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青藏高原东缘高寒湿地时空演化机制研究

Exploring the spatiotemporal change mechanism of alpine wetlands on the eastern Qinghai-Tibet Plateau

  • 摘要: 青藏高原东缘湿地是全球重要的生态屏障,在气候变化与人类活动的双重胁迫下,湿地生态系统正面临逆向演替、干旱化、沙化等环境问题。本研究基于谷歌地球引擎(GEE)计算平台,集成高分辨率影像、多源地球科学数据集和野外调查样本,采用面向对象分类(OBIA)、逻辑回归(LR)和最大熵(MaxEnt)模型,系统评估了青藏高原东缘高寒湿地的时空分异特征及其关键驱动因子。研究结果表明,采用OBIA进行高寒湿地分类时,当影像分辨率由30 m提高到5 m时,分类精度呈现提高−饱和−下降的变化规律,当影像分辨率为10 m时(尺度为26)可以准确识别沼泽湿地的结构和空间分布特征。基于此计算出湿地资源总量为174545.6 hm2;湿地分布受气候(气温、降水量)、地形(海拔、坡度)及人类活动(道路密度、居民点分布)多因子协同驱动,其中500 m空间尺度下的驱动力解析效能最优(线下面积为0.81);证实了气候因子主导长期变化,而人类活动显著影响生态格局。2021—2040年,低碳排放情景下湿地极适宜区面积比高排放情景高了1.66%,升温导致非常高适宜区向高海拔收缩,面积减少了3.91%;2041—2060年,随着气温的上升,非常高适宜区面积逐渐减少;2081—2100年,极适宜区和非常高适宜区面积分别减少了0.75%和3.47%;在高碳排放情景下,高海拔地区气温上升使得湿地分布的适宜性提高。本研究提出了一种基于GEE平台的OBIA高寒湿地资源估算方法,整合逻辑回归和MaxEnt模型揭示了高寒湿地的时空分异机制,为青藏高原湿地研究提供了一种有效的技术框架。

     

    Abstract: The wetlands on the eastern Qinghai-Tibet Plateau (EQXP) are a vital global ecological barrier. However, under the dual pressures of climate change and human activities, these wetland systems face environmental challenges such as retrogressive succession, aridification, and desertification. This study utilized the Google Earth Engine (GEE) remote sensing cloud computing platform, and integrated high-resolution imagery, multi-source geoscience datasets, and field survey samples. By employing object-based image analysis (OBIA), logistic regression, and MaxEnt models, we systematically assessed the spatiotemporal dynamics of alpine wetlands in the EQTP and their key driving factors. The results showed that when classifying alpine wetlands using OBIA, the classification accuracy improved, saturated, and fragmented as the image resolution increased from 30 m to 5 m. At a resolution of 10 m (Scale=26), the structure and spatial distribution of marsh wetlands could be accurately identified, with a total wetland area of 174545.6 hm2. Wetland distribution was driven by a combination of climatic factors (temperature, precipitation), topographic factors (elevation, slope), and human activities (road density, settlement distribution). The optimal spatial scale for analyzing these driving forces was 500 m (AUC=0.81), confirming that climatic factors dominate long-term changes, while human activities significantly influenced ecological patterns. From 2021 to 2040, the area of highly suitable wetland zones under low-emission scenarios was larger than under high-emission scenarios, with warming causing the contraction of highly suitable zones (very high) to higher altitudes. From 2041 to 2060, the area of excellently suitable wetland zones decreased as regional temperatures rise. From 2081 to 2100, high carbon emission scenarios led to warming in the high-altitude regions of the study area, increasing the suitability for wetland distribution. This study proposes a GEE-based OBIA method for estimating alpine wetland resources, integrating logistic regression and MaxEnt to reveal the spatiotemporal dynamics of alpine wetlands, providing an effective technical framework for wetland research on the Qinghai-Tibet Plateau.

     

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