Arctic shrub effects on NDVI, summer albedo and soil shading
The influence of Arctic vegetation on albedo, latent and sensible heat fluxes, and active layer thickness is a crucial link between boundary layer climate and permafrost in the context of climate change. Shrubs have been observed to lower the albedo as compared to lichen or graminoid-tundra. Despite...
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ftunivzuerich:oai:www.zora.uzh.ch:104474 2024-05-12T07:52:09+00:00 Arctic shrub effects on NDVI, summer albedo and soil shading Juszak, Inge Erb, Angela M Maximov, Trofim C Schaepman-Strub, Gabriela 2014 application/pdf https://www.zora.uzh.ch/id/eprint/104474/ https://www.zora.uzh.ch/id/eprint/104474/1/Juszak_etal_2014_preprint.pdf https://doi.org/10.5167/uzh-104474 https://doi.org/10.1016/j.rse.2014.07.021 eng eng Elsevier https://www.zora.uzh.ch/id/eprint/104474/1/Juszak_etal_2014_preprint.pdf doi:10.5167/uzh-104474 doi:10.1016/j.rse.2014.07.021 urn:issn:0034-4257 info:eu-repo/semantics/openAccess Juszak, Inge; Erb, Angela M; Maximov, Trofim C; Schaepman-Strub, Gabriela (2014). Arctic shrub effects on NDVI, summer albedo and soil shading. Remote Sensing of Environment, 153:79-89. Institute of Evolutionary Biology and Environmental Studies Global Change and Biodiversity 570 Life sciences biology 590 Animals (Zoology) 3D radiative transfer modelling Manipulation experiment Arctic shrubs Shortwave radiation balance NDVI Albedo tPAR Branch to leaf ratio Journal Article PeerReviewed info:eu-repo/semantics/article 2014 ftunivzuerich https://doi.org/10.5167/uzh-10447410.1016/j.rse.2014.07.021 2024-04-17T15:20:33Z The influence of Arctic vegetation on albedo, latent and sensible heat fluxes, and active layer thickness is a crucial link between boundary layer climate and permafrost in the context of climate change. Shrubs have been observed to lower the albedo as compared to lichen or graminoid-tundra. Despite its importance, the quantification of the effect of shrubification on summer albedo has not been addressed in much detail. We manipulated shrub density and height in an Arctic dwarf birch (Betula nana) shrub canopy to test the effect on shortwave radiative fluxes and on the normalized difference vegetation index (NDVI), a proxy for vegetation productivity used in satellite-based studies. Additionally, we parametrised and validated the 3D radiative transfer model DART to simulate the amount of solar radiation reflected and transmitted by an Arctic shrub canopy. We compared results of model runs of different complexities to measured data from North-East Siberia. We achieved comparably good results with simple turbid medium approaches, including both leaf and branch optical property media, and detailed object based model parameterisations. It was important to explicitly parameterise branches as they accounted for up to 71% of the total canopy absorption and thus contributed significantly to soil shading. Increasing leaf biomass resulted in a significant increase of the NDVI, decrease of transmitted photosynthetically active radiation, and repartitioning of the absorption of shortwave radiation by the canopy components. However, experimental and modelling results show that canopy broadband nadir reflectance and albedo are not significantly decreasing with increasing shrub biomass. We conclude that the leaf to branch ratio, canopy background, and vegetation type replaced by shrubs need to be considered when predicting feedbacks of shrubification to summer albedo, permafrost thaw, and climate warming. Article in Journal/Newspaper Active layer thickness albedo Arctic Arctic Betula nana Climate change Dwarf birch permafrost Tundra Siberia University of Zurich (UZH): ZORA (Zurich Open Repository and Archive Arctic |
institution |
Open Polar |
collection |
University of Zurich (UZH): ZORA (Zurich Open Repository and Archive |
op_collection_id |
ftunivzuerich |
language |
English |
topic |
Institute of Evolutionary Biology and Environmental Studies Global Change and Biodiversity 570 Life sciences biology 590 Animals (Zoology) 3D radiative transfer modelling Manipulation experiment Arctic shrubs Shortwave radiation balance NDVI Albedo tPAR Branch to leaf ratio |
spellingShingle |
Institute of Evolutionary Biology and Environmental Studies Global Change and Biodiversity 570 Life sciences biology 590 Animals (Zoology) 3D radiative transfer modelling Manipulation experiment Arctic shrubs Shortwave radiation balance NDVI Albedo tPAR Branch to leaf ratio Juszak, Inge Erb, Angela M Maximov, Trofim C Schaepman-Strub, Gabriela Arctic shrub effects on NDVI, summer albedo and soil shading |
topic_facet |
Institute of Evolutionary Biology and Environmental Studies Global Change and Biodiversity 570 Life sciences biology 590 Animals (Zoology) 3D radiative transfer modelling Manipulation experiment Arctic shrubs Shortwave radiation balance NDVI Albedo tPAR Branch to leaf ratio |
description |
The influence of Arctic vegetation on albedo, latent and sensible heat fluxes, and active layer thickness is a crucial link between boundary layer climate and permafrost in the context of climate change. Shrubs have been observed to lower the albedo as compared to lichen or graminoid-tundra. Despite its importance, the quantification of the effect of shrubification on summer albedo has not been addressed in much detail. We manipulated shrub density and height in an Arctic dwarf birch (Betula nana) shrub canopy to test the effect on shortwave radiative fluxes and on the normalized difference vegetation index (NDVI), a proxy for vegetation productivity used in satellite-based studies. Additionally, we parametrised and validated the 3D radiative transfer model DART to simulate the amount of solar radiation reflected and transmitted by an Arctic shrub canopy. We compared results of model runs of different complexities to measured data from North-East Siberia. We achieved comparably good results with simple turbid medium approaches, including both leaf and branch optical property media, and detailed object based model parameterisations. It was important to explicitly parameterise branches as they accounted for up to 71% of the total canopy absorption and thus contributed significantly to soil shading. Increasing leaf biomass resulted in a significant increase of the NDVI, decrease of transmitted photosynthetically active radiation, and repartitioning of the absorption of shortwave radiation by the canopy components. However, experimental and modelling results show that canopy broadband nadir reflectance and albedo are not significantly decreasing with increasing shrub biomass. We conclude that the leaf to branch ratio, canopy background, and vegetation type replaced by shrubs need to be considered when predicting feedbacks of shrubification to summer albedo, permafrost thaw, and climate warming. |
format |
Article in Journal/Newspaper |
author |
Juszak, Inge Erb, Angela M Maximov, Trofim C Schaepman-Strub, Gabriela |
author_facet |
Juszak, Inge Erb, Angela M Maximov, Trofim C Schaepman-Strub, Gabriela |
author_sort |
Juszak, Inge |
title |
Arctic shrub effects on NDVI, summer albedo and soil shading |
title_short |
Arctic shrub effects on NDVI, summer albedo and soil shading |
title_full |
Arctic shrub effects on NDVI, summer albedo and soil shading |
title_fullStr |
Arctic shrub effects on NDVI, summer albedo and soil shading |
title_full_unstemmed |
Arctic shrub effects on NDVI, summer albedo and soil shading |
title_sort |
arctic shrub effects on ndvi, summer albedo and soil shading |
publisher |
Elsevier |
publishDate |
2014 |
url |
https://www.zora.uzh.ch/id/eprint/104474/ https://www.zora.uzh.ch/id/eprint/104474/1/Juszak_etal_2014_preprint.pdf https://doi.org/10.5167/uzh-104474 https://doi.org/10.1016/j.rse.2014.07.021 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Active layer thickness albedo Arctic Arctic Betula nana Climate change Dwarf birch permafrost Tundra Siberia |
genre_facet |
Active layer thickness albedo Arctic Arctic Betula nana Climate change Dwarf birch permafrost Tundra Siberia |
op_source |
Juszak, Inge; Erb, Angela M; Maximov, Trofim C; Schaepman-Strub, Gabriela (2014). Arctic shrub effects on NDVI, summer albedo and soil shading. Remote Sensing of Environment, 153:79-89. |
op_relation |
https://www.zora.uzh.ch/id/eprint/104474/1/Juszak_etal_2014_preprint.pdf doi:10.5167/uzh-104474 doi:10.1016/j.rse.2014.07.021 urn:issn:0034-4257 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5167/uzh-10447410.1016/j.rse.2014.07.021 |
_version_ |
1798841858729705472 |