Phenological responses of Icelandic subarctic grasslands to short-term and long-term natural soil warming
Leblans, Niki I. W. (Landbúnaðarháskóli Íslands)
Sigurdsson, Bjarni D. (Landbúnaðarháskóli Íslands)
Vicca, Sara (Universiteit Antwerpen. Departement Biologie)
Fu, Yongshuo H.. (Sino-French Institute for Earth System Science)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Janssens, Ivan (Universiteit Antwerpen. Departement Biologie)

Data:	2017
Resum:	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 °C soil warming up to the highest soil warming levels (ca. +10°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°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.
Ajuts:	European Commission 610028
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Climate change ; Geothermal warming ; Iceland ; Normalized difference vegetation index ; Phenology ; Subarctic grassland
Publicat a:	Journal of vegetation science, Vol. 23, issue 11 (Nov. 2017) , p. 4932-4945, ISSN 1654-1103

DOI: 10.1111/gcb.13749

Post-print 38 p, 1.0 MB

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