You may have noticed the hillside turning yellow. Thankfully, it is not the bark beetle in action, and the trees are not dying. These yellow-needled trees are Western Larch trees, otherwise known as Tamaracks.
Tamaracks are the only deciduous conifers in the west. They are related to the Eastern Larch which is East of the Mississippi. The largest Western Larch is actually located in Seeley Lake, MT.
Western Larch are one of the only deciduous cone-baring trees that loose their needles. They are also highly sought out for firewood because they burn hotter and they are easy to split.
During the spring, Western Larch are a lighter green in the spring and eventually turn a dark green so they are hard to distinguish from the rest of the forest. In the fall, after the aspens and cottonwoods have lost their leaves, Western Larch needles loose their chlorophyll and turn yellow. Eventually all the needless fall to the ground and they are left bare for the winter.
So, this fall take a moment to view these magnificent Western Larch colors. They are quite a sight and cover many mountains around Glacier Park and the Flathead Valley.
Reference – http://fwp.mt.gov/mtoutdoors/HTML/articles/portraits/tamarack.htm