Hema system : traditional conservation of plant life in Saudi Arabia

الملخص EN

Traditional conservation of plant life by the hema system has been successfully achieved in the SW mountainous region of Saudi Arabia.

The unwritten, but very respectable rules of the tribe are, in fact, the most effective factor that keeps on the running of the system since pre-Islamic era.

Three representative hemas, namely: Hema Bani Sar, Hema Thamala and Hema Sakhayet, have been studied ecologically.

The plant cover and soil characteristics in- and outside the hemas (Ahmia) vary considerably.

Overgrazing outside the hemas has bad effect not only on the plant life but also on the soil development.

Inside the hemas, the condition of the plants differ according to the state of grazing.

In the main channel and on the lower zones of the side-slopes of Hema Sakhayet and Hema Thamala, where grazing is allowed only for cattle, the aerial parts of the grazeable plants (mainly grassesa) re absent.

On the higher zones of the slopes,t he grassesa nd other plants grow well.

In Hema Bani Sar, where grazing is strictly prohibited for all livestock, the vegetation, in general, is relatively ricker and the soil shows no symptoms of erosion.