Using High-Spatial Resolution UAV-Derived Data to Evaluate Vegetation and Geomorphological Changes on a Dune Field Involved in a Restoration Endeavour

Abstract

Nowadays, the employment of high-resolution Digital Surface Models (DSMs) and RGB orthophotos has become fundamental in coastal system studies. This work aims to explore the potentiality of low-cost Unmanned Aerial Vehicle (UAV) surveys to monitor the geomorphic and vegetation state of coastal sand dunes by means of high-resolution (2–4 cm) RGB orthophotos and DSMs. The area of study (Punta Marina, Ravenna, Italy), in the North Adriatic Sea, was considered very suitable for these purposes because it involves a residual coastal dune system, damaged by decades of erosion, fragmentation and human intervention. Recently, part of the dune system has been involved in a restoration project aimed at limiting its deterioration. RGB orthophotos have been used to calculate the spectral information of vegetation and bare sand and therefore, to monitor changes in their relative cover area extension over time, through the using of semi-automatic classification algorithms in a GIS environment. Elevation data from high-resolution DSMs were used to identify the principal morphological features: (i) Dune Foot Line (DFL); (ii) Dune Crest Line (DCL); Dune seaward Crest Line (DsCL); Stable Vegetation line (SVL). The USGS tool DSAS was used to monitor dune dynamics, considering every source of error: a stable pattern was observed for the two crest lines (DCL and DsCL), and an advancing one for the others two features (DFL and SVL). Geomorphological data, as well as RGB data, confirmed the effectiveness of planting operations, since a constant and progressive increase of the vegetated cover area and consolidation of the dune system was observed, in a period with no energetic storms. The proposed methodology is rapid, low-cost and easily replicable by coastal managers to quantify the effectiveness of restoration projects.

Proposed improvement of coastal habitat resilience: The case study of Pantano forest of Policoro in southern Italy

“…Despite their dynamic structure and the high resilience of biotic communities, these ecosystems are fragile due to general fragmentation, limited extensions, and excessive anthropogenic pressure (Lazarus, 2017). Compared to terrestrial ecosystems, because of the environmental and microclimatic conditions, they have selected peculiar and specialised fauna and flora, often also exclusive (Gracia et al, 2019;Fabbri et al, 2021). Furthermore, these environments represent important ecological corridors for the animals in the coastal environment (Cooper and Jackson, 2020).…”

Assessment of Canopy Health with Drone-Based Orthoimagery in a Southern Appalachian Red Spruce Forest

“…From a conservation management perspective, the efficiency and effectiveness of consumer-grade drone-based landscape modeling favor its broadscale use compared to conventional field surveying methods. The use of UAV Structure-from-Motion (SfM) data is gaining attention for landscape monitoring and change detection [13][14][15][16], and forest structure modeling [17,18]. SfM algorithms use consecutive georeferenced images to model 3-D subjects effectively.…”

Demystifying the Differences between Structure-from-MotionSoftware Packages for Pre-Processing Drone Data

“…Drone data have been captured to provide information across a range of environmental fields, predominantly to assess vegetation coverage, composition, and/or structure in the terrestrial environment (e.g., [4][5][6][7][8]). However, they have also been used to study a range of other environments, including mangroves [9][10][11], oyster reefs [12], coral reefs [13,14], coastal dunes [15,16], and seagrass beds [17]. They have also been used to identify invasive plant species [18][19][20] and estimate animal populations [21][22][23].…”