نتایج جستجو برای: forest and rangelands
تعداد نتایج: 16850589 فیلتر نتایج به سال:
the zagros forests (west of iran) have been highly exploited in recent decades by human impacts. easy access, abundance and variety of valuable forest yields have led to population growth density, creation of new residential areas and deforestation activities. in order to determinate the distribution and rate of deforestation from 1995 to 2006 by using the satellite imagery (irs-1c and landsat...
the fire as one of the ecological factor has positive or negative effects on ecosystems components. therefore, this study was evaluated the effect of fire on some soil physico-chemical properties in winter rangelands of behshahr. so that two burned sites were selected in rangelands and changed rangelands to wheat and barley with two control areas (unburned) in each of them. the soil sampling wa...
in natural ecosystems, biological relationships have serious effects on system stability. allelopathic is negative or positive effect of a plant on other plant growth. today this word is used for rangelands, same as agricultural areas. because of good herbage production, medicago is most common plant in agricultural rotations and rangelands. therefore investigation of its allelopathic qualities...
natural resources are valuable capitals for all nations. rangelands as the most extensive natural ecosystems in iran provide numerous services, including fodder production and red meat supply, soil conservation and water regulation. although uncontrolled exploitation of these resources has imposed much pressure and caused many losses within the ecosystems. impacts of overutilization of nomadic ...
the aim of this research was to measure the relative efficiency of forest management plans in north of iran. in order to fulfill the research, data of 12 forest management plans were collected from the financial balance sheets of shafaroud forest company during a ten years period. first of all, basic data envelopment analysis (dea) models (bcc and ccr) were used to determine the efficiency. the...
The main objective of this study was to assess factors affecting early entrance and later exit of herders from summer rangelands. The study population consisted of heads of Nomads in Kouhdasht region, Lorestan province, Iran. According to Cochran formula among 1038 Nomadic families, 310 families were selected with stratified random sampling in 2015. In order to assess validity, expert's opinion...
Zagros forest as a widest forests of Iran, has a special place on economical development and maintain the stability of water and soil. In order to apporopriate planning for this forest information about forest extend during past, present and future is necessary. The present research was conducted to determine the forest area reduction, during 1955 to 1997, Modeling possibility forest exten...
The Santa Rita Experimental Range is 100 years old this year, providing an occasion to celebrate and to reflect. The first of many experimental ranges in the United States, the Santa Rita was founded at a time when both range science and plant ecology were in their infancy. The purpose was to conduct research that would aid in the management of Southwestern rangelands by public agencies and pri...
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