نتایج جستجو برای: sabalan grasslands

تعداد نتایج: 6155  

Journal: :Science 2012
Zak Ratajczak Jesse B Nippert

Hirota et al. (Reports, 14 October 2011, p. 232) used spatial data to show that grasslands, savannas, and forests represent opposing stable states. Reanalyzing their data and drawing from temporal studies, we argue that spatial analyses underestimate the bistability of grasslands and savannas due to limitations of substituting space for time. We propose that temporal and spatial data are needed...

شهبازی شیران, حبیب, شفائی مقدم, هادی ,

Trachyandesites, trachytes and latites associated with ignimbrite and pyrocalstic rocks, characterized by shoshonitic affinity are the main Plio-Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagioclase, K-feldspar, biotite associated with clinopyroxene and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic com...

2013
ROBERT J. STEIDL

Like all grasslands across North America, the distribution of desert grasslands has been reduced markedly, and remnants have been altered extensively by humans. In Arizona, NewMexico, Texas, USA, and in Mexico, desert grasslands have been invaded by dozens of non-native plants, especially perennial grasses that evolved in arid systems with similar climate and disturbance regimes. In desert gras...

2013
Lourdes Martínez-Estévez Patricia Balvanera Jesús Pacheco Gerardo Ceballos

Anthropogenic impacts on North American grasslands, a highly endangered ecosystem, have led to declines of prairie dogs, a keystone species, over 98% of their historical range. While impacts of this loss on maintenance of grassland biodiversity have been widely documented, much less is known about the consequences on the supply of ecosystem services. Here we assessed the effect of prairie dogs ...

Journal: :Conservation biology : the journal of the Society for Conservation Biology 2011
Janine Bolliger Thomas C Edwards Stefan Eggenberg Sascha Ismail Irmi Seidl Felix Kienast

Abandonment of agricultural land has resulted in forest regeneration in species-rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site-selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. ...

2011
Nianpeng He Xingguo Han Guirui Yu Quansheng Chen

An understanding of the factors controlling plant community composition will allow improved prediction of the responses of plant communities to natural and anthropogenic environmental change. Using monitoring data from 1980 to 2009, we quantified the changes in community composition in Leymus chinensis and Stipa grandis dominated grasslands in Inner Mongolia under long-term grazing-exclusion an...

2018
M Arasumani Danish Khan Arundhati Das Ian Lockwood Robert Stewart Ravi A Kiran M Muthukumar Milind Bunyan V V Robin

Tropical montane habitats, grasslands, in particular, merit urgent conservation attention owing to the disproportionate levels of endemic biodiversity they harbour, the ecosystem services they provide, and the fact that they are among the most threatened habitats globally. The Shola Sky Islands in the Western Ghats host a matrix of native forest-grassland matrix that has been planted over the l...

Journal: Desert 2016

     Miqan desert wetland is one of the 10 major wetlands in Iran. In 2008, it has changed into a non-hunting area due to its fragile ecology.  Evaluating the change trends of the wetland and the use of its surrounding lands is of high significant in order to maintain the wetlands. In this regard, the satellite images of the ETM+ and OLI sensors of years 2002 and 2013 were initially collected. ...

2002
Lia Hemerik Lijbert Brussaard

In grasslands under restoration succession, the effect of nutrient impoverishment on the vegetation has been intensively studied. The invertebrate soil animal community has, however, rarely been studied under such conditions. We hypothesised that a plant community in nutrient-poor grasslands supports fewer macro-invertebrate individuals than richer grasslands. We also hypothesised that the comp...

Journal: :Applied and environmental microbiology 1995
R P Herman K R Provencio J Herrera-Matos R J Torrez

The resource island hypothesis predicts that soil resources such as nitrogen, phosphorus, and water will be distributed evenly in grasslands but have a patchy distribution focused around plants in shrublands. This hypothesis predicts that microorganism numbers will follow resources and be (i) evenly distributed in grasslands, (ii) concentrated around individual plants in shrublands, and (iii) h...

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