Xinshi Zhang

Effects of water stress on water use efficiency and water balance components of Hippophae rhamnoides and Caragana intermedia in the soil-plant-atmosphere continuum.

Hippophae rhamnoides (Sea buckthorn) and Caragana intermedia (Intermediate peashrub), which are nitrogen-fixing and perennial temperate shrubs, are extensively used in the agroforestry systems in the loess areas of China. In this study, artificially controlled water gradient experiments were carried out with both shrubs, based on four levels of water supply (normal precipitation, slight drought, drought, and extreme drought). The results showed significant impacts of drought on net photosynthesis rate, biomass accumulation, and biomass allocation in both species. Water use efficiency (WUE) varied with different species, scales, and water stress intensities. WUE at the leaf scale (WUEi) was highest under moderate water stress, while the WUE at the community scale (WUEb) decreased with increasing water stress. We observed alteration in the diel and seasonal transpiration of both species in response to water stress. The night-time transpiration accounted for a small but significant proportion of the water balance, and its importance tended to increase with increasing drought. Both species experienced water deficits under all treatments. Soil moisture of H. rhamnoides declined more severely than that of C. intermedia. The ratio of transpiration to evapotranspiration (T/ET) ranged from 50 to 80% for both species in the growing season. The T/ET and WUEi of H. rhamnoides were comparatively smaller under severe water stress but increased under moist conditions. Our data suggest that H. rhamnoides uses water resources more efficiently under favorable water conditions, and C. intermedia shows competitive advantages under drought conditions. Moreover, possible strategies to maintain water balance in the water-limited agroforestry systems are discussed.

Studies on the Change of Land use/Cover and Ecosystem Service Values of the Three-Belt of Mountain_Oasis_Desert in the Northwestern China

Characteristics of land use/cover change (LUCC), ecosystem service values change and their spatial heterogeneity of three-belt of mountain-oasis-desert in the northern slope of Tianshan Mountains, were analyzed, based on GIS and data of remote sensing and LUCC in 1989 and 2000. And related sustainable development countermeasure was put forward referring to rules of ecosystem services functions change along the typical three-belt ecosystem complex of Northwestern China.

Study on the Spatio-Temporal Changes of Ecosystem Service Value in the Northern Slope of Tianshan Mountains

The spatio-temporal trend of ecosystem services value change along the profile of landscape heterogeneity of a mountain-basin system (MBS) in the north slope of Tianshan Mountain during 1988 to 2003 was analyzed based on the data of land use/cover change (LUCC), taking Manas County as an example. Results showed that the total value of ecosystem services of Manas County was 58.98 times 108 yuan RMB in 1988, 49.76 times 108 yuan in 1997 and 50.22 times 108 yuan in 2003. The total decreased quantity was 8.76 times 108 yuan from 1988 to 2003, with the change rate of 14.85%. From Tianshan Mountain to piedmont alluvial fan, oasis and desert, villages and towns of Manas County were estimated orderly. Correspondingly the spatial trend and dynamic change of ecosystem service value along this typical profile of MBS and related countermeasures were discussed.

Vulnerability assessment of the mountain-basin system in the northern tianshan mountains

Mountain-basin system (MBS) is the basic pattern of natural heterogeneity and regionalization in North-western China, and its big extent, multi-Layer and regular complex of terrestrial ecosystems in Northern Tianshan Mountains, Xinjiang, China, is the basin and frame to form this kind of pattern. To support regional sustainable development both on theory and practice, more and more vulnerability assessments became comprehensive studies by combining the ecosystem with socioeconomic system. Based on the vulnerability meaning that was composed of impact and adaptive ability, a vulnerability assessment on fifteen counties in the northern Tianshan Mountains was presented in this paper. The ecosystem services changing to land use/cover change (LUCC) was regarded as impact. Based on fourteen indexes from resource holding, society and economy development data, the adaptive ability was evaluated by using various methods and means such as AHP (the analytic hierarchy process), fuzzy comprehensive judging model, LUCC data and GIS. The impact was divided into four grades and the adaptive capacity three grades. And the fifteen counties were divided into five grades under the certain assessment principles, and the higher grade meant more vulnerability. Results showed that: The first grade included Usu City and Changji City. The second included Hutubi County, Miquan County, Fukang City, Jimsar County, Qitai County and Mori Kazak Autonomous County. Karamay City and Urumqi City were in the third grade, the fourth grade was composed of Kuytun City and Shawan County, and Jinghe County, Shihezi City and Manas County fell into the fifth grade. Vulnerability assessment results reflected both eco-environment change and socio-economic development level, which were the key references to ecological restoration and industry structural adjustment. It is necessary to make great efforts to carry out relevant counter-measures and decrease vulnerability, which would benefit the sustainable development of this kind of typical terrestrial ecosystem complex of MBS in North-western China, and additionally other similar areas.