A comparative study on intra-annual classification of invasive saltcedar with Landsat 8 and Landsat 9

• Published in: International journal of remote sensing 2023-03, Vol.44 (6), p.2093-2114
• Main Authors: Li, Ruixuan, Wang, Le, Lu, Ying
• Format: Article
• Language: English
• Subjects: Algorithms; Classification; Comparative analysis; Comparative studies; Ecological effects; Image acquisition; Landsat; Machine learning; Remote sensing; Satellite imagery; Short wave radiation; Support vector machines; Tamarix africana; Windows (intervals)
• ISSN: 0143-1161; 1366-5901
• DOI: 10.1080/01431161.2023.2195573

The rapid expansion of exotic saltcedar along riparian corridors has dramatically altered the landscape structure and ecological function of riparian habitats in the western United States. The development of accurate and reproducible mapping methods with remote sensing plays an indispensable role in the timely monitoring of saltcedar, re-evaluating its ecological functions, and establishing effective control measures. The utmost challenge for achieving this goal is manifested as the lack of time series of remote sensing images to capture the saltcedar phenology adequately. To this end, the newly available Landsat 9 images, combined with its counterpart of Landsat 8, offer a precious opportunity to compensate for the temporal image shortage. To understand Landsat 9 in the saltcedar classification and to discover helpful information for its application, this study presents the first attempt to classify saltcedar using intra-annual Landsat 8 and Landsat 9 images. We adopted two machine learning algorithms, support vector machine (SVM) and random forest (RF), to compare the performance of Landsat 9 and Landsat 8 for intra-annual saltcedar classification. In addition, we investigated the respective contribution of each spectral band to the overall performance and identified the optimal time window for saltcedar classification. The results indicated that the difference in classification performance between Landsat 9 and Landsat 8 was insignificant. The shortwave infrared bands associated with both Landsat 8 & 9 have contributed most to the process of saltcedar identification. Image acquired in July, November, and December yielded better results than other months for saltcedar classification. It is concluded that Landsat 8 & 9 constellation has the potential to refine saltcedar classification accuracy on larger spatial and temporal scales.