نتایج جستجو برای: steppe

تعداد نتایج: 4241  

2016
Zhenzhu Xu Yanhui Hou Lihua Zhang Tao Liu Guangsheng Zhou

Global warming is projected to continue, leading to intense fluctuations in precipitation and heat waves and thereby affecting the productivity and the relevant biological processes of grassland ecosystems. Here, we determined the functional responses to warming and altered precipitation in both typical and desert steppes. The results showed that watering markedly increased the aboveground net ...

2009
S. E. GEORGESCU MARIA ADINA MANEA MIHAELA ZAULET MARIETA COSTACHE

The genetic diversity found in domestic breeds allows farmers to develop new characteristics in response to changes in the environment, the appearance of diseases, or of modifications in market conditions. Indigenous breeds often possess gene combinations and special adaptations (such as disease resistance, adaptation to harsh conditions or poor-quality feeds) not found in other breeds. Five Ro...

2012
S. A. Zimov N. S. Zimov A. N. Tikhonov F. S. Chapin

At the last deglaciation Earth’s largest biome, mammoth-steppe, vanished. Without knowledge of the productivity of this ecosystem, the evolution of man and the glacialeinterglacial dynamics of carbon storage in Earth’s main carbon reservoirs cannot be fully understood. Analyzes of fossils 14C dates and reconstruction of mammoth steppe climatic envelope indicated that changing climate wasn’t a r...

2012
S. Aghainajafi Zadeh M. R. Hemami F. Heydari

Knowledge of food resource of the houbara which an endangered species would be a important step toward the preservation of this bird. Adequate study has not been done in this field and therefore the food sources of the houbara during the brooding season was studied in the central steppe of Iran. In order to determine the density of insect in plant communities the pitfall trap was used , positio...

2012
Ping Zhang Shiping Chen Wenli Zhang Haixia Miao Jiquan Chen Xingguo Han Guanghui Lin

Aims Ecosystem carbon models often require accurate net ecosystem exchange of CO2 (NEE) light-response parameters, which can be derived from the Michaelis–Menten equation. These parameters include maximum net ecosystem exchange (NEEmax), apparent quantum use efficiency (a) and daytime ecosystem respiration rate (Re). However, little is known about the effects of land conversion between steppe a...

2013
Matt Lavin Tyler J Brummer Ryan Quire Bruce D Maxwell Lisa J Rew

Fire is thought to profoundly change the ecology of the sagebrush steppe. The Idaho National Laboratory provides an ideal setting to compare the effects of fire and physical disturbance on plant diversity in high-native-cover sagebrush steppe. Seventy-eight 1-hectare transects were established along paved, green-striped, gravel, and two-track roads, in overgrazed rangeland, and within sagebrush...

2016
Anne Kemmling Birgit Pfeiffer Rolf Daniel Michael Hoppert A. Kemmling M. Hoppert

Biological Soil Crusts (BSCs), consisting of prokaryotes, microalgae, lichens, mosses and eventually small vascular plants, cover wide areas in arid and semi-arid environments. In the present study, the microbial diversity of these crusts was explored at extrazonal mountain steppe sites in the western Khentej (Northern Mongolia). At the study site the Siberian taiga borders on the Mongolian-Dau...

2007
Marilyn D. Walker Donald A. Walker Kaye R. Everett Susan K. Short MARILYN D. WALKER

The hypothesized presence of large regions of grass and forb-dominated "steppe tundra" across Alaska and Siberia during the Pleistocene glacial epochs has led to a search for modern analogs. Evidence is presented for the presence of steppe vegetation on south-facing slopes and summits of pingos within the central Arctic Coastal Plain of Alaska. Vegetation, floristics, soils, and climatic factor...

2010
Grant D. Zazula Glen MacKay Thomas D. Andrews Beth Shapiro Brandon Letts Fiona Brock

A partial steppe bison (Bison priscus) carcass was recovered at Tsiigehtchic, near the confluence of the Arctic Red and Mackenzie Rivers, Northwest Territories, Canada in September of 2007. The carcass includes a complete craniumwith horn cores and sheaths, several complete post-cranial elements (many of which have some mummified soft tissue), intestines and a large piece of hide. A piece of me...

2007
W. L. Zhang S. P. Chen J. Chen L. Wei

An increasing amount of grasslands in Inner Mongolia of Northern China has been converted to cropland. The conversions in this extensive semiarid region have produced adverse ecological consequences at local and regional scales (e.g., dust storms). An important research need is to understand the fundamental ecosystem processes, such as energy and material fluxes, associated with the land conver...

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