title: Effects of long-term nutrient additions on Arctic tundra, stream, and lake ecosystems: beyond NPP.
abstract: Primary producers form the base of food webs but also affect other ecosystem characteristics, such as habitat structure, light availability, and microclimate. Here, we examine changes caused by 5-30+ years of nutrient addition and resulting increases in net primary productivity (NPP) in tundra, streams, and lakes in northern Alaska. The Arctic provides an important opportunity to examine how ecosystems characterized by low diversity and low productivity respond to release from nutrient limitation. We review how responses of algae and plants affect light availability, perennial biotic structures available for consumers, oxygen levels, and temperature. Sometimes, responses were similar across all three ecosystems; e.g., increased NPP significantly reduced light to the substrate following fertilization. Perennial biotic structures increased in tundra and streams but not in lakes, and provided important new habitat niches for consumers as well as other producers. Oxygen and temperature responses also differed. Life history traits (e.g., longevity) of the primary producers along with the fate of detritus drove the responses and recovery. As global change persists and nutrients become more available in the Arctic and elsewhere, incorporating these factors as response variables will enable better prediction of ecosystem changes and feedbacks in this biome and others.
authors: Department of Biological Sciences, Towson University, Towson, MD, 21252, USA. lgough@towson.edu.
authors: Laura
authors: 0000-0002-9312-7910
authors: L
authors: Gough
authors: Cary Institute for Ecosystem Studies, PO Box AB, Millbrook, NY, 12545, USA.
authors: Neil D
authors: ND
authors: Bettez
authors: University of Michigan Biological Station, 930 N. University, Ann Arbor, MI, 48109, USA.
authors: Karie A
authors: KA
authors: Slavik
authors: Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT, 05405, USA.
authors: William B
authors: WB
authors: Bowden
authors: Marine Biological Laboratory, Ecosystems Center, Woods Hole, MA, 02543, USA.
authors: Anne E
authors: AE
authors: Giblin
authors: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors: George W
authors: GW
authors: Kling
authors: Marine Biological Laboratory, Ecosystems Center, Woods Hole, MA, 02543, USA.
authors: James A
authors: JA
authors: Laundre
authors: Marine Biological Laboratory, Ecosystems Center, Woods Hole, MA, 02543, USA.
authors: Gaius R
authors: GR
authors: Shaver
mesh_terms: D001110:Arctic Regions; D017753:Ecosystem; D060106:Lakes; D045483:Rivers; D065929:Tundra
keywords: Fertilization; Habitat; Light; Oxygen; Temperature