Regeneration of Natural Pine Forest – Review of Work Done After the 1989 Fire in Mount Carmel, Israel

Abstract

In September 1989 a fire burned a large natural Pinus halepensis Mill. forest on Mt. Carmel, Israel. This paper summarizes the main results of five years of research, in which the effects of natural factors and management on the development of the forest and the vegetation were studied. It was found that the burned pine tree skeletons were correlated with the spatial pattern of seed germination.. Fewer pine seedlings were found one year after the fire near the burned trunks, but the survival and growth rate of these young pine trees was higher in the following four years. Pine ash was found to inhibit post-fire seed germination, offering a possible explanation for the apparent effect of the old burned trees on the spatial pattern of the new pine seedlings. Both laboratory experiments and field measurements indicate that the high pH of the ash, is the main factor responsible for the inhibition of germination. We examined several management regimes designed to enhance the growth of the young post-fire pine trees and assess their influence on the recovery of the forest. The results revealed that four years after fire, and three years after treatments, forest regeneration was mainly affected by the natural process while management had only a marginal effect. Management such as cutting and leaving, or cutting and removing the burned trunks and twigs from the plots, had almost no effect on species composition and cover. However, thinning of Pinus and Cistus seedlings increased survival and growth of remaining seedlings.