摘要
Arid and semi-arid regions are characterized by low rainfall and high potential evaporative demand. Here, water is the major limiting factor for plant growth and productivity. Soil and surface hydrology properties （e.g. field capacity, infikration rates） effectively control the water re-distribution in the ecosystem, a fact that is aggravated in arid environments. Information of the spatial and temporal accessibility of soil water in desert ecosystems is limited. The purpose of the studies is the application of plant water potential to estimate the spatial and temporal variations of soil water availability in different arid ecosystems of the Negev （Israel） and southern Morocco. As model plants the evergreen shrubs Retama raetam, Thymelaea hirsuta and trees （Acacia tortilis） were chosen. Seasonal and spatial variations of the pre-dawn water potential （ψpd） were examined as diagnostic tool to determine water availability on the landscape level. The seasonal differences in the pre-dawn water potential were less pronounced on the dune compared to the interdune. This showed a better water availability on the dune slope. Also in the investigated wadis systems spatial differences of the water potential could be detected and related to the vegetation pattern.
Arid and semi-arid regions are characterized by low rainfall and high potential evaporative demand. Here, water is the major limiting factor for plant growth and productivity. Soil and surface hydrology properties （e.g. field capacity, infikration rates） effectively control the water re-distribution in the ecosystem, a fact that is aggravated in arid environments. Information of the spatial and temporal accessibility of soil water in desert ecosystems is limited. The purpose of the studies is the application of plant water potential to estimate the spatial and temporal variations of soil water availability in different arid ecosystems of the Negev （Israel） and southern Morocco. As model plants the evergreen shrubs Retama raetam, Thymelaea hirsuta and trees （Acacia tortilis） were chosen. Seasonal and spatial variations of the pre-dawn water potential （ψpd） were examined as diagnostic tool to determine water availability on the landscape level. The seasonal differences in the pre-dawn water potential were less pronounced on the dune compared to the interdune. This showed a better water availability on the dune slope. Also in the investigated wadis systems spatial differences of the water potential could be detected and related to the vegetation pattern.
