Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis
High-latitude treeless ecosystems represent spatially highly heterogeneous landscapes with small net carbon fluxes and a short growing season. Reliable observations and process understanding are critical for projections of the carbon balance of the climate-sensitive tundra. Space-borne remote sensin...
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ftdoajarticles:oai:doaj.org/article:c4aed1486d604a1da6121de5930c81b2 2023-05-15T15:14:26+02:00 Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis S. Walther L. Guanter B. Heim M. Jung G. Duveiller A. Wolanin T. Sachs 2018-10-01T00:00:00Z https://doi.org/10.5194/bg-15-6221-2018 https://doaj.org/article/c4aed1486d604a1da6121de5930c81b2 EN eng Copernicus Publications https://www.biogeosciences.net/15/6221/2018/bg-15-6221-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-6221-2018 1726-4170 1726-4189 https://doaj.org/article/c4aed1486d604a1da6121de5930c81b2 Biogeosciences, Vol 15, Pp 6221-6256 (2018) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2018 ftdoajarticles https://doi.org/10.5194/bg-15-6221-2018 2022-12-31T02:15:11Z High-latitude treeless ecosystems represent spatially highly heterogeneous landscapes with small net carbon fluxes and a short growing season. Reliable observations and process understanding are critical for projections of the carbon balance of the climate-sensitive tundra. Space-borne remote sensing is the only tool to obtain spatially continuous and temporally resolved information on vegetation greenness and activity in remote circumpolar areas. However, confounding effects from persistent clouds, low sun elevation angles, numerous lakes, widespread surface inundation, and the sparseness of the vegetation render it highly challenging. Here, we conduct an extensive analysis of the timing of peak vegetation productivity as shown by satellite observations of complementary indicators of plant greenness and photosynthesis. We choose to focus on productivity during the peak of the growing season, as it importantly affects the total annual carbon uptake. The suite of indicators are as follows: (1) MODIS-based vegetation indices (VIs) as proxies for the fraction of incident photosynthetically active radiation (PAR) that is absorbed (fPAR), (2) VIs combined with estimates of PAR as a proxy of the total absorbed radiation (APAR), (3) sun-induced chlorophyll fluorescence (SIF) serving as a proxy for photosynthesis, (4) vegetation optical depth (VOD), indicative of total water content and (5) empirically upscaled modelled gross primary productivity (GPP). Averaged over the pan-Arctic we find a clear order of the annual peak as APAR ≦ GPP < SIF < VIs∕VOD. SIF as an indicator of photosynthesis is maximised around the time of highest annual temperatures. The modelled GPP peaks at a similar time to APAR. The time lag of the annual peak between APAR and instantaneous SIF fluxes indicates that the SIF data do contain information on light-use efficiency of tundra vegetation, but further detailed studies are necessary to verify this. Delayed peak greenness compared to peak photosynthesis is consistently found across years ... Article in Journal/Newspaper Arctic Tundra Directory of Open Access Journals: DOAJ Articles Arctic Biogeosciences 15 20 6221 6256 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 S. Walther L. Guanter B. Heim M. Jung G. Duveiller A. Wolanin T. Sachs Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
High-latitude treeless ecosystems represent spatially highly heterogeneous landscapes with small net carbon fluxes and a short growing season. Reliable observations and process understanding are critical for projections of the carbon balance of the climate-sensitive tundra. Space-borne remote sensing is the only tool to obtain spatially continuous and temporally resolved information on vegetation greenness and activity in remote circumpolar areas. However, confounding effects from persistent clouds, low sun elevation angles, numerous lakes, widespread surface inundation, and the sparseness of the vegetation render it highly challenging. Here, we conduct an extensive analysis of the timing of peak vegetation productivity as shown by satellite observations of complementary indicators of plant greenness and photosynthesis. We choose to focus on productivity during the peak of the growing season, as it importantly affects the total annual carbon uptake. The suite of indicators are as follows: (1) MODIS-based vegetation indices (VIs) as proxies for the fraction of incident photosynthetically active radiation (PAR) that is absorbed (fPAR), (2) VIs combined with estimates of PAR as a proxy of the total absorbed radiation (APAR), (3) sun-induced chlorophyll fluorescence (SIF) serving as a proxy for photosynthesis, (4) vegetation optical depth (VOD), indicative of total water content and (5) empirically upscaled modelled gross primary productivity (GPP). Averaged over the pan-Arctic we find a clear order of the annual peak as APAR ≦ GPP < SIF < VIs∕VOD. SIF as an indicator of photosynthesis is maximised around the time of highest annual temperatures. The modelled GPP peaks at a similar time to APAR. The time lag of the annual peak between APAR and instantaneous SIF fluxes indicates that the SIF data do contain information on light-use efficiency of tundra vegetation, but further detailed studies are necessary to verify this. Delayed peak greenness compared to peak photosynthesis is consistently found across years ... |
format |
Article in Journal/Newspaper |
author |
S. Walther L. Guanter B. Heim M. Jung G. Duveiller A. Wolanin T. Sachs |
author_facet |
S. Walther L. Guanter B. Heim M. Jung G. Duveiller A. Wolanin T. Sachs |
author_sort |
S. Walther |
title |
Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
title_short |
Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
title_full |
Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
title_fullStr |
Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
title_full_unstemmed |
Assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
title_sort |
assessing the dynamics of vegetation productivity in circumpolar regions with different satellite indicators of greenness and photosynthesis |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-15-6221-2018 https://doaj.org/article/c4aed1486d604a1da6121de5930c81b2 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Tundra |
genre_facet |
Arctic Tundra |
op_source |
Biogeosciences, Vol 15, Pp 6221-6256 (2018) |
op_relation |
https://www.biogeosciences.net/15/6221/2018/bg-15-6221-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-6221-2018 1726-4170 1726-4189 https://doaj.org/article/c4aed1486d604a1da6121de5930c81b2 |
op_doi |
https://doi.org/10.5194/bg-15-6221-2018 |
container_title |
Biogeosciences |
container_volume |
15 |
container_issue |
20 |
container_start_page |
6221 |
op_container_end_page |
6256 |
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1766344888516870144 |