Both water and nitrogen (N) availability have significant effects on ecosystem CO2 exchange (ECE), which includes net ecosystem productivity (NEP), ecosystem respiration (ER) and gross ecosystem photosynthesis (GEP). How water and N availability influence ECE in arid and semiarid grasslands is still uncertain. A manipulative experiment with additions of rainfall, snow and N was conducted to tes...

It has widely been documented that nitrogen (N) enrichment stimulates plant growth and net primary production. However, there is still dispute on how N addition affects net ecosystem CO2 exchange (NEE), which represents the balance between ecosystem carbon (C) uptake and release. We conducted an experimental study to examine effects of N addition on NEE in a temperate steppe in northern China f...

Land degradation is one of the major environmental problems worldwide and has become particularly severe in recent decades in China, with its rapid economic developments. China has an enormous area of grasslands, covering 41% of its territory (3.93 million km), and grasslands are regarded as among the most important natural resources because of their ecological and economic importance. However,...

Building models is an important way of integrating knowledge. Testing and updating models of social-ecological systems can inform management decisions and, ultimately, improve resilience. We report on the outcomes of a six-year, multidisciplinary model development process in the sagebrush steppe, USA. We focused on creating state-and-transition models (STMs), conceptual models of ecosystem chan...

WILLIAM A. REINERS Department of Botany University of Wyoming PO Box 3165 Laramie, Wyoming 82071-3165, USA ABSTRACT / Carbon sequestration was estimated a northern mixed-grass prairie site and a sagebrush–steppe site in southeastern Wyoming using an approach that integrates remote sensing, CO2 flux measurements, and meteorological data. Net ecosystem exchange (NEE) of CO2 was measured using air...

Different grazing strategies impact grassland plant production and may also regulate the soil carbon formation. For a site in semiarid temperate steppe, we studied the effect of combinations of rest, high and moderate grazing pressure over three stages of the growing season, on the process involved in soil carbon sequestration. Results show that constant moderate grazing (MMM) exhibited the hig...

The effects of fall and spring sheep use on cover components and recovery following a change in seasonality of grazing practices, were studied within long-term grazing treatments of threetip sagebrush (Artemisia tripartitu Rydb.) steppe on the U.S. Sheep Experiment Station near Dubois, Ida. Few significant differences existed among treatments within the litter, moss, lichen, and soil components...

Soil carbon dioxide (CO2) emission is one of the largest fluxes in the global carbon cycle. Therefore small changes in the size of this flux can have a large effect on atmospheric CO2 concentrations and potentially constitute a powerful positive feedback to the climate system. Soil CO2 fluxes in the alpine steppe ecosystem of Northern Tibet and their responses to short-term experimental warming...

The Gagauzes are a small Turkish-speaking ethnic group living mostly in southern Moldova and northeastern Bulgaria. The origin of the Gagauzes is obscure. They may be descendants of the Turkic nomadic tribes from the Eurasian steppes, as suggested by the "Steppe" hypothesis, or have a complex Anatolian-steppe origin, as postulated by the "Seljuk" or "Anatolian" hypothesis. To distinguish these ...

Soil freezing-thawing cycle may substantially influence soil physical properties, microbial activity, and the rates of carbon and nitrogen cycling in soils. In this study, the soil water soluble organic C, N (WSOC, WSON) as well as microbial biomass C, N (MBC, MBN) of two alpine grassland types, alpine meadow and alpine steppe, were investigated after freezing-thawing cycles in a grassland land...