Understory Edge Effects in Roadside Forest

and the Impact of Forest Management

Edge effects are changes to processes and species diversity along the edge into the forest. The edge has a large influence on tree and seedling mortality and somewhat lesser but still important effects on species richness and abundance. Forest management, particularly in the unique community of the roadside forest, may enhance the edge effects acting on plant communities.

In 8 of the Stormwise demonstration sites in CT a section of roadside forest was cut according to the Stormwise treatment and a section was left untouched (control). Within each section of forest, 3 transects were established running perpendicular to the road, 30m long, 30m from an edge (other than the road), and 10m from one another. Along the transects, each of the following were tracked throughout the growing season.

  1. Woody plants (in 4m wide belts along the transects)
  2. Herbaceous plants (in 1-sq-m plots along transects)
  3. Light conditions (looked at with a ceptometer, as well as hemispherical photos along the transects)

Project Goals and Updates

The objectives of this study are to quantify the depth of road edge effects and environmental conditions in Stormwise treatment sites compared to control treatments throughout Connecticut. Specifically, between the management and control sites, we want to look at:

  1. Differences in native versus invasive plant communities
  2. Differences in the plant community structure and composition
  3. Differences in light environments

➡ Depth-of-Edge Influence Analyses have been developed (Harper and MacDonald 2011) to test the significance of the magnitude of the edge influence at various distances from the edge, as compared to what would be expected in an interior forest plot.

➡ Preliminary results have shown us that the Stormwise treatments enhance the edge effects in the roadside forests, which was expected. Stormwise treatments are also promoting the growth of woody vegetation, both invasive and native, in the roadside forest. However, there is a lack of edge influence in control sites, indicating that the forests have had time to seal the edge following the establishment of the road.

➡ Phase 2 of the project, now underway, will involve a close look at the growth and development of native and invasive species growing in the Stormwise treatment sites as well as controls.