Decadal Land cover change Near Barrow and Atqasuk, Northern Alaska

Decadal Micro-Topographic Change in Tundra Near Point Barrow, Alaska

Craig E. Tweedie, Robert D. Hollister, Patrick J. Webber, Steven P. Rewa, Olga I. Sumina and Stuart Gage

Results:

Plot based studies suggest changes in land cover at Barrow have been greater than those at Atqasuk (Figs. 1&2).
At both Barrow and Atqasuk, the largest changes were documented in pioneer or disturbed communities. Change occurred due to change in species abundance as well as composition (Figs. 1&2).
In Barrow, the largest changes in undisturbed plots were in wet and mesic communities. Dry sites appeared to be the most stable over time (Figs. 1,2&3).
At Atqasuk, the largest changes in undisturbed plots were the same as those documented for Barrow, although less overall change was documented (Figs. 1,2&4).
The thaw lake cycle^4,5 as interpreted by Webber (1978) has been re-interpreted for Barrow, showing dry communities are generally more stable than wet communities (Fig. 5).
Resampling of the former Barrow IBP Site 4 Microptopographic grid suggests that, although there has been little change in microtopography, there has been a dramatic change in vegetation with the 3 wettest vegetation types classified in 1973 almost entirely disappearing by 2000 (Fig. 7).
Resampling of the former IBP Site 4 topographic grid also suggests there has been a dramatic shift in vegetation with most dry vegetation types increasing in areal cover whilst coverage of most moist and wet vegetation types has decreased (Fig. 8&9).


Fig. 1 - Land Cover Change at Former Barrow IBP Plots 1972-1999	Fig. 2 - Land Cover Change at Former Atqasuk RATE Plots 1975-2000


Fig. 3 - Land cover change at former Barrow IBP plot 1319 (Arctophila Pond Margin).	Fig. 4 - Land cover change at former Atqasuk RATE plot 18 (Shallow Lake/Pond Margin).


Fig. 5 - A Re-interpretation of the Thaw-Lake cycle as interpreted by Webber et al. (1978) for Barrow.	Fig. 6 - Former Barrow IBP Site 4 Microtopographic grid in 1973 and 2000. The three wettest vegetation types classified in 1973 have almost entirely disappeared by 2000.


Fig. 7 - Microtopographic position and vegetation change at the microtopographic grid between 1973 and 2000	Fig. 9 - Vegetation cover in 1973 and 2001 at the former Barrow IBP Site 4 topographic grid.


Fig. 8 - Vegetation of former Barrow IBP Site 4 Topographic Grid showing vegetation change between 1973 (left) and 2001 (right).

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