Abstract
Currently, grazing exclosure is one of the most important grassland management measures for restoring all types of degraded alpine grassland in the Qinghai-Tibetan Plateau (QTP). The most widely distributed grassland ecosystems across the northeastern QTP are the alpine meadow (AM), alpine meadow steppe (AMS), and alpine steppe (AS) in the northeastern QTP. However, how the effects of fencing on vegetation characteristics and soil properties vary among different grassland types remains poorly understood despite numerous individual studies have conducted. This study investigated the vegetation characteristics and soil properties in fenced and grazed AM, AMS and AS in the northeastern QTP after 8-9 years of fencing. Grazing exclosure significantly increased the vegetation coverage and Shannon-Wiener diversity index in all the three grasslands. Plant species richness was significantly increased in AM but there were no significant effects in AMS and AS. Aboveground biomass were significant increase after long-term exclosure in AMS and AS but no significant in AM. Increase in the percentage of high-quality forage grasses was only observed in AMS. Fencing significantly decreased the soil bulk density, increased soil organic carbon and total nitrogen at a depth of 0-50 cm in AMS and AS but had no effect in AM. Our results indicate that the use of fencing for restoring degraded AM might not achevie the same expected results as in AS and AMS on the QTP.
Highlights
Land degradation has been increasing at an annual rate of 5–10 million ha and affecting about 1.5 billion people globally (Gisladottir and Stocking, 2005; Ilan and Rattan, 2015)
In order to avoid the impact of different fencing durations on the ecosystem, we selected three alpine grassland types (AM, alpine meadow steppe (AMS), alpine steppe (AS)), which was fenced off grazing at the same year
There was no significant increase in species richness (R) and Shannon–Wiener diversity index (H) after longterm fencing in all three grasslands (Table 2)
Summary
Land degradation has been increasing at an annual rate of 5–10 million ha and affecting about 1.5 billion people globally (Gisladottir and Stocking, 2005; Ilan and Rattan, 2015). The alpine grassland on the Qinghai–Tibetan Plateau (QTP), occupying over 60% total area of the QTP, is proved to be sensitive to climate change and human activities (Wu et al, 2012; Xue et al, 2015; Bakhshi et al, 2019) and has important functions in protecting the headwaters of major rivers in Asia (Yan and Lu, 2015). It has severely degraded since the 1980s (Saito et al, 2009; Li et al, 2013; Zhao et al, 2015; Xue et al, 2017). The results will inform alpine grassland conservation and sustainable management in the future
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