226 university of colorado studies 



Communities at Boulder Park 



Forest. — Lodgepole pine forest is the association of the hills around 

 Boulder Park. This forest is invaded sparingly on steep slopes by 

 Engelmann spruce and sub-alpine fir. It is replaced in moist seepage 

 areas and in recently burned-over places by aspens. Where best 

 developed the individual lodgepole pine trees stand close together and 

 there is very little growth on the forest floor. 



On dry exposed ridges, such as the top of the " Giant's Ladder" (the 

 hill to the north of the park), an invasion of the lodgepole forest by 

 limber pines takes place, and isolated groups of limber pine trees occur 

 in various dry and windswept stations. Along the railway track east 

 of Tolland there is such a group of trees, also some on Baltimore Ridge 

 to the south and some at the western edge of the park. Limber pine 

 never covers large areas as a pure forest. 



Pure Engelmann spruce forest belongs properly to the sub-alpine 

 zone but is found in South Boulder Canyon, north exposure, to the west 

 of the park. It is the usual forest at higher altitudes up to timberline. 

 Engelmann spruces invade old moors or swamps along streams in the 

 sub-alpine zone. They live in cold, wet soil. 



Aspen forests in this region are seldom of wide extent except where 

 they occupy areas recently denuded of coniferous trees. The aspen 

 association or society represents a stage in reforestation by conifers. 

 In moist areas around springs or where there is considerable seepage, 

 aspens may maintain themselves for long periods. They tend to form 

 rather permanent groves in the basins of old morainal lakes at high 

 elevations. 



Willow and alder thickets are confined to stream banks and wet areas 

 around springs. The face of the mountain (Giant's Ladder) which 

 bounds Boulder Park on the north has very dense willow-alder thickets 

 alternating with groves of aspen. 



There is no rock pine forest in the immediate vicinity of Tolland 

 although a few isolated trees are to be found to the east of the alder 

 and willow thickets mentioned in the previous paragraph. A single 

 large tree stands on a south-facing slope at the west end of the park. 

 Typical rock pine forest is to be seen near Rollinsville on hillsides having 



