White Spruce Vs. Black Spruce in Denali
The two tree species you are most likely to see in Denali National Park are the white spruce and the black spruce, however you are unlikely to see them together. This is due to the fact that, however similar they sound, the white and black spruce are very different trees that like to live in very different conditions. Additionally, both trees have a complex relationship with the constantly developing state of permafrost in Alaska.
Let’s begin with some descriptions of how the white spruce vs. the black spruce. The typical height for a white spruce tree is between forty and sixty feet tall, with few white spruces, particularly in Canada, eclipsing one hundred feet in height. Fully grown, their trunks are generally between two and three feet in diameter, with grayish-brown flakey or scaly bark. As both tree species are varieties of spruce, they naturally have needles rather than leaves. White spruce needles are slightly longer, around one and a half to two centimeters in length, and they grow on twigs that are hairless and slightly pinkish. Finally, white spruce cones are brown, cylindrical, about two inches long, and drop off the tree once mature.
Black spruce, on the other hand, are the smallest of all spruce trees, and that is only the beginning of the differences. The black spruce has an average height of only twenty to thirty feet, though in rare instances with ideal conditions you can find black spruces more than double that height. Both spruces have fairly similar bark, however black spruce bark can have red or green tinges to the normal gray-brown coloration, and trunk diameter is only around twelve inches. Black spruce needles are shorter and blunter than those of the white spruce, and grow on twigs that are hairy and yellowish brown. In addition to being the smallest of all spruce trees, black spruce have the smallest cones of any spruce. Their cones are between a half inch and one and a half inches, egg-shaped, and harder than most other varieties of cone.
Although black spruce are much smaller than white spruce in pretty much every facet, they make up for it by being tough as nails. Black spruce trees live easily in nutrient poor soil, very wet soil with poor drainage, even in areas where permafrost has frozen the surface or subsurface of the ground. Conversely, white spruce needs warmer, drier, more nutrient rich soil to grow. This is closely related to the state of permafrost in Alaska, because as the climate changes, so too will the habitats where these trees have been growing. It seems that as Alaska warms and permafrost coverage decreases, the white spruce will benefit as the black spruce suffers, but it’s not quite that simple. The precipitation in many areas should increase in the coming years which could very well provide an advantage to black spruce who can handle wetter conditions. There is also the factor of forest fires, which are much more common in forests of black spruce than white. This may sound negative, but it’s important to remember that natural black spruce forest fires are an important part of the life cycle for those trees.
The future for white spruce versus black spruce trees in Alaska is unclear, with many factors that have complicated intertwining relationships that are too much to get into in this short introduction. To get more in depth about white and black spruce, permafrost, and plenty of other fascinating natural relationships in the Alaskan wilderness, check out Northern Epics and book a tour with one of our naturalist hiking guides who will tell you everything you need to know!
