The ongoing disproportionate increases in temperature and precipitation over the Arctic region may greatly alter the latitudinal gradients in greenup and snowmelt timings as well as associated carbon dynamics of tundra ecosystems. Here we use remotely-sensed and ground-based datasets and model results embedding snowmelt timing in phenology at seven tundra flux tower sites in Alaska during 2001–2018, showing that the carbon response to early greenup or delayed snowmelt varies greatly depending upon local climatic limits. Increases in net ecosystem productivity (NEP) due to early greenup were amplified at the higher latitudes where temperature and water strongly colimit vegetation growth, while NEP decreases due to delayed snowmelt were alleviated by a relief of water stress. Given the high likelihood of more frequent delayed snowmelt at higher latitudes, this study highlights the importance of understanding the role of snowmelt timing in vegetation growth and terrestrial carbon cycles across warming Arctic ecosystems.
Bibliographical noteFunding Information:
We sincerely acknowledge the contribution of the editors and the five anonymous referees, whose constructive suggestions have significantly improved the manuscript from its earlier version. We deeply appreciate Nancy Kiang for sharing Ent-GVSD data and also for providing constructive comments on the manuscript. We also thank Xiaoyang Zhang and Charlotte Levy for supporting the evaluation of MODIS greenup, and Erik Larson for advising on the ED2 parameter calibration. This study was funded by grants from the Korea Polar Research Institute (KOPRI, PE17900, and PE18900) and the National Research Foundation of Korea (NRF) from the Korean government (MSIT; the Ministry of Science and ICT) (2020R1C1C1014886, 2020R1A2C2007670, 2016M1A5A1901769, and 2021M1A5A1065425). D.Z. and W.O. were funded by the NSF OPP (1204263 and 1702797), NASA ABoVE (NNX15AT74A, NNX16AF94A, and NNX17AC61A), NOAA EPP (NA16SEC4810008), EU Horizon 2020 (727890), and NERC UK (NE/P002552/1).
© 2021, The Author(s).
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)