Aerial photography collected with a multirotor drone reveals impact of Eurasian beaver reintroduction on ecosystem structure

Abstract

Beavers are often described as ecological engineers with an ability to modify the structure and flow of fluvial systems and create complex wetland environments with dams, ponds, and canals. Consequently, beaver activity has implications for a wide range of environmental ecosystem services including biodiversity, flood risk mitigation, water quality, and sustainable drinking water provision. With the current debate surrounding the reintroduction of beavers into the United Kingdom, it is critical to be able to monitor the impact of beavers upon the environment. This study presents the first proof of concept results showing how a lightweight hexacopter fitted with a simple digital camera can be used to derive orthophoto and digital surface model (DSM) data products at a site where beavers have recently been reintroduced. Early results indicate that analysis of the fine-scale (0.01 m) orthophoto and DSM can be used to identify impacts on the ecosystem structure including the extent of dams and associated ponds, and changes in vegetation structure due to beaver tree-felling activity. Unmanned aerial vehicle data acquisition offers an effective toolkit for regular repeat monitoring at fine spatial resolution, which is a critical attribute for monitoring rapidly changing and difficult to access beaver-impacted ecosystems.Résumé : On décrit souvent les castors comme étant des ingénieurs ayant la capacité de modifier la structure et le débit des systèmes fluviaux et de créer des environnements de milieux humides complexes avec des barrages, des étangs et des canaux. Par conséquent, les activités des castors ont des répercussions sur une vaste gamme de services écosystémiques y compris la biodiversité, l'atténuation des risques d'inondation, la qualité des eaux et l'approvisionnement durable en eau potable. Au moment où un débat se déroule sur la réintroduction des castors au Royaume-Uni, il est crucial d'être en mesure de surveiller l'impact qu'ont les castors sur l'environnement. Cette étude présente les premiers résultats de validation de concept montrant comment un hexacoptère léger muni d'un appareil photonumérique simple embarqué peut servir à prélever des données orthophotos et des modèles numériques de surface (DSM) d'un site où on a réintroduit les castors. Les résultats préliminaires indiquent qu'on peut utiliser les analyses des orthophotos et des DSM à petite échelle (0.01 m) afin de déterminer les impacts sur les structures écosystémiques y compris l'étendue des barrages et des étangs reliés, et les changements de la structure de la végétation attribuables aux activités des castors relativement

Individual Tree Detection from Unmanned Aerial Vehicle (UAV) Derived Canopy Height Model in an Open Canopy Mixed Conifer Forest

“…In particular, UAV equipped with consumer-grade onboard system camera and different sensors have been used to estimate tree counts, tree heights and crowns measurements due to its low cost and faster performance compared to traditional methods [22,23,[69][70][71][72][73][74]. In this paper, we present a simplified framework for automated ITD from UAV-SfM derived CHM based on algorithms designed for LiDAR data processing.…”

Sediment and nutrient storage in a beaver engineered wetland

“…In the presented figures this constructed pond is displayed as Pond 8a and has since expanded to cover the area labelled 8b, which are analysed herein together as pond 8. Beaver activity has created a complex wetland environment, dominated by ponds, dams and an extensive canal network (DWT, 2013; Puttock et al ., 2015). The age of ponds is detailed in Table 1.…”

Wildlife research and management methods in the 21st century: Where do unmanned aircraft fit in?

“…We showed that high-resolution UAS imagery revealed fine-scale wetland habitat cover details that were not detected by ground surveys (Chabot and Bird 2013), leading to conclusions about breeding habitat associations of the threatened least bittern (Ixobrychus exilis) that may otherwise have been overlooked using strictly conventional data collection methods (Chabot et al 2014). Puttock et al (2015) report on the use of multirotor UAS imagery to assess the impact of Eurasian beaver (Castor fiber) reintroduction on wetland ecosystem structure. Several other studies have focused on the ability to automatically or semi-automatically classify vegetation in high-resolution UAS imagery of wetlands and bogs (Kalacska et al 2013;Knoth et al 2013;Husson et al 2014a;Zweig et al 2015).…”