Birds, Bogs, and Forestry – a two-day Lowland Spruce Workshop in Minnesota

Written by Christian Nelson, Forest Stewards Guild Lake States Coordinator  

The two-day event was organized by American Bird Conservancy Northern Forests Conservation Delivery Network Coordinator, and Guild member, Jayme Strange, in partnership with several organizations including the Forest Stewards Guild and the University of Minnesota. The event tied in aspects of the recently completed Forestry for Minnesota Birds Guidebook.

Black spruce (   Picea mariana   ) is a long-lived, boreal tree species found in areas with cold and short growing seasons. This species is at the southern extent of its range in the Great Lakes and Northeastern parts of the U.S. but is found widely across the Canadian and Alaskan boreal forest before diminishing as the boreal forest meets the tundra in the far-north.     

In Minnesota, black spruce is primarily found in low, peatland and muck soil bogs and fens that range in size from small depressions to massive bog complexes. Black spruce is also found as an upland species in the far northeastern part of the state on shallow soils over bedrock. Overall, black spruce is considered the dominant cover on roughly nine percent or 1.4 million acres of the state’s forested lands. Many of the peatland stands are nearly pure black spruce. In other areas, it grows in association with other species. On wet sites it is found in association with tamarack and northern white cedar, and on dryer sites it is found with aspen, paper birch, jack pine, red maple, white spruce, and black ash.   

Black spruce stands also provide essential habitat for several wildlife species including the Connecticut Warbler, Golden- and Ruby-crowned Kinglet, Boreal Chickadee, Dark-eyed Junco, Spruce Grouse, Great Gray Owl, bog lemming, and snowshoe hare. The understory of black spruce stands often consists of a soft carpet of sphagnum mosses and wetland plant and shrub species like leatherleaf, cottongrass, pink, yellow, and Showy Lady Slippers (Minnesota’s state flower). Dense stands can provide cool summer habitat and warmer winter habitat with lower snow depth than adjacent areas.   

Historically, black spruce has been managed using even-aged silviculture techniques such as clear cutting and strip-cutting. Post-harvest areas are often replanted with nursery stock or aerial-seeded using planes or helicopters. Dwarf mistletoe, a native-parasitic plant that causes short-stubby growth, slow decline, and eventual mortality  ,  has long been cited as a reason to harvest all trees over five feet tall within a stand with no reserves.   

A cultural shift in forestry practices and concern for declining wildlife dependent on spruce stands, has many foresters looking for silvicultural alternatives that more closely resemble historic disturbance patterns and the resulting heterogeneity in stand structure, age, and species composition that may result. Climate issues also fuel concern for the long-term prospects of a species growing at the southern edge of its range across the U.S.   

Throughout the two-day workshop, experts made a case that concerns about dwarf mistletoe may be overstated. Pockets of mistletoe-caused mortality are often found to harbor other tree species, adding to species diversity, climate change resilience, and providing more habitat than black spruce alone. Structural diversity can be enhanced by strip cutting, or group-selection, providing continuous habitat not seen in traditionally managed clearcut areas, while reducing reforestation costs. Stand features, such as species diversity, vertical and horizontal structure, age diversity, standing dead trees, downed wood, gaps, and retained groups of living legacy trees, greatly increase the value of the stand to wildlife without degrading the short-term economic viability of management nor long-term economic value of the stand. Foresters and wildlife managers at the meeting discussed experimentation and thinking about outside-of-the-box approaches to achieve economic goals while retaining and enhancing wildlife value.

The morning and afternoon first-day presentations were recorded and can be watched in their entirety on the Northern Forest Birds Network YouTube channel:https://www.youtube.com/@northernforestbirdsnetwork