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| Titel |
Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity |
| VerfasserIn |
J. M. Chen, X. Chen, W. Ju |
| 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 ; 10, no. 7 ; Nr. 10, no. 7 (2013-07-18), S.4879-4896 |
| Datensatznummer |
250018350
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| Publikation (Nr.) |
 copernicus.org/bg-10-4879-2013.pdf |
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| Zusammenfassung |
| Due to the heterogeneous nature of the land surface, spatial scaling is an
inevitable issue in the development of land models coupled with
low-resolution Earth system models (ESMs) for predicting land-atmosphere
interactions and carbon-climate feedbacks. In this study, a simple spatial
scaling algorithm is developed to correct errors in net primary productivity
(NPP) estimates made at a coarse spatial resolution based on sub-pixel
information of vegetation heterogeneity and surface topography. An
eco-hydrological model BEPS-TerrainLab, which considers both vegetation and
topographical effects on the vertical and lateral water flows and the carbon
cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the
Qinling Mountain, Shanxi Province, China. Assuming that the NPP simulated at
30 m resolution represents the reality and that at 1 km resolution is
subject to errors due to sub-pixel heterogeneity, a spatial scaling index
(SSI) is developed to correct the coarse resolution NPP values pixel by
pixel. The agreement between the NPP values at these two resolutions is
improved considerably from R2 = 0.782 to R2 = 0.884 after the
correction. The mean bias error (MBE) in NPP modelled at the 1 km resolution
is reduced from 14.8 g C m−2 yr−1 to 4.8 g C m−2 yr−1 in
comparison with NPP modelled at 30 m resolution, where the mean NPP is 668 g C m−2 yr−1.
The range of spatial variations of NPP at 30 m
resolution is larger than that at 1 km resolution. Land cover fraction is
the most important vegetation factor to be considered in NPP spatial
scaling, and slope is the most important topographical factor for NPP
spatial scaling especially in mountainous areas, because of its influence on
the lateral water redistribution, affecting water table, soil moisture and
plant growth. Other factors including leaf area index (LAI) and elevation
have small and additive effects on improving the spatial scaling between
these two resolutions. |
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