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Overview Researchers in the Multiple Element Limitation in Northern Hardwood Ecosystems (MELNHE) project are studying N and P acquisition and limitation through a series of nutrient manipulations in northern hardwood forests. This project is supported by the National Science Foundation, and builds upon the Northern Hardwood Forest Calcium Cycling Project, which established our sites at Bartlett. The project is also affectionately called the Shoestring Project, for the continued effort prior to continued funding.
Although temperate forests are generally thought of as N-limited, resource
optimization theory predicts that ecosystem productivity should be
co-limited by multiple nutrients. These ideas are represented in the
Multi-Element Limitation (MEL)
model, developed by Ed Rastetter at the Marine Biological Laboratory in
Woods Hole, Massachusetts. To test the patterns of resource limitation
predicted by MEL, we are conducting nutrient manipulations in three study
sites in New Hampshire: the Bartlett Experimental Forest, the Hubbard
Brook Experimental Forest, and Jeffers Brook in the White Mountain
National Forest.
At Bartlett, we have three replicate stands of three ages (~20, 30, and >
100 years). At Hubbard Brook and Jeffers Brook, there are two stands at
each site, corresponding to the mid-aged and mature stands at Bartlett
(total 13 stands). In each stand, there are four treatment plots, each
1/4 ha (50 m x 50 m), treated with N (30 kg N/ha/yr as NH4NO3), P (10
kg P/ha/yr as NaH2PO4), N+P, or control, beginning in spring 2011. At 5 of
the 13 stands, we also have a Ca treatment plot (1150
kg Ca/ha in the form of CaSiO3). We are monitoring stem diameter, leaf area, sap flow, foliar chemistry, leaf litter production and chemistry, foliar nutrient resorption, root biomass and production, mycorrhizal associations, soil respiration, heterotrophic respiration, N and P availability, N mineralization, soil phosphatase activity, soil carbon and nitrogen, nutrient uptake capacity of roots, and mineral weathering. Results will be posted as they develop. MELNHE is led by 6 principal investigators: Ruth Yanai, SUNY College of Environmental Science and Forestry, Syracuse, NY; Melany Fisk, Miami University of Ohio, Oxford, OH; Tim Fahey and Christy Goodale, Cornell University, Ithaca, NY; Joel Blum, University of Michigan, Ann Arbor, MI, and Ed Rastetter, Marine Biological Laboratory, Woods Hole, MA; with a host of additional collaborators, including graduate students, technicians, undergraduate students, high school teachers and visiting scientists.
This text was adapted from NSF Grant Proposal # DEB 0949324, "Collaborative Research: Nutrient Co-limitation in Young and Mature Northern Hardwood Forests" Yanai, Goodale, Rastetter, Blum, Fisk, 2009. The project has been supplemented by work in Proposals: 1112743 (REU 2011), 1112749 (ROA 2011), 1214425 (REU 2012)
Research Highlights:
Nitrogen and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near-total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake, litterfall, and net mineralization are nearly the same. Disturbance can disrupt this synchronization if there is a disproportionate loss of one nutrient relative to the other. We model the resynchronization of N and P cycles following harvest of a northern hardwood forest. In our simulations, nutrient loss in the harvest is small relative to postharvest losses. More info The Calcium Project's quantitative pit method featured by the popular press arm of the Soil Science Society of America! Vadeboncoeur, M.A., S.P. Hamburg, J.D. Blum,M.J. Pennino, R.D. Yanai, and C.E. Johnson. 2012. The quantitative soil pit method for measuring belowground carbon and nitrogen stocks. Soil Sci. Soc. Am. J. 76(6) in press doi:10.2136/sssaj2012.0111 was highlighted in the November issue of CSA News. See former student Paul Lilly in a pit on page 15 More Info Annual Meeting. The MELNHE group presented on many phases of research at the 2012 Hubbard Brook Cooperator's Meeting, July 11, 2012. More Info Sap Flow Results. Virginia Hernandez-Santana and Heidi Asbjornsen measured sap flow summer 2011 in beech, maple, and birch trees at Hubbard Brook (mature) and Bartlett (C8) in control, N, P, and N+P treatments. Posted 3/20/12 More Info
Soil N&P Availability. Melany Fisk provides the initial assessments of nutrient availability HERE.
Northern Forest Research featured at U Ohio-Miami. Dr. Melany Fisk, Associate Professor of Zoology, and Ph.D. candidate Shinjini Goswami describe their research in the New Hampshire's northern hardwood forest in September, 2011. Posted 2/17/12. Video and Transcript
Previous Highlights are available here
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