Patches of black spruce and larch stand in marshy valleys. Most stands are even-aged due to frequent fire intervals in black spruce forests. For example, it is frequently an early invader after fire in black spruce boreal forests. Pen trials suggest black spruce is not actually preferred. These forests are composed of black pine, white spruce, and black spruce. In areas of muskeg there are stands of black spruce or tamarack. In the north woods, white and black spruce grow. Fertilization reduced root growth in black spruce but not of white spruce. Fast-food chopsticks are often made from black spruce. The geographic range of the black spruce is much larger than the red spruce. These include jack pine, balsam fir, black spruce, white birch, and poplar. Most of the taiga consists of black spruce, aspen and poplar forest. Coniferous trees such as black spruce, white spruce, and balsam fir dominate the native vegetation. During the Pleistocene, a population of black spruce became geographically isolated, likely due to glaciation. The black spruce dominant tree cover is sparse and stunted from these environmental constraints.