I ndicates P Limitation in Northern Hardwood Forests Shan Shan 1 Spencer Stutenroth 1 Melany Fisk 1 1 Department of Biology Miami University Oxford OH N P Colimitation Nutrient limitation amp ecosystem productivityfunction ID: 1032620
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1. Soil Enzyme Activity Indicates P Limitation in Northern Hardwood ForestsShan Shan1, Spencer Stutenroth1, Melany Fisk1*1Department of Biology, Miami University, Oxford, OH
2. N P ColimitationNutrient limitation & ecosystem productivity/functionSingle-nutrient limitationN P colimitation: larger productivity response to N+P together than to either aloneElser et al., 2007
3. Optimized Resource Acquisition & Nutrient Limitation CarbonResourcesLight limitation
4. Decompose organic matter, release various nutrients into the soilIndicate nutritional demands of plants and microbesHigh production = High demand for the target nutrientSoil Extracellular EnzymesN-acquiring enzymeP-acquiring enzymeC-acquiring enzymeaminopeptidase N-acetyl-glucosaminidasephosphataseβ-glucosidasecellobiohydrolase
5. HypothesisRatios of C-, N-, and P-acquiring enzymes respond to changes in nutrient availability in a direction that minimizes limitation by any single nutrient.
6. Study SitesHubbard Brook stands: 1 mid-age1 matureBartlett stands:3 young3 mid-age3 matureJeffers Brook stands: 1 mid-age1 matureStand locations in Central NH
7. N: 30 kg/ha/yr as NH4NO3 P: 10 kg/ha/yr as KH2PO4 ) N+P ControlAnnual fertilization began in 2011
8. MethodsSoilsOeOaMineralEnzyme activity (fluorescent method)N: leucine aminopeptidase, alanine amino peptidaseP: acid phosphataseC: β-glucosidase, cellobiohydrolaseAverage 4.9 cm
9. Results
10. Prediction
11. Con N P NPP limitation is suggested by vector angles.N limitation of organic horizon C breakdown is suggested by vector length.
12. P effect on N-acquiring enzymes developed over timeP-enzyme ↓N-enzyme −P-enzyme ↓N-enzyme ↑
13. ConclusionsP limitation is suggested by shift from P- to N- acquiring enzymes in response to elevated P.N limitation of C use is suggested by shift to C-acquiring enzymes in response to elevated N.Delayed response of N-acquiring enzymes to P addition suggests development of colimitation overtime.Shan Shanshans@miamioh.edu
14. Melany FiskRuth YanaiTim Fahey