Vegetation phenology in Greenland and links to cryospheric change

Jeffery A Thompson,Lora S Koenig

doi:10.1017/aog.2018.24

Abstract

ABSTRACTRecent greening of vegetation across the Arctic is associated with warming temperatures, hydrologic change and shorter snow-covered periods. Here we investigated trends for a subset of arctic vegetation on the island of Greenland. Vegetation in Greenland is unique due to its close proximity to the Greenland Ice Sheet and its proportionally large connection to the Greenlandic population through the hunting of grazing animals. The aim of this study was to determine whether or not longer snow-free periods (SFPs) were causing Greenlandic vegetation to dry out and become less productive. If vegetation was drying out, a subsequent aim of the study was to determine how widespread the drying was across Greenland. We utilized a 15-year time-series obtained by the MODerate Resolution Imaging Spectroradiometer (MODIS) to analyze the Greenland vegetation by deriving descriptors corresponding with the SFP, the number of cumulative growing degree-days and the time-integrated Normalized Difference Vegetation Index. While the productivity of most vegetated areas increased in response to longer growing periods, there were localized regions that exhibited signs consistent with the drying hypothesis. In these areas, vegetation productivity decreased in response to longer SFPs and more accumulated growing degree-days.

Highlights

AND BACKGROUNDIn recent years, the rate of climatic warming in the Arctic has been roughly double that of the lower latitudes, an occurrence referred to as Arctic amplification (Serreze and others, 2000; Screen and Simmonds, 2010)
We investigated the links between changes in snow seasonality and vegetation phenology in Greenland using remote sensing
The results indicated that most vegetated surfaces experienced an increase in accumulated growing degree-days (AGDD) throughout the study period (Fig 3b)

Summary

Introduction

The rate of climatic warming in the Arctic has been roughly double that of the lower latitudes, an occurrence referred to as Arctic amplification (Serreze and others, 2000; Screen and Simmonds, 2010) They operate on different spatial and temporal scales, there are a number of causes of this amplification. Increased photosynthetic capacity of vegetation in response to longer snow-free periods (SFPs) (Déry and Brown, 2007; Sturm and others, 2005) is another phenomenon associated with Arctic amplification (Bhatt and others, 2010; Beck and Goetz, 2011) This increase in photosynthetic capacity of vegetation has been accompanied by an expansion of woody shrubs in the tundra (Sturm and others, 2001; Markus and others, 2009). Myers-Smith and others (2011) noted there are several important implications associated with shrub expansion It will alter the exchange of energy, carbon and water fluxes between the atmosphere and biosphere. Shrub expansion may increase fire frequency; Higuera and others (2008) reported that fire was more prevalent in the past when temperatures and moisture were higher, and shrubs were more abundant

Objectives

Methods

Results

Discussion

Conclusion