Habitats of Special Concern
Dry–Forest old growth
The idea –
Avian species richness and abundance has been shown to differ between old-growth stands and younger managed stands, and several studies have described groups of species classified as “associated with” or “dependent on” old-growth forests. Thus, these stands may support unique avian communities. In 2007, we conducted point counts in stands considered to be old growth (Greene et al. 1992) on 5 National Forests in Region 1 (Bitterroot, Helena, Kootenai, Lolo, and Nez Perce) to investigate whether the bird community composition was significantly different from the bird community associated with similar but otherwise younger managed stands.
Methods –
We used Hawths Tools (a program run within ArcGIS) to generate and randomly place survey points within mature and adjacent old-growth stands (see map), with the only stipulation that each point be at least 250 m from the edge of the forest and from any other point within that transect. These points were not associated with roads or trails. The field crews used GPS units and aerial photos to navigate to these pre-established points where they conducted stan
dard point counts (click here for a copy of our point-count protocol).
Results –
Field technicians surveyed a total of 643 points along 132 transects and detected a total of 83 bird species within a 100-m radius of survey points. Results of logistic regression analyses indicated that we were able to detect statistically significant differences for 10 of 38 bird species, with five being more likely to occur in old growth, and five more likely to occur in mature forests. Interestingly, a 2-way discriminant function analysis was able to detect a bird-community ‘signature’ that successfully predicted the seral stage associated with more than 83% of the transects.
These results suggest that common landbird species form “indicator groups” that reflect management effects, and that old-growth stands provide a unique habitat for the regional bird community. You can use our newly developed geospatial web interface (link) to view the locations of all survey points associated with this program, to query any point to obtain information associated with that point, and to obtain summary graphs.
Annual Reports for this project–
Click to download the Dry Forest Old Growth report.
Funder–
USDA Forest Service Northern Region