A Novel Method For Surveying Invasive Species Based On Car-carrying Camera And UAV (Unmaned Aerial Vehicle)

Biological invasion is one of major threats to biodiversity. Monitoring of invasive species is critical for effective management. Current survey methods of invasive plants include field survey and remote sensing, Field survey is time- and labor-demanding, Remote sensing is less effective for scattered distributed invasive species, In this study, car-carrying camera and UAV (Unmanned Aerial Vehicle), combined with image analysis, were proposed to survey invasive plants.The target species is Tithonia diversifolia, which produces yellow flowers in winter and thus is easily to be identified from background, In Yunnan, Tithonia spreads along roads,resulting in linear distribution, and form large dense monoculture, Accordingly, car-carrying camera and UAV were used to monitor the linear and monoculture distribution, respectively, Specifically, a) pictures were produced using car-carrying camera or UAV in the targeted area; b) pictures were analyzed using software, combined with manual check, screening out all the images of target species; c) the selected pictures were further analyzed using HOLUX and Photoscan, and the data of distribution were calculated based on the results of image modeling, Based on the distribution data (field and specimen data), I modeled the potential distribution of T. diversifolia in Yunnan, using Maxent and GARP methods.The results are as follows:1)This new method based on car-carrying camera and UAV perform well in monitoring of invasive Tithonia diversifolia;2) The car-carrying camera can identify the target species with a high success rate,with an error rate of 12.77% and 4.64% along roads with various levels when the car speed was between 40-80 km/h,. The data based on UAV produced similar results comparing with field survey, with an error rate of 7.28% and 2.44% in 70 and 400 m2 plot, respectively;3) The potential distribution of T. diversifolia in Yunnan was produced by Maxent and GAPR, with the AUC values were 0.904 and 0.814, respectively, Factor analysis showed that,in Yunnan,the potential distribution of T. diversifolia was sensitive to temperature, followed by altitude, and was relatively insensitive to precipitation.Taken together, these results validate the effectiveness of the method based on car-carrying camera and UAV in surveying invasive plants like T. diversifolia, Comparing to field survey, this new method was cost-effective and highly efficient, which is highly suitable for monitoring. This method needs pictures by camera or UAV, thus is not suitable for invasive species under dense canopy. As the identification of invasive species by software is affected by the contrast between target object and community background, it may be not effective for species without prominent color (e.g. flowers) and need to be improved in further studies.