Forest floor and mineral soil manipulations have an effect on the soil biogeochemical properties important for pine tree growth. We assessed the impacts of forest floor manipulations on soil aggregate stability and the presence of ectomycorrhizal fungi (ECM) to elucidate the relationship between ECM community success and aggregate stability levels. The soil samples were collected from the top 3 inches of the rhizosphere. The study site consists of 14 year old loblolly pine (Pinus taeda L.) trees managed by Weyerhaeuser Company in the Lower Coastal Plain, approximately 8 miles east of New Bern, North Carolina. The treatments include three levels of forest floor retention: removed, control, and doubled and two levels of forest floor mixing with the mineral soil: mixed and unmixed. ECM community success was evaluated with fatty acid methyl ester (FAME) and acid-phosphatase enzyme activity analyses while aggregate stability was assessed using the soil mean weight diameter approach.
Results/Conclusions
Forest floor manipulations did not have a significant impact on aggregate stability or ECM abundance. However, we found a positive relationship between ECM abundance and aggregate stability. Removing the forest floor resulted in a bulk density increase of 0.18 g cm-3 compared to doubling the forest floor. Our results confirm the resiliency of mineral soil to rapid change as a result of forest floor manipulations. We hope our study will inform forest managers in planning site preparation techniques and in preserving site quality.