藏香猪翻拱型放牧对不同类型高寒草甸植物特征的影响及土壤环境驱动力

生态系统脆弱的高寒草甸是生态学研究的热点。藏香猪翻拱土壤并取食地下草根层,是藏族自治区一种特有的放牧类型,关于该放牧类型对藏区高寒草甸的影响尚缺乏研究。以滇西北高原国际重要湿地——纳帕海流域的典型高寒草甸为对象,研究了不同高寒草甸类型(陆生草甸与沼泽化草甸)中的植物群落结构特征对藏香猪翻拱型放牧的响应。结果表明,翻拱型放牧显著降低了植被盖度(63.5%)、地上生物量(84.6%)与地下生物量(97.4%),并促进植物生物量向地上部分的再分配。翻拱型放牧下随着植被盖度与生物量降低,植物竞争强度减小,植株高度与空间利用率提高。然而,不同草甸类型中的植物群落结构对翻拱型放牧表现出差异响应。陆生草甸上的群落组成基本未变,而沼泽化草甸上的优势植物华扁穗草(Blysmus sinocompyessus)向1年生水生植物水蓼(Polygonum hydropiper)演替。土壤含水率是导致植物响应差异的关键驱动力。综上,藏香猪翻拱型放牧对植物生物量及盖度等特征均产生不利影响,导致高寒草甸生物量积累锐减,而植物群落结构的变化是放牧干扰与土壤水分、空间竞争协同作用的结果,反映出植物在不同环境中对放牧干扰的差异化响应。研究区域环境特征与放牧干扰的耦合关系,可以为藏香猪放牧作用下的高寒草地植物多样性保护及恢复提供理论依据。

The influence of Tibetan pig uprooting on plant community characteristics in different types of alpine meadow and the underlying soil driving forces

The fragile alpine meadow ecosystem is a hotspot for ecological studies. Pig uprooting is characteristic of feeding behaviors on roots below-ground, which is a unique herding pattern in the Tibetan area; yet its impact on Tibetan alpine meadow has not been extensively studied. The study area was Napahai, which is located in the Northwestern Yunnan and belongs to the Ramsar Site of international importance. The responses of plant community characteristics in two alpine meadow types (terrestrial meadow and swamp meadow) to pig uprooting were studied. The results showed that pig uprooting significantly decreased plant coverage (63.5%), above-ground biomass (84.6%), below-ground biomass (97.4%), and promoted the re-distribution of biomass from below-to above-ground. Under pig uprooting, accompanied by decreased plant coverage and biomass, the competition among different species decreased, which increased the plant height and degree of space utilization. We further observed divergent responses of the community structure in two typical alpine meadow types to pig uprooting. The structure remained unchanged in terrestrial meadow, while the dominant plant shifted from Blysmus sinocompyessus to an annual aquatic plant (Polygonum hydropiper) in swamp meadow. Soil moisture was the key driving force explaining the divergent responses of plants to pig uprooting. Overall, pig uprooting was detrimental to plant biomass and coverage, leading to reduced biomass accumulation in the alpine meadow ecosystem. The changed community structure resulted from the synergistic effects among bio-disturbance, soil moisture, and spatial competition, and thus may reflect the divergent responses of plants in different environments to pig uprooting. The study of coupling relationships between regional environments and herding disturbance could provide a scientific basis for plant protection and restoration under Tibetan pig uprooting in alpine meadow.