连续封育过程中退化高寒草甸植被恢复能力分析

2012—2018年,选择香格里拉市小中甸镇退化高寒草甸为研究对象,观测和分析草地地上生物量及植物学组成在连续封育过程中的变化趋势,运用冗余理论、中度干扰假说、临界阈值理论和方法,探究草地的抵抗力、恢复力、临界阈值以及适宜载畜量。结果表明：①封育能够显著（P<0.05）提高草地地上生物量,因试验点生态环境条件和草地基本状况的差异,地上生物量在年度间的波动幅度及差异性不尽一致,但随封育时间的变化趋势均表现为幂函数型（Y=aX^b）;②依据地上生物量变化趋势推算,试验区退化高寒草甸的抵抗力为250.4~518.8 g/m²,草地恢复力为54.7~68.0个月,草地利用的临界阈值为420.6~588.7 g/m²;③草地适宜封育时间为2~5年,连续封育导致牧草生长冗余;封育5年后的草地适宜载畜量为1.1~3.4 个羊单位/hm²;连续封育7年后,草地中不可饲用植物（包括有毒有害植物）仍然占到15.3%~65.8%,草地适宜载畜量低下;④封育应结合除杂等措施,消减草群组分冗余,有效提高草地载畜量。

Analysis on Vegetation Restoration of Degraded Alpine Meadow during Continuous Enclosure Period

From 2012 to 2018, the degraded alpine meadow in Xiaozhongdian Town of Shangri-La City had been chosen and enclosed as test pastures. Aboveground biomass and botanical composition were observed and analyzed for both degraded and enclosed pastures. Redundancy theory, intermediate disturbance hypothesis and threshold value theory were used to evaluate the resistance, resilience, critical threshold and reasonable stocking capacity of the test pastures. The results showed that：（1） pastures enclosure could significantly （P<0.05） increase the aboveground biomass; due to the differences in ecological environment conditions at the test sites and basic situations of the pastures, the inter-annual fluctuation range and variations of the aboveground biomass were inconsistent, but its changing trend with enclosure duration exhibited an power function type （Y=aX^b）; （2） according to the changing trend of aboveground biomass, the resistance of the degraded alpine meadow in the test area was 250.4-518.8 g/m², the pastures resilience was 54.7-68.0 months, and the critical threshold of pastures utilization was 420.6-588.7 g/m²; （3） suitable enclosure period for degraded alpine meadow was 2 to 5 years; continuous enclosure led to redundant growth of forage; the suitable stocking capacity of pastures after 5 years of enclosure was 1.1-3.4 sheep unit/hm²; after 7 years of continuous enclosure, non-feedable plants （including poisonous and harmful plants） in the pastures still accounted for 15.3% to 65.8%, and the suitable stocking capacity was low; （4） enclosure should be combined with measures such as weeds removing to reduce the redundancy of grass community components and to improve the stocking capacity of pastures.