摘要:明确植物群落退化阈值，进而划分草甸退化程度对指导高寒草甸退化修复有重要意义。为建立识别植物群落退化阈值的方法，并基于阈值划分草甸退化程度，于2018年在云南省香格里拉市选取受人类活动干扰严重的典型高寒草甸开展植物群落调查，然后在地理编码的基础上用Mann-Kendall突变检验识别植物群落的结构指标（物种丰富度，R；优良牧草综合优势度，P_SDR）和功能指标（地上生物量，AGB）的突变点，这些突变点即植物群落结构指标和功能指标的变化阈值。据此划分高寒草甸植物群落的退化程度。结果表明：1）研究区内草甸植物群落R的变化阈值为10种、13种和17种；P_SDR的变化阈值为0.25、0.30和0.39；植物群落AGB的变化阈值为31.98 g/m²和91.68 g/m²；2）研究区内高寒草甸植物群落退化等级可划分为"基本退化类型"和"过渡退化类型"两大类。其中，"基本退化类型"包括三类：I级退化，即13种≤ R<17种、0.30 ≤ P_SDR<0.39、31.98 g/m² ≤ AGB<91.68 g/m²；II级退化，即10种≤ R<13种、0.25 ≤ P_SDR<0.30、31.98 g/m² ≤ AGB<91.68 g/m²；III级退化，即R<10种、P_SDR<0.25、AGB<31.98 g/m²；"过渡退化类型"为介于3个基本退化类型之间的类型，包括四类：1）I级正向过渡，即I级退化向健康草甸过渡阶段；2）I级反向过渡阶段，即I级退化向II级退化过渡阶段；3）II级反向过渡阶段，即II级退化向III级退化过渡阶段；4）III级正向过渡阶段，即III级退化向II级退化过渡阶段。本研究表明，可基于地理编码和突变分析识别高寒草甸植物群落结构和功能指标的退化阈值，进而客观、完整地划分高寒草甸植物群落的退化阶段，为其生态修复提供支撑。



Abstract:The classification of degradation level according to degradation thresholds is crucial to guide the restoration of alpine meadows. In order to establish a method to identify the degradation thresholds of plant communities and classify meadow degradation levels, a field survey was conducted in a typical alpine meadow in Shangri-La, Yunnan Province, which was seriously disturbed by tourism in 2018. Based on the process of geo-coding, a Mann-Kendall abruption test was used to identify the tipping points of structural (species richness, R; summed dominance ratio of preferred herbage, P_SDR) and functional indexes (aboveground biomass, AGB) of plant communities, which were used as the change thresholds of structural and functional indexes of meadow plant communities. And the degradation level of meadow plant communities was classified according to these tipping points. The results indicated that:1) the tipping points of species richness of the alpine meadow in the study area were 10, 13 and 17, respectively. The tipping points of the P_SDR were 0.25, 0.30 and 0.39, respectively. And the tipping points of AGB were 31.98 g/m² and 91.68 g/m², respectively. 2) The plant community could be divided into primary degradation type and transitional degradation type. The primary degradation type included three sub-types:degradation level I, i.e., 13 ≤ R<17, 0.30 ≤ P_SDR<0.39 and 31.98 g/m² ≤ AGB<91.68 g/m²; degradation level II, i.e., 10 ≤ R<13, 0.25 ≤ P_SDR<0.30, and 31.98 g/m² ≤ AGB<91.68 g/m²; and degradation level III, i.e., R<10, P_SDR<0.25 and AGB<31.98 g/m². The transitional degradation type was the type whose degradation level was between each two primary degradation types, which included four sub-types:1) positive transition from level I, i.e., the meadow's situation changed from degradation level I to a healthy status; 2) negative transition from level I, i.e., the meadow's situation changed from degradation level I to level Ⅱ; 3) negative transition from level Ⅱ, i.e., the meadow's situation changed from degradation level Ⅱ to level Ⅲ; and 4) positive transition from level Ⅲ, i.e., the meadow's situation changed from degradation level Ⅲ to level Ⅱ. Our results suggest that the degradation thresholds of structural and functional indexes of alpine meadow plant communities can be identified according to a geo-coding based on abruption analysis. The degradation level of meadow plant communities, there by, can be classified more objectively and integrally according to these thresholds. And then, the method will support ecological restoration of alpine meadows.





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