نتایج جستجو برای: barren/range land and forestland) for 1989

تعداد نتایج: 19063704  

Journal: :پژوهش های جغرافیای طبیعی 0
وحید امینی پارسا دانشجوی دکتری برنامه ریزی محیط زیست دانشگاه تهران اطهره نژادی دکتری برنامه ریزی محیط زیست دانشگاه تهران

introduction land use and land cover change (lucc) is a complex issue resulted from biophysical, socio-economic, cultural, organizational and technological factors in different spatial and temporal scales. lucc considered as an important threat to biodiversity as causing the fragmentation, natural vegetation destruction and natural areas isolation the regions which managed by environmental prot...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یزد - دانشکده جغرافیا 1392

the west of esfahan province, iran, is one of the most important agricultural areas throughout the country due to the climate variability and life-giving water of zayanderood river. rice is one of the major and economic crops in this area. the most important climatic elements in agricultural activities which should be considered include temperature, relative humidity, precipitation and wind. so...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تهران - دانشکده علوم 1357

in his last years of life americans had almost forgotton steinbeck, and those who had not, occasionally criticized him for supporting and praising the u. s. military intervention in the vietnam war. althought ateinbeck incorporates different themes into his works, each one bears many signs of his concern and sympathy for america and the american common people in particular. steinbecks to a god ...

2004
Yaoqi Zhang Jeffrey Vincent

Based on the comparative advantages of forestland in providing a variety of products and services, it is not arguable that different kinds of forestland should produce different compositions of outputs. To investigate the issue regarding forestland-use specialization or the pursuit of multiple uses on same piece of land, this paper starts by revisiting Vincent and Binkley’s paper ‘Efficient Mul...

2017
Han Zhang Jari Kuuluvainen Hongqiang Yang Yi Xie Can Liu

China’s new round tenure reform has devolved collective forests to individuals on an egalitarian basis. To balance the equity–efficiency dilemma, forestland transfers are highly advocated by policymakers. However, the forestland rental market is still inactive after the reform. To examine the role of off-farm employment in forestland transfers, a simultaneous Tobit system of equations was emplo...

2016
Changzhen Li Luhong Zhao Pingsheng Sun Fazhu Zhao Di Kang Gaihe Yang Xinhui Han Yongzhong Feng Guangxin Ren

In the Loess Hilly Region of China, the widespread conversion of cropland to forestland and grassland has resulted in great increased in organic carbon (C), nitrogen (N) and phosphorus (P) stocks in the shallow soil layers. However, knowledge regarding changes in C, N, and P in deep soil is still limited. To elucidate the responses of deep soil C, N, and P stocks and stoichiometry in response t...

2011
Kurt H. Riitters John W. Coulston James D. Wickham

Forest fragmentation threatens the sustainability of forest communities in the eastern United States. Forest communities exhibiting either a low total area or low percentage of intact forest are subject to relatively higher risk of shifts in stand composition towards edge-adapted and invasive species. Such changes in stand composition could result in local extirpation of communities, homogeniza...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1390

introruction khawf in(iran)-herat and mazaresharif and shirkhan bandar in (afghanistan)-dushanbe in (tajikistan)_(kirgizstan)-kashghar in(china) project railway network is under construction that it is as a significant corridor for revitalizing silk road corridor in the region .at the present there are three different gauge in the region central asia with 1,520 mm gauge and turkey-islamic repu...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده مهندسی عمران 1388

چکیده روش های متعددی برای برآورد رواناب حاصل از بارش در حوضه های آبریز وجود دارد. یکی از این روش ها استفاده از مدل های هیدرولوژیکی است. با استفاده از مدل های هیدرولوژیکی و شبیه سازی فرآیندهای هیدرولوژیکی می توان با صرف کمترین زمان و هزینه، رواناب و مولفه های دیگر چرخ? هیدرولوژیکی را برآورد کرد. از آنجا که در حوضه های آبریز اندازه گیری تمام کمیت های مورد نیاز برای تحلیل رواناب ممکن نیست، انتخاب...

Journal: :Environmental management 2009
Miao Liu Yuanman Hu Yu Chang Xinyuan He Wei Zhang

Scientists have aimed at exploring land use and land cover change (LUCC) and modeling future landscape pattern in order to improve our understanding of the causes and consequences of these phenomena. This study addresses LUCC in the upper reaches of Minjiang River, China, from 1974 to 2000. Based on remotely sensed images, LUCC and landscape pattern change were assessed using cross-tabulation a...

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