TY - JOUR
T1 - High-resolution satellite data reveal an increase in peak growing season gross primary production in a high-Arctic wet tundra ecosystem 1992-2008
AU - Tagesson, Håkon Torbern
AU - Mastepanov, Mikhail
AU - Tamstorf, Mikkel
AU - Eklundh, Lars
AU - Per, Schubert
AU - Ekberg, Anna
AU - Sigsgaard, Charlotte
AU - Christensen, Torben
AU - Strøm, Lena
PY - 2012
Y1 - 2012
N2 - Arctic ecosystems play a key role in the terrestrial carbon cycle. Our aim was to combine satellite-based normalized difference vegetation index (NDVI) with field measurements of CO2 fluxes to investigate changes in gross primary production (GPP) for the peak growing seasons 1992-2008 in Rylekærene, a wet tundra ecosystem in the Zackenberg valley, north-eastern Greenland. A method to incorporate controls on GPP through satellite data is the light use efficiency (LUE) model, here expressed as GPP = εpeak ×PARin ×FAPARgreen peak; where εpeak was peak growing season light use efficiency of the vegetation, PARin was incoming photosynthetically active radiation, and FAPARgreen peak was peak growing season fraction of PAR absorbed by the green vegetation. The εpeak was measured for seven different high-Arctic plant communities in the field, and it was on average 1.63 g CO2 MJ-1. We found a significant linear relationship between FAPARgreen peak measured in the field and satellite-based NDVI. The linear regression was applied to peak growing season NDVI 1992-2008 and derived FAPARgreen peak was entered into the LUE-model. It was shown that when several empirical models are combined, propagation errors are introduced, which results in considerable model uncertainties. The LUE-model was evaluated against field-measured GPP and the model captured field-measured GPP well (RMSE was 192 mg CO2m-2 h-1). The model showed an increase in peak growing season GPP of 42 mg CO2m-2 h-1 y-1 in Rylekærene 1992-2008. There was also a strong increase in air temperature (0.15 {ring operator}C y-1), indicating that the GPP trend may have been climate driven.
AB - Arctic ecosystems play a key role in the terrestrial carbon cycle. Our aim was to combine satellite-based normalized difference vegetation index (NDVI) with field measurements of CO2 fluxes to investigate changes in gross primary production (GPP) for the peak growing seasons 1992-2008 in Rylekærene, a wet tundra ecosystem in the Zackenberg valley, north-eastern Greenland. A method to incorporate controls on GPP through satellite data is the light use efficiency (LUE) model, here expressed as GPP = εpeak ×PARin ×FAPARgreen peak; where εpeak was peak growing season light use efficiency of the vegetation, PARin was incoming photosynthetically active radiation, and FAPARgreen peak was peak growing season fraction of PAR absorbed by the green vegetation. The εpeak was measured for seven different high-Arctic plant communities in the field, and it was on average 1.63 g CO2 MJ-1. We found a significant linear relationship between FAPARgreen peak measured in the field and satellite-based NDVI. The linear regression was applied to peak growing season NDVI 1992-2008 and derived FAPARgreen peak was entered into the LUE-model. It was shown that when several empirical models are combined, propagation errors are introduced, which results in considerable model uncertainties. The LUE-model was evaluated against field-measured GPP and the model captured field-measured GPP well (RMSE was 192 mg CO2m-2 h-1). The model showed an increase in peak growing season GPP of 42 mg CO2m-2 h-1 y-1 in Rylekærene 1992-2008. There was also a strong increase in air temperature (0.15 {ring operator}C y-1), indicating that the GPP trend may have been climate driven.
U2 - 10.1016/j.jag.2012.03.016
DO - 10.1016/j.jag.2012.03.016
M3 - Journal article
SN - 0303-2434
VL - 18
SP - 407
EP - 416
JO - International Journal of Applied Earth Observation and Geoinformation
JF - International Journal of Applied Earth Observation and Geoinformation
ER -
