Sax Zim Boardwalk Project

Eastern Larch Beetle

In Minnesota, the Eastern larch beetle has killed over 50% of mature Eastern larch trees on 103,700 acres since 2000. The beetle occurs anywhere Eastern larch grows and is now affecting 440,000 acres in Minnesota, with no indication that it is subsiding.  

Besides affecting water, timber and wildlife, beetle-killed trees can fuel fires. Wind blow-downs also lead to more fuel while climate change increases the risk for more frequent wildfires and disease. To mitigate these challenges, it is important to find and demonstrate uses for Eastern larch.

Thermal Modification

Thermal modification is a chemical-free, heat-treatment process that can add value to Eastern larch and other wood species by increasing its dimensional stability and decay and moisture resistance. This technology, however, suffers from low awareness and few demonstrations. The NRRI houses one of the few pilot-scale thermal modification kilns in North America. This technology equips NRRI to research, develop and demonstrate thermally modified wood in a range of new applications. NRRI researchers have the ability to evaluate the physical and mechanical performance of a wide range of wood materials in the Mechanical Testing Laboratory and Wood Shop.

Sax-Zim Bog

The Sax-Zim Bog is a 300 square-mile expanse of bogs, rivers, lakes, meadows and farms near Toivola, MN that is home to a diverse range of wildlife, attracting birder-watchers from across the region. Because of its unique mix of habitats, boreal birds such as the Great Gray Owl, Black-backed Woodpecker, Boreal Chickadee, Yellow-bellied Flycatcher and Connecticut Warbler are drawn to the area.  However, because of the area's damp landscape, most of the birding is done from the roads that crisscross the area. With this project, the new boardwalk will allow visitors to safely walk into sensitive, damp areas to get even closer to the wildlife.

In this project, the Natural Resources Research Institute (NRRI), Friends of Sax-Zim Bog, and industry partners constructed a wooden boardwalk at the Sax-Zim Bog near Toivola, MN. The boardwalk is manufactured from thermally modified Eastern larch, a low-value tree species threatened by the Eastern larch beetle.

Project Goals

The project goal is to improve forest health and reduce wildfire hazards in Northeast Minnesota while supporting the regional forest products industry by promoting the increased production, sales, and utilization of thermally modified Eastern larch from hazardous fuels. The project objectives are to:

1. Design, install, and demonstrate a public boardwalk from Eastern larch.

2. Disseminate the economic and environmental benefits of thermally modified Eastern larch utilization to landowners, timber harvesters and processors, wood products distributors/wholesalers, and other industry stakeholders.

Project Outcomes

The anticipated outcomes are successful boardwalk installation leading to increased thermally modified wood production, and dissemination of results to a wide range of stakeholders. The key anticipated result is that the project demonstrates the economic opportunities presented by thermal modification while improving forest health and reducing wildfire hazards in Northeastern Minnesota.