Assessing the soil quality of alpine grasslands in the Qinghai-Tibetan Plateau using a modified soil quality index
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Assessing the soil quality of alpine grasslands in the Qinghai-Tibetan Plateau using a modified soil quality index Yuanyuan Li & Shikui Dong & Lu Wen & Xuexia Wang & Yu Wu
Received: 28 September 2012 / Accepted: 26 February 2013 / Published online: 15 March 2013 # Springer Science+Business Media Dordrecht 2013
Abstract Soil degradation has caused various problems on the planet. Human disturbance and land use changes always negatively affect soil quality. In this study, we used a modified soil quality index (SQI) to assess soil quality under differing degrees of human disturbance and land use. The alpine grasslands were studied at different levels of degradation [i.e., severely degraded grassland, heavily degraded grassland, moderately degraded grassland, and non-degraded grassland (NDG)] in a case study conducted in Qinghai-Tibetan Plateau (QTP) to test the feasibility of using the SQI. Fifteen chemical, physical, and biological soil parameters were measured in each type of grassland. Significant variations in SQI were found across the different types of grasslands according to severity of human disturbance and changes in land use. Urease, the ratio of microbial biomass nitrogen to total nitrogen, proteinase, and soil organic carbon were found to be the most important indicators for assessing soil quality. NDG had a higher SQI than the other three types of grasslands. It was concluded that SQI is effective for assessing the soil quality of alpine grasslands in the QTP. The intensity Y. Li : S. Dong : L. Wen : X. Wang : Y. Wu State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China S. Dong (*) Natural Resources Department, Cornell University, Ithaca, NY 14583-3001, USA e-mail: [email protected]
of human disturbance had a negative effect on soil quality in the QTP. Keywords Soil quality index . Qinghai-Tibetan Plateau . Soil enzymes . Microbial biomass
Introduction The Qinghai-Tibetan Plateau (QTP), which is the largest geomorphological unit on the Eurasian continent, is the main region of low-latitude frozen soil in the world (Wang et al. 2002). It is also the source of headwaters for the Yangtze, Yellow, and Mekong Rivers, as well as several other inland rivers in Asia (Li et al. 2007b). In addition, the QTP is of critical importance to the ecological security of China and southeastern Asia, especially in terms of its sensitivity to global climate change (Fan et al. 2010). Alpine grasslands (mostly alpine meadow and steppe) cover two thirds of the total plateau, amounting to an area approximately 1.5 million square kilometers in size (Li and Tang 1988). However, the alpine grasslands in the QTP have suffered from severe degradation due to natural and anthropogenic activities (Zhou et al. 2005; Harris 2010). Overgrazing is considered to be one of the important disturbance factors causing grassland degradation, alterations in community function, and an increase in spatial heterogeneity and soil desertification (Akiyama and Kawamura 2007; Wu et a
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