Treesearch

Although clearcutting has been demonstrated to be an effective means to regenerate aspen, stand replacement may be retarded under conditions of intense browsing of regeneration, such as that experienced near elk feedgrounds in northwestern Wyoming. We studied the effects of ungulate browsing on regenerating aspen following clearcutting on the National Elk Refuge. Nine deteriorating, aspen-dominated stands were clearcut in the spring of 1988, and regeneration characteristics were subsequently measured periodically through 1996. Big game exclosures were placed in three stands immediately...

We collected nesting data on bird use of aspen stands in the Routt and Medicine Bow National Forests between 1987 and 1989. We found active nest sites of 28 species of small nongame birds on nine study plots in undisturbed aspen forests. We compared logistic regression models predicting nest success (at least one nestling) from nest-site or stand-level habitat predictors. Most common species used nest sites in aspen trees in forest interior locations (distance to edge >100 m), with dense trees (opening >100 m away) despite no apparent positive correlation with use of these habitat features...

In Rocky Mountain National Park, aspen has been observed to decline on elk winter range for many decades. The SAVANNA ecosystem model was adapted to explore interactions between elk herbivory and aspen dynamics on the elk winter range. Several scenarios were explored that considered different levels of overall elk population; different levels of elk utilization of aspen, reflected by the length of time during which elk utilized the aspen stand; and different fencing treatments where fences were removed following a specified, variable number of years.

Composition and structure data were analyzed to determine the characteristics of trees encroaching on the montane meadows and subalpine grasslands of the North Rim, Grand Canyon National Park. Tree invasion in the 1900s showed a pattern of increasing establishment, with quaking aspen comprising the majority (52%) of encroaching trees. Most aspen established in the last 10-20 years, with a mean establishment date of 1982 (mean age = 10 years). Interestingly, meadow encroachment began as early as 1903, followed by a distinct lack of aspen establishment from 1913 to 1933. This 20-year gap in...

A 3-year study of evapotranspiration from aspen clearcuts 1 to 14 years of age indicated the following: (1) The annual evapotranspiration from 1- to 5-year-old clearcuts ranges from 0 to 143 mm less than a mature forest on the same site. Evapotranspiration is highly dependent upon the amount of precipitation. (2) These effects can vanish in as few as 2 years with low precipitation (300 mm) or persist for 40 to 45 years with high precipitation (600 mm). These results were confirmed by data from the Spring Creek experimental watershed. Simulated water yield increase from the harvested...

A reserve tree method (RTM) of harvesting was installed in six 70- to 75-yearold aspen-dominated stands to determine if retaining 10 to 15 dominant aspen per acre would decrease sucker density to facilitate restoration of a conifer component. A reserve shelterwood cut was applied to three additional stands to evaluate performance of white pine planted under 50% crown cover. After the first full growing season following harvest, 96% of the RTM harvested areas were stocked; sucker density averaged 27,000 (27 k) per acre versus 38.2 k per acre on a clearcut control, 41% greater. Basal...

As we developed plans for the symposium on sustaining aspen in western landscapes (held in Grand Junction, Colorado, on June 13-15, 2000), we solicited support from state and federal agencies, universities, and the Rocky Mountain Elk Foundation. The widespread support was very encouraging, and only one agency turned down the opportunity to join in supporting this symposium because, it said, "We already know all about aspen." It's true that aspen has been a focal point for research for 100 years in the West, and much of this knowledge was compiled in a wonderful report in 1985 (DeByle and...

Quaking aspen (Populus tremuloides Michx.) is widely dispersed across the landscape of North America. Seventy-five percent of the aspen in the western United States occurs in the states of Colorado (50%) and Utah (25%). Reproduction in aspen is primarily by asexual means, e.g., root sprouts that are generally referred to as suckers. An aspen clone consists of numerous stems that are genetically alike that began from a single seed that germinated sometime in the past. Generally, these clones have been perpetuated on site by disturbance that allowed the clones to survive and expand in the...

Using repeat photography, we conducted a qualitative and quantitative analysis of changes in forest cover on the western slope of the Rocky Mountains in Colorado. For the quantitative analysis, both images in a pair were classified using remote sensing and geographic information system (GIS) technologies. Comparisons were made using three landscape metrics: total relative cover, mean relative patch size, and number of patches per major vegetation type. We noted several important changes in the pattern of the landscape and the structure of the forests. The relative area covered by interspers...

We investigated aspen (Populus tremuloides) regeneration in the Gros Ventre River Valley, the National Elk Refuge, and a small part of Grand Teton National Park, Wyoming, to see if elk (Cervus elaphus) browsing was as damaging as previously thought. We conducted a landscape-scale survey to assess aspen regeneration across gradients of wintering elk concentrations using 68 randomly selected aspen stands in the 1,090 km2 study area. Forty-four percent of the stands sampled supported regeneration of saplings (stems greater than 2 m in height but less than 10 cm in diameter). There were no...