October 2017


Long-standing industry research project turns attention to bees

The Pennsylvania State Game Lands 33 (SGL33) research began in 1953 in central Pennsylvania at the urging of local hunters looking to understand the impact of vegetation management practices on wildlife within electric transmission rights-of-way.

Now, a new phase of this important research could be instrumental in the efforts to preserve native bee populations and diversity, especially within rights-of-way corridors.

Over the last 60 years, the SGL33 project (also known as the Bramble and Byrnes project, after the two Pennsylvania State University professors who initiated the research) has measured the effects of herbicides and mechanical vegetation management practices on plant, mammal, bird, reptile, amphibian and butterfly diversity and populations throughout central Pennsylvania. It has also examined their effects on wildlife habitat as well as wildlife use within rights-of-way.

Today, led by research partners from Penn State, SGL33 claims the distinction of being the longest continuous study of its kind. And, starting in 2016, it widened its scope to begin studying the effects of vegetation management practices on bee populations and diversity within rights-of-way.

Bee conservation a high priority
Why bees? Well, it’s estimated that 4,000 different species of bees are responsible for pollinating nearly 75 percent of the fruits, nuts and vegetables grown in the United States. With bee species in serious decline in the United States and worldwide, their conservation has become a priority.

Many in the vegetation management industry believe that one promising strategy to combat this decline is to promote native flowering plants and suitable nesting habitat in transportation and utility corridors. With millions of acres of power line rights-of-way in the United States alone, there is great potential to develop critical habitat needed for native bee species while at the same time effectively managing vegetation for safe, reliable power.

Spurred by increased industry interest, SGL33 researchers, along with cooperators from Dow AgroSciences, Asplundh Tree Expert Co., FirstEnergy Corp., PECO Energy Company and the Pennsylvania Game Commission, agreed to initiate a multiyear study to better understand the impact of various vegetation management practices on bee populations and diversity.

In 2016, SGL33 conducted bee surveys at six different sites every month over the course of four months. Each site represented a different vegetation management method, including high-volume foliar, ultra low-volume foliar, mechanical mowing, mechanical mowing followed by a cut-stubble application, low-volume basal treatments and hand cutting.

Initial findings point toward benefits of selective treatments
SGL33 released a report after the first year of its bee study, and its initial results have been summarized in two points:
  1. The most diverse assemblages of bees were collected from sites at which a low or ultra low volume of herbicide had been applied selectively.
  2. The least diverse assemblages of bees were collected from sites that had used broadly applied treatments, whether herbicidal or mechanical.

Travis_RogersTravis Rogers, market development specialist with Dow AgroSciences, has been an active participant on the bee research and commented on the initial results. “The key findings from the first year of research align with what we anticipated,” says Rogers. “The broadcast treatments which were found to lead to lower bee populations versus the more selective treatment methods shouldn’t be a surprise, as the broadly applied treatments would have eliminated a majority of the herbaceous broadleaf plant species that were present. These findings are also consistent with operational experience that has demonstrated how integrated vegetation management practices are capable of reducing woody plant species on rights-of-way, while at the same time selecting compatible vegetation that is seen as desirable habitat for the animal species that use those rights-of-way.”

The project team met in early July to begin data collection for this year’s phase of research, and Rogers is excited to compare the data collected this year against last year.

“Last year’s data was collected four years post treatment, whereas this year’s data collection will be one year after treatment,” says Rogers. “So, it will be interesting to see what differences there may be based on plant response following each application method.”

For more information, including both the full and summary versions of the report, visit: http://sites.psu.edu/brambleandbyrnes.