Season to supply an annual estimate. Keller et al. (2010) measured strontium isotope ratios (87Sr86Sr), which decrease with depth in soils at the Arctic LTER, to estimate the escalating depth of water flow within the soil. Employing the point-frame technique described by Walker (1996), Gould and Mercado-Diaz (in Shaver et al. 2014) monitored the response of plant communities to ambient climate in 155 permanent plots. Measurements were created at 5- to 7-year intervals considering that 1989 in two 1 km2 grids setTable two Environmental and ecological variables measured over the long-term at Toolik and Zackenberg web-sites Web-site Toolik Website Climate Thaw depth Biology Kuparuk River Climate, NSC305787 (hydrochloride) biological activity Physics Biology Climatic norms for river basin (1989010) and discharge and temperature (1972010) are in Bowden et al. (2014) Major production and respiration (1984998), epilithic chlorophyll (1983010), bryophyte cover (1992006), benthic insect taxa (1984998), and grayling growth (1985005) data are in Bowden et al. (2014) Epilimnion temperature (July, 1985007) and summer alkalinity (1975011) data are in Luecke et al. (2014) Chlorophyll (July, 1985010) data are in Luecke et al. (2014) Temperature, 1991005, wind path and speed (1985005), and precipitation, 1997005, are given in Hansen et al. (2008). Data are accessible at Greenland Ecosystem Monitoring (http:www.data.g-e-m.dk) The summer time thaw depth progression from June 1 to September 7 at ZEROCALM-2, 1996005, is provided in Christiansen et al. (2008) Plant communities were analyzed (1997, 2008) in relation to summer time temperature and spring snow cover. 5 replicate plots in eight plant communities had been sampled (Schmidt et al. 2012). NDVI measures (Tagesson et al. 2012) gave gross main production at the peak on the increasing season from 1992 to 2008 Precipitation, temperature, and snow depth measured hourly (1996010). Abundance of six plant species, six taxa of arthropods, four species of birds, and three mammals measured weekly and seasonally (Mortensen et al. 2014). At 2 lakes, temperature, ice cover, and nutrients had been measured (1997005) as well as volume of phytoplankton and abundance of zooplankton (Christoffersen et al. 2008) Air temperature, precipitation, wind speed and direction, and expanding season dates for 1989010 are in Cherry et al. (2014) Summer season depths of thaw for July and August inside the Tussock Watershed, 1989010, are in Kling et al. (2014) Net key production aboveground for moist acidic tundra from six harvests 1989000 and point-frame data (4 harvests 1989008) are in Shaver et al. (2014) Environmental and ecological variablesToolik Lake Physics and chemistry Biology Zackenberg Physics Thaw depth Plant communities and production Variations and trends in biotic and abiotic PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21300681 ecosystem compartmentsThe Author(s) 2017. This article is published with open access at Springerlink.com www.kva.seenAmbio 2017, 46(Suppl. 1):S160SFig. 2 Annual imply Barrow SAT (surface air temperature, closed circles) for 1950014, annual imply Toolik SAT (x’s) for 1989-2014, and Zackenberg SAT (open squares) for 1996014. Also shown are the linear regressions for Barrow 1950014 (dashed dot line), Barrow 1996014 (short-dashed line), Toolik 1996014 (long-dashed line), and Zackenberg 1996014 (dotted line). Regression lines and coefficients are ordered from top rated to bottom as Toolik, Zackenberg, Barrow (1996014), and Barrow (1950014). Only the Barrow 1950014 and Zackenberg 1996014 linear regressions are important (p \ 0.01). Data from Alaska Climate Research Ce.