Because of the large geographic areas involved (in many cases, remote areas), forestry applications of remote sensing and geographic information systems predate their adoption in agriculture. Foliage from unhealthy trees—whether insects, diseases, drought, or air pollution—differs in reflectance from healthy foliage. With sufficient spatial and wavelength resolution, it is also possible to discriminate different tree species, in some cases.
Because trees are not the only landscape feature distinguishable from satellite imagery (one can see water, grassland, brush, rocks, and so forth), detailed measurements of land features can be used by many types of land managers and policymakers. In addition, as remotely sensed data are combined with digital terrain data and ground-based inventory data, a detailed landscape picture can be formed.
Light detection and ranging (LIDAR) uses laser sensors to analyze forests in a 3-D format to generate the vertical structure of forest canopies, as well as the topography on which they reside. With tree height and canopy information, it is possible to readily estimate tree diameter and biomass, among other forest characteristics. Biomass estimates are important for projecting carbon storage. Because wood is a primary economic resource, much effort has also been placed in estimating timber volume and value and allocating parts of each tree to its optimal wood products. These estimates allow landowners to manage forest lands more effectively and to reduce waste as wood goes to the proper processing mills.
While remote sensing plays a significant role in precision forestry, “less remote” sensing has gained in interest and adoption. Global positioning systems now allow inventory crews to locate permanent sample plots with less difficulty. Once at a permanent plot, inventory personnel can use: (1) digital cameras to image trees(for later office processing) and to capture understory species presence and development, and (2) ultrasound devices to determine tree soundness and disease incidence.
During some timber harvesting operations, harvesting equipment is able to measure and tally tree volume as trees are cut. For thinning operations, then, the operator would know exactly when the proper timber volume had been removed. With coming advances in robotics and mechatronics (the marriage of electronics and mechanical systems), it is likely that many more precision activities will be performed directly in forest stands.