scholarly journals Nitrogen retention patterns and their controlling factors in an alpine meadow: implications for carbon sequestration

2007 ◽  
Vol 4 (4) ◽  
pp. 2641-2665 ◽  
Author(s):  
X. L. Xu ◽  
H. Ouyang ◽  
G. M. Cao
Keyword(s):  
Alpine Meadow ◽  
Nitrogen Retention ◽  
Tibet Plateau ◽  
Short Term ◽  
Organic Carbon Concentration ◽  
Long Term Retention ◽  
Abiotic And Biotic Factors ◽  
One Year ◽  
Qinghai Tibet Plateau

Abstract. We hypothesized that the patterns of NO3− and NH4+ retention are different over short-term scales while they are similar over long-term scales in alpine meadows and that abiotic and biotic factors might be responsible for their different patterns over short-term scales. In order to test the hypotheses, a 15N-labeled experiment was conducted in an alpine meadow in the Qinghai-Tibet Plateau over four years. Our results showed that 15NO3− and 15NH4+ retention was distinctly different within two months, and even one year after tracer additions. The long-term retention of 15N at the whole-plot level did not differ significantly between 15NH4+ and 15NO3− treatments, and averaged 50% after four years. Higher soil temperature or soil organic carbon concentration enhanced 15NH4+ retention, but significantly reduced 15NO3− retention in the soil within two months following tracer additions. Soil moisture significantly affected 15N recovered in soil organic matter and microbial biomass as well as aboveground parts, but had no significant effects on 15N recovered in roots. These findings have important ecological implications with regard to the consequences of deposited nitrogen because of the possible difference in the fate of NH4+ vs. NO3− in alpine meadow ecosystems.

Long-term grazing exclusion greatly improve carbon and nitrogen store in an alpine meadow on the northern Qinghai-Tibet Plateau

CATENA ◽  
2021 ◽  
Vol 197 ◽  
pp. 104955
Author(s):  
Licong Dai ◽  
Ruiyu Fu ◽  
Xiaowei Guo ◽  
Yangong Du ◽  
Li Lin ◽  
...  
Keyword(s):  
Alpine Meadow ◽  
Tibet Plateau ◽  
Carbon And Nitrogen ◽  
Grazing Exclusion ◽  
Qinghai Tibet Plateau

scholarly journals A Pilot Study on Deworming Wild Foxes for Echinococcus spp. in Qinghai, China

2021 ◽  
Author(s):  
Zhihong Guo ◽  
Hong Duo ◽  
Xueyong Zhang ◽  
Yijuan Ma ◽  
Xiuying Shen ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Parasite Species ◽  
Scientific Basis ◽  
Tibet Plateau ◽  
Plateau Area ◽  
One Year ◽  
And Control ◽  
Qinghai Tibet Plateau ◽  
Echinococcus Spp

Background: Wild foxes play an important role in echinococcosis epidemics. There have been a few studies investigating Echinococcus spp. in the Qinghai-Tibet Plateau area, China, but none on the prevention and control of Echinococcus spp. in wild foxes. Methods: From 2016 March through December 2019, two wild fox dens were selected as two test sites based on prior long-term camera screening and observation. Anthelmintic praziquantel tablets were placed near the two dens of wild foxes, and the wild foxes freely consumed the anthelmintic drugs. Morphological methods were used to detect initially the parasite species, and PCR molecular methods were used to identify accurately parasite and host species. Results: Parasite eggs of E. multilocularis (2/11, 18.2%) were found in 11 fecal samples. Importantly, the eggs of E. multilocularis (1/21, 4.8%) were found again in the feces of the foxes one year later; moreover, the eggs of E. multilocularis (2/19, 10.5%) still existed in the feces of the foxes two years later. Conclusion: Wild foxes were repeatedly infected with E. multilocularis and that deworming for prevention and control is required at least twice per year. Prevention and control methods for echinococcosis in wild foxes were explored, providing a scientific basis for the prevention and control of echinococcosis in wild animals.

scholarly journals Spatial and Temporal Differences in Alpine Meadow, Alpine Steppe and All Vegetation of the Qinghai-Tibetan Plateau and Their Responses to Climate Change

2021 ◽  
Vol 13 (4) ◽  
pp. 669
Author(s):  
Hanchen Duan ◽  
Xian Xue ◽  
Tao Wang ◽  
Wenping Kang ◽  
Jie Liao ◽  
...  
Keyword(s):  
Climate Change ◽  
Alpine Meadow ◽  
Global Climate ◽  
Growing Season ◽  
Tibet Plateau ◽  
Vegetation Types ◽  
Analysis Method ◽  
Alpine Steppe ◽  
Qinghai Tibet Plateau ◽  
Variation Trends

Alpine meadow and alpine steppe are the two most widely distributed nonzonal vegetation types in the Qinghai-Tibet Plateau. In the context of global climate change, the differences in spatial-temporal variation trends and their responses to climate change are discussed. It is of great significance to reveal the response of the Qinghai-Tibet Plateau to global climate change and the construction of ecological security barriers. This study takes alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau as the research objects. The normalized difference vegetation index (NDVI) data and meteorological data were used as the data sources between 2000 and 2018. By using the mean value method, threshold method, trend analysis method and correlation analysis method, the spatial and temporal variation trends in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau were compared and analyzed, and their differences in the responses to climate change were discussed. The results showed the following: (1) The growing season length of alpine meadow was 145~289 d, while that of alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau was 161~273 d, and their growing season lengths were significantly shorter than that of alpine meadow. (2) The annual variation trends of the growing season NDVI for the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau increased obviously, but their fluctuation range and change rate were significantly different. (3) The overall vegetation improvement in the Qinghai-Tibet Plateau was primarily dominated by alpine steppe and alpine meadow, while the degradation was primarily dominated by alpine meadow. (4) The responses between the growing season NDVI and climatic factors in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau had great spatial heterogeneity in the Qinghai-Tibet Plateau. These findings provide evidence towards understanding the characteristics of the different vegetation types in the Qinghai-Tibet Plateau and their spatial differences in response to climate change.

Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau

2018 ◽  
Vol 19 (3) ◽  
pp. 1109-1119 ◽  
Author(s):  
Xiaolei Sun ◽  
Meng Li ◽  
Guoxi Wang ◽  
Marios Drosos ◽  
Fulai Liu ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Phosphorus Fractions ◽  
Tibet Plateau ◽  
Qinghai Tibet Plateau

scholarly journals Contrarian and Momentum Strategies in the Indian Capital Market

2002 ◽  
Vol 27 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Sanjay Sehgal ◽  
I Balakrishnan
Keyword(s):  
Stock Returns ◽  
Indian Market ◽  
Momentum Effect ◽  
Short Term ◽  
Momentum Strategy ◽  
Momentum Strategies ◽  
Holding Period ◽  
The Us ◽  
One Year

The study attempts to evaluate if there are any systematic patterns in stock returns for the Indian market. The empirical findings reveal that there is a reversal in long-term returns, once the short-term momentum effect has been controlled by maintaining a one year gap between portfolio formation period and the portfolio holding period. A contrarian strategy based on long-term past returns provides moderately positive returns. Further, there is a continuation in short-term returns and a momentum strategy based on it provides significantly positive payoffs. The results in general are in conformity with those for developed capital markets such as the US.

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