GLIFWC study on the effects of logging on understory plants
By Alex Wrobel, GLIFWC Forest Ecologist
Oodenaang (Odanah), Wis.—Much of the original forest cover of the ceded territories was old-growth northern hardwood forests. In addition to important tree species such as sugar maple (ininaatig), hemlock (gaagaagiwa), and yellow birch (wiinizik), this plant community type includes 35 herb and shrub species traditionally and presently used by the Great Lakes Ojibwe (Meeker et al. 1993), and many other species with no recorded uses.
Many of the understory plant species have adapted to the environmental conditions existing under deciduous tree canopies. The spring ephemerals begin their growth cycles in the early spring while there is plenty of sunlight under the still leafless trees. Once the trees leaf out, these plants will either go to seed or die back, giving way to the late summer understory species.
Extensive logging activity as well as changes in fire suppression policies in the ceded territories have altered the natural disturbance regime (i.e. wind events and fires), and in turn altered the natural dynamics of the forest ecosystems. Increased light and temperature on the forest floor, compaction or erosion of soils, the introduction of non-native invasive species 
and various others conditions may be changing the distribution and abundance of the native plants in the understory.
While small-scale logging operations using horses and small machinery in the winter months may have caused some changes in the understory of northern hardwood forests, large-scale operations using larger machinery and year-round logging may be having more dramatic effects.
One way to test if modern logging activities are causing changes in the understory of our northern forests is to compare the species composition and abundance of understory plants "before logging" against the "after logging" understory. Because forests recover slowly from logging, one challenge we face is capturing the very gradual changes over an extended period of time, which could range anywhere from 10-50+ years from now. Will these sites ever return to the pre-logging conditions, or are there permanent changes in the composition of the understory? Are species being lost or added?
In 1997, GLIFWC and the USDA Forest Service entered into a Memorandum of Agreement to conduct a long-term research project to study the impact of selective cut harvest on understory plants. Four study sites were established on the Medford District of the Chequamegon-Nicolet National Forest. They all have a history of logging, but have had minimal disturbance since the 1920's. Paired plots, one treatment plot (to be logged) and one control plot (to remain un-logged) were established at each site.
Data collection began in 1997, six years prior to the start of treatment (logging) activities. This is one unique aspect of this study in that we have significant pre-treatment data to compare to the post-treatment data. Sampling occurs twice each year, once in late May to record the early blooming spring ephemerals and again in late July to record the late blooming summer plants.
Logging activities began in 2003 and included a selective-cut harvest with trees being hand felled, cut into logs and removed from the sites by a forwarder. All logging was completed at all sites by 2006. Post-treatment sampling occurred twice each year beginning when the logging on an individual site was completed until 2007. Due to personnel changes at GLIFWC, the sites were not sampled again until this year (2011).
The information collected to this point provides us with a good picture of what species grow in the sampled northern hardwood forests and how common they are. We also know what species are absent from the forest. Logging has occurred, and we will now discover what changes have happened to these forested stands after the logging activities.
We will be able to document how much of a change occurred, how many species declined in abundance, how many increased in abundance, what species (if any) disappeared and what species were present post-harvest that were not present pre-harvest. This is the short-term information. Over the long term we will discover how these new plant communities change over time and whether they 'return' to their pre-harvest conditions. Stay tuned, we will let you know in about 50 years…..
