基于改进ConvNeXt模型与多源遥感数据协同的海南热带雨林树种精细分类方法

Fine classification method for tree species in Hainan tropical rainforest based on an improved ConvNeXt model and multi-source remote sensing data collaboration

  • 摘要: 热带雨林树种精细分类是评估生态功能与生物多样性的重要基础。针对单一遥感数据源难以解决雨林“异物同谱”的难题, 以及常规卷积神经网络在多源特征利用上的局限, 提出一种融合CBAM注意力机制的ConvNeXt模型, 以海南热带雨林国家公园为研究区, 协同谷歌地球亚米级影像的空间细节与四个时相的Sentinel-2影像的物候光谱特征, 实现树种高精度分类。该模型通过通道与空间注意力机制自适应增强关键特征响应, 提升了对多源异构数据的判别能力。结果表明: (1)相较于单时相数据, 多时相Sentinel-2数据能有效捕捉树种物候演变规律, 使ConvNeXt-CBAM模型总体精度从66.41%提升至89.06%;(2)多源数据融合的协同效应显著, “高分辨率空间纹理+多时相光谱”策略在各模型上均取得最优性能;(3)在融合数据上, ConvNeXt-CBAM模型总体精度达97.27%(卡帕系数=0.967), 分别比原始ConvNeXt、ResNet-18高出1.57和2.35个百分点, 证实了注意力机制对复杂多源特征判别力的增强作用。研究为海南热带雨林国家公园的树种分类、生态监测与可持续经营提供了技术支持。

     

    Abstract: Although tropical rainforests cover only about 6% of the Earth′s land surface, they harbor more than 50% of the world′s known species and store approximately 25% of the terrestrial vegetation carbon stock, playing an irreplaceable role in maintaining global ecological security. It is essential to accurately obtain the spatial distribution of tree species composition within such ecosystems, as it forms the core foundation for assessing ecosystem functions, monitoring biodiversity, and estimating forest carbon stocks. Due to the widespread phenomena of "same species with different spectra" and "different species with the same spectrum" in rainforest environments, traditional single-source remote sensing data often struggle to provide sufficient spectral and textural discriminative information. Furthermore, conventional convolutional neural networks (CNNs) have inherent limitations in deep feature extraction and multi-modal data synergy, resulting in inadequate generalization capabilities when dealing with highly heterogeneous forest backgrounds. These challenges severely constrain the accuracy of fine-scale tree species classification and the reliability of large-scale mapping applications. Taking the Bawangling and Wuzhishan areas of Hainan Tropical Rainforest National Park as the study region, this research proposes a ConvNeXt model integrated with a Convolutional Block Attention Module (CBAM) for tree species classification in tropical rainforests. By adaptively enhancing the spatial and channel discriminability of feature maps through a dual attention mechanism, the model significantly improves the extraction, fusion, and weighting of multi-source features. Additionally, the synergistic fusion of spatial detail information from Google Earth sub-meter imagery with the temporal spectral characteristics of multi-temporal Sentinel-2 imagery further enhances the accuracy of tropical rainforest tree species classification. The results demonstrate that: 1) Multi-temporal Sentinel-2 data can effectively capture the phenological evolution patterns of different forest stands, achieving better classification accuracy than single-temporal Sentinel-2 data. 2) Multi-source data fusion serves as a crucial approach to overcoming the bottleneck in tree species identification. The synergistic strategy combining "high-resolution spatial details with multi-temporal spectra" outperforms all single-source data schemes in classification performance. 3) The proposed ConvNeXt-CBAM model achieves an overall classification accuracy of 97.27% when processing Google Earth sub-meter imagery, multi-temporal Sentinel-2 data, and multi-source heterogeneous data, which substantially outperforms classic models such as the original ConvNeXt, ResNet-18, and DenseNet-121. These results fully demonstrate that the CBAM attention mechanism can significantly enhance the model′s discriminative capability for complex multi-source features by suppressing background noise and strengthening key feature responses. This study provides reliable technical pathways for tree species classification in complex tropical forest environments, as well as effective support for ecological monitoring, carbon accounting, and sustainable management in Hainan Tropical Rainforest National Park.

     

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