Cao Guangchao

Land Cover Change and its Environmental Impact in the Upper Reaches of the Yellow River, Northeast Qinghai-Tibetan Plateau

Abstract Many studies have focused on desertification processes in northern China in an attempt to understand desertification-related ecological problems. Desertification on the Qinghai-Tibetan Plateau has received little attention, even though desertification resulting from overgrazing is a widespread phenomenon there. This study focuses on the Gonghe Basin in the upper reaches of the Yellow River, located on the northeast Qinghai-Tibetan Plateau, to shed light on desertification processes and associated environmental impacts during a 10-year period from 1987 to 1996. We first used 2 thematic mapper images to classify land cover for 2 summers (1987 and 1996) into 9 land cover types related to desertification. To assess the severity of desertification and to calculate the total soil carbon emission caused by desertification, we first defined severity by comparing land cover differences between 1987 and 1996 and then determined the differences in organic carbon content of the soil in grasslands during different stages of desertification between 1987 and 1996. The results showed that about 240 km2 of grasslands was lost to agricultural encroachment and about 190 km2 became sand-covered area between 1987 and 1996. During the same period, desertification affected 569.6 km2 of grasslands, with desertification assessed as very severe for 41.8%, severe for 15.1%, and moderate for 43.1% of the area. The results also show that carbon emissions from grassland deterioration caused by desertification amounted to 2.06 × 106 tC during the 10-year period, the average annual emission rate being 0.206 × 106 tC.

Grassland desertification and its impacts on carbon cycle in the source region of the Yellow River, northeastern Qinghai-Tibetan Plateau by remote sensing

This study deals with desertification and its impacts on environment in the source region of the Yellow River. Our objectives were to reveal and quantify desertification changes from 1990-2000 by remote sensing and GIS, and discuss its impacts on carbon cycle. The results indicate that the study area is one of the most desertified regions in northeast Qinghai-Tibetan Plateau. The study area is now a carbon source. The desertification would have contributed to CO/sub 2/ emission from grasslands of Qinghai-Tibetan Plateau. Otherwise, there are great potential to resequestration carbon through controlling grazing, restoring ecosystem, and reducing desertification.

Variation Features of Soil Physical Property of Different Forest Land Types in Southern Slope of Qilian Mountain

The research material in this article is the four forest lands in the southern slope of Qilian Mountain, they are the forest of Picea crassifolia, Sabina przewalskii and the Potentilla fruticosa shrubwood, Caragana jubata shrubwood, we discuss the influence of different forest land types to the soil physical property and the water conservation function. The research result shows that the soil water content and porosity of different types of forest lands present a decreasing trend along with the increase of soil depth. Different soil depth acts roughly as Picea crassifolia > Potentilla fruticosa > Sabina przewalskii, Caragana jubata changes between the three ones, on the whole, it would be Picea crassifolia > Potentilla fruticosa > Sabina przewalskii, the soil water content of Caragana jubata and Potentilla fruticosaare are almost the same.

Construction of regional integrated transportation networks in Qinghai province under circular economy model

Circular economy is a new concept of development and an economic growth model. This paper studied the relationship between the integrated transport network and circular economy; the characteristics of traffic flow developed by circular economy in Qinghai province, and constructed the regional integrated network mating with circular economy in Qinghai province. Results showed that passenger and cargo transportation capacity has obvious positive correlation with economy development, but the growth rate of passenger and cargo transportation does not match smoothly with that of Qinghai provincial GDP growth in some periods, their significant differences imply that the increase of passenger and cargo transportation is strongly affected by other factors. Traffic flow has positive correlation with road network levels. The development of Qinghai province circular economy mainly relies on the Qaidam areas and the east circular economy area as the core of Xining now. On the above basis, also put forward the suggestions of construction regional integrated network mating with circular economy in Qinghai province to the development of the regional circular economy in the future.