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博斯腾湖湿地芦苇株高遥感反演及空间分布特征研究

Remote sensing inversion of reed height and spatial distribution characteristics in the Bosten Lake Wetland

  • 摘要: 芦苇(Phragmites australis)作为新疆博斯腾湖湿地的优势种,其生长状况对于湿地动态变化及生态功能具有重要影响。卫星遥感是监测大面积芦苇动态变化的有效工具,为了研究博斯腾湖湿地芦苇的株高和空间分布特征,基于2023年9月的Sentinel-1A/2A遥感影像并结合无人机及野外实测数据,以人工目视解译和野外调查采样作为判别依据,构建机器学习模型,以实现芦苇株高的遥感反演和空间特征提取。研究结果表明,博斯腾湖湿地芦苇面积为422.55 km2,主要分布在黄水沟、大湖西岸、落霞湾、苦水沟、博斯腾湖南岸小湖湿地等区域,形成了环湖及沿河连续狭长的带状分布格局,与水体呈密切邻接关系,除了在大湖西岸和开都河周边呈破碎化外,在其他地区均形成了规模化分布和显著集中群落。利用机器学习算法构建多个特征组合下的芦苇株高反演模型,其中拟合效果最好的是随机森林回归模型,决定系数R2为0.87,均方根误差RMSE为0.50 m,平均绝对误差MAE为0.29 m,依据植株高度差异可分为低矮型、中低型、中高型和高大型4类,面积分别为4.47 km2、73.41 km2、160.04 km2和184.63 km2,自然区芦苇生长状况整体优于人工苇区。研究结果可为博斯腾湖湿地芦苇研究提供理论参考。

     

    Abstract: As the dominant species in Bosten Lake Wetland of Xinjiang, Phragmites australis plays a vital role in the wetland dynamic evolution and ecological functional maintenance, and its growth status directly reflects the health level of the wetland ecosystem. Satellite remote sensing technology has become an efficient and reliable means to monitor the dynamic changes of large-scale reed vegetation, which can overcome the limitations of traditional field surveys such as small monitoring range and high time cost. To systematically explore the height characteristics and spatial distribution patterns of reeds in the Bosten Lake Wetland, this study adopted multi-source data including Sentinel-1A/2A satellite remote sensing images acquired in September 2023, unmanned aerial vehicle (UAV) imagery, and field measured data. Taking artificial visual interpretation and field sampling surveys as the discrimination basis, multiple machine learning models were constructed to realize the remote sensing inversion of reed height and the extraction of reed spatial distribution characteristics. The results showed that the total reed coverage area of Bosten Lake Wetland was 422.55 km2. Reeds were mainly distributed in multiple typical wetland areas including the Huangshui Ditch, the west bank of the main lake, the Luoxia Bay, the Kushui Ditch, and the small lake wetland on the southern bank of Bosten Lake. The overall spatial distribution presented a continuous and narrow zonal pattern around the lake and along the rivers, showing a tight adjacency relationship with the water body. Except for the fragmented reed distribution in the west bank of the main lake and the surrounding areas of the Kaidu River, large-scale and densely distributed reed communities were formed in other wetland regions. In this study, several optimal reed height inversion models under different feature combinations were constructed based on multiple machine learning algorithms. Among all the established models, the random forest regression model exhibited the best fitting performance. The precision evaluation results indicated that the coefficient of determination (R2) of the optimal model reached 0.87, while the root mean square error (RMSE) and mean absolute error (MAE) were 0.50 m and 0.29 m, respectively, demonstrating high stability and prediction accuracy of the model. The statistical results of the reed area showed that the total reed coverage area of Bosten Lake Wetland was 422.55 km2. According to the difference in plant height, reeds were classified into four growth types, namely low-type, medium-low type, medium-high type, and high-type, with corresponding areas of 4.47 km2, 73.41 km2, 160.04 km2, and 184.63 km2, respectively. In addition, the overall growth condition of reeds in the natural wetland area was superior to that in the artificially managed reed area. This study clarifies the spatial distribution law and height differentiation characteristics of reeds in the Bosten Lake Wetland, and constructs a high-precision reed height inversion model, which can provide a reliable theoretical reference and technical support for the ecological protection, vegetation monitoring, and scientific management of reed resources in the Bosten Lake Wetland.

     

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