Using daily NDVI to understand climate-induced changes in vegetation phenology during critical time periods for caribou foraging in northern Alaska

Theme 1. Environmental protection
Session Name 1.11 Reindeer & caribou in the Arctic system: Interactions between environmental, social and biophysical processes
Presentation Type Oral
Author(s) Katharine Kelsey (University of Alaska Anchorage, USA), A. Joshua Leffler (South Dakota State University, USA), Joseph Sexton (University of Maryland, USA), Stine Højlund Pedersen (Colorado State University and University of Alaska Anchorage, USA), Jeffrey Welker (UArctic; University of Oulu and University of Alaska Anchorage, Finland)
Abstract text

Caribou life history is closely tied to vegetation phenology, and therefore climate change induced shifts in vegetation phenology of Arctic regions have far-reaching implications for caribou. Changes to timing and duration of the growing season and the rate at which the Arctic annually greens and browns can influence vegetation quantity and quality during parturition, lactation, and the late summer/autumn transition, an important time period for forage intake of mother-offspring pairs.  However, understanding how climate change will affect forage during these critical timeframes is a challenging problem because it requires assessing changes in vegetation phenology at fine temporal-scales across expansive and remote regions of the Arctic.  To address this problem, we are creating a unique dataset of daily remotely sensed normalized difference vegetation index (NDVI) data across the North Slope of Alaska to elucidate the fine-scale temporal trends of vegetation phenology in this region over the last nearly 20 years (2001 to 2017).  Specifically, we will examine changes in the start, end and duration of the growing season, the rate and duration of green-up and brown-down and the time-integrated NDVI (the area under the NDVI curve during the growing season).  Further, we will examine the variation in these metrics across different vegetation types used by the caribou of Alaska’s North Slope.  These data will help identify climate-driven changes in vegetation phenology that are not discernable from datasets with a courser temporal-scale, and illustrate how these dynamics vary across the large regions used by caribou.

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