利用无人机遥感技术结合采样开展水生植物调查——以滇池大泊口水域为例

Surveying the Composition,Coverage,and Biomass of Aquatic Vegetation by Unmanned Aerial Vehicle and Sampling Survey:Lake Dapokou of Lake Dianchi as An Example

水生植物对改善水环境、维持生态系统正常功能具有不可替代的作用,恢复水生植物已成为湖泊生态修复中最重要的手段之一。准确高效地调查水生植物的组成、盖度和生物量是评价水生态系统的健康状况、开展和评价受损湖泊生态修复的基础。基于固定样点采样的水生植物调查方法(如网格法)劳动强度大,且无法准确反映水生植物的整体分布状况,而无人机遥感技术在此方面有非常大的应用前景。基于此,文章拟开发无人机遥感技术和采样调查相结合的水生植物监测方法,并应用于滇池大泊口水域。首先对无人机遥感影像进行校正和拼接,获得整个水域的遥感影像。通过影像分析,共分辨出74个相互独立的斑块,分别鉴定为挺水植物莲(Nelumbo nucifera)、香蒲(Typha orientalis)和菰(Zizania latifolia),浮叶植物莕菜(Nymphoides peltata)、野菱(Trapa incisa)和睡莲(Nymphaea spp.),以及沉水植物穗状狐尾藻(Myriophyllum spicatum)和艾格草(Egeria densa)。根据不同斑块的类型和面积,计算出大泊口水域水生植物盖度为17.23%,其中挺水、浮叶和沉水植物的层盖度分别为3.30%、5.29%和10.05%。结合采样调查,计算出水生植物总生物量为676 t,其中挺水、浮叶和沉水植物的生物量分别为90、97、489 t。无人机遥感结合针对性的采样调查,能准确获得水生植物在整个水域的分布和生物量信息,为水生植物的调查和研究提供强有力的支持。该方法特别适合水生植被恢复的重点水域的水生植被生物量和盖度常规监测。

Aquatic plants play an key role in improving the water environment and maintaining the normal functions of the ecosystem.Restoring aquatic plants has become one of the most important methods in lake ecological restoration.Accurately and efficiently investigating the composition,coverage and biomass of aquatic plants is essential for the evaluation of the health status of aquatic ecosystems and for the evaluation of the ecological restoration of degraded water bodies.The investigation method of aquatic plants based on fixed samples(such as grid method)is labor-intensive and cannot provide the accurately information of spatial distribution of aquatic plants on the whole lake scale.Unmanned aerial vehicle(UAV)remote sensing technology has a great application prospect in aquatic plant investigation.This research intends to develop an aquatic plant monitoring method combining UAV remote sensing technology and sampling survey,and the method has been applied to the survey of Lake Dapokou of Lake Dianchi.Firstly,the UAV remote sensing image is corrected and spliced to obtain the remote sensing image of the whole water body.Through image analysis,74 independent patches were classified into 8 groups,corresponding to Nelumbo nucifera,Typha orientalis and Zizania latifolia,Nymphoides peltata,Trapa incise,Nymphaea spp,Myriophyllum spicatum and Egeria densa.According to the area and plant density of different plaques,the coverage of aquatic plants in Lake Dapokou was calculated to be 17.23%,among which the coverage of emergent,floating and submerged plants was 3.30%,5.29%and 10.05%,respectively.Combined with sample monitoring,the total biomass of aquatic plants was calculated to be 676 t,among which the biomass of emergent,floating and submerged plants was 90 t,97 t and 489 t,respectively.The accuracy of UVA remote sensing was much higher than boat-based sampling methods for the investigation of aquatic plants.UAV remote sensing combined with targeted sampling surveys can accurately monitoring the distribution and biomass of aquatic plants on the whole lake scale,which would definitely promote the survey and research of aquatic plants.This method is particularly suitable for routine monitoring of aquatic vegetation biomass and coverage in key water areas for aquatic vegetation restoration.