不同恢复措施对若尔盖沙化草地的恢复效果比较

The effect of different restoration measures on the desertified alpine grassland in Zoigê

若尔盖高原是黄河上游主要的水源补给地,也是我国重要的生态安全屏障区,但近年来由于超载过牧、气候变化、鼠害等原因出现了严重的沙化问题.通过比较分析合理放牧、围封禁牧以及自然恢复3种恢复措施对若尔盖典型沙化草地植物群落结构、生物量和土壤理化性质的恢复效果.结果显示,恢复6年后,自然恢复草地恢复效果不明显,而合理放牧草地恢复效果最好.与自然恢复和围封禁牧恢复草地相比,(1)合理放牧使得草地植物群落盖度、物种丰富度、地上生物量和地下生物量显著增加,分别为93%、9、396.41 g/m^2和693.4 g/m^2;(2)合理放牧恢复草地土壤容重、pH显著降低;含水量、最大持水量、可溶性全氮、硝态氮、可溶性有机氮和可溶性有机碳显著增加.本研究表明合理放牧有利于沙化草地更快恢复,建议制定相关标准在适当区域进行应用和推广.

Zoige plateau wetland is the third-largest peat swamp wetland in China. Ecological security of Zoige plateau wetland is not only related to biomass production, but also to the ecological balance of the Yellow River Basin. In recent years, due to overgrazing and other factors, Zoige grassland has suffered serious degradation and desertification, which have decreased grassland productivity, and caused other serious ecological problems. Enclosure following reseeding is considered the most effective way to restore desertified grassland. On the other hand, some researchers and local herdsmen have found reasonable grazing after reseeding and early period enclosure more conducive to the restoration of the desertified grassland by increasing the plant community coverage, the number of species, and gross primary production. To compare the effect of these two recovery strategies, we measured the aboveground biomass, underground biomass, soil physical and chemical properties, soil microbial carbon, soil microbial nitrogen and release rate of root exudates from the root of Elymus nutans. The results showed that, after 6 years of restoration, compared with enclosure, grazing significantly increased plant community coverage （93%）, species richness （9）, aboveground biomass （396.41 g m-2） and 0-20 cm underground biomass （693.46 g mg）in the grassland. The degraded grassland with grazing showed significantly decreased soil bulk density but significantly increased soil water content, maximum moisture capacity, soil pH, total soluble nitrogen, nitrate nitrogen, dissolved organic nitrogen, and dissolved organic carbon. The results indicated that the reasonable grazing is more conducive than enclosure to the restoration of vegetation and soil physical and chemical properties of degraded grasslands.