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Ben Gurion University of the Negev (2013)

Spatial valuation of planting trees in lines, in the northern Negev, using remote sensing and GIS techniques

Kagan, Gal

Titre : Spatial valuation of planting trees in lines, in the northern Negev, using remote sensing and GIS techniques

Auteur : Kagan, Gal

Université de soutenance : Ben Gurion University of the Negev

Grade : Master of Arts (MA) 2013

Résumé
The northern Negev, located at the desert fringe, has gone through extensive vegetation cover changes in the last few decades due to climatic and anthropogenic factors. High frequency of droughts has caused desertification of the area, and weather forecasts predict an increase in the frequency and severity of these extreme weather events in the future, thus, vegetation mortality in the water limited northern Negev expected to increase considerably. On the other hand, afforestation of the northern Negev is a flag project of the Jewish National Fund (JNF) that for years has been taking measures to combat desertification in the area through extensive plantation and rehabilitation. The lines pattern planting is one of the methods used by the JNF for tree planting, designed to increase the amount of water availability for trees in water limited areas. This study evaluates how three topographic variables (slope angle, distance from stream, and slope aspect) affect the success or failure of the tree plantation under drought conditions. The study is based on high resolution satellite and aerial images used to ascertain tree productivity, using vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and mortality respectively as indicators of tree condition under the WHS. The study took place in Dudaim forest in the northern Negev, one of the sites where the WHS method was applied. Out of almost 20,000 trees mapped in the study site, 1191 trees were identified as dead and the vast majority were located at southeast and south aspects (38.5% and 49.2% of the respectively). The NDVI results showed a similar trend, suggesting that radiation was a key factor in determining tree status. Both tree mortality and NDVI were significantly influenced by all three variables although a high level of unexplained variance remained. The directionality of the effect of each variable was complicated by the multifaceted nature of each and the complex interactions between them and is discussed in detail.

Mots clés : Tree planting — Israel — Negev — Remote sensing ; Tree planting — Israel — Negev — Geographic information systems ; Afforestation — Arid regions — Technique

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Page publiée le 8 avril 2015, mise à jour le 13 septembre 2017