Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Eighteen Years of Vegetation Monitoring in the Arctic National Wildlife Refuge, Alaska
Janet C. Jorgenson1, Colette A. Buchholtz2
1Arctic NWR, USFWS, 101 12th Ave, Room 236, Box 20, Fairbanks, AK, 99701, USA, Phone 907-456-0216, Fax 907-456-0428, janet_jorgenson@fws.gov
2Arctic NWR, USFWS, 101 12th Ave, Room 236, Box 20, Fairbanks, AK, 99701, USA, Phone 907-455-1835, Fax 907-456-0428, colettte_buchholtz@fws.gov
Temperatures in northern Alaska have shown a warming trend over the past 30 years, so we expect that vegetation would be changing also. However, little evidence of recent vegetative changes measured on the ground exists for northern Alaska. This may be due mainly to the lack of permanent plots established before the warm 1990s. Also, year-to-year variability may mask long-term trends and vegetation changes may lag behind climate changes.
Botanists from the Arctic Refuge in northeastern Alaska sampled twenty-six permanently-marked vegetation plots five or six times between 1984 and 2002. The plots were the undisturbed controls from a study tracking recovery of winter seismic trails. They are the oldest permanent vegetation plots in the Refuge and represent all of the major vegetation types on the coastal plain tundra of the Refuge. We estimated percent cover of vascular and nonvascular plant species using point-sampling, lowering pins from a frame and recording species encountered. We also measured depth of the soil active layer and took photographs from permanent photo points. At four plots in riparian shrublands we measured height of the willows. Vegetation data were collected in 1984, 1985, 1986, 1988, 1991, and 2002. Active layer depth was measured in 1984, 1985, 1988, 1991, 1998, and 2002.
We examined results from the undisturbed control plots for evidence of change over time. We tested the common overall trends among plots using linear mixed-effects regression models. Models are still being refined so results reported here are preliminary. We found small but statistically significant decreases in moss, liverwort, and lichen cover over the 18-year period. Depth of the soil active layer increased. No significant changes were detected in vascular plant cover or shrub height. The results are supported by data from other vegetation plots in the Arctic Refuge. At plots established between 1996 and 1998 and resampled five years later, cover of nonvascular plants declined at almost all plots while no trends were found for vascular plants.
Much of the year-to-year variability at our plots can be explained by temperature records from northern Alaska. Because of the lack of plant cover data between 1991 and 2002, we need to continue collecting data so that current conditions are better estimated and accounted for in the models and analyses.
Abstract Categories: Changes on Land
Back to main abstract page
To view the list of records returned in your search you can use your browser's
back button, or perform the same search again:
| 