The larches that have looked dead for the past six months have not disappointed us. They have greened up! Oh happy day! Our mountains are once again adorned with that incredible praying mantis green.
The fact that larches (Larix occidentalis) drop their needles defines so much of their existence. Most conifers keep their needles year round, enabling them to photosynthesize whenever the temperatures rise above freezing, but larches can only grow half of the year. They make up for this fact by situating themselves in full sun on mostly east, west, and north-facing slopes where it’s cooler and the soil stays moister. These factors enable larch trees to grow quite fast.
Losing their needles gives larch several advantages over other conifers. If insects damage their needles, larch trees just grow new needles the next year. If a late summer or fall fire burns the larch but doesn’t kill the cambium layer, new needles sprout the following spring.
Subalpine larch trees (Larix lyallii) have a couple other advantages over their year-round, needle-bearing conifer companions – by dropping their needles each fall, they do not lose life-sustaining moisture to the alpine winter winds. And their needleless limbs are way less likely to get damaged by deep snows. As a result, larches have the distinction of being the Rocky Mountain tree genus that grows at the highest elevations and the most northerly latitudes.
The Seeley Swan Valley is one of best places in Montana to see larches turn the mountainsides bright yellow in the fall, then decorate the forest floor with rusty yellow as the needles drop from the trees. Having been raised back East, I find their color display very satisfying.