Recovery of Carbon and Nutrient Pools in a Northern Forested Wetland
Eleven years after harvesting a wetland forest in the Upper Peninsula of Michigan, we went back to measure the change in above- and below-ground carbon and nutrient pools to explore effects of forest management. The original stand of black spruce (Picea mariana), jack pine (Pinus banksiana) and tamarack (Larix laricina) was whole-tree harvested, and three post-harvest treatments (disk trenching, bedding, and none) were randomly assigned to three Latin square blocks (n = 9). Nine control plots were also established in an adjoining uncut stand. At the time of harvest, carbon and nutrients were measured in three strata of above-ground vegetation, woody debris, roots, forest floor, and mineral soil to a depth of 1.5 m.
When we measured again 11 years after harvest, soil nutrient pools were similar among the three site preparation treatments and the uncut stand. However, there were differences in ecosystem-level nutrient pools because of differences in live biomass. Coarse roots comprised approximately 30 percent of the tree biomass carbon in the cut stands and 18 percent in the uncut stand. These are the only reported findings on long-term effects of harvesting and site preparation on this particular type of forested wetland, and the results illustrate the importance of understanding the ecohydrology and nutrient dynamics of the wetland forest. This wetland type appears less sensitive to disturbance than upland sites, and is capable of sustained productivity under these silvicultural treatments.
Forest Service Partners