أثر الجفاف على توزيع الغطاء النباتي في حوض قرى العرضة (أحد روافد وادي الطوقي)‎ منطقة الرياض

الملخص EN

Arabian deserts in general and the deserts of central Arabia in particular, are considered virgin lands with respect to physical, and natural plant studies.

In addition, published researches in Arabic language in these topics are scarce, which cause so many graduate students and researchers to avoid addressing research problems in those topics.

In view of the important role natural plants play in the ecological system, the distribution characteristics of natural plant cover of shrubs and small trees was investigated in an ephemeral drainage basin, in central Arabia.

In al-Ardha creek (100km N.E.

Riyadh City), five plant species were included in the aligned spatial sample.

The analysis revealed that Panicum turgidum was the most dominant, most frequent, and have the highest relative density.

Never the less, it became second in basal area, which clearly reflect the high grazing effect on such a pleasant type for grazing animals (e.

a.

cameIs).The null hypothesis that the distances for each plant type are identical was not tenable.

Chi square test showed that the relative presence of each of those species is significantly different from the theoretically expected.

Furthermore, presence histogram showed that plant species in the basin could be divided into two groups in terms of presence, high presence group and low presence group.

It was also shown that overall plant coverage in the basin is only, 10 shrubs per 100 squared meters.