Seedling Mortality in Regeneration of Aleppo Pine Following Fire and Attack by the Scale Insect Matsucoccus josephi

Abstract

Mortality of Pinus halepensis seedlings was investigated in Israel during the first years of natural regeneration after fire, with special emphasis on the role of Matsucoccus josephi, drought and competition. The investigations were conducted in the native natural forest on Mt. Carmel, and in a plantation severely damaged by the scale insect at Horeshim in Samaria. M josephi was the dominant mortality agent during the first five years after regeneration, killing almost 73 % and 54% of the seedlings at Mt. Carmel and Horeshim, respectively. Neither injury nor mortality due to the scale insect was recorded during the first year after regeneration, but subsequently mortality occurred during the third and the fourth years. About 23% of the seedlings died due to drought, interspecific and intraspecific competition. Mortality due to other biotic agents, i.e., Hylastes linearis and Pityophthorus pubescens was practically nil. It is shown that resistance of regenerating population of native P. halepensis on Mt. Carmel to the scale did not differ significantly from that of regeneration of a planted Aleppo pine forest of unknown seed sources at Horeshim, despite differences in the level of injury to the adult trees on each site. Five years after natural seeding seedling density in scale-infested plots is high enough to ensure stand development. This second growth possibly displays lower susceptibility to M. josephi than the present adult population.