Unmanned aerial vehicle-based structure from motion biomass inventory estimates

Abstract

Riparian vegetation restoration efforts demand cost effective, accurate, and replicable impact assessments. In this thesis a method is presented using an Unmanned Aerial Vehicle (UAV) equipped with a GoPro digital camera to collect photogrammetric data of a 2.02-acre riparian restoration. A three-dimensional point cloud was created from the photos using Structure from Motion (SfM) techniques. The point cloud was analyzed and compared to traditional, ground-based monitoring techniques. Ground truth data collected using the status-quo approach was collected on 6.3% of the study site and averaged across the entire site to report stem heights in stems/acre in three height classes, 0-3 feet, 3-7 feet, and greater than 7 feet. The project site was divided into four analysis sections, one for derivation of parameters used in the UAV data analysis, and the remaining three sections reserved for method validation. The most conservative of several methods tested comparing the ground truth data to the UAV generated data produced an overall error of 21.6% and indicated an r 2 value of 0.98. A Bland Altman analysis indicated a 99% probability that the UAV stems/plot result will be within 159 stems/plot of the ground truth data. The ground truth data is reported with an 80% confidence interval of +/-844 stems/plot, thus the UAV was able to estimate stems well within this confidence interval. Further research is required to validate this method longitudinally at this same site and across varying ecologies. These results suggest that UAV derived environmental impact assessments at riparian restoration sites may offer competitive performance and value.

Identifying Species and Monitoring Understorey from UAS-Derived Data: A Literature Review and Future Directions

“…In total, we downloaded 131 articles that were then re-checked to assess their relevance. Ultimately, we only found 18 original-research articles that assessed both understorey vegetation and used high resolution remote sensing (Table 1; [1,18,19,22,[36][37][38][39][40][41][42][43][44][45][46][47][48][49]). We reviewed all of them.…”

A Review of Unoccupied Aerial Vehicle Use in Wetland Applications: Emerging Opportunities in Approach, Technology, and Data

“…Restoration projects provide ecosystem services such as habitat for aquatic flora and fauna, improved water quality and quantity [120], and increased carbon storage [56]. In our review, we found fifteen papers that focused on restoration goals, involving seven mapping, two modeling, four change over time, and two novel method studies (Figure 3).…”

“…In our review, we found fifteen papers that focused on restoration goals, involving seven mapping, two modeling, four change over time, and two novel method studies (Figure 3). Although restoration monitoring is a vital component of ecological management, it is rarely prioritized due to time and personnel constraints associated with ground surveys, lags between project implementation and data analysis, and the need for high-resolution data [26,120]. UAVs are tools that enable restoration assessment at the whole-site levels and allow for cost-effective change analysis of restored environments [8,9,121,122] due to their flexibility in flight times and heights and lack of disturbance to sensitive restoration areas [56].…”

“…UAV-based restoration monitoring involves a variety of objectives, including biomass estimates [120], hydrological mapping [8,9,11,123], morphological evaluations [43,57], and classification of plant communities in peatlands [10,56,119,122] and coastal regions [44,117,118,121]. While many researchers leverage RGB aerial imagery for restoration monitoring [8,9,120,122,123], multispectral imagery, and specifically the near-infrared wavelength, which can detect species and topography in shallow wetland environments [155]. This is particularly useful in invasive species identification [121] and peatland biodiversity assessments [56] at restoration sites.…”

Post-variable density treatment monitoring in dry-site mixed conifer stands in unmanned aircraft systems.

“…Unmanned aircraft systems (UAS) technology has been shown to produce quantitative and interpretive data that is meaningful to forest managers in numerous applications and offers a potential solution for increasing efficiency of post-treatment monitoring activities (Bedell et al 2017, Pádua et al 2017, Wing et al 2014. Although the USDA Forest Service has been conservative in the implementation of UAS technology, the 2018 modernization agenda (USDA Forest Service 2018) and a 2018 Executive Order 2 all but ensure eventual integration, making the current era an optimal time to think about how to best leverage this technology.…”