A PhD student at the University of New Brunswick in Fredericton is working to develop a set of guidelines for the forest industry that will allow a balance between protecting forest soils and utilizing biomass (tree limbs and tops) as a source of bio-energy.

Forests are an extremely valuable natural resource in large part because of their renewability. However, even though they are renewable, forests are still sensitive to disturbances.

“Forest machinery can reach up to 40 metric tons once loaded,” said Eric Labelle, UNB PhD candidate. “Unlike our province’s highways, the natural bearing capacity of soils is most often not sufficient to withstand high loadings, especially under wet conditions.”

Large forest machinery such as forwarders and skidders transport trees out of the forest, making dozens of trips over forest trails.

These machine operating trails, located directly on forest soil, can quickly become rutted and compacted by traffic thus interrupting the normal exchange of water, air, and nutrients that allow trees and plants to grow.

In Atlantic Canada and in many other areas throughout the world, harvesting equipment travels on trails usually covered by tree limbs. This debris acts as a brush mat, which disperses machine load over a greater area thereby reducing the risk of soil disturbances.

Currently this brush mat is left on the forest floor to decompose, but with the fluctuating prices of fossil fuels combined with the need to reduce carbon emissions, there is growing interest in utilizing a portion of this brush mat as a source of bio-energy instead.

Mr. Labelle, along with his supervisor Dirk Jaeger, professor of forestry and environmental management at UNB, are in the process of determining the minimum amount of brush that should be left on machine operating trails for effective soil protection, allowing the remaining brush to potentially be used for bio-energy operations. Mr. Labelle and Dr. Jaeger are now investigating the effects brush mats with different thicknesses have on ground pressure.

Previous studies have proven the benefit of using brush mats on trails for prolonging trail drivability and reducing disturbance, but no one has determined how much brush is actually needed says Mr. Labelle.

“Knowing the minimum amount of brush required on machine operating trails will protect forest soils against compaction and rutting caused by heavy load, while allowing remaining brush to be used for other uses such as bio-energy generation. ”

Once the research is complete, a set of best management practices will be developed and forestry companies will have a better understanding of how to use biomass as a new source of income without compromising forest soil productivity.

This research is being supported by the Natural Science and Engineering Research Council (NSERC), FPInnovations, the New Brunswick Innovation Foundation (NBIF), the University of New Brunswick Research Fund, the New Brunswick Department of Transportation, and Debly Forest Services Ltd.

 

About UNB

Established in 1785, UNB is one of the oldest public universities in North America. With more than 12,500 full- and part-time students from more than 100 countries, UNB has the best student-to-faculty ratio of Canada’s comprehensive universities, according to Maclean’s magazine. As the largest research institution in New Brunswick, UNB conducts over 75 per cent of the province’s university research. The university has an annual operating budget of more than $165 million and annually employs more than 3,500 faculty, staff and students. UNB’s two main campuses are located in Fredericton and Saint John, New Brunswick.

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