Landscape-scale regeneration dynamics of disturbed Mediterranean maquis

Long-term regeneration dynamics of Mediterranean maquis was investigated by analysing historical aerial photographs of Mt. Carmel, one of the largest protected areas in the Mediterranean region of Israel. Two sets of aerial photographs were processed, one from 1960 (before the area was protected), and the second from 1992 (21 yr after the area was declared a nature reserve). The photographs of each year were classified into three vegetation states based on the percentage cover of trees: open maquis with tree cover <33.3%, moderately developed maquis (tree cover 33.3 - 66.6%), and closed maquis (tree cover >66.6%). Grid maps constructed from the classified images were used to determine probabilities of transition between vegetation states. Closed maquis showed zero probability of transition to either open or moderately developed maquis. Probabilities of 'forward' transitions (transitions from low-cover to high-cover classes) were higher on north-facing than on south-facing slopes. On north-facing slopes, the area of open maquis decreased from 87% to 46% during the period studied, while that of closed maquis increased from 3% to 29%. On south-facing slopes open maquis decreased from 87% to 69% while closed maquis increased from 1% to 8%. Within a particular aspect, tree cover in 1960 was a reliable predictor of tree cover in 1992. This indicates that micro-scale patterns of tree distribution in 1960 were important in determining the structure of the maquis 32 yr later. Simulations based on the empirically derived transition probabilities suggest that, under current climatic conditions, the process of maquis regeneration on Mt. Carmel may take 500 - 1000 yr.