Abstract
Abstract. Wild parsnip is an invasive plant that has serious health risks to humans due to the toxin in its sap. Monitoring its presence has been a challenging task for conservation authorities due to its small size and irregular shape. Unmanned Aerial Vehicles (UAV) can obtain ultra-high resolution (UHR) imagery and have been used for vegetation monitoring in recent years. In this study, UAV images captured at Lemoine Point Conservation Area in Kingston, Ontario, are used to test a methodology for distinguishing wild parsnip. The objective of this study is to develop an efficient invasive wild parsnip classification workflow based on UHR digital UAV imagery. Image pre-processing flow includes image orientation, digital elevation model (DEM) and digital surface model (DSM) extractions, and orthomosaicking using Simactive’s software. Three vegetation indices and three texture features are calculated and added to the mosaicked images as additional bands. Image analysis frameworks namely pixel- and object-based method and three classifiers are tested and the object-based Support Vector Machine (SVM) is selected to distinguish wild parsnip from other vegetation types. The optimal image resolutions are undertaken by comparing accuracy assessments. The results provide an executable workflow to distinguish wild parsnip and show that UAV images, with a simple digital camera, are an appropriate and economic resource for small and irregular vegetation detection. This method yields reliable and valid outcomes in detecting wild parsnip plants and demonstrates excellent performance in mapping small vegetation.
Highlights
Invasive plants are non-native plants to a specific region with a tendency of spreading (Boersma et al, 2006) and can change or destroy the local habitat, affect native plants, and potentially increase human and animal health risks (Paz-Kagan et al, 2019)
The object-based method requires an additional step of image segmentation, it warrants shorter processing time compared to the pixel-based method
This study has developed and tested a simplified object-based method to distinguish wild parsnip in vegetation fields based on Unmanned Aerial Vehicles (UAV) images
Summary
Invasive plants are non-native plants to a specific region with a tendency of spreading (Boersma et al, 2006) and can change or destroy the local habitat, affect native plants, and potentially increase human and animal health risks (Paz-Kagan et al, 2019). Wild parsnip is an invasive plant that grows up to 1.5 m high with umbrella-shaped yellow flowers of diameter up to 15 cm (“Wild parsnip | Ontario.ca,” 2019) (Figure 1). It can be found in large patches or a single plant. The affected area can remain discolored for up to two years (Carlsen and Weismann, 2007). Organizations such as the Ontario Invasive Plant Council have put greater importance on monitoring and controlling wild parsnip (Danielle and Kellie, 2014). Identifying wild parsnip and monitoring its presence in a vast region has been challenging for conservation agencies due to its small size and irregular shape, especially for single scattered plants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
