首页 > , Vol. , Issue () : -
山地生态系统的自然特征和服务功能与其自身的垂直自然带分布有着密切的关系,定量识别其分布的海拔范围,能够快速捕捉气候和植被之间的相互作用结果。过渡范围海拔的定量识别往往会受到数据的时空连续性和模型分析能力的限制。本研究将温带荒漠、山地草原、山地针叶林、高山草甸、高山垫状植被作为生态系统稳定状态,利用Landsat-8和SRTM DEM数据,基于稳态转换原理结合势能分析方法,估算垂直自然带相邻两个状态的势能量,识别博格达北坡垂直自然带的生态过渡区域及分带海拔。研究结果：(1)沿海拔梯度,LST概率密度分布呈现多峰模式,赤池信息准则(Akaike Information Criterion,AIC)最小值对应的模式数为2,二者均揭示存在不同的生态系统状态；(2)势能分析识别出沿海拔梯度相邻垂直自然带间的生态过渡区域及分带海拔,温带荒漠带-山地草原带(海拔1062-1093 m, 1066 m),山地草原带-山地针叶林带(海拔1689-1764 m,1707 m),山地针叶林带-高山草甸带(海拔2690-2744 m,2714 m),高山草甸带-高山垫状植被带(海拔3251-3263 m,3257 m)；(3)通过2018年7月的野外考察数据验证了结果的可靠性,总体RMSE为19.19。结果表明基于遥感对地观测数据及生态多稳态原理和势能分析方法为快速准确的提取垂直自然带的生态过渡区域及分带的海拔位置提供了参考依据。
The distribution of altitudinal natural zones is closely related to the natural characteristics and service functions of mountain ecosystems. Quantitative identification of its elevation range can efficiently capture the results of the interaction between climate change and vegetation. Digital extraction and extensive analysis in such a critical elevation range is often restricted by the suitability of the experimental model and the spatial-temporal continuity of the data. In this study, temperate deserts, montane steppes, montane coniferous forests, alpine meadows and alpine cushion vegetation were considered as ecosystem states. The land surface temperature was derived from Landsat 8 Thermal Infrared Sensor（TIRS）data using the mono-window algorithm. Latent class analysis was used to test whether the remotely sensed indicator exhibited a multi-peak mode and to evaluate the number of states in actual ecosystem. The potential energy of two adjacent states of the altitudinal natural zone was estimated by the potential energy analysis model, and the ecological transition range and demarcation elevation on the northern slope of Bogda were identified. The results showed that the frequency distribution of LST was bimodal (two adjacent states, temperate desert- montane steppes: approximately 38°C, 43°C, montane steppes- montane coniferous forests: approximately 24°C, 28°C, montane coniferous forests-alpine meadows: approximately 20°C, 28°C, alpine meadows- alpine cushion vegetation : approximately 27°C, 30°C), which indicates that there were distinct alternative modes. At the same time, the number of system modes changed from 1 to 2, the AIC decreased rapidly. Then, the AIC fluctuated slightly but remained stable. Both of them revealed the existence of different ecosystem states. Secondly, potential energy analysis was used to identify the ecological transition area and demarcation elevation between adjacent altitudinal natural zones along the elevation gradient, temperate desert-montane steppes (transition range: 1062-1093 m, demarcation elevation: 1066 m), montane steppes-montane coniferous forests (transition range: 1689-1764 m, demarcation elevation: 1707 m), montane coniferous forests-alpine meadows (transition range: 2690-2744 m, demarcation elevation: 2714 m), alpine meadows-alpine cushion vegetation (transition range: 3251-3263 m, demarcation elevation: 3257 m). Taking temperate desert- montane steppes as an example, the two ecosystem states co-occurred within the elevation range of 1062–1093 m, which is a transition from temperate desert to montane steppes. The shifts of the ecosystem states along the elevation gradient started at the elevation of 1066 m. There was also an abrupt and discontinuous critical transition at the elevation of 1093 m. Finally, the reliability of the results was verified by fieldwork data in July 2018, and the overall RMSE was 19.19. In this study, the remotely sensed indicator and the principle of ecological stable states, combined with the potential energy analysis method, it provides a reference basis for quickly and accurately extracting the ecological transition range and demarcation elevation of the altitudinal natural zones.