7 pp. / Preventing catastrophic stand replacing events are best accomplished through thinning. Lower tree densities result in greater tree growth. Stands with lower tree densities have greater plant diversity. Determining stand conditions will provide a baseline for formulating a plan to improve stand conditions. Thinning around individual trees can improve individual tree health reducing the likelihood of damage from bark beetles, fire or drought.

In an attempt to provide low-cost, low-input alternatives for regenerating pine-hardwood mixtures, this study examined several mechanisms that influence the growth of pine-hardwood stands. The Regeneration Alternatives Study is an ongoing experiment that was designed to gain biological and economical information concerning the growth and yield of loblolly pine and mixed hardwood species. Low-cost herbicide applications (stump treatment, basal stem spray, release, and soil spot release) were used to control competing vegetation during the study. The four even-aged regeneration treatments applied to loblolly pine and mixed hardwood stands of this study had a significant effect on their growth. Loblolly pine growth increased and mixed hardwood growth decreased as the intensity of herbicide treatment increased for all age classes. In general, loblolly pine was more productive with more intense treatment applications on poorer sites following a growing season harvest. Hardwood species were more productive with less intense treatment applications on higher-quality sites following a dormant season harvest for all age classes. Loblolly pine planting following clearfelling, coupled with a herbicide stump and release treatment (treatment 4), resulted in the highest yields of loblolly pine, the greatest economic returns, and the greatest level of site utilization. However, treatment 4 also resulted in the lowest yield of mixed hardwoods and the lowest level of species richness. Loblolly pine planting following clearfelling, with (treatment 3) and without (treatment 2) a hardwood stump treatment application, resulted in a more even distribution of pines and hardwoods, depending on the treatment. Treatment 3 favored loblolly pine growth, especially following a growing season harvest on poor sites. Treatment 2 favored mixed hardwood growth, especially following a dormant season harvest on good sites. There were no differences between methods of release (basal spray or soil spot herbicide application). Economically, treatments 2 and 3 did not realize a profit on returns. Pine yields, dbh, and basal area were all significantly greater following a summer season harvest as opposed to pine growth following a winter harvest with the same chemical treatments. The pine growth data indicated that less intense chemical treatments following a summer harvest can achieve the same or greater growth results than more intense chemical treatments following a winter harvest. The results of this study indicate a significant biological and economic tradeoff, depending on the level of hardwood control applied and the time of harvesting. / Master of Science

This study compares financially optimal uneven-aged and even-aged silvicultural regimes of loblolly pine (Pinus Taeda). Uneven-aged regimes which maximize net present value (NPV) are found by quantifying the effects of diameter distribution (Q factor), maximum diameter, cutting cycle, and residual basal area on NPV. For the benchmark inputs, the regime yielding the highest NPV had a maximum diameter of 12 inches, residual basal area of 45 ft²/acre, and a cutting cycle of 11 years. Financially optimal even-aged regimes are taken from published literature of even-aged silviculture. Even-aged and uneven-aged silvicultural regimes are simulated starting from, 1) bare land, 2) a balanced uneven-aged loblolly pine stand, and 3) a mature even-aged loblolly pine stand. For the three starting conditions and selected benchmark variable values, simulation of even-aged silviculture yields NPVs of $877, $2,152 and $3,400 per acre and simulation of uneven-aged silviculture yields NPVs of $644, $2,084, and $2,569 per acre. Sensitivity analysis shows, for the levels of the variables tested, that even-aged silviculture yields higher NPVs than uneven-aged silviculture when starting from bare land or from a mature even-aged stand. When starting from an uneven-aged stand, for the variable values tested, uneven and even-aged silviculture are financially very competitive. Aside from the aesthetic benefits of avoiding clearcutting under uneven-aged silviculture, non-timber considerations between loblolly pine silvicultural systems are not well documented. Resource professionals hold opinions often in direct conflict with each other regarding the non-timber costs and benefits of even-aged and uneven-aged silviculture when considering wildlife, soil and water, and catastrophic damage events. / Master of Science

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

The purpose of this research was to model the growth and yield of bottomland hardwood forests of the Lower Mississippi Alluvial Valley and to explain the economic tradeoffs of even- and uneven-aged management. The US Forest Service (USFS) Forest Vegetation Simulator was used to model growth and yield for four different bottomland hardwood forest types using USFS inventory data. Even- and uneven-aged management scenarios were optimized for timber revenue maximization using the Land Expectation Value formula. Analyses suggested that growth and yield of even-aged and uneven-aged management approaches differ in terms of end products and harvesting time. The even-aged management scenarios performed better over the uneven-aged management scenarios with few exceptions; however, the magnitude of the economic tradeoff depended upon initial stand conditions and required rates of return. These analyses will allow landowners to understand how much economic gain or loss they may realize by adopting an alternative management.

In managed forests, the enormous complexity of an ecologic system meets a vast range of economic and other impact factors. Thus, to determine, analyze and understand economically optimal stand management is a task which has kept forest economists occupied for the past 200 years. The approach which has been followed since the days of Martin FAUSTMANN is the analysis of models which describe rather specific management scenarios using a set of clearly defined model assumptions. Unfortunately, the applicability of the findings to more general scenarios is limited. On the other side, the possibility of analyzing general management environments with single models is also limited by increasing complexity. Thus, a holistic understanding of optimal forest management is still missing. This statement also holds for the extensive field of optimal even-aged timber production, which essentially consists of only three main components, i.e., planting, thinning and final harvest. Therefore, this dissertation aims to make a contribution to further increase the general understanding of even-aged forest management. To achieve this goal three steps were taken. First, a qualitative analysis of a combined management plan including decisions on all three basic components is presented based on HALBRITTER and DEEGEN (2015). It provides a discussion of the direct and indirect dependencies between the decision variables of a rotation in a rather classical management environment. Second, three studies are presented which dissolve some of the classical model assumptions and extend the existing knowledge on even-aged forestry to relevant but more complex mangement questions. HALBRITTER (2015) includes natural regeneration and a shelter period in an even-aged system and explores the borders between the even- and uneven-aged management. Thereby, the influence of natural regeneration and the impact of several age classes were studied. HALBRITTER (2020) drops the assumption of stand homogeneity and investigates stand management under heterogeneous tree growth in which, for example, different social classes of trees are maintained. Lastly, HALBRITTER et al. (2020) extend the classical deterministic management environment in the direction of density-dependent hazard risk. This adds an additional aspect to the thinning and the rotation decision because, in this scenario, the probability of stand destruction can be controlled by thinning. As a third step, the studies above were embedded in a patchwork representing a conglomeration of models which are connected and validated by overlapping scopes. Using this approach, a wide range of different management scenarios can be covered by rather simple models. Thus, the complexity of the analysis decreases compared to single models with a more generally applicable framework and the problem of model complexity is mitigated. In addition, the inclusion of reference models with a particular focus on the management components stand establishment, thinning or rotation allows for a clear identification of the relationship between optimal stand management and the characteristics of a scenario. Applied to the qualitative analysis of the four studies above, the approach yields insights which contribute to a better understanding of even-aged forest management.:1. Introduction 2. The FAUSTMANN Framework 2.1 Model Definition 2.2 The FAUSTMANN Model 2.3 Assumptions 2.4 Basic Applications 2.4.1 The Rotation Model 2.4.2 The Thinning Model 2.4.3 The Planting Model 2.4.4 The Uneven-aged Model 3. Problem 4. Methodology 5. The Combined Model 5.1 Model 5.2 Optimal Management 5.3 Impact of Timber Price and Interest Rate 5.4 Discussion in Comparison to the Basic FAUSTMANN Applications 6. Extensions 6.1 Uneven-Aged Extension: The Double-Cohort Model 6.1.1 Even-Aged and Uneven-Aged Stands 6.1.2 Model 6.1.3 Optimal Management 6.1.4 Impact of Timber Price and Interest Rate 6.1.5 Discussion in Comparison to the Basic FAUSTMANN Applications 6.2 Heterogeneous Extension: The Heterogeneous Stand Model 6.2.1 Homogeneous and Heterogenous Stands 6.2.2 Model 6.2.3 Optimal Management 6.2.4 Impact of Timber Price and Interest Rate 6.2.5 Discussion in Comparison to the Basic FAUSTMANN Applications 6.3 Stochastic Extension: The Natural Risk Model 6.3.1 Deterministic and Stochastic Scenarios 6.3.2 Model 6.3.3 Optimal Management 6.3.4 Impact of Timber Price and Interest Rate 6.3.5 Discussion in Comparison to the Basic FAUSTMANN Applications 7. Conclusions 7.1 Optimal Management Strategy 7.1.1 Optimal Planting 7.1.2 Optimal Thinning 7.1.3 Optimal Rotation 7.2 The Patchwork Approach 7.2.1 Applicability of the Patchwork Approach 7.2.2 Limitations of the Patchwork Approach 7.2.3 Comparison to the Holistic Approach 8. Summary