Calviño-Cancela María, Méndez-Rial Roi, Reguera-Salgado Javier, Martín-Herrero Julio
Departament of Ecology and Animal Biology, University of Vigo, Vigo, Galicia, Spain.
Departament of Signal Theory and Communications, University of Vigo, Vigo, Galicia, Spain.
PLoS One. 2014 Jul 10;9(7):e102381. doi: 10.1371/journal.pone.0102381. eCollection 2014.
Effective management of invasive plants requires a precise determination of their distribution. Remote sensing techniques constitute a promising alternative to field surveys and hyperspectral sensors (also known as imaging spectrometers, with a large number of spectral bands and high spectral resolution) are especially suitable when very similar categories are to be distinguished (e.g. plant species). A main priority in the development of this technology is to lower its cost and simplify its use, so that its demonstrated aptitude for many environmental applications can be truly realized. With this aim, we have developed a system for hyperspectral imaging (200 spectral bands in the 380-1000 nm range and circa 3 nm spectral resolution) operated on board ultralight aircraft (namely a gyrocopter), which allows a drastic reduction of the running costs and operational complexity of image acquisition, and also increases the spatial resolution of the images (circa 5-8 pixels/m(2) at circa 65 km/h and 300 m height). The detection system proved useful for the species tested (Acacia melanoxylon, Oxalis pes-caprae, and Carpobrotus aff. edulis and acinaciformis), with user's and producer's accuracy always exceeding 90%. The detection accuracy reported corresponds to patches down to 0.125 m(2) (50% of pixels 0.5 × 0.5 m in size), a very small size for many plant species, making it very effective for initial stages of invasive plant spread. In addition, its low operating costs, similar to those of a 4WD ground vehicle, facilitate frequent image acquisition. Acquired images constitute a permanent record of the status of the study area, with great amount of information that can be analyzed in the future for other purposes, thus greatly facilitating the monitoring of natural areas at detailed spatial and temporal scales for improved management.
有效管理入侵植物需要精确确定其分布范围。遥感技术是实地调查的一种很有前景的替代方法，当需要区分非常相似的类别（如植物物种）时，高光谱传感器（也称为成像光谱仪，具有大量光谱波段和高光谱分辨率）特别适用。这项技术发展的一个主要优先事项是降低其成本并简化其使用，以便能够真正实现其在许多环境应用中已证明的适用性。出于这个目的，我们开发了一种高光谱成像系统（在380 - 1000纳米范围内有200个光谱波段，光谱分辨率约为3纳米），该系统安装在超轻型飞机（即旋翼机）上运行，这使得图像采集的运行成本和操作复杂性大幅降低，同时还提高了图像的空间分辨率（在约65公里/小时和300米高度时约为5 - 8像素/平方米）。该检测系统被证明对所测试的物种（黑木相思、酢浆草、食用滨藜和剑叶滨藜）有用，用户精度和生产者精度始终超过90%。报告的检测精度对应于小至0.125平方米的斑块（50%的像素尺寸为0.5×0.5米），对于许多植物物种来说这是非常小的尺寸，这使得它在入侵植物传播的初始阶段非常有效。此外，其低运营成本与四轮驱动地面车辆的成本相似，便于频繁进行图像采集。获取的图像构成了研究区域状况的永久记录，包含大量可在未来用于其他目的的信息，从而极大地便于在详细的空间和时间尺度上对自然区域进行监测，以改进管理。
