Tamartash R, Jalilvand H, Tatian M R
Department of Range and Watershed Management, Sari Agricultural Sciences and Natural Resources University, Sari, Mazandaran, Iran.
Pak J Biol Sci. 2007 Dec 15;10(24):4391-8. doi: 10.3923/pjbs.2007.4391.4398.
This research is conducted to study the effects of grazing on chemical soil properties and vegetation cover in three areas separated as the key, reference and critical areas. The study area is located at the river basin of Kojour in the Southwestern of Noushahr (in the North of IR-Iran). Sampling and collecting the soil and vegetation cover data from the site areas are accomplished in the first step of the research. The vegetation cover data was collected in 20 sample plots of 1 m2 in each area. The data was collected through a random- systematic method in the early grazing season. The soil data was collected out of two layers (0-10, 10-30 cm), in two time intervals before and after grazing. Five samples were selected per layer. Some edaphical factors such as organic carbon, percentage of soil organic matters, total nitrogen, absorbable phosphorus and potassium, pH and EC were measured. The results revealed that there is an inverse relationship between the grazing intensity and amount of carbon, nitrogen, soil organic matter and EC. However, a direct relation exists between the grazing intensity and amount of soil potassium, phosphorus, pH and the ratio of carbon to nitrogen. Vegetation in class 1 and 2 which were cereals and forbs had greatest percentage in the reference area. Furthermore, the percentage forage cover increases with the grazing intensity. The more unpalatable vegetation of class 3 forms the prevailing coverage in the critical area. The conclusion of this study shows that overgrazing is considered as a threat for the nutritional elements of soil and vegetation cover.
本研究旨在探讨放牧对分为关键区、参照区和临界区的三个区域土壤化学性质和植被覆盖的影响。研究区域位于诺沙赫尔西南部（伊朗北部）的科乔尔河流域。在研究的第一步完成了从这些区域采集土壤和植被覆盖数据的工作。植被覆盖数据是在每个区域的20个1平方米的样地中收集的。这些数据是在放牧季节初期通过随机系统抽样法收集的。土壤数据是在放牧前后的两个时间间隔内从两层（0 - 10厘米、10 - 30厘米）采集的，每层选取5个样本。测量了一些土壤因子，如有机碳、土壤有机质百分比、总氮、有效磷和钾、pH值和电导率。结果表明，放牧强度与碳、氮、土壤有机质和电导率的含量呈负相关。然而，放牧强度与土壤钾、磷、pH值以及碳氮比呈正相关。1类和2类植被（谷物和杂草）在参照区所占比例最大。此外，牧草覆盖百分比随放牧强度增加。3类更难吃的植被在临界区形成了主要覆盖。本研究的结论表明，过度放牧被认为是对土壤营养元素和植被覆盖的一种威胁。
