Premium
Trade‐offs between global warming and day length on the start of the carbon uptake period in seasonally cold ecosystems
Author(s) -
Wohlfahrt Georg,
Cremonese Edoardo,
Hammerle Albin,
Hörtnagl Lukas,
Galvagno Marta,
Gianelle Damiano,
Marcolla Barbara,
Cella Umberto Morra
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl058182
Subject(s) - environmental science , ecosystem , carbon dioxide , climate change , global warming , atmospheric sciences , daytime , daylight , photosynthesis , solstice , climatology , ecology , biology , geography , geology , botany , latitude , physics , optics , geodesy
Abstract It is well established that warming leads to longer growing seasons in seasonally cold ecosystems. Whether this goes along with an increase in the net ecosystem carbon dioxide (CO 2 ) uptake is much more controversial. We studied the effects of warming on the start of the carbon uptake period (CUP) of three mountain grasslands situated along an elevational gradient in the Alps. To this end, we used a simple empirical model of the net ecosystem CO 2 exchange, calibrated, and forced with multiyear empirical data from each site. We show that reductions in the quantity and duration of daylight associated with earlier snowmelts were responsible for diminishing returns, in terms of carbon gain, from longer growing seasons caused by reductions in daytime photosynthetic uptake and increases in nighttime losses of CO 2 . This effect was less pronounced at high, compared to low, elevations, where the start of the CUP occurred closer to the summer solstice when changes in day length and incident radiation are minimal.