Assessment of ecosystem sensitivity and adaptation strategies to desertification and climate change in Lebanon

摘要

Lebanon has been affected by changing climatic conditions.Impacts on vegetation was assessed through a systematic overlaying the forest map with current and projected bioclimatic levels.The expected changing parameter was computed for the periods 2020-2044 and 2080-2098.Results confirmed drastic picture in North Lebanon,with a shift in bioclimatic levels from sub-humid to semi-arid.Vulnerability to desertification has been exacerbated in the last four decades through the oscillating rainfall patterns and increasing temperature by 1.8 °C.The primary impact has been well pronounced on water resources; there is an acute decrease in the discharge in rivers and springs,reaching up to 60％,while the groundwater level has abruptly drawn down tens of meters.Also,time series analysis of the normalized differential vegetation index(NDVI)showed an increase in areas affected by higher surface temperature and lower soil humidity reserve creating the situation for recurrent drought incidences.Lebanese soils are vulnerable to erosion processes,witnessing high erosion rates exceeding 70 ton ha-1.This is preconditioning low resilience to drought.Observations have also revealed the mountain shallow Leptosols,Luvisols and Arenosols to be the most vulnerable to fire incidences.In the light of the existing situation,however,adaptation measures have been demonstrated in this study,considering the sensitivity of the Lebanese ecosystem to desertification along with changing climatic conditions.It will serve as first hand information for decision makers in proposing strategies for risk mitigation.