DDD Conference

3. Dr. Eli Zaady

Drought as a Climate Change Agent Affects Afforestation in Runoff Water Harvesting Systems under Semiarid Conditions

Volcani Institute, Agricultural Research Organization, Israel

Water is the principal limiting resource in many dry environments, and its redistribution by landscape heterogeneity tightly controls landscape function, productivity, and diversity. The northern Negev characterizes by a semiarid climate where water availability is limited, which leads to the development of landscape patchiness. The landscape patchiness characterizes shrubs surrounded by a biocrust matrix. The shrub patches are sinks for the runoff water transported from the biocrusts. The source-sink relationship between the two patch types is critical for the system’s functioning; in the existing ecosystem, part of the water, not absorbed by the shrubs, leaks out of the system. Afforestation under these conditions utilized the knowledge acquired in studying the ecological system using local resources. Counter-banks were built horizontally to the hill slopes to stop the water leakage from the system. Different tree species, adapted to grow in water-enriched patches, were planted to increase the biological productivity of the areas.

Since the beginning of the 2000s, consecutive years of droughts have characterized northern Negev and led to a 25-30 percent decrease in the annual amount of rainfall. This phenomenon has led to the mortality of many shrubs whose runoff created by biocrusts has not been sufficient to support their survival. The planted trees responded partly to droughts, and Mediterranean species did not survive in part compared to native species that characterize arid areas. The need to consider climate change has led to change and the need to adapt plantings to species more adapted to arid areas.


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