High-resolution satellite data reveal an increase in peak growing season gross primary production in a high-Arctic wet tundra ecosystem 1992–2008

• Published in: International journal of applied earth observation and geoinformation Vol. 18; pp. 407 - 416
• Main Authors: Tagesson, Torbern, Mastepanov, Mikhail, Tamstorf, Mikkel P., Eklundh, Lars, Schubert, Per, Ekberg, Anna, Sigsgaard, Charlotte, Christensen, Torben R., Ström, Lena
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.08.2012; Elsevier
• Subjects: Applied geophysics; Climate change; Earth and Related Environmental Sciences; Earth sciences; Earth, ocean, space; Exact sciences and technology; FAPAR; Geovetenskap och miljövetenskap; GPP; Internal geophysics; Light use efficiency; Natural Sciences; Naturgeografi; Naturvetenskap; NDVI; Physical Geography; Remote sensing; polar regions; Arctic region; Greenland; Climate change; Light use efficiency; NDVI; GPP; Remote sensing; FAPAR; satellites; models; efficiency; remote sensing; vegetation; air; climate; carbon cycle; tundra; propagation; radiation; regression; ecosystems; temperature; uncertainties; valleys; errors; climate change; high resolution
• ISSN: 1569-8432; 1872-826X
• DOI: 10.1016/j.jag.2012.03.016

▸ The light use efficiency (LUE) of high-Arctic plant communities was measured. Combining satellite data with LUE-modeling was used to study carbon uptake. ▸ Field measured FAPAR was shown to be linearly related to satellite based NDVI. ▸ Gross primary production was shown to have increased 1992–2008 in a high-Arctic fen. 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=ɛpeak×PARin×FAPARgreen_peak; where ɛpeak 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 ɛpeak was measured for seven different high-Arctic plant communities in the field, and it was on average 1.63g CO2MJ−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 192mg CO2m−2h−1). The model showed an increase in peak growing season GPP of 42mg CO2m−2h−1y−1 in Rylekærene 1992–2008. There was also a strong increase in air temperature (0.15°Cy−1), indicating that the GPP trend may have been climate driven.