Spruce!

 Red spruce are able to outcompete other species on poor soils and harsh climate.

Seeing the Forest Through its Trees Part VI 

By Larry Ely

Much of northern Maine and New Hampshire is covered by a spruce-fir forest type, and after looking at balsam fir, this series looks at three common spruce species occurring in our region. Red spruce (Picea rubens) is the one most commonly found at lower elevations within the spruce-northern hardwoods forest type as well as within the more northerly and higher elevation spruce-fir forests. White and black spruce may also be interspersed in both forest types to a lesser extent and will be examined next in this series. 

In 1905 the forests of northern NH had been described as “primarily a spruce country, but lumbering has brought a great change to the species.” Later, a USFS silviculturist noted that the region’s pulpwood lands had been cut clean by 1913 and that “areas that had supported nearly pure stands of spruce and fir were left practically treeless.”  Most of those spruce-fir forests have returned in under a century despite acid rain impacts but will likely be challenged in the future by climate change and insect pests. Fortunately, high-elevation, cool-slope pockets in the Mahoosuc Mountains may offer a climate refuge to red spruce, a cornerstone species in the Acadian forest. 

 From songbirds to iconic fur bearers, countless species depend on red spruce for food and winter cover.

Red spruce is most commonly found on relatively poor soils at higher elevations in the mountains and on steep, rocky slopes where it outcompetes other species. It likes a cool climate with cold winters and moist summers and prefers shallow glacial soils. It is shade tolerant and can reproduce and live in dense shade for many years and remain established in the understory of mixed stands. While it often mixes with hardwoods and other softwoods including hemlocks, it usually becomes dominant in the spruce-fir forest at 3,000 feet in elevation until fir becomes more dominant at 3,500 feet in elevation.

In the Mahoosucs, spruce is a cornerstone of the spruce-fir forest, sheltering wildlife through the hardest winters.

Red spruce and black spruce are capable of inter-breeding and creating hybrids, making identification between those species sometimes challenging. One distinct difference is that black spruce may hold cones for many years, while red spruce always drops its cones by summer. The specific site conditions preferred by black spruce also help make identification easier.

 High on cool mountain slopes, the cones of red spruce (Picea rubens) signal the quiet resilience of the northern spruce-fir forest

Red spruce has a long trunk with a taper and can grow to 60-80 feet in height with a diameter of one to two feet and sometimes larger. It is also a long-lived species and can live up to 350 years. Its shiny, dark green needles are four-sided with pointy tips, unlike the fir’s flat, rounded needles. The needles also grow individually around the twig which has rusty to black hairs. The bark of the mature tree appears as having grayish-brown flakes over a reddish-brown layer, though younger trees lack deep fissures. 

Red spruce and the spruce-fir forests provide a significant portion of the diet for red squirrels, spruce grouse, and White-winged Crossbills, among other species. These forests are also important habitats for pine marten, Canada lynx, and snowshoe hare. 

The forests of red spruce, almost eliminated by 1913, are back but are still heavily managed through various harvesting techniques because the tree is valued for its dimensional lumber and use as pulp for paper-making. It is also highly valued as a soundboard for stringed instruments, and in the 1900s its resin was the source for America’s commercial chewing gum. 

This is part of a continuing series looking at the life of the common trees in our Mahoosuc Mountain Region.

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