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Soil respiration, as one of the key ecological processes, plays an important role in terrestrial ecosystems. Quantitative analysis of soil respiration is critical to assessment of ecosystem carbon budget and responses of soils to global climate change. Semi鄄arid and arid area covers a vast and continuous region and provides special habitats for lives,thus research in environmental factors influence on soil respiration in semi鄄arid and arid area is contributive to estimating soil carbon storage and understanding the process of carbon cycle. This paper summarizes the impacts of the Non鄄biotic factors and biotic factors including soil temperature, soil moisture, precipitation, vegetation type, aboveground and underground biomass, leaf area index, and litter on soil respiration. The interaction of the above environmental factors were analyzed with special focuses on soil temperature, moisture and the Q 10 value of soil respiration based on summarization of related researches. A good deal of literatures and papers indicated that soil temperature and moisture, especially in arid areas, are

Agriophyllum squarrosum is an annual psammophyte species and wildly distributed in all deserts and sand lands in China. Changes of plant height, survival rate, photosynthetic rate ( Pn) , transpiration rate ( Tr) , stomatal conductance ( Gs) and water use efficiency ( WUE) of A. squarrosum seedlings was measured in a sand burial experiment during 2010-2011 in Horqin Sand Land of Inner Mongolia to understand effect of sand burial on the growth, photosynthesis and transpiration of annual psammophyte seedlings. The experiment included ten burial treatments: buried to 0% ( CK, no burial) , 25% ( A) , 50% ( B) , 75% ( C) , 100% ( D) , 133% ( E) , 166% ( F) , 200% ( G) , 233% ( H) and 266% ( I) of seedling height. The results showed that A. squarrosum had a strong ability to withstand sand burial. The survival rate and the plant height of A. squarrosum seedlings increased significantly at 25% burial depth of the seedling height. When subjected to sand burial at 50%-100%, the difference was not significant between the sand鄄buried treatments and the none鄄sand buried CK although the plant height and the survival rate decreased. The survival rate and the plant height decreased significantly only when the burial depth exceeded the height of the seedlings, but some individuals still kept survived when the burial depth was 266% of the seedling height. Buried by sand to the fifth day, the photosynthesis rate of A. squarrosum seedlings decreased slowly, the transpiration rate and the stomatal conductance and the water use efficiency

There is a great deal of literatures on the effects of sand burial upon the survival and growth of desert plants, but the physiological and ecological adaption of desert plants to sand burial have as yet rarely been studied. Artemisia halodendron is widely distributed in the semiarid deserts of China and is a dominant species in semi鄄moving dune vegetation.In order to understand the ecological and physiological adaptation of prammophytes to sand burial,,changes of survival rate, plant height, biomass, osmotic regulation substances, protective enzymes and membrane permeability of A. halodendron in different sand burial depths were studies during 2010-2011 in the Horqin Sand Land of Inner Mongolia. The experiment included ten burial treatments: buried to 0% ( CK, no burial) , 25% ( A) , 50% ( B) , 75% ( C) , 100% ( D) , 125% ( E) , 150% ( F ) , 175% ( G ) and 200% ( H ) and 225% ( I ) of seedling height. The results showed that 1 ) A.halodendron had a stronger ability to withstand sand burial stress, with some plants still surviving even if buried to a depth reaching 200% of the seedling heights. Although seedling growth was inhibited significantly once the depth of sand burial reached 50% of seedling height, seedling survive did not decrease significantly until the burial depth exceeded 100% of seedling height; 2 ) MDA content was significantly lower in the partial sand burial treatments compared to CK, but http: / / www.ecologica.cn membrane permeability did not increase significantly. After being subjected to complete sand burial, MDA content was still lower in most the treatments compared to CK, while membrane permeability increased significantly. Sand burial did not produce water stress in the seedlings, a major mechanism causing decreased MDA content is that the darkness, hypoxia and low temperature inhibit production of oxygen free radicals and membrane lipid peroxidation; 3) Compared with CK, SOD activity was significantly lower in all sand burial treatments except for treatments D and H, POD activity was higher in all sand burial treatments except treatment D, and CAT activity showed no significant changes with any of the sand burial treatments except for being elevated in treatments C and D. In general, POD activity increased when the activities of SOD and CAT decreased, and SOD and CAT activities increased when POD activity decreased. MDA content had a positive correlation with SOD and POD and a negative correlation with CAT. These results suggested that although there was a complementary interplay among the three enzymes, POD played a central role and SOD and CAT played supporting roles in scavenging active oxygen and minimizing cell membrane damage; 4) When subjected to partial burial with sand, proline content showed no significant changes and the soluble sugar content decreased significantly compared to CK. After sand burial exceeded the seedling height, proline content increased significantly; although soluble sugar content increased, the difference from CK did not reach a significant level. The res...