Tracking the health of trees over time on Forest Health Monitoring plots
| Authors: | Jim Steinman |
| Year: | 2000 |
| Type: | Scientific Journal |
| Station: | Southern Research Station |
| Source: | In Hansen, Mark; Burk, Thomas, eds. Integrated tools for natural resources inventories in the 21st century: an international conference on the inventory and monitoring of forested ecosystems; 1998 August 16-19; Boise, ID. Gen. Tech. Rep. NCRS-212. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Research Station: 334-339. |
Abstract
The Forest Health Monitoring (FHM) Program was initiated in 1990 as a cooperative effort between the USDA Forest Service and the National Association of State Foresters. Program efforts include detecting changes in tree health from a national grid of one-sixth acre permanent sample plots. Tree data have been collected in various States since 1991, and include species, diameter at breast height (d.b.h.), status (live, dead, or cut), and various ratings of crown condition and damage.In this study, remeasured tree data were used to track changes in health over a 4-yr period, by using status (live, dead, or cut), crown dieback, transparency, and density, and damage measurements of type, severity, and location. Initial analyses identified categories of individual crown and damage measurements associated with trees that eventually died. These thresholds were then integrated into categorical models to estimate the probability of mortality for trees with different combinations of crown and damage conditions. Separate models were constructed for different groups of tree species, with the premise that each group has a unique set of tolerable amounts of damage and foliage loss. Analyses also included statistical tests to verify differences among models.
Results will be incorporated into a field guide for use by land managers to help assess tree health, predict the likelihood of mortality, and rate the health of forest stands. Use of this tool will also help foresters make silvicultural decisions to select trees to be cut when regeneration, thinning, pre-salvage, or salvage operations are considered.