%0 Journal Article %J Global Change Biology %D 2008 %T Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs %A Alan K. Knapp %A J. M. Briggs %A Scott. L. Collins %A S.R. Archer %A Bret-Harte, M.S. %A Ewers, B.E. %A Peters, D.P. %A Young, D.R. %A Shaver, G.R. %A Pendall, E. %A Cleary, M.B. %X
Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (>1000 g m−2) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being nonlinear in grasslands to linear in shrublands. Thus, relatively abrupt (<50 years) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental-scale pattern of C inputs and their control by MAP in ways that exceed the direct effects of climate change alone.
%B Global Change Biology %V 14 %P 615 -623 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2007.01512.x %M KNZ001149 %R 10.1111/j.1365-2486.2007.01512.x