أثر الوحدة الجيمورفولولجية على خصائص النبات الطبيعي
الشجري في البيئة الجافة
دراسة حالة لأودية جنوب مدينة مكة المكرمة
إعداد : د. محمد سعيد البارودي
قسم الجغرافيا - جامعة أم القرى
مجلة جامعة أم القرى للعلوم التربوية والاجتماعية والإنسانية - المجلد 20 - العدد الأول - ذو الحجة 1428 هـ - يناير 2008 م - ص ص 283 - 423 :
Impact of the Geomorphologic Unit on the Morphology ofthe Arborous Vegetation in Dry Environments: The Caseof Valleys to the South of MakkahAl Mukarramah
Dr. Mohammad S. Al-BaroodiA
bstract
In dry environments, the arborous vegetation cover areas are regarded asone of the most important places for public recreation and amusement. Suchareas could be identified in beds of valleys to the South of Makkah city;exemplified in Daim, Rahgan, Magareesh. The objective of this study is tocorrelate the arborous vegetation cover and the features of the geomorphologicunits such as importance of relative density, relative dominance, and relativefrequency. This study adopted the floristic composition method of study where plant species and plant abundance will be researched.
This research reviewed related recent literature, relevant spatial imagesand first-hand field data. To be in conformity with our research objectives, thisstudy adopts the "squares" method as a means to measure plant populations based on concepts of minimal area, and species/area curve.
The most important areas selected for examination and vigorous studywere fluvial terraces, flood plains, and valley channels. The research outcomesreveal the dominance of torrifluvents in all valley channels and flood plains,while fluvial terraces are dominated by Torriorthents. The main findings ofresearch could be listed as:
1. Existence of four types of dominant plant populations that include, acacia-tortilis Communiyt, Community Acacia-ehrenbbergiana , Community Acacia-hamulosa and Community Acacia-seyal
2. Evident impact of geomorphologic units on the general morphologyof the plant populations of the area.
3. Evident differences between these units with regard to themorphology of the vegetation cover where fluvial terraces witness the highestdominant cover, followed by flood plains, and valley channels.
4. Acacia-ehrenbbergiana and Acacia-tortilis are the most widelyspreading types of trees. In the fluvial terraces the acacia-tortilis Community dominates followed by
Acacia-hamulosa , while acacia-ehrenbbergiana community prevails in flood plains and valley channels. The acacia-seyal community extends mainly in valley channels.
5. Rules and regulations should be imposed to protect the vegetationcover, particularly in fluvial terraces. If succeeded, these places could be openedto the public as recreational places for the holy city.
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