The effects of moose and snowshoe hare browsing on root production, growth and survival in Alaskan forests dominated by willows (Salix spp.) was measured in this study. Aboveground herbivory significantly reduced monthly rates of fine root production, and on an annual basis, fine root production of browsed plots was significantly less than that of unbrowsed plots when averaged over the 3 years. Because herbivory had less of an effect on monthly or annual rates of fine root mortality, fine root turnover was higher for browsed stands. Two-factor models indicated that time-dependent survival and decomposition rates of fine roots differed significantly between browsed and unbrowsed stands, among the 10 fine root age groups, and among the three study sites. Browsing significantly reduced fine root survival, but this effect varied among sites. Fine root decomposition rates were consistently lower in browsed stands. Two important additional features distinguish fine root dynamics in these stands from temperate and more southerly boreal ecosystems: 1) low overwinter survival of roots, and 2) a substantial time lag between leaf out and maximum fine root growth, suggesting greater reliance on aboveground stores for spring regrowth. The results of this study indicated that browsing by moose and snowshoe hares alters fine root dynamics in Alaskan forests and also that the effects of browsing on fine root dynamics in this region vary significantly from the effects of browsing in other climactic regions.
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