Treesearch

Differences in percent germination, percent filled, and weights of true mountainmahogany achenes collected on four mountain soils were highly significant (p=.01). Germination, fill and weight were greater, also at the .01 level, for achenes from northwest aspects than for achenes from southwest aspects. Achenes with highest germination were from plants on northwest aspects in the least fertile soil, which had the lowest natural population of mahogany. Contrastingly, achenes with lowest germination were from southwest aspects on the most fertile soil, where mahogany plants were most...

Presents results of a study of wilderness users in the Bob Marshall, Bridger, High Uintas, and the Boundary Waters Canoe Area (BWCA) to determine their perception of, and reaction to, problems such as crowding, littering, and conflicts between user groups, and to management actions to alleviate such problems. Definitions of crowding included references to conflicts with other users, excessive levels of use, and to inability to find isolated campsites. Suggested management actions include (1) limit party size; (2) restrict motors in the BWCA; (3) encourage "off-season" use; and (4) zoning.

Rains of 12 inches or more in 6 hours fell on the east slopes of the Black Hills the night of June 9, 1972. Resulting flash floods exacted a disastrous toll in human life and property. Rainfall and discharge so greatly exceeded previous records that recurrence intervals have been presented in terms of multiples of the estimated 50- or 100- year event. Quick runoff was produced in the heaviest rainfall areas regardless of hydrologic condition. Flood sources included all major geologic and soil types and practically all land uses in the Black Hills. The highest measured peak runoff per unit...

The accuracy of a BOD oxygen probe for field measurements of primary production by the light and dark bottle oxygen technique is analyzed. A figure is presented with which to estimate the number of replicate bottles needed to obtain a given accuracy in estimating photosynthetic rates.

A generalized, non-linear population dynamics model of an ecosystem is used to investigate the direction of selective pressures upon a mutant by studying the competition between parent and mutant populations. The model has the advantages of considering selection as operating on the phenotype, of retaining the interaction of the mutant population with the ecosystem as a whole, and of setting a reasonable balance between theoretical manageability and quantitative testability.

Five existing fire models, both experimental and theoretical, did not adequately predict rate-of-spread (ROS) when tested on single- and multiclump fires in oak chaparral in Arizona. A statistical model developed using essentially the same input variables but weighted differently accounted for 81 percent ofthe variation in ROS. A chemical coefficient that accounts for effects of fuel chemistry on ROS is applied to the model. The model provides usable guidelines for predicting fire spread in Arizona oak chaparral.

As a matter of policy and good forest resource management, the Forest Service will manage the timber resources on the National Forests to achieve the various multiple use objectives established for the respective management units. In so doing, we are not to be bound to any particular system of management as the primary system, but we are to prescribe and use the system of management and the cutting methods associated with that system which will best fit the resource conditions and needs of the situation at hand. Consequently, we must be prepared to prescribe and apply correctly uneven-aged...

Describes a set of computer programs for developing prognoses of the development of existing stand under alternative regimes of management. Calibration techniques, modeling procedures, and a procedure for including stochastic variation are described. Implementation of the system for lodgepole pine, including assessment of losses attributed to an infestation of mountain pine beetle, is described.

A provenance test of 49 origins of Scotch pine (Pinus sylvestris L.) from eastern Europe, Russia, and Siberia was established at three locations in North Dakota and one in Nebraska. After 10 years (7 in Nebraska), trees from 50º to 55º latitude and 20º to 40º longitude survived best, were taller, and had greener winter foliage. Several provenances appear to be well suited for planting in shelterbelts and for Christmas tree culture.

A mathematical fire model for predicting rate of spread and intensity that is applicable to a wide range of wildland fuels and environment is presented. Methods of incorporating mixtures of fuel sizes are introduced by weighting input parameters by surface area. The input parameters do not require a prior knowledge of the burning characteristics of the fuel.