Abstract
Climate-induced changes in vegetation phenology at northern latitudes are still poorly understood. Continued monitoring and research are therefore needed to improve the understanding of abiotic drivers. Here we used 14 years of time lapse imagery and climate data from high-Arctic Northeast Greenland to assess the seasonal response of a dwarf shrub heath, grassland, and fen, to inter-annual variation in snow-cover, soil moisture, and air and soil temperatures. A late snow melt and start of growing season is counterbalanced by a fast greenup and a tendency to higher peak greenness values. Snow water equivalents and soil moisture explained up to 77 % of growing season duration and senescence phase, highlighting that water availability is a prominent driver in the heath site, rather than temperatures. We found a significant advance in the start of spring by 10 days and in the end of fall by 11 days, resulting in an unchanged growing season length. Vegetation greenness, derived from the imagery, was correlated to primary productivity, showing that the imagery holds valuable information on vegetation productivity.
Highlights
Vegetation growth and phenology are important indicators of climate change on both plant level (Cleland et al 2012) and global scale (Walther 2010)
We present 14 years of image- and gross primary productivity data from high-Arctic Zackenberg
We show that the green chromatic coordinate vegetation index can successfully be used to determine phenological transitions in vegetation growth in high-Arctic ecosystems
Summary
Vegetation growth and phenology are important indicators of climate change on both plant level (Cleland et al 2012) and global scale (Walther 2010). 2011), as well as in in situ observation data on flowering and growing season length (Kerby and Post 2013) Such shifts in seasonality, and the duration of the individual seasons, can have important consequences for the functioning of ecosystems and on the carbon cycle (McGuire et al 2009). A meta-analysis by Oberbauer et al (2013) did not find a general advancement of the start of the growing season based on studies from 12 different Arctic and alpine sites. It is still uncertain how the relationship between warming and vegetation greening in the Arctic is affected by other variables such as water and nutrients (Xu et al 2013).
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