Phenological responses of Icelandic subarctic grasslands to short-term and long-term natural soil warming

The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades...

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Bibliographic Details
Published in:Global Change Biology
Main Authors: Leblans, Niki I. W., Sigurdsson, Bjarni D., Vicca, Sara, Fu, Yongshuo, Penuelas, Josep, Janssens, Ivan A.
Other Authors: Leblans, NIW (reprint author), Univ Antwerp, Dept Biol, Wijlrijk, Belgium., Univ Antwerp, Dept Biol, Wijlrijk, Belgium., Agr Univ Iceland, Borgarnes, Iceland., Peking Univ, Sinofrench Inst Earth Syst Sci, Coll Urban & Environm Sci, Beijing, Peoples R China., CREAF, Catalonia, Spain., CSIC, Global Ecol Unit, Catalonia, Spain.
Format: Journal/Newspaper
Language:English
Published: GLOBAL CHANGE BIOLOGY 2017
Subjects:
climate change
geothermal warming
Iceland
normalized difference vegetation index
phenology
subarctic grassland
TIBETAN PLATEAU GRASSLANDS
VEGETATION GREEN-UP
CLIMATE-CHANGE
SPRING PHENOLOGY
LEAF PHENOLOGY
HIGH-LATITUDES
GEOTHERMAL ECOSYSTEMS
MONITORING VEGETATION
HEAT REQUIREMENT
GLOBAL CHANGE
Subarctic
Online Access:https://hdl.handle.net/20.500.11897/470401
https://doi.org/10.1111/gcb.13749
Description
Summary:The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades, the largest extensions of LOS have been reported at high northern latitudes, but further warming-induced LOS extensions may be constrained by too short photoperiod or unfulfilled chilling requirements. Here, we studied subarctic grasslands, which cover a vast area and contain large C stocks, but for which LOS changes under further warming are highly uncertain. We measured LOS extensions of Icelandic subarctic grasslands along natural geothermal soil warming gradients of different age (short term, where the measurements started after 5 years of warming and long term, i.e., warmed since 50 years) using ground-level measurements of normalized difference vegetation index. We found that LOS linearly extended with on average 2.1 days per degrees C soil warming up to the highest soil warming levels (ca. +10 degrees C) and that LOS had the potential to extend at least 1 month. This indicates that the warming impact on LOS in these subarctic grasslands will likely not saturate in the near future. A similar response to short- and long-term warming indicated a strong physiological control of the phenological response of the subarctic grasslands to warming and suggested that genetic adaptations and community changes were likely of minor importance. We conclude that the warming-driven extension of the LOSs of these subarctic grasslands did not saturate up to +10 degrees C warming, and hence that growing seasons of high-latitude grasslands are likely to continue lengthening with future warming (unless genetic adaptations or species shifts do occur). This persistence of the warming-induced extension of LOS has important implications for the C-sink potential of subarctic grasslands under climate change. Research Foundation-Flanders; European Research Council Synergy [610028]; Research Council of the University of Antwerp SCI(E) ARTICLE 11 4932-4945 23

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