TY - JOUR T1 - Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs JF - Global Change Biology Y1 - 2008 A1 - Alan K. Knapp A1 - J. M. Briggs A1 - Scott. L. Collins A1 - S.R. Archer A1 - Bret-Harte, M.S. A1 - Ewers, B.E. A1 - Peters, D.P. A1 - Young, D.R. A1 - Shaver, G.R. A1 - Pendall, E. A1 - Cleary, M.B. AB -

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.

VL - 14 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2007.01512.x ER -