[Analysis of water sources of plants in artificial sand-fixation vegetation area based on large rainfall events.].

Water is a major limiting factor for plant growth in arid and semi-arid regions. To find out the main sources of water for two artificial sand-fixation plants (Caragana korshinskii and Artemisia ordosica), we analyzed the characteristics of hydrogen and oxygen stable isotopes in water molecules of rainfall, soil water and xylem water. To analyze water sources of these two plants, we used a direct comparison method and a multi-variate mixed linear model.

Leaf senescence induced by EGY1 defection was partially restored by glucose in Arabidopsis thaliana.

Background: Ethylene-dependent gravitropism-deficient and yellow-green 1 (EGY1) protein is required for chloroplast development and photosynthesis conduction. The egy1 deletion mutants have a yellow-green phenotype and reduced granal thylakoids. Furthermore, the yellow-green phenotype of egy1 mutants is more obvious than that of wild-type (WT) plants with increasing leaf age, suggesting an early senescence in the egy1 mutants.

Carbon pools and fluxes in a Tibetan alpine Kobresia pygmaea pasture partitioned by coupled eddy-covariance measurements and ¹³CO₂ pulse labeling.

The Tibetan highlands host the largest alpine grassland ecosystems worldwide, bearing soils that store substantial stocks of carbon (C) that are very sensitive to land use changes. This study focuses on the cycling of photoassimilated C within a Kobresia pygmaea pasture, the dominating ecosystems on the Tibetan highlands. We investigated short-term effects of grazing cessation and the role of the characteristic Kobresia root turf on C fluxes and belowground C turnover.

[Landscape pattern and its dynamics in typical oasis-desert transitional zone of Minqin Region in 1960-2005].

By using ERDAS and GIS techniques, a systematic analysis was made on the landscape pattern and its dynamics in typical oasis-desert transitional zone of Minqin Region in 1960-2005. Forest land and cultivated land were the dominant factors leading to the landscape change. During the research period, oasis expanded toward the periphery by 2-3 km, and the transitional zone moved toward desert, with its width increased from 4 km in 1960 to about 9 km in 1987 and decreased rapidly then.

[Challenge to the desertification reversion in Horqin Sandy Land].

Analyses of the changes in desertified land area, water resource availability, land use, and plant productivity in Horqin Sandy Land in recent 50 years showed that from 1950 to the late 1980s, the land desertification in Horqin Sandy Land had a rapid expansion, but reversed since then. The annual runoff of Xiliaohe River decreased consistently, and in 1999, the middle reach at Tongliao section was dried up. In recent 20 years, the water table of Xihu Lake was decreased by about 10 m, and dried up in 2001.

Phylogenetic and physiological diversity of bacteria isolated from Puruogangri ice core.

The microbial abundance, the percentage of viable bacteria, and the diversity of bacterial isolates from different regions of a 83.45-m ice core from the Puruogangri glacier on the Tibetan Plateau (China) have been investigated. Small subunit 16S rRNA sequences and phylogenetic relationships have been studied for 108 bacterial isolates recovered under aerobic growth conditions from different regions of the ice core.

Molecular characterization of PeSOS1: the putative Na(+)/H (+) antiporter of Populus euphratica.

Populus euphratica is a salt-tolerant tree species growing in semi-arid saline areas. A Na(+)/H(+) antiporter gene was successfully isolated from this species through RACE cloning, and named PeSOS1. The isolated cDNA was 3665 bp long and contained a 3438 bp open reading frame that was predicted to encode a 127-kDa protein with 12 hypothetical transmembrane domains in the N-terminal part and a long hydrophilic cytoplasmic tail in the C-terminal part.

Social, economic, and ecological impacts of the "Grain for Green" project in China: a preliminary case in Zhangye, Northwest China.

This paper provides applications of the integrated assessment (IA) approach in a case study in the Heihe River Basin of Northwest China. Some socio-economic and ecological impact results of forestry land use scenarios are presented in the paper. While seven types of land use scenarios for carbon sequestration purposes were considered for the IA applications, this paper mainly presents impacts of land use scenarios within the Grain for Green (GFG) category [see Yin et al.

[Effect of grazing on sandy grassland ecosystem in Inner Mongolia].

This experiment was carried out for 5 years in Horqin sandy land, lnner Mongolia, which had 4 treatments: Non-grazing (NG), light grazing (LG), moderate grazing (MG) and over grazing (OG). The results showed that different grazing intensities resulted in different development trend of the pasture ecosystem, of which, the injury of OG on pasture ecosystem was very great. The plant diversity, vegetation coverage, plant height and primary productivity under continuous overgrazing for 5 year were 87.

[Dynamic tendency of arid oasis under the influence of water resources decrease--a case study of Ejina oasis in Heihe River Basin].

The runoff changes of arid inland river seriously influenced on the formations and changes of oasis in the lower reach. By the oasis patches dynamic modeling, the vegetation-water interrelated analysis, and the estimation of water demand by the ecological system, the dynamic tendency of the Ejina oasis in the lower reach of Heihe River Basin under difference water resources allocating were studied. The results showed that the lowest water demanded for preserving the present oasis area was about 5.

[Landscape change in middle Heihe River Basin].

Using GIS and a landscape structure analysis program FRAGSTATS, this paper dealt with the landscape change in the middle Heihe River Basin during the past 20 years. During the past 20 years, the landscape elements had a complex change of landscape structure and an apparent transition of landscape composition, but the landscape in a whole still displayed a pattern of sharply contrast between oasis landscape and desertification landscape. Human activities significantly changed the distribution and allocation of the limited water resource in the basin, leading to an acute contradiction between desertification and oasisfication.

[Influence of plant species diversity on productivity of sandy grassland in Kerqin Region].

The relationship between species diversity indices and sandy grassland productivity was studied in Kerqin sandy land, and the results showed that the relations could be divided in to two categories based on the indices and productivity. The first type includes function and composition diversities, their maximal biomass varied form 299 to 336 g.m-2, and had a simple linear relation with the productivity.

[Elevation distribution of precipitation chemistry in middle/upper troposphere in summer, the northern slope of central Himalayas].

During 1997 summer, fresh snow samples were collected from four snowfall events from the elevation of 5800 to 7000 m in the Dasuopu Glacier region on the northern slope of Mt. Xixabangma (28 degrees 33'N, 85 degrees 44'E), in order to understand the elevation distribution of the middle/upper tropospheric components in the remote region. The correlation between SO4(2-), NO3-, Ca2+ and Mg2+ in precipitation differs with type of air mass, indicating the dominant sources of ions vary in short-term (e.