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Wang J.,Tibet Institute of Agriculture and Animal Husbandry | Zhong Z.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Wang Z.,Tibet Institute of Agriculture and Animal Husbandry | Zhang X.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 2 more authors.
Journal of Plant Resources and Environment | Year: 2013

Taking vegetation of nineteen grassland types of four natural transects (alpine grassland, alpine shrub and meadow, mountain semidesert and desert, mountain shrub steppe) in alpine steppe ecosystem in Tibetan Plateau as research objects, distribution characteristics of vegetation C/N value and its influence factors in alpine steppe ecosystem were studied by means of combining field investigation and laboratory analysis. The results show that the vegetation C/N value of alpine steppe ecosystem in Tibetan Plateau appears generally a tendency with lower in east and west parts and higher in the middle part of Tibetan Plateau, and a patch distribution pattern. There are obvious differences in C/N value of above- ground part and root among different natural transects and different grassland types, and C/N value in above-ground part is higher than that in root. Average C/N value in above-ground part of vegetation of nineteen grassland types is 34. 17 with coefficient of variation (CV) of 35. 87%, and that in root is 29. 58 with CV of 40. 02%. While that in above-ground part of vegetation of four natural transects is 31. 98 with CV of 13. 82%, and that in root is 31. 86 with a CV of 16. 92%. Regression analysis result shows that C/N value in above-ground part of vegetation has a significant positive correlation with above ground part biomass, total N and total K contents in soil, and has a significant negative correlation with vegetation height; C/N value in root has a significant positive correlation with altitude and soil bulk density in 20-30 cm soil depth, and has a significant negative correlation with mean annual precipitation and mean annual evaporation. And these factors are the key environmental factors influencing vegetation C/N value of alpine steppe ecosystem in Tibetan Plateau. General, the influence of geographical, climatic and soil physical factors on vegetation C/N value of alpine steppe ecosystem in Tibetan Plateau is not significant, while that of vegetation and soil chemical factors is significant. Source


Wang J.-L.,Tibet Institute of Agriculture and Animal Husbandry | Zhong Z.-M.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Wang Z.-H.,Tibet Institute of Agriculture and Animal Husbandry | Chen B.-X.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 4 more authors.
Chinese Journal of Applied Ecology | Year: 2013

The distribution characteristics of soil N/P ratio in alpine grassland ecosystem of Qinghai-Tibet Plateau were surveyed by field investigation and laboratory analysis. Horizontally, soil N/P ratio was generally higher in west and lower in east in a manner of staggered patch distribution, with higher N/P ratios mainly centralized in the hinterland of northern part of Tibet Plateau and in the lake basin area of the northern foot of Himalayas. Significant differences in soil N/P ratio were observed among grassland types and natural transects. Vertically, the distribution of N/P ratio along the soil profile from aboveground to underground among different grass types could be categorized into five patterns, including low-high-low-high, low-high-low, low-high, high-low-high-low, and high-low-high. The N/P ratio showed a significant positive correlation with soil bulk density at 0-20 cm depth, soil water content at 20-30 cm depth, contents of soil available K and total nitrogen, respectively. However, it showed significant negative correlation with soil bulk density at 20-30 cm depth, contents of soil available P and total P, respectively. Source


Wang J.L.,Tibet Institute of Agriculture and Animal Husbandry | Zhong Z.M.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Wang Z.H.,Tibet Institute of Agriculture and Animal Husbandry | Chen B.X.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 5 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Regional distribution regularities on soil C/N have been a hot topic in recent years, but currently there were few studies reporting the soil C/N distribution in alpine steppe ecosystem under different vegetation zones in Qinhai-Tibetan plateau. In order to reveal the spatial distribution characteristics of the soil C/N on the alpine steppe ecosystem in different vegetation zones, and to provide scientific basis for understanding a regional specific acclimation of vegetation to climate change in Qinhai-Tibetan plateau, we surveyed the soil C/N of alpine steppe ecosystem under different vegetation zones. Collectively, we sampled 67 sampling points. The soil C/N of the alpine steppe ecosystem in Qinhai-Tibetan plateau was also compared with that of 14 natural transects in areas outside the plateau. The results showed that: (1) Along the horizontal direction in Qinhai-Tibetan plateau, C/N appeared higher in northwest and lower in southeast. The higher C/N appeared mainly in the regions with a concentration in the hinterland of northern part of Tibetan Plateau and in the lake basin region of the northern foot of Himalayas. There were significant differences of C/N among different grassland types and natural transects. (2) Along the vertical direction of the soil profiles from aboveground to underground, it could be divided into 5 types of low-high-low, from high to low, from low to high, high-low-high-low and high-low-high of C/N distribution patterns among different grassland types and natural transects, and there was significant difference of C/N between the surface soil depths from 0 cm to 20 cm and the deeper soil depths from 30 cm to 40 cm. (3) C/N was significantly and positively correlated with average temperature in the coldest month, average annual evaporation, average annual relative humidity and soil total nitrogen content, respectively. The C/N was significantly correlated with average annual sunshine hours, average annual temperature and soil available K content negatively, respectively. The effect magnitude of environmental factors on the C/N followed an order of average annual relative humidity > average annual sunshine hours > average temperature in the coldest month > average annual temperature > average annual evaporation > soil total nitrogen content > soil available K content. Due to the complex spatial distribution along both horizon and vertical directions, the research work of soil C and N and the relationship between C and N of the alpine steppe ecosystem in Qinhai-Tibetan plateau are highly important. Conclusively, climate is the most important environmental influence factor on the soil C/N of alpine steppe in Qinhai-Tibetan plateau. Future research work should focus on the relationship between soil C/N and climatic factor, especially the relationship between soil C/N and moisture factor. © 2014, Science Press. All rights reserved. Source

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