02 Soil respiration (root/microbial respiration) Adding nutrients (N, P, N+P) Soil respiration before fertilization (09’-11’) Annual soil respiration (gC/m2)
Hypothesis Soil respiration (root/microbial respiration) Adding nutrients (N, P, N+P) Forest age Young: N+P > N > P > Control Old: N+P > P > N > Control Soil respiration more
Study sites • Bartlett Experimental Forest (BEF) • Hubbard Brook (HB, WS 101) • Jeffers Brook (JB) Intensive trenching Young (20~22 yrs) Middle (30~40 yrs) Old (77~127 yrs) • Bartlett • C4 • C5 • C6 • Jeffers Brook • Mid • Hubbard Brook • Mid • Bartlett • C7 • C8 • C9 • Jeffers Brook • Old • Hubbard Brook • Old • Bartlett • C1 • C2 • C3
Methods • Soil respiration: Chamber (Licor8100). • Root respiration (Soil respiration – without live root respiration): Trenching
Results (Fertilization on soil respiration) Fertilization start Fertilization start P < 0.001
Fertilization start Fertilization start Fertilization start Fertilization start P = 0.006
Fertilization start Fertilization start Fertilization start Fertilization start
Results (Root contribution on soil respiration) Soil respiration – without live root respiration
Results (Fertilization on trenching) Fertilization start Fertilization start
Fertilization start Fertilization start Fertilization start
Summary Soil respiration No change (except C9 and HB mid) Root respiration No change Adding nutrients (N, P, N+P) Regardless of nutrients (N, P, N+P) and forest age Soil respiration No change
Conclusion • There was little evidence of fertilization effects on soil respiration after 2 years nutrient addition.
Future plans • Keep measuring soil respiration. • How do N, P, and N+P additions affect root growth? May June http://wric.ucdavis.edu/yst/images/none/nc5.JPG
Acknowledge Ruth Yanai Tim Fahey Melany Fisk
Thank you... kbae02@syr.edu