نتایج جستجو برای: desertification intensity

تعداد نتایج: 182836  

2006
J. XIAO Y. SHEN

The grain size composition of topsoil characterizes the soil texture and other physical properties. The coarsening of topsoil grain size is a visible symbol of land degradation; thereby the change in topsoil grain size can be potentially used to monitor desertification using remote sensing. This study proposes a new index for detecting topsoil grain size composition through ground in situ soil ...

Journal: Desert 2012
H. Khosravi M. Ghodsi M.S. Ziaei R. Masoudi

Desertification is more related to social and anthropogenic issues than natural causes and it becomes moreimportant over the time. Human effects on desertification could be classified as direct and indirect factors. This studyhas focused on the effect of management factor, as a dominant case, on desertification of Kashan region based onIMDPA (IMDPA: Iranian Model of Desertification for Potentia...

2002
Zhang Fengrong Wang Lixin Li Chao

YiJinHuoLuo Banner is a county of Inner Mongolia with obvious semiarid monsoon climate. Because of unsuitable land use, such as cultivating marginal land and over pasture, desertification was getting severer and severer before 1974. Since 1974, People have been doing their best to grow woods, shrubs and grasses for increasing the coverage of vegetation. People have taken suitable and available ...

Journal: :The New phytologist 2009
Sujith Ravi Paolo D'Odorico Scott L Collins Travis E Huxman

A common form of land degradation at the desert margins involves the rapid encroachment of woody plants into historic grasslands and the acceleration of soil erosion as a result of the loss of grass cover (Archer, 1989; Schlesinger et al., 1990). The conversion of perennial grasslands into desert scrublands has been documented worldwide (Van Auken, 2000; Ravi, 2008) and has important implicatio...

2014
S. Bouharati F. Allag M. Belmahdi M. Bounechada

In terms of ecology forecast effects of desertification, the purpose of this study is to develop a predictive model of growth and adaptation of species in arid environment and bioclimatic conditions. The impact of climate change and the desertification phenomena is the result of combined effects in magnitude and frequency of these phenomena. Like the data involved in the phytopathogenic process...

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...

2008
Tao Wang

Please note that Tyndall working papers are "work in progress". Whilst they are commented on by Tyndallresearchers, they have not been subject to a full peer review. The accuracy of this work and the conclusions reached are the responsibility of the author(s) alone and not the Tyndall Centre. Introduction China's economy is growing rapidly with nearly 10% per year increases in GDP over the last...

Journal: :journal of rangeland science 2012
sedigheh zare kia hossein arzani mohammad jafari seyyed akbar javadi ali ashraf jafari

this study aims to assess the effect of grazing intensity on vegetation structure, soil nutrient concentrations and soil physical properties. the study was carried out in steppe rangelands of saveh, markazi province, iran. four sites with four grazing intensities including very high, high, moderate and non-grazed with the same ecological conditions were selected. to study various vegetation and...

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