Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs

Alan K. Knapp, John M. Briggs, Scott L. Collins, Steven R. Archer, M. Syndonia Bret-Harte, Brent E. Ewers, Debra P. Peters, Donald R. Young, Gaius R. Shaver, Elise Pendall, Meagan B. Cleary

Research output: Contribution to journalArticle

330 Scopus citations

Abstract

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 gm-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.

Original languageEnglish (US)
Pages (from-to)615-623
Number of pages9
JournalGlobal change biology
Volume14
Issue number3
DOIs
StatePublished - Mar 2008

Keywords

  • Above ground net primary production
  • Carbon
  • Climate change
  • Grasslands
  • Growth form
  • LAI
  • MAP
  • Shrub lands

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

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    Knapp, A. K., Briggs, J. M., Collins, S. L., Archer, S. R., Bret-Harte, M. S., Ewers, B. E., Peters, D. P., Young, D. R., Shaver, G. R., Pendall, E., & Cleary, M. B. (2008). Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global change biology, 14(3), 615-623. https://doi.org/10.1111/j.1365-2486.2007.01512.x