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MELNHE - Multiple Element Limitation in Northern Hardwood Ecosystems

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 has also been called the Shoestring Project, during the period of unfunded effort between major research grants.

The MELNHE project is currently funded by USDA National Institute of Food and Agriculture (2019-67019-29464) and NSF Long-Term Ecological Research (DEB-1637685).

NSF previously supported Biotic control of calcium supply: Distinguishing sources to regrowing forests (DEB-0235650), Nutrient co-limitation in young and mature northern hardwood forests (MELNHE) (DEB-0949324 to ESF and collaborative grants to MBL, Miami University, Cornell University, and University of Michigan), and Long-Term Ecological Research grants to the Hubbard Brook Ecosystem Study (DEB-1114804 and DEB-0423259).

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 (Rastetter et al. 2012). To test the patterns of resource limitation predicted by MEL, we are conducting nutrient manipulations in three study sites in the White Mountain National Forest in New Hampshire: Bartlett Experimental Forest, Hubbard Brook Experimental Forest, and Jeffers Brook.
At Bartlett, we have three replicate stands of three ages, young (clearcut 1985-1990), mid-aged (clearcut 1975-1978), and mature (clearcut 1883-1890). At Hubbard Brook and Jeffers Brook, we have stands that correspond to the mid-aged and mature stands at Bartlett, for 4 more stands. Each of the 13 stands has four 1/4 ha (50 m x 50 m) treatment plots, treated annually each spring beginning in 2011, with N (30 kg N/ha/yr as NH4NO3), P (10 kg P/ha/yr as NaH2PO4), N+P, or nothing (an untreated control). Five stands also have a Ca treatment plot (1150 kg Ca/ha in the form of CaSiO3).

We are monitoring stem diameter, leaf litter production and nutrient flux, foliar chemistry and nutrient resorption, canopy reflectance, sap flow, root biomass and production, mycorrhizal associations, soil respiration, soil N and P availability, N mineralization, soil phosphatase activity, soil carbon and nitrogen, and bird activity. See highlights below for our results to date!

MELNHE is led by 4 principal investigators...

with a host of additional collaborators, including graduate students, technicians, undergraduate students, high school teachers and visiting scientists


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