TITLE: Toolik Snowfence Experiment: 1995-2001 Snow free date PRINCIPAL INVESTIGATOR: Dr. Marilyn Walker Leader, Boreal Ecology Cooperative Research Unit USFS PNW Research Station and University of Alaska Fairbanks Boreal Ecology Cooperative Research Unit School of Agriculture and Land Resources Management P.O. Box 756780 University of Alaska Fairbanks Fairbanks, AK 99775-6780 Phone: 907-474-2424 Fax: 907-474-6251 E-mail: ffmdw@uaf.edu FUNDING SOURCE: National Science Foundation ARCTIC SYSTEM SCIENCE PROGRAM: Land-Atmosphere-Ice Interactions (LAII) and The International Tundra Experiment (ITEX) GRANT TITLES AND GRANT NUMBERS: 1994 - 1998: OPP-9400083 -- ITEX / Comparative Responses of Moist and Dry Arctic Tundra to Altered Snow and Temperature Regimes 1999 - 2003: OPP-9907127 -- ITEX / Collaborative Research: Species Responses to Changes in Climate Across Arctic Gradients Using the North America ITEX Network (NATEX): Influences On Community and Ecosystem Processes 1999 - 2003: OPP-9996383 -- ITEX / Comparative Responses of Moist and Dry Arctic Tundra to Altered Snow and Temperature Regimes CONDITIONS FOR USE AND CITATION: For permission to use these data, contact the Principal Investigator. Grant numbers must be cited in any manuscripts resulting from these data. In addition, a copy of the manuscript must be sent to the PI. DATA SET OVERVIEW: This file contains snow free date data collected for the Toolik Snowfence Experiment from 1995 to 2001. The Toolik Snowfence Experiment (part of the International Tundra Experiment network) examines the short- and long-term effects of increased snow depth (shortened growing season) and increased summer temperature on arctic tundra vegetation. The goal of this project is to assess potential changes in tundra plant communities in response to global climate change. Time period covered by data: 19950522 to 20010625 Physical location of measurement: Toolik Field Station, Alaska USA (68.62710 N, 149.59322 W) DATA COLLECTION AND PROCESSING: Data were collected from 1995 to 2001, beginning at first snowmelt and each day thereafter, until all plots were snow free. Plots are consistently monitored in the late afternoon and recorded as snow free when three-quarters of the snow within a plot has melted. See the data remarks section below for annual variation of this method. The Toolik Snowfence Experiment's design and manipulation are described further in: Walker, M. D., D. A. Walker, J. M. Welker, A. M. Arft, T. Bardsley, P. D. Brooks, J. T. Fahnestock, M. H. Jones, M. Losleben, A. N. Parsons, T. R. Seastedt and P. L. Turner. 1999. Long-term experimental manipulation of winter snow regime and summer temperature in arctic and alpine tundra. Hydrological Processes 13: 2315-2330. DATA FORMAT: File name: USTOOLIK_snowfree95-01.txt SUMMARY OF VARIABLES FOR 1995-2001 DATA 1. SITE: country/site/project title 2. SNOW_FREE_DATE: date plot was snow free (YYYYMMDD) 3. LOCATION: site; moist, dry or snowfield 4. ZONE: 0-6 5. PLOT: unique plot number 6. DESCRIPTION: plot treatment or plot type 7. DAY OF YEAR 8. NOTES DESCRIPTION OF SELECT VARIABLES: SITE USTOOLIK: Toolik Field Station, Alaska, USA; Comparative responses of moist and dry arctic tundra to altered snow and temperature regimes LOCATION Research site: Snowfences are erected and grids established at both a moist tussock site (68.62032 N, 149.59931) and a dry heath site (68.62261 N, 149.59589 W). In addition, monitored plots are established where a natural snowdrift occurs. This site is referred to as the snowfield. ZONE Snow manipulation: A 60 m snowfence is aligned on an east-west axis at both the moist and dry sites. Both snowfences are perpendicular to the predominant winter winds from the Brooks Range to the south, effectively creating a leeward drift 50-60 m long on the north side of the fence. An established grid on the north side of the fence divides the drift into 6 parallel zones (60 m x 10 m). Zone number increases from 1 to 6, as distance from the snowfence increases. Zones 1, 2 and 3 accumulate the most snow (2-3 m), while zones 4, 5 and 6 accumulate the least snow (0.5-2 m). Zone 0 (the control) is located adjacent to the snowfence grid and does not receive supplemental snow. DESCRIPTION ITEX warming treatment. OTC: Open-topped chamber (warming), CTL: No chamber (control) or Plot Type: NDVI: Normalized Difference Vegetation Index. NDVI plots are subjected to snow manipulation only. Temperature is not manipulated at any of the NDVI plots. DAY_OF_YEAR The years 1996 and 2000 are both leap years; day of year is modified accordingly. CODES USED IN DATA SET In all years "-9999" indicates missing data. Questionable or bad data is indicated by asterisks (****) and estimated data is indicated by an "EEEE" in the notes column. DATA REMARKS: Snow free dates were not recorded for every plot in all years. LOCATION OF ORIGINAL DATA SHEETS: Boreal Ecology Cooperative Research Unit, University of Alaska, Fairbanks, Alaska, USA DOCUMENTATION AUTHOR: Original: Amy Breen Carroll, 29 March, 2001 Updated by: Amy Breen Carroll, 20 December, 2001 Updated by: Amy Breen Carroll, 18 February, 2002 PRINCIPAL FIELD WORKERS: Andrew Borner PRINCIPAL POSTDOCS: Michael H. Jones Anna Arft PUBLICATIONS WHICH INCLUDE THESE DATA: Walker, M. D., D. A. Walker, J. M. Welker, A. M. Arft, T. Bardsley, P. D. Brooks, J. T. Fahnestock, M. H. Jones, M. Losleben, A. N. Parsons, T. R. Seastedt and P. L. Turner. 1999. Long-term experimental manipulation of winter snow regime and summer temperature in arctic and alpine tundra. Hydrological Processes 13: 2315-2330.