title: Ecosystem responses to climate change at a Low Arctic and a High Arctic long-term research site.
abstract: Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness.
authors.affiliation: Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, 02543, USA. jhobbie@mbl.edu.
authors.forename: John E
authors.initials: JE
authors.lastname: Hobbie
authors.affiliation: Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
authors.forename: Gaius R
authors.initials: GR
authors.lastname: Shaver
authors.affiliation: Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
authors.forename: Edward B
authors.initials: EB
authors.lastname: Rastetter
authors.affiliation: International Arctic Research Center, University of Alaska, Fairbanks, AK, 99775, USA.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Cherry
authors.affiliation: Woods Hole Research Center, Falmouth, MA, 02540, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Goetz
authors.affiliation: Woods Hole Research Center, Falmouth, MA, 02540, USA.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Guay
authors.affiliation: International Institute of Tropical Forestry, Río Piedras, PR, 00926, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Gould
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: George W
authors.initials: GW
authors.lastname: Kling
mesh_terms: D000413:Alaska; D001110:Arctic Regions; D044822:Biodiversity; D018533:Biomass; D057231:Climate Change; D064308:Ecological Parameter Monitoring; D017753:Ecosystem; D006116:Greenland; D018521:Plant Physiological Phenomena; D011156:Population Density; D011157:Population Dynamics; D013696:Temperature
keywords: Alaska Toolik; Climate change; Ecological effects; Greenland Zackenberg; Medium pass filter; Vegetation