Summer warming explains widespread but not uniform greening in the Arctic tundra biome

Logan T Berner,Benjamin V Gaglioti,Gilles Gauthier,Timo Kumpula,Richard Massey,Bruce C Forbes,Pentti Zetterberg,Laia Andreu-Hayles,Isla Myers-Smith,Marc Macias-Fauria,Scott J Goetz,Patrick Burns,Rosanne D’Arrigo,Patrick Jantz

doi:10.1038/s41467-020-18479-5

Abstract

Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Yet ecological change across the Arctic tundra biome remains poorly quantified due to field measurement limitations and reliance on coarse-resolution satellite data. Here, we assess decadal changes in Arctic tundra greenness using time series from the 30 m resolution Landsat satellites. From 1985 to 2016 tundra greenness increased (greening) at ~37.3% of sampling sites and decreased (browning) at ~4.7% of sampling sites. Greening occurred most often at warm sampling sites with increased summer air temperature, soil temperature, and soil moisture, while browning occurred most often at cold sampling sites that cooled and dried. Tundra greenness was positively correlated with graminoid, shrub, and ecosystem productivity measured at field sites. Our results support the hypothesis that summer warming stimulated plant productivity across much, but not all, of the Arctic tundra biome during recent decades.

Highlights

Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities
Our analysis reveals extensive but not uniform greening in the Arctic tundra biome during recent decades that tended to occur in warm areas with increasing summer air temperature, soil temperature, and soil moisture
We provide here a pan-Arctic assessment of changes in tundra greenness using high-resolution Landsat NDVImax and evaluate links between tundra greenness and field measurement of plant productivity

Summary

Introduction

Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Long-term field studies that do exist document recent increases in plant cover, growth, height, and biomass, and a shift towards shrub dominance in some tundra ecosystems[6,7,8,9], while other areas show little change in vegetation[10,11], or even warming-induced declines in plant growth[12,13]. Pan-Arctic changes in NDVI since the 1980s have been exclusively assessed with the Advanced Very HighResolution Radiometers (AVHRR)[17] These satellites show increasing NDVI (greening) across large parts of the Arctic, but decreasing NDVI (browning) in several regions The prevalence and spatial patterns of greening and browning differ considerably among AVHRR NDVI data sets[18] These discrepancies partially reflect challenges with cross-calibrating sensors flown on 16 separate satellites[18,19]

Methods

Results

Conclusion