objective: more than 75 percent of iran is located in arid and semi-arid then land degradation and desertification are one of the crises ecological. we require a proper understanding of causes and processes of desertification to control the huge phenomenon on the global and regional situation. because southeast of iran located in arid land then assessment of desertification is very importance f...

BACKGROUND There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assembla...

palynological analyses from exposed palaeolacustrine deposits located at the flanks of damavand volcano, in the central alborzmountains in northern iran, provide a broad idea of the temporal variation of vegetation according to climate changes during a rangeof limited time intervals during the quaternary period. this research reveals that the regional vegetation of the study area had been asemi...

A model analysis of climate and CO2 controls on tree growth in a semi-arid woodland G. Li, S. P. Harrison, and I. C. Prentice Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia School of Archaeology, Geography and Environmental Sciences (SAGES), Reading University, Reading, UK AXA Chair of Biosphere and Climate Impacts, Grand Challenges in Ecosystem and the...

This paper identifies rare climate challenges in the long-term history of seven areas, three in the subpolar North Atlantic Islands and four in the arid-to-semiarid deserts of the US Southwest. For each case, the vulnerability to food shortage before the climate challenge is quantified based on eight variables encompassing both environmental and social domains. These data are used to evaluate t...

Ice bodies in the semi-arid mountainous regions of Chile are of vital importance for the local population. As variations of their extent are often associated with climate change, this study focuses on the glaciers and glacierets situated in the Commune Alto del Car‐ men and local and regional climate. We combine statistically Landsat satellite imagery, historical and ongoing weather data. The p...

What does a horticulturist or landscape architect strive to attain when choosing plants for a naturalistic animal exhibit in any major zoo? Should visitors come upon bananas and tropical figs complementing an exhibit featuring giraffes or zebras that naturally roam the hot, arid Serengeti? Let’s hope not. Likewise, they should not be confronted by trees that resemble the acacias of arid Kenya a...

Societies in semi-arid areas in developing regions are amongst those, most vulnerable to climate variability and potentially most vulnerable to climate change. The vulnerability to climate variability is caused by the strong restrictions that limited water availability poses on the use of natural resources, by the generally low reliability of water availability and, on the other hand, an often ...

A large reservoir of bioavailable nitrogen (up to approximately 10(4) kilograms of nitrogen per hectare, as nitrate) has been previously overlooked in studies of global nitrogen distribution. The reservoir has been accumulating in subsoil zones of arid regions throughout the Holocene. Consideration of the subsoil reservoir raises estimates of vadose-zone nitrogen inventories by 14 to 71% for wa...

................................................................................................................................................... ii Preface...................................................................................................................................................... 1 Background ..............................................................................