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| Titel |
Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration |
| VerfasserIn |
P. Choler |
| 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 ; 12, no. 12 ; Nr. 12, no. 12 (2015-06-26), S.3885-3897 |
| Datensatznummer |
250118001
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| Publikation (Nr.) |
 copernicus.org/bg-12-3885-2015.pdf |
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| Zusammenfassung |
| A remote sensing approach is used to examine the direct and indirect effects
of snow cover duration and weather conditions on the growth response of
mountain grasslands located above the tree line in the French Alps.
Time-integrated Normalized Difference Vegetation Index (NDVIint), used as a
surrogate for aboveground primary productivity, and snow cover duration were
derived from a 13-year long time series of the Moderate-resolution Imaging
Spectroradiometer (MODIS). A regional-scale meteorological forcing that
accounted for topographical effects was provided by the
SAFRAN–CROCUS–MEPRA model chain. A hierarchical path analysis was
developed to analyze the multivariate causal relationships between forcing
variables and proxies of primary productivity. Inter-annual variations in
primary productivity were primarily governed by year-to-year variations in
the length of the snow-free period and to a much lesser extent by
temperature and precipitation during the growing season. A prolonged snow
cover reduces the number and magnitude of frost events during the initial
growth period but this has a negligible impact on NDVIint as compared
to the strong negative effect of a delayed snow melting. The maximum NDVI
slightly responded to increased summer precipitation and temperature but the
impact on productivity was weak. The period spanning from peak standing
biomass to the first snowfall accounted for two-thirds of NDVIint and this
explained the high sensitivity of NDVIint to autumn temperature and autumn
rainfall that control the timing of the first snowfall. The ability of
mountain plants to maintain green tissues during the whole snow-free period
along with the relatively low responsiveness of peak standing biomass to
summer meteorological conditions led to the conclusion that the length of
the snow-free period is the primary driver of the inter-annual variations in
primary productivity of mountain grasslands. |
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