Effects of clearing and herbicide treatments on coniferous seedling establishment and growth in newly planted Mediterranean forests

Abstract

Abstract The clearing of the natural vegetation and herbicide applications are commonly used to facilitate the establishment and growth of coniferous seedlings in newly planted forests in the Mediterranean region. Casual observations in Israel indicated that these operations drastically reduce biomass and species diversity of the herbaceous vegetation in the first years. The subjective impressions created by the effect of the herbicides have caused several public confrontations between foresters and conservationists in Israel. Less vegetation control may reduce tensions. However, no quantitative data was available on tree seedling performance under lower amounts of herbicide applications than those typically used for the region. The aim of the present study was to evaluate coniferous seedling establishment and growth under different intensities and frequencies of simazine applications in newly afforested areas in the Judean Mountains, Israel. Two experimental sites differing in soil types, temperature and rainfall were selected. In each site of 0.7 ha, 6-months-old seedlings of Pinus brutia , Pinus pinea and Cupressus sempervirens were planted at standard densities. The results for both experimental sites showed that seedling mortality significantly increased with decreasing intensities and frequencies of simazine applications. However, height and crown diameter of the surviving seedlings were not always significantly correlated to the amounts of herbicide sprayed in the adjacent areas. Standard current management practices showed highest seedling establishment success. The present study provides for the first time in Israel meaningful insights into the early stages of coniferous seedling establishment in newly planted Mediterranean forests after disturbance by clearing and simazine applications.