Dave Hallock, Peak-to-Peak. Forests of lodgepole pine seem to get a bad rap from many people. Some consider them “biological deserts” while others fear their propensity to burn. They often form stands of dense timber with few showy flowers and fewer singing birds than a nearby aspen forest. Nonetheless, being one of the dominant forest types of our mountains, their ecological value may be less obvious but still significant.

Lodgepole pine is a tree of the north, being common in Canada and the northern Rockies. They reach their southern extent in Colorado in the hills and mountains bordering the northern San Luis Valley. They are found between 8,000 and 10,000 feet. Considered a successional species, they rapidly colonize sites after a fire but are shade intolerant and will give way to shade-loving species such as Douglas-fir at lower elevations and Engelmann spruce and subalpine fir at higher sites.

But in their central range, lodgepole pine forests appear to be self-sustaining as the periodic return of stand-replacing fire precludes succession. Aspen and lodgepole pine can grow on many of the same sites and may co-dominate a post-fire landscape, with lodgepole eventually taking over dominance with time. Sites that favor aspen tend to have deeper soils and more moisture.

But lodgepole pine forests are far from being biological deserts. Much of their biological diversity is found at and below ground level. Lodgepole pine forests are some of the best places to search for mushrooms. Pine squirrels favor the closed canopy interior forests created by stands of lodgepole pine: fleshy fungi and pine cone seeds are their staples. Other smaller mammals common in these forests include red-backed vole, who also favor fungi for food; porcupines, chipmunks, and shrews.

Lodgepole pine forests may not be as alive as an aspen forest with the songs of birds during summer, but they are more valuable for resident birds during winter.  Many resident species, such as mountain chickadees, hairy woodpeckers, red-breasted nuthatches, and brown creepers, favor stands of lodgepole pine where they can feed on the resting stages of insects and spend lots of time searching in the crevices of bark for their prey.

The dense forests also provide some respite from winter winds. Aspen forests are chock-full of birds in the summer, but many of them are migrants, such as warbling vireos, warblers, and sapsuckers, who head south for the winter. The lodgepole pine forest is a more consistent source of food on a year-round basis.

Elk also find value in these dense forests. Occupying the central portion of their range between lower montane/foothills winter habitat and subalpine/tundra summer habitat, lodgepole pine forests provide important hiding and thermal cover for elk as well as secluded routes for movement. The dense forests provide cover and wind protection. Some of us who track the local herds have noticed a downward post-breeding movement by elk in the fall into lodgepole pine forests.

There are varying theories as to why this occurs. One person has observed elk eating mushrooms. Others feel they are coming for the green sedges, often the appropriately named elk sedge, present on the forest floor in higher elevation stands of lodgepole pine.

So, we shouldn’t undervalue these forests and judge them simply by what we can see or hear. Their ecological importance may be more subtle and is often hidden from our senses.

Following are some of the April nature happenings in the Nederland area: Bird species returning from the south include Wilson’s snipe, band-tailed pigeon, broad-tailed hummingbird (end of the month), red-naped and Williamson’s sapsuckers, tree swallow, ruby-crowned kinglet, yellow-rumped warbler (end of the month), common grackle, fox sparrow, and song sparrow (sometimes they arrive in March and a few may even overwinter). Late April is the peak time for great horned owls to hatch. April is a prime time for hearing the calls of our small forest owls: northern pygmy-owl, northern saw-whet owl, and boreal owl.

Mammals tend to be emerging or moving. Snow level permitting, elk will begin a movement from their winter to transitional range.  Chipmunks and ground squirrels may be seen during periods of mild weather. Black bears are emerging from dens in March and April; their favorite foods at this time of year are vegetation and carrion. The peak time for bobcat young to be born is April and May. Mink breed from late February until early April. Long-tailed weasel litters are born in April and May.

Butterflies that overwinter as adults, such as mourning cloaks, tortoiseshells, and commas, may appear during periods of mild weather. Pasque flowers may be found blooming on south-facing hillsides if the weather is mild enough.