Does Forest Management have Unintended Consequences for Habitat Restoration?

Habitat management often includes the use of large equipment such as trucks, mowers, and brush hogs to clear vegetation, create fire breaks, or control unwanted species. Such activities are intended to benefit the ecosystem, but the vehicles may be so heavy that they can compact the soil. Such soil compaction can have negative consequences that counterbalance the positive effects of the management. Therefore, we need to know if the machines are compacting the soil, and if so, to what degree the compaction is occurring. We tested whether soil compaction occurs at the Albany (NY) Pine Bush Preserve. Managers at this inland pine barren use brush hogs to clear woody vegetation in preparation for prescribed fire. We hypothesized that the vehicles compact the soil, resulting in denser soil in treated sites compared to untreated sites. We also hypothesized that compaction would intensify with the number of times that treatment occurred and decrease as time passed from its most recent treatment. We sampled soil at 36 sites throughout the Albany Pine bush that had experienced a range of brush clearing treatments. Each soil core was sampled in 5 cm increments to a depth of 20 cm. We compared the bulk density of soil cores that had and had not been treated with brush hogs using a t-test. We also used linear regression to test how bulk density changed as the time since treatment varied as well as how bulk density changed as the number of times a site had been treated increased. We found no signs of soil compaction stemming from management activities. Bulk density in treated sites was not significantly different from sites that had never been treated. We also did not find a significant effect of treatment frequency, nor the time since last treatment, on bulk density. Given that bulk density remained mostly consistent across all brush hog treatments, we conclude that the Albany Pine Bush's management practices do not cause soil compaction. This is a favorable result, as the use of such heavy equipment can be used for its intended purposes, without concern for secondary, negative effects.