No abstract

A major concern in the management of northern red oak (Quercus rubra L.) is the difficulty in regenerating stands that have dense understories of shade tolerant species. A replicated study in southern Iowa indicated that over a 5 yr period, tree shelters have a major impact on establishment of underplanted, 1-0, northern red oak bareroot stock. Sheltered seedlings had increased height growth during the first 3 growing seasons. But during the next 2 growing seasons, annual height growth of sheltered seedlings declined to a level of annual height growth similar to that of nonsheltered seedlings. After 5 growing seasons, sheltered seedlings were approximately 30 cm taller than nonsheltered seedlings. Sheltered and nonsheltered seedlings were one-third to two-thirds the height of the shelters. At the end of the fifth growing season, total mortality for sheltered seedlings was 40 and 55%, whereas for nonsheltered seedlings, mortality was 26 and 28% at the McNay and Stephens sites, respectively. Tree shelters may be a viable alternative in open areas (e.g., clearcuts or plantations), but in this study, tree shelters reduced both growth and survival when used to protect underplanted, 1-0, red oak seedlings. North. J. Appl. For. 16(2):103-107.

There is an urgent need for students in agriculture and natural resource management to develop competencies to solve problems in multiple-goal situations. Useful materials for problem-based experiential teaching are being incorporated into curricula and courses at agricultural universities worldwide. A forestry and an agronomy course at Iowa State University have incorporated problem-based team projects on real-world situations as a means of providing students with integrative and meaningful experiential learning. Teams pick their own problems, identify the subject matter competencies required to confront the problems, decide on team membership based on these competencies, and spend a significant portion of a semester in out-ofclass activities researching their problems and developing recommendations to confront the problems. Teams present their recommendations before an audience composed of class members and/or clients for whom they have developed their analyses and recommendations. Grades are assigned in a way that recognizes both the effectiveness of a team in meeting its assignment and the contribution of each individual to team activities. Student evaluations of these courses indicate that students recognize the integrative nature of the problem-based team activities and appreciate the practical value of this teaching approach. P ROBLEM-SOLVING AND CRITICAL-THINKING SKILLS EfC among the most cited educational needs in curriculum revitalization efforts of colleges of agriculture and natural resource management the world over (Bentley et al.

A land and timber expectation value (LTEV) was developed by modifying the Faustmann formula (Le) to allow for overlapping rotations, easy sensitivity analysis, alternative management strategies with different rotation lengths, and a unique initial, existing timber stand. This LTEV establishes a value (i.e., price one can pay) for a parcel of land, existing timber thereon, and management scenario analyzed that will result in a rate of return equal to the selected discount rate. LTEV was then used to analyze management scenarios typical of Iowa and Missouri for oak shelterwood, oak clearcutting, oak underplanting, and conversion to sugar maple. In stands with medium and high initial stand values, which tend to occur on sites that produce higher yields of quality oaks, sugar maple has the largest LTEV if the oak stand is past economic maturity, because of higher carrying and silvicultural costs associated with the oak alternatives. In general, the preferred oak alternatives on these sites were clearcutting, then underplanting, and then shelterwood. In stands with low initial stand values, which tend to occur on poorer sites, where there are lower market prices or where there was poor past management, oak has larger LTEVs than sugar maple. In general, shelterwood was the most economical for oak, followed by clearcutting and then underplanting. If the existing oak stand can be entered before the stand reaches economic maturity, oak shelterwood and underplanting LTEVs can be larger than those for sugar maple, even on the better sites, because carrying costs are offset by stand value growth. When this occurs, the higher final stand value of oak causes it to rank higher than sugar maple. In making the final decision to favor oak or maple, other factors such as landowner values and objectives must also be considered. North. J. Appl. For. 6:165-169, December 1989.

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