Drought events in the Mediterranean region have been documented with increasing regularity over the past two decades. Livestock grazing is widespread in the extensive coniferous forests of Israel, both as a husbandry practice and as an important tool for reducing understory biomass and subsequently the risk of wildfires. It is believed that grazing plays a role in alleviating drought stress in trees by eliminating understory competition for limited water resources. However, despite its prevalence as a management tool, little is known about the effect of grazing on the physiological status of pine trees.

The aim of this project is to research the effect of livestock grazing (cattle, goats and sheep) on tree growth, and water and nutrient relations, to determine the relationship between grazing and planting density, and to observe the effect of grazing on natural forest regeneration in semi-arid coniferous forests. The study is set up at three different sites (Yatir, Sataf, and Mt. Horshan), over a range of growing conditions and accompanying vegetation types typical of the Eastern Mediterranean. All three sites contain plots fenced off to prevent grazing, adjacent to control plots that are subject to seasonal grazing of various types, over a range of different stand densities.

This research will help determine the effects of livestock grazing on the physiological function of pine trees under a variety of growth conditions common to this part of the world. Additionally, it will contribute to understanding the relationship between grazing, forest thinning practices, and forest regeneration. These results will play a role in developing new integrated forest management strategies and help ascertain whether livestock grazing can be effectively utilized to mitigate water shortage and ensure survival of forests in semi-arid areas threatened by future climate change.

Collaboration: Yagil Osem, Agricultural Research Organization, Bet Dagan, Israel

Co-workers: Levi Burrows (MSc student)