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The DIRT Project (Detrital Input and Removal Treatments) |
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DESCRIPTION OF SITES AND TREATMENTS Harvard Forest DIRT, Petersham, Massachusetts Site The 1.87 ha study site is located in a mixed hardwood forest approximately 90 years old. Aspect is northwesterly and slope is 4%. Dominant trees species are northern red oak (Quercus borealis Michx. F.), red maple (Acer rubrum L.), and paper birch (Betula papyrifera Marsh). The soil, an inceptisol, is a moderately well-drained stony-loam of the Charleton series. Plot Location Plot and and treatment combinations were determined by stratified random design, using three adjacent spatially-defined blocks. Each block contains 7 plots, one of each treatment and two controls. Block III is upslope, block II is midslope, and block I is downslope. No trees are located within the plots. Litter Manipulation Above-ground litter transfers and removals are performed in the fall of each year. Litterfall collection nets are spread on the NO LITTER and NO INPUTS plots in early September. At two-week intervals during leaf-fall (approximately two months), litter from each NO LITTER plot is transferred to the corresponding DOUBLE LITTER plot in the same block. Litterfall collected from NO INPUTS plots is carried off-site. Coarse woody debris input larger than 2.5 cm diameter is excluded from all controls and treatments. |
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Bousson Forest, Allegheny College, Pennsylvania Site The Bousson Environmental Research Reserve is located in northwestern Pennsylvania. The study site is an approximately 80 year old mixed deciduous forest dominated by black cherry (Prunus serotina Ehrh.) and sugar maple (Acer saccharum Marsh). Soils are alfisols and are poorly-drained sandy-loams of the Cambridge series. O horizon is minimal or not present at all. The aspect is westerly and the slope is 5%. Plot Location Established in October 1991, treatment plots were located using a stratified random approach, with one plot of each treatment randomly located at an upslope, a midslope, and a downslope position. Treatments are identical to those at the Harvard Forest DIRT site. Trenches surrounding the NO ROOTS and NO INPUTS plots are lined with GriffolynŽ. No trees are located within plot borders. Litter Manipulation Above-ground litter manipulations are carried out in the same manner as at the Harvard Forest DIRT site |