Treesearch

Eggshell weight and thickness indices of Richardson’s Merlin (Falco columbarius richardsonii) eggs collected in southeastern Montana were significantly (p < 0.01) lower than pre-1946 samples. Montana eggshells showed reductions of 13% in shell weight and 20% in shell thickness indices when compared to eggshells collected before 1946. The decreased eggshell weights and thickness indices and the occurrence of 7 organochlorine compounds in Merlin eggs recently collected in southeastern Montana indicates that this raptor population merits periodic monitoring.

Twenty-six hybrid poplar clones were planted as cuttings on a gold mine tailings in the Black Hills. Four exhibited very good survival and growth. Other clones had relatively high (exceeding 50 percent) survival but slow growth (below 60 cm) over a 5-year period.

We studied the effects of observer variability when estimating vegetation characteristics at 75 0.04-ha bird plots. Observer estimates were significantly different for 31 of 49 variables. Multivariate analyses showed significant interobserver differences for five of the seven classes of variables studied. Variable classes included the height, number, and diameter of trees, height to the first live tree branch, height and number of shrubs, and composite variables. We then compared observer estimates with measurements of the same habitat variables. Univariate and multivariate comparisons of...

Browse utilization estimates based on twig length and twig weight were compared for skunkbush sumac, wax currant, and chokecherry. Linear regression analysis was valid for twig length data; twig weight equations are nonlinear. Estimates of twig weight are more accurate. Problems encountered during development of a utilization model are discussed.

Literature pertaining to woodlands of southwestern North Dakota is reviewed. Woodland species composition and distribution, and factors influencing woodland ecosystems such as climate, logging, fire, and grazing are described. Potential management and improvement techniques using vegetation and livestock manipulation have been suggested.

Keys, brief descriptions, habitat data, and pertinent synonomy are provided for the vascular flora of the Desert Experimental Range to assist in range, wildlife, ecological, and other studies conducted on the area.

A vegetation classification based on concepts and methods developed by Daubenmire and refined by others were used to identify 16 forest habitat types on the Medicine Bow National Forest. Included were two habitat types in the Pinus flexilis series; three each in the Pinus ponderosa, Populus tremuloides, and Abies lasiocarpa series; and five in the Pinus contorta series. A key to identify the habitat types and the management implications associated with each are provided.

Engelmann spruce seed production and dispersal, and seedling establishment in the central Rocky Mountains indicate that in the Abies Iasiocarpa/Vaccinium scoparium habitat type, shaded, mechanically scarified, mineral soil seedbeds on north aspects can be adequately restocked naturally within a 5-year period in clearcut openings 300 to 450 feet wide. With shade or scarification alone, size of opening that will restock is reduced to 200 to 350 feet. The effective seeding distance is so limited on unshaded natural seedbeds on north aspects and on south aspects regardless of the seedbed...

Third in a series of proceedings of sYmposia on wildland shrubs, this publication brings together current knowledge of plants belonging to two important genera. Topics addressed by the 54 papers include distribution, systematics, genetics, revegetation and control, animal relationships, ecological relationships, entomology, pathology, and physiology.

This paper reviews the literature on factors affecting the yield and nutritional value of crested wheatgrass (Agropyron cristatum, A. desertorum or A. fragile). The Agropyrons are cool-season perennial bunch grasses that are grown in the western United States and Canada where annual precipitation ranges from 9 to 18 inches (230 to 460 mm) and forage yield ranges from 400 to 3000 pounds of dry matter per acre (450 to 3360 kg/ha). Forage production in the northern Great Plains is best correlated with April to June precipitation whereas in the area west of the Rocky Mountains production is...