Vegetation Productivity Trends in the NWT

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View of a tundra landscape from atop an esker near the Daring Lake Tundra Ecological Research Station, NWT.

Introduction:

After finishing my PhD, I worked for five months as a Research Associate with Dr. Ryan Danby at Queen’s University.  The purpose of this work was to quantify recent changes in vegetation productivity across the range of the Bathurst Caribou Herd in the Northwest Territories.  The Bathurst Herd has been in decline over the past several decades (numbers have dropped from ~180,000 in 2003 to less than 20,000 in 2015), but reasons for this decline remain unclear.  One possible explanation is that recent plant responses to climate warming have dramatically altered their habitat.

Methods and Results:

We used MODIS satellite imagery to measure the change in vegetation productivity across the Bathurst Herd’s annual range from 2000 to 2017.  We found that significant increases in vegetation productivity (termed “greening”) were far more common than decreases (“browning”) over this time period.  Specifically, 16% of the herd’s annual range (almost 24,000 km2) has undergone significant greening, while only 1% (less than 1500 km2) has undergone significant browning (not counting areas that have burned).  This prominent greening could be linked to a recent increase in tall deciduous shrub abundance.  Caribou might be avoiding areas with tall shrubs because they are unable to spot predators from within a shrub field, or because tall shrubs are less preferable as a food source than other vegetation types.  Future shrub sampling and analysis of caribou collar data will investigate these hypotheses.  Find out more at the project’s website here.

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