| 西藏退化草地植被和土壤特征及其关系 |
| 摘要点击 2163 全文点击 517 投稿时间：2023-09-18 修订日期：2023-12-08 |
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| 中文关键词 西藏草地退化 植被指标 土壤理化性质 相关性 随机森林 |
| 英文关键词 Xizang grassland degradation vegetation indicators soil physical and chemical properties correlation random forest |
| DOI 10.13227/j.hjkx.20240934 |
| 作者 | 单位 | E-mail | | 李晴婉 | 中国林业科学研究院高原林业研究所, 昆明 650233
南京林业大学风景园林学院, 南京 210037 | liqingwan1130@163.com | | 古晋锴 | 中国林业科学研究院高原林业研究所, 昆明 650233
南京林业大学风景园林学院, 南京 210037 | | | 李庆琳 | 云南大学国际河流与生态安全研究院, 昆明 650504 | | | 李婉池 | 中国林业科学研究院高原林业研究所, 昆明 650233
南京林业大学风景园林学院, 南京 210037 | | | 向生建 | 中国林业科学研究院高原林业研究所, 昆明 650233
南京林业大学风景园林学院, 南京 210037 | | | 唐国勇 | 中国林业科学研究院高原林业研究所, 昆明 650233 | tangguoyong1980@caf.ac.cn |
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| 中文摘要 |
| 为探究区域尺度上西藏草地退化特征,收集西藏第二次草原普查成果中草地退化数据及国家青藏高原科学数据中心12个植被和土壤参数数据,利用ArcMap在栅格数据上随机选取10 000个样点（剔除非草地、 沙化和盐碱化草地数据,剩余7 949个有效样点）,采取多值提取到点的方法提取每个样点退化和参数数据,分析西藏退化草地植被和土壤特征及其关系,并基于以上指标进行随机森林建模来预测草地生态系统变化趋势. 结果表明：①西藏草地主要以高寒草原类和高寒草甸类为主,分别占有效样点45.83%和41.15%；②随草地退化程度加剧,在17个草地类型中,草地型种类的数量逐渐下降,以紫花针茅（Stipa purpurea）和青藏苔草（Carex moorcroftii）等为优势物种的草地型占比下降,杂类草和金露梅（Dasiphora fruticosa）等占比增加；③随退化程度加剧,植被指标普遍呈下降趋势,土壤全氮、 全磷、 全钾和有机碳降低,土壤pH和容重升高,土壤水分变化不明显；④土壤水分、 全氮、 全磷、 全钾、 有机碳、 植被覆盖度、 植被净初级生产力、 归一化植被指数、 地上生物量和生物多样性生境指数之间均呈正相关关系,但与土壤pH和容重呈负相关关系,且随退化程度加剧,各指标之间的相关系数降低；⑤随机森林模拟结果表明,在退化过程中土壤容重和生物多样性生境指数的贡献率均超过12%,模型预测准确率达到78%. 研究揭示西藏草地退化主要与土壤容重和生物多样性生境指数密切相关,即土壤容重越大或生物多样性生境指数越小,草地退化程度可能越重,可为以后草地保护与管理提供科学依据. |
| 英文摘要 |
| To investigate the characteristics of grassland degradation on a regional scale in Xizang, data on grassland degradation from the second grassland survey of Xizang and 12 vegetation and soil indicators from the National Tibetan Plateau Data Center were collected. Using ArcMap, 10 000 random sample points were selected on raster data （excluding non-grassland, desertification, and salinization data, leaving 7 949 valid sample points）. The multi-value extraction to-point method was applied to extract degradation and indicator data for each sample point. The characteristics of degraded grassland vegetation and soil and their relationships were analyzed in Xizang. Moreover, random forest modeling was conducted to predict the trend of grassland ecosystem changes. The results indicated that： ① The grasslands in Xizang were primarily composed of alpine steppe and alpine meadow types, accounting for 45.83% and 41.15% of the valid sample points, respectively. ② With the intensification of grassland degradation, the number of steppe-type species among the 17 grassland types gradually decreased, and the proportion of steppe dominated by species such as Stipa purpurea and Carex moorcroftii decreased, whereas the proportion of miscellaneous grasses and Dasiphora fruticosa increased. ③ As the degree of degradation increased, vegetation indicators generally showed a declining trend, with soil total nitrogen, total phosphorus, total potassium, and organic carbon decreasing, whereas soil pH and bulk density increased, and soil moisture content was not significant. ④ A positive correlation exists between soil moisture content, total nitrogen, total phosphorus, total potassium, organic carbon, vegetation cover, net primary productivity of vegetation, normalized difference vegetation index, aboveground biomass, and habitat quality. However, there was a negative correlation between pH and soil bulk density, and the correlation coefficients among various indicators decreased with the intensification of degradation. ⑤ The random forest simulation results showed that during the degradation process, the contribution rates of soil bulk density and habitat quality both exceeded 12%, with the model prediction accuracy reaching 78%. The study revealed that grassland degradation in Xizang was closely related to soil bulk density and habitat quality, indicating that higher soil bulk density or lower habitat quality may correspond to more severe grassland degradation. This provides a scientific basis for future grassland conservation and management. |
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