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Water From Colorado's Bark Beetle Forests -Project Overview <br />Elder, Rhoades & Hubbard; USFS Rocky Mountain Research Station; 5/15/08 <br />Forest Recovery and Site Productivity <br />Our analysis of forest recovery combines measurements of the stocking and growth of <br />tree seedlings, understory vegetation and soil nutrient characteristics. Additionally, we <br />will evaluate the links between soil disturbance and forest productivity (Curran et al. <br />2005; Aust and Blinn 2004). We will enumerate and measure the height and basal stem <br />diameter of seedlings in five permanent 1 m2 subplots in each management treatment plot <br />(n =160 seedling subplots). Surveys will be conducted 1, 2 and 3 years after completion <br />of harvesting activities as part of the proposed study (Page-Dumroese et al. 2002); we <br />also intend to re-visit the plots in year 5 to complete federally-mandated post-harvest <br />restocking surveys. In each seedling subplot, we will also estimate the percent cover of <br />herbaceous, sub-shrub and shrub layer species. <br />To evaluate site productivity we will use soil nitrogen (N) cycling indices that correlate <br />well to forest plant growth (Powers 1980; Hinkley and Hart 1989; Hart et al. 1994). <br />Growing season and wintertime in situ net nitrogen mineralization and nitrification rates <br />will be measured yearly. Forest floor and surface mineral soils (0-25 cm) will be <br />incubated inside closed-top, PVC cores (Hart et al. 1994). We will also conduct <br />laboratory assays of net N dynamics in order to separate the influence of the management <br />treatment on soil temperature and moisture from those regulated by substrate quality and <br />microbial processes (Powers 1990; Hart et al. 1994). To index plant N availability and <br />movement in the rooting zone, ion exchange resins contained within mesh packets will be <br />installed concurrently with N incubations (Hinkley and Matson 1983). Biomass and foliar <br />nutrient content will be measured on a subset of tree seedlings at the end of the third <br />growing season.