Precipitation-Sensitive Dynamic Threshold: A New and Simple Method to Detect and Monitor Forest and Woody Vegetation Cover in Sub-Humid to Arid Areas

Remote Sensing

卷:12

Ron Drori¹  Efrat Sheffer¹  Michael Sprintsin²  Harel Dan³ 

[1] Institute of Plant Science and Genetic in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel;

[2] Land Development Authority, Jewish National Fund-Keren Kayemet LeIsrael, Eshtaol, M.P. Shimshon 99775, Israel;

[3] The Steinhardt Museum of Natural History, Tel-Aviv University, Tel Aviv-Yafo 6997801, Israel;

关键词: semi-arid;    precipitation gradient;    rainfall;    leaf area index;    SENTINEL II;    NDVI.;   

DOI  :  10.3390/rs12081231

来源: DOAJ

【 摘 要 】

Remote-sensing tools and satellite data are often used to map and monitor changes in vegetation cover in forests and other perennial woody vegetation. Large-scale vegetation mapping from remote sensing is usually based on the classification of its spectral properties by means of spectral Vegetation Indices (VIs) and a set of rules that define the connection between them and vegetation cover. However, observations show that, across a gradient of precipitation, similar values of VI can be found for different levels of vegetation cover as a result of concurrent changes in the leaf density (Leaf Area Index—LAI) of plant canopies. Here we examine the three-way link between precipitation, vegetation cover, and LAI, with a focus on the dry range of precipitation in semi-arid to dry sub-humid zones, and propose a new and simple approach to delineate woody vegetation in these regions. By showing that the range of values of Normalized Difference Vegetation Index (NDVI) that represent woody vegetation changes along a gradient of precipitation, we propose a data-based dynamic lower threshold of NDVI that can be used to delineate woody vegetation from non-vegetated areas. This lower threshold changes with mean annual precipitation, ranging from less than 0.1 in semi-arid areas, to over 0.25 in mesic Mediterranean area. Validation results show that this precipitation-sensitive dynamic threshold provides a more accurate delineation of forests and other woody vegetation across the precipitation gradient, compared to the traditional constant threshold approach.

【 授权许可】

Unknown