Noah Howie recently joined the LSU AgCenter as a research associate specialist in forestry at the Hill Farm Research Station. He will assist with research and management of the AgCenter forest resources.

By Noah Howie

Landowners play a vital role in the conservation and management of forested land. However, landowner knowledge on best management practices for their land is often limited, with almost 90% of private forest owners having no written forest management plan. Providing easily accessible tools and information for landowners is essential for them to make informed decisions on the management of their forest land.

Diameter at breast height (DBH) and tree height are two of the most basic tree metrics needed to understand a forest. Typically, these measurements are acquired using diameter tapes, calipers, clinometers, Biltmore sticks, etc. However, recent advances in technology have brought light detection and ranging (LiDAR) sensors to newer smartphone and tablet models. These sensors allow for the 3D mapping of trees in a forest, and with the use of different apps, can supply the user with valuable information about their forest land.

To assist landowners, we conducted a study to evaluate the accuracy and efficiency of smartphone-based LiDAR measurement applications in a practical forestry setting, using two popular applications: ForestScanner and Arboreal Forest. These applications were compared to traditional diameter tape measurements conducted by a two-person team. Both ForestScanner and Arboreal Forest use the built-in LiDAR sensors on newer tablets and smartphones to scan trees and return information such as DBH and coordinate locations. Data is saved and able to be transferred to the computer for further analysis. Having easy-to-use, precise and time efficient methods of forest inventory is increasingly desired among both private landowners and foresters alike.

Across 30 tree measurement plots we found that both apps had diameter measurements that were in good agreement with traditional diameter tape measurements. On average, the apps tended to slightly underestimate the diameter measured by the tape. This most likely had to do with the abundance of understory vegetation that may have impeded the sensors from getting an accurate reading on the bole of the trees. The amount of time needed to measure all the trees on a plot was significantly faster when using the apps compared to tape measurements. On average, the apps were two times faster than tape measurements, with a typical plot taking just around 50 seconds to measure through the apps.

When conducting a forest inventory, two important factors to consider are the accuracy of measurements and the efficiency of data collection. If LiDAR smartphone applications are to become more common in field settings, the accuracy of measurements should be no less than that of traditional methods (i.e., diameter tape or calipers). We concluded both ForestScanner and Arboreal Forest are acceptable alternatives to tape measurements when acquiring tree metrics.

Smartphones and tablets equipped with LiDAR technology and related applications have the potential to simplify forest inventories. ForestScanner offers a user-friendly interface and no upfront costs for use. However, data from ForestScanner must be transferred to another application to analyze it. Alternatively, Arboreal Forest has multiple plot sizes to select from and has functionalities to measure tree height. This allows the app to automatically calculate other forestry metrics, such as basal area, tree density, volume and carbon capture, which may be attractive to landowners.