Does the Normalized Difference Vegetation Index explain spatial and temporal variability in sap velocity in temperate forest ecosystems?

Understanding the link between vegetation characteristics and tree transpiration is a critical need to facilitate satellite-based transpiration estimation. Many studies use the Normalized Difference Vegetation Index (NDVI), a proxy for tree biophysical characteristics, to estimate evapotranspiration...

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Vydáno v:Hydrology and earth system sciences Ročník 23; číslo 4; s. 2077 - 2091
Hlavní autoři: Hoek van Dijke, Anne J., Mallick, Kaniska, Teuling, Adriaan J., Schlerf, Martin, Machwitz, Miriam, Hassler, Sibylle K., Blume, Theresa, Herold, Martin
Médium: Journal Article
Jazyk:angličtina
Vydáno: Katlenburg-Lindau Copernicus GmbH 25.04.2019
Copernicus Publications
Témata:
Correlation
Correlation analysis
Deciduous forests
Ecosystems
Environmental aspects
Evapotranspiration
Evapotranspiration estimates
Forest ecology
Forest ecosystems
Forests
Geology
Hydrologie en Kwantitatief Waterbeheer
Hydrology and Quantitative Water Management
Laboratorium voor Geo-informatiekunde en remote sensing
Laboratory of Geo-information Science and Remote Sensing
Landsat
Landsat satellites
Leerstoelgroep Hydrologie en kwantitatief waterbeheer
Normalized difference vegetative index
PE&RC
Precipitation
Precipitation (Meteorology)
Proxy
Remote sensing
Satellites
Sensors
Temperate forests
Temporal variability
Temporal variations
Transpiration
Vegetation
Vegetation index
Velocity
Water availability
Watersheds
WIMEK
ISSN:1607-7938, 1027-5606, 1607-7938
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Popis
Shrnutí:Understanding the link between vegetation characteristics and tree transpiration is a critical need to facilitate satellite-based transpiration estimation. Many studies use the Normalized Difference Vegetation Index (NDVI), a proxy for tree biophysical characteristics, to estimate evapotranspiration. In this study, we investigated the link between sap velocity and 30 m resolution Landsat-derived NDVI for 20 days during 2 contrasting precipitation years in a temperate deciduous forest catchment. Sap velocity was measured in the Attert catchment in Luxembourg in 25 plots of 20×20 m covering three geologies with sensors installed in two to four trees per plot. The results show that, spatially, sap velocity and NDVI were significantly positively correlated in April, i.e. NDVI successfully captured the pattern of sap velocity during the phase of green-up. After green-up, a significant negative correlation was found during half of the studied days. During a dry period, sap velocity was uncorrelated with NDVI but influenced by geology and aspect. In summary, in our study area, the correlation between sap velocity and NDVI was not constant, but varied with phenology and water availability. The same behaviour was found for the Enhanced Vegetation Index (EVI). This suggests that methods using NDVI or EVI to predict small-scale variability in (evapo)transpiration should be carefully applied, and that NDVI and EVI cannot be used to scale sap velocity to stand-level transpiration in temperate forest ecosystems.
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ISSN:1607-7938
1027-5606
1607-7938
DOI:10.5194/hess-23-2077-2019