نتایج جستجو برای: technogenic desertification

تعداد نتایج: 2649  

2004
Juan J. Oñate Begoña Peco

Two related land use change dynamics characterise the Guadalent!ın basin (southeast Spain) as one of the most severe cases of desertification in Europe: (1) expansion of highly productive irrigated agriculture in the valley, and (2) intense contemporary changes in the surrounding impoverished dry lands. On the basis of documented information, we trace the effects of past policies on these dynam...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1997
J H Brown T J Valone C G Curtin

Natural ecosystems contain many individuals and species interacting with each other and with their abiotic environment. Such systems can be expected to exhibit complex dynamics in which small perturbations can be amplified to cause large changes. Here, we document the reorganization of an arid ecosystem that has occurred since the late 1970s. The density of woody shrubs increased 3-fold. Severa...

Journal: :desert 2005
gh. r. zehtabian h. ahmadi h. khosravi a. rafiei emam

desertification process as a great problem affects most of the countries in the world specially developing countries. this process has a high rate in arid and semi-arid countries such as iran. the main objective of this research was to investigate land degradation status and desertification mapping of kashan area. different studies have been carried out in the world in order to assess desertifi...

Journal: :مرتع و آبخیزداری 0
ریحانه مسعودی دانشجوی دکتری بیابان زدایی، دانشکدة منابع طبیعی دانشگاه تهران غلامرضا زهتابیان استاد دانشکدة منابع طبیعی دانشگاه تهران حسن احمدی استاد دانشگاه آزاد اسلامی ـ واحد علوم تحقیقات تهران شهرام خلیقی سیگارودی دانشیار دانشکدة منابع طبیعی دانشگاه تهران

desertification is a major problem in many countries. international efforts have been considered to combat and prevent this phenomenon. the most important cases of these measures are the united nations convention to combat desertification. in this study, imdpa model and gis were used to assess desertification phenomena in kashan plain. some indices of climate and water criteria were selected to...

2016
Hao Jiang Sheng Zhang Yanbao Lei Gang Xu Dan Zhang

Population sex ratios of many dioecious plants in nature are biased. This may be attributed to sexually different resource demands and adaptive capacity. In male-biasedPopulus, males often display stronger physiological adaptation than females. Interestingly, Populus and Salix, belonging to Salicaceae, display an opposite biased sex ratio, especially in nutrient-poor environmental conditions. D...

Extended abstract 1- INTRODUCTION Destructive phenomenon of desertification is one of the serious ecological crises at the present time. In order to improve efficiency of combating desertification projects and inhibiting destruction of natural resources and our asset, it sounds considerably meaningful to reach a systematic and comprehensive method that can use different criteria and indicator...

Journal: :Hygiene and sanitation 2019

ژورنال: علوم آب و خاک 2017

This paper aimed to assess the severity of desertification in Segzi plain located in the eastern part of Isfahan city, focusing on groundwater quality criteria used in MEDALUS model. Bayesian Belief networks (BBNs) were also used to convert MEDALUS model into a predictive, cause and effects model. Different techniques such as Kriging and IDW were applied to water quality data of 12 groundwater ...

2014
Chikara Hashimoto Kentaro Torisawa Julien Kloetzer Motoki Sano István Varga Jong-Hoon Oh Yutaka Kidawara

We propose a supervised method of extracting event causalities like conduct slash-and-burn agriculture→exacerbate desertification from the web using semantic relation (between nouns), context, and association features. Experiments show that our method outperforms baselines that are based on state-of-the-art methods. We also propose methods of generating future scenarios like conduct slash-and-b...

2018

Most of the issues regarding desertification are always related to soil fertility and water quality [1,2]. Hence United Nation Framework Convention on Climate Change (UNFCCC) seriously globalized the issues of desertification in 1992. The developed and developing including hilly mountainous countries are the conference of the parties and so as Nepal [3]. The catchments in hill and Himalayan reg...

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