Saving species, time and money: Application of unmanned aerial vehicles (UAVs) for monitoring of an endangered alpine river specialist in a small nature reserve

• Published in: Biological conservation Vol. 233; pp. 162 - 175
• Main Authors: Woellner, Romy, Wagner, Thomas C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2019
• Subjects: Alps region; bedload; case studies; computer software; Conservation; conservation areas; cost effectiveness; data collection; dead wood; decision making; environmental factors; extinction; floodplains; geographic information systems; Germany; habitats; monitoring; natural capital; remote sensing; risk; River restoration; rivers; stream channels; terraces; UAV application; unmanned aerial vehicles; vegetation cover; Vegetation mapping; Alps region; Germany; River restoration; UAV application; Vegetation mapping; Conservation
• DOI: 10.1016/j.biocon.2019.02.037
• ISSN: 0006-3207

The increasing importance of conservation and restoration of our natural capital is associated with a growing demand for reliable and cost-effective scientific data to support decision making and monitoring of implemented measures. Such data include information about habitats, abiotic conditions and disturbances. The small extent or small-scale structure of most restoration sites requires a high spatial resolution exceeding that provided by standard satellite imagery. When the site is still unstable during the initial phase or when frequent disturbance is expected, additionally a high temporal resolution is required. In this case study, we demonstrate the usefulness of a UAV (unmanned aerial vehicle) for monitoring river and floodplain restoration based on a conservation project aimed to preserve Germany's last remaining population of the highly endangered alpine river plant C. chondrilloides. This population is confined to a small, 5 ha area within a highly dynamic alluvial fan in the Bavarian Alps. We used the data acquired by UAV to monitor stream channel dynamics, to quantify bedload transport, erosion and deadwood structures and to characterize vegetation cover and height with the aim of identifying types and loss of habitats and consequently estimating extinction risk. The results show a highly dynamic stream channel and considerable bedload transport and erosion between flood events. The majority of the remaining C. chondrilloides population is found on terraces which are prone to erosion and escape habitats are missing. Between 2016 and 2017 we documented a loss of almost 25% of the species' potential habitats due to erosion events. Three percent of the existing population was lost to those events. Substantial spread of the species was only at the edge terrace which is subject to a high risk of extinction. Our study further demonstrates that many important parameters for the implementation of evidence-based conservation can be easily and cost-effectively derived from standard RGB images taken by UAVs and GIS software. As a consequence, we encourage the increased use of UAVs for restoration and monitoring practice.