Forest management is a complex practice that involves the evaluation of forest stands, underlying ground cover, soil, the contours of the land itself and land survey mapping information. Forests are managed to determine the maturity of timber and the ease of access to that timber, as well as for replanting and forest growth and preservation.
The centerpiece to forest management has always been the forest cruise. Cruises determine the types of trees that are on a specific tract of land, the maturity and the health of those trees, the width and height of trees, the presence of streams and wetlands, and ultimately the worth of a parcel’s entire timber inventory. Presently and in the past, much of this cruise work has been done on the ground, with forest experts physically going through forest tracts and performing tree counts.
Increasingly, however, more forest management is being performed with the help of LiDAR technology.
- Tree height estimates generated from airborne remotely sensed LiDAR data now compare with or exceed the accuracy of field-based height estimates.
- Discrete return scanning LiDAR, used in mapping applications, presents structural renderings of a forest by yielding a cloud of points, with the lower points representing the forest ground and the upper points representing the canopy.
- These structural characteristics can be further used to produce a bare-earth Digital Elevation Mode l(DEM) that illustrates fine-scale topographic variations like stream, drainage and riparian features, as well as topographic features associated with abrupt changes in relief that show estimates of vegetation height that can be calculated by subtracting non-ground LiDAR hits from the terrain surface hits.
- Finally, land contours and survey maps can be overlaid, which goes far in enabling a complete picture of a tract of forest land.
This movement to LiDAR for forest management has been fueled by a need to economically and efficiently manage and monitor vast tracts of forest acreage that are impractical to manually survey and maintain. To date, airborne and satellite-based LiDAR have been used, but in the future it is also likely that more drone-based LiDAR applications will be deployed in forest management.
A proof of concept LiDAR project using drones is project CANOPOR, which was revealed in March 2014, when Carbomap, a U.K. forest mapping company, announced that it had collaborated with l’Avion Juane S.A.R.L. and IRD (Institut de recherches pour le developpement) in France to complete the first canopy model of a rainforest by using data from a UAV-ready LiDAR system. Carbomap CEO Professor Iain Woodhouse said, “The exciting prospect here is that it demonstrated how a UAV LiDAR can map rainforests in 3D on the landscape scale. The UAV LiDAR approach offers a low-cost alternative to sending people into the field.”
Both airborne and UAV-supported LiDAR are well suited to assist forest management planning for forest harvesting and regeneration, and in road building logistics for access into these remote areas.
Clearly, the State of Maryland is defining a central role for LiDAR in its continuing effort to manage forests to ensure that 40 percent of Maryland remains in tree cover. The debate in Maryland is whether to use space-based single source LiDAR, or smaller drone-propelled LiDAR to manage and monitor forests. But regardless of transport choice, LiDAR technology has established itself as the most effective means of managing and maintaining forest growth.