Desertification processes affect ground surface properties and soil-water availability, thus impacting vegetation dynamics and ecosystem functioning. Semiarid areas – encompassing the major part of grazing lands and providing a wide range of ecosystem services – are subjected to both ‘natural’ and anthropogenic degradation processes Afforestation projects that have been implemented by the Keren Kayemet Le’Israel (KKL) to restore degraded lands rely on water harvesting systems (WHS).
In this study, we analyzed the temporal development of different planted sites in the Ambassador’s afforestation land. This area has been under afforestation since 2005. For this study, we selected four multi-aged sites within the afforestation area, including undisturbed, hillslopes, where no water harvesting systems or tree planting have been conducted.
Long-term analysis of meteorological trends revealed that the area had been subjected to substantial climatic change. A decadal rate increase of 0.45°C was observed in air temperature, while a 1.3% decrease in (minimal) relative humidity. Although a long-term change in evapotranspiration has not been detected, summer values have been significantly increased.
For each of the afforestation sites, a significant reduction in seasonal NDVI values was recorded compared to the undisturbed slopes. However, following the WHS construction, the seasonal NDVI average was significantly higher than that in the prior seasonal values, as well as higher than that in the undisturbed hillslopes. At the same time, in the newly disturbed sites (planted in 2016), the average seasonal values were substantially lower after the establishment of runoff harvesting systems than those in the prior year.