Arid to dry-subhumid Mediterranean forests and woodlands have great potential for sequestering carbon dioxide from the atmosphere and storing it in long-term stocks, mainly soil organic carbon (SOC). These processes can be influenced by various biotic and abiotic factors, such as plant type, climatic factors and topography. Furthermore, Mediterranean ecosystems are subject to various pressures, including land-use and climate change. The objective of our studies was to increase scarce knowledge on the impacts of these factors and pressures on forest and woodland SOC storage in Israel.
Stocks of SOC decreased significantly along the aridity gradient of Israel (~800-250 mm of mean annual precipitation). The reduction in SOC was parallel in natural woodlands and planted Aleppo pine forests to a depth of 0.5 m. SOC stocks increased slightly with decreasing elevation (840-40 m asl), a potential proxy for rising temperature.
Determining SOC stocks at time intervals of ten years or more may allow for an assessment of SOC sequestration rates following land use change. Afforestation by Aleppo pine in an arid region (Yatir) lead to relatively high and steady SOC sequestration rates after 35 and 50 years. In contrast, 10 years of preventing cattle grazing on the dry, southern edge of oak woodlands in Israel (Amatzia) have not led to a change in SOC stocks. Climate and land-use change can significantly affect SOC stocks, though these effects differ among climate factors and land-use types. Long-term monitoring of soils is necessary to assess SOC storage and to formulate efficient land management policies.
