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Helman, D., Department of Geography and Environment, Bar Ilan University, Ramat-Gan, Israel
Lensky, I.M., Department of Geography and Environment, Bar Ilan University, Ramat-Gan, Israel
Tessler, N., Department of Biology and Environment, University of Haifa at Oranim, Kiryat Tivon, Israel
Osem, Y., Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
We present an efficient method for monitoring woody (i.e., evergreen) and herbaceous (i.e., ephemeral) vegetation in Mediterranean forests at a sub pixel scale from Normalized Difference Vegetation Index (NDVI) time series derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The method is based on the distinct development periods of those vegetation components. In the dry season, herbaceous vegetation is absent or completely dry in Mediterranean forests. Thus the mean NDVI in the dry season was attributed to the woody vegetation (NDVIW). A constant NDVI value was assumed for soil background during this period. In the wet season, changes in NDVI were attributed to the development of ephemeral herbaceous vegetation in the forest floor and its maximum value to the peak green cover (NDVIH). NDVIW and NDVIH agreed well with field estimates of leaf area index and fraction of vegetation cover in two differently structured Mediterranean forests. To further assess the method's assumptions, understory NDVI was retrieved form MODIS Bidirectional Reflectance Distribution Function (BRDF) data and compared with NDVIH. After calibration, leaf area index and woody and herbaceous vegetation covers were assessed for those forests. Applicability for pre- and post-fire monitoring is presented as a potential use of this method for forest management in Mediterranean-climate regions. © 2015 by the authors.
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A phenology-based method for monitoring woody and herbaceous vegetation in mediterranean forests from NDVI time series
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Helman, D., Department of Geography and Environment, Bar Ilan University, Ramat-Gan, Israel
Lensky, I.M., Department of Geography and Environment, Bar Ilan University, Ramat-Gan, Israel
Tessler, N., Department of Biology and Environment, University of Haifa at Oranim, Kiryat Tivon, Israel
Osem, Y., Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
A phenology-based method for monitoring woody and herbaceous vegetation in mediterranean forests from NDVI time series
We present an efficient method for monitoring woody (i.e., evergreen) and herbaceous (i.e., ephemeral) vegetation in Mediterranean forests at a sub pixel scale from Normalized Difference Vegetation Index (NDVI) time series derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The method is based on the distinct development periods of those vegetation components. In the dry season, herbaceous vegetation is absent or completely dry in Mediterranean forests. Thus the mean NDVI in the dry season was attributed to the woody vegetation (NDVIW). A constant NDVI value was assumed for soil background during this period. In the wet season, changes in NDVI were attributed to the development of ephemeral herbaceous vegetation in the forest floor and its maximum value to the peak green cover (NDVIH). NDVIW and NDVIH agreed well with field estimates of leaf area index and fraction of vegetation cover in two differently structured Mediterranean forests. To further assess the method's assumptions, understory NDVI was retrieved form MODIS Bidirectional Reflectance Distribution Function (BRDF) data and compared with NDVIH. After calibration, leaf area index and woody and herbaceous vegetation covers were assessed for those forests. Applicability for pre- and post-fire monitoring is presented as a potential use of this method for forest management in Mediterranean-climate regions. © 2015 by the authors.
Scientific Publication
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