A recent study looked at how different forest management strategies affect bird populations and wood production. Researchers compared three intensive forest management treatments (Light, Moderate, and Intensive) created with levels of herbicide application used to control competing vegetation. The 8-year study focused on young forest associated leaf-gleaning birds, which are species that rely on picking insects off leaves and are of concern due to declining populations. They compared the number of bird species using treated sites to a control group where no herbicides were used.
In the first four years, leaf-gleaning bird species had 20-50 percent fewer species in areas treated with herbicides. However, once the treatments ended, the effects lessened, resulting in 13-20 percent fewer species in treated sites after four more years. Other types of birds also had fewer species (19-27 percent lower) in treated sites during the first four years, but the number of species did not differ from untreated sites in later years. Despite this recovery, by the end of the study, there were still fewer bird species in the Light treatment areas compared to the control group.
In contrast, trees in the Moderate and Intensive treatments grew much faster. Conifers in these areas were 40-44 percent taller and had 74-81percent larger diameters compared to the control group. This led to significant gains in tree volume which equates with future wood production. Overall, the study showed that current forest practices provide a balance between supporting bird diversity and increasing wood production.
While sites with herbicides applied had fewer bird species initially, researchers conclude that populations of mobile species like birds can be supported by nearby habitat at different stages of forest growth. The results of this research support having some areas focus on wood production while others are conserved for long-term ecological goals, like protecting older forests.