Conversion of tundra to exposed peat habitat by snow geese (Chen caerulescens caerulescens) and Ross’s geese (C. rossii) in the central Canadian Arctic

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• 作者：John Conkin ; Ray T. Alisauskas
• 关键词：GIS ; Landsat ; Queen Maud Gulf ; Remote sensing ; Ross’s geese ; Snow geese ; Tundra ; Vegetation mapping
• 刊名：Polar Biology
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：40
• 期：3
• 页码：563-576
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Ecology; Oceanography; Microbiology; Plant Sciences; Zoology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-2056
• 卷排序：40

文摘

The region south of Queen Maud Gulf in Canada’s central Arctic now annually harbors several million nesting and non-breeding Ross’s (Chen rossii) and lesser snow geese (C. caerulescens caerulescens). Here, and in other Arctic and Subarctic areas, abundant goose populations have been demonstrated to have impacted biomass and composition of vegetative communities. We applied the classification scheme that Didiuk and Ferguson (Land cover mapping of Queen Maud Gulf Migratory Bird Sanctuary, Nunavut. Environment Canada, Ottawa, 2005) used on 1986–1992 Landsat Imagery to produce a habitat map for 2011 of the eastern portion of the Queen Maud Gulf Bird Migratory Bird Sanctuary (QMGMBS). We used a Geographic Information System for change detection between 1988 and 2011 and found a > fivefold increase in area of exposed peat habitat from 269 to 1373 km2 in our 36,370 km2 study area. About 323 km2 (24) % of the area classified as exposed peat in 2011 was previously wet sedge meadow, a preferred feeding habitat of geese, and which declined from 2856 to 1488 km2 (−48 %) in our study area. Combined open water categories declined from 9688 to 7960 km2 (−18 %), suggesting that some of the reduction in wet sedge meadow could have been caused by drawdown. However, of the 1981 km2 of open water that was lost between 1988 and 2011, only 142 km2 (7 %) was classified as exposed peat and 250 km2 (13 %) as active deposits, while 171 km2 (9 %) was classified as wet sedge meadow. Of the remaining open water coverage that was lost, 118 km2 (6 %) was classified as hummock or graminoid tundra, 459 km2 (23 %) as moss-lichen or lichen-heath tundra, and 764 km2 (39 %) as low shrub tundra/shrub thicket. Approximately 562 km2 (41 %) of exposed peat in 2011 was formerly moss-lichen and lichen-heath tundra, upland habitats commonly used by nesting snow geese and Ross’s geese. By 2011, the proportion of ground covered by exposed peat habitat surrounding the four largest known colonies of light geese, all in the eastern half of QMGMBS, was strongly linked to the amount of previously vegetated habitat (i.e., potential exposed peat), and was inversely related to distance from colony perimeters. About 50 % of the spatial variance in coverage by exposed peat was explained by nearness to nesting by large concentrations of light geese. While some increase in exposed peat was likely a result of drier conditions in 2011 compared to 1988, spatial patterns of habitat change suggest that much of the increase in exposed peat was likely a result of intensive foraging in wet sedge meadow habitat and nest-building activities in tundra habitats by high densities of snow geese and Ross’s geese. Of the 269 km2 of exposed peat originally identified in 1988, only 55 km2 of it was still classified as exposed peat in 2011, but detailed ground studies will be required to determine at what rate exposed peat habitats revert back to wet sedge meadow and other vegetated tundra. We recommend comparison of habitat changes in areas with and without large populations of lesser snow geese and Ross’s geese to better assess changes caused by geese in relation to any change that may result from changes in hydrology over time.