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| Titel |
Forest summer albedo is sensitive to species and thinning: how should we account for this in Earth system models? |
| VerfasserIn |
J. Otto, D. Berveiller, F.-M. Bréon, N. Delpierre, G. Geppert, A. Granier, W. Jans, A. Knohl, A. Kuusk, B. Longdoz, E. Moors, M. Mund, B. Pinty, M.-J. Schelhaas, S. Luyssaert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 8 ; Nr. 11, no. 8 (2014-04-29), S.2411-2427 |
| Datensatznummer |
250117384
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| Publikation (Nr.) |
 copernicus.org/bg-11-2411-2014.pdf |
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| Zusammenfassung |
Although forest management is one of the instruments proposed to mitigate
climate change, the relationship between forest management and canopy albedo
has been ignored so far by climate models. Here we develop an approach that
could be implemented in Earth system models. A stand-level forest gap model
is combined with a canopy radiation transfer model and satellite-derived
model parameters to quantify the effects of forest thinning on summertime
canopy albedo. This approach reveals which parameter has the largest affect
on summer canopy albedo: we examined the effects of three forest species
(pine, beech, oak) and four thinning strategies with a constant forest floor
albedo (light to intense thinning regimes) and five different solar zenith
angles at five different sites (40° N 9° E–60° N 9° E).
During stand establishment, summertime canopy albedo is driven by tree
species. In the later stages of stand development, the effect of tree
species on summertime canopy albedo decreases in favour of an increasing
influence of forest thinning. These trends continue until the end of the
rotation, where thinning explains up to 50% of the variance in
near-infrared albedo and up to 70% of the variance in visible canopy
albedo.
The absolute summertime canopy albedo of all species ranges from 0.03 to
0.06 (visible) and 0.20 to 0.28 (near-infrared); thus the albedo needs to be
parameterised at species level. In addition, Earth system models need to
account for forest management in such a way that structural changes in the
canopy are described by changes in leaf area index and crown volume (maximum
change of 0.02 visible and 0.05 near-infrared albedo) and that the
expression of albedo depends on the solar zenith angle (maximum change of
0.02 visible and 0.05 near-infrared albedo). Earth system models taking into
account these parameters would not only be able to examine the spatial
effects of forest management but also the total effects of forest management
on climate. |
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