Age-age correlations and prediction of early selection age for diameter growth in a 35-years old Pinus brutia Ten. Genetic experiment

Aim of study: Forest geneticists developed various methods to predict an early selection age for forest tree species in order to shorten the breeding cycles. This study aims to estimate age-age correlations among diameter growth of trees at different ages and predict early selection age for Pinus brutia Ten. Area of study: P. brutia populations in the study were sampled from the most productive distribution range of the species, which is an important forest tree in the eastern Mediterranean Basin. To understand genetic variation and determine early selection age for the species, a common garden experiment was established in two test sites near Antalya city, Turkey, in 1979. Material and methods: Wood increment cores at breast height were collected at age 30 years, and diameters (dbh) were measured for the ages 13, 15, 19, 21, 23, 25, and 27 years on the cores. Diameters at ground level (dgl) and dbh were also measured on live trees at age 35. Variance components, age-age correlations, heritability and selection efficiency were estimated for the diameters. Main results: Age-age genetic correlations for diameters were high (mostly > 0.90). Genetic correlations between dgl (at age 35) and dbh (at all measurement ages) ranged from 0.84 to 0.99. Regressions of genetic correlation on natural log of age ratio (LAR) of juvenile age to older age were significant (P < 0.0001). Selection efficiencies estimated by employing the prediction equation indicated that for rotation age 40, the optimum selection age would be between 3 to 5 years, and for rotation age 100 it would be between 5 to 9 years. Research highlights: The results of this study provide information that can be used to find early selection ages in P. brutia. On relatively poor test sites most trees may not attain enough height growth to have measurable dbh trait. In such cases, dgl and/or tree height traits (both of which are highly correlated with dbh traits of all ages) can be measured and used instead of dbh trait for evaluations.

Model-Based Growth Comparisons between Loblolly and Slash Pine and between Silvicultural Intensities in East Texas

Growth differences between key commercial species and between silvicultural intensities (phases) within a species in a region are of great interest to foresters. This study used modeling methods to investigate these differences in east Texas. Datasets collected from loblolly and slash pine plots installed in extensively managed plantations (Phase I) and loblolly pine plots installed in intensively managed plantations (Phase II) were used. Species and silvicultural phase growth differences were determined by comparing their height–age, diameter–age, and height–diameter relationships. Slash and loblolly pine had significantly different parameter estimates for the Chapman and Richards function-based height– and diameter–age models. Slash pine grew faster than loblolly pine, with the superiority in height increasing while that of diameter growth decreased slightly with age. Slash and loblolly pine differed also in all parameter estimates of the exponential function-based height-diameter model. Loblolly pine was taller than the slash for small size (DBH ≤ 18 cm) trees, but thereafter, slash pine outperformed loblolly. While these results may encourage planting slash pine in the region, more studies are needed before definitive conclusions can be made. The differences in the height–age models for loblolly pine Phase I and II plots suggest that intensive management significantly enhanced tree height growth. However, this enhancement did not substantially change the maximum height; instead, trees reached the maximum height younger, thus effectively shortening the rotation age.

Opportunities and Challenges for Intensive Silviculture in Alberta, Canada

Intensive silviculture is practiced in many parts of the world but is rare in the public forests of western Canada. Here, we make the argument that intensive silviculture could be justified in Alberta but has not been implemented due to philosophies and policy decisions by foresters from government, industry and academia. These include adherence to long rotations, management goals that are aimed at sustained total volume yield rather than economic value, limitations in the types of stands that are allowed to be regenerated and models that do not include intensive silviculture options. In Mixedwood Growth Model projections, we demonstrate the potential of intensive silviculture that includes combinations of selecting good sites and thinning to produce merchantable stands by age 50 compared to the standard rotation age of 80 with basic silviculture. There could be even more gains if forest level constraints in timber flow were removed due to the increased growth of regenerating stands. Finally, we examine the attitude and policy changes that we believe are necessary for adoption of more intensive silviculture systems on parts of Alberta’s forest landbase.

Capital Return Rate and Carbon Storage on Forest Estates of Three Boreal Tree Species

In this study, the capital return rate and carbon storage on forest estates with three boreal tree species are discussed. A growth model is applied, along with verified yield models of sawlogs and veneer logs. Using the normal forest principle, thinning schedules and rotation ages maximizing the estate-level capital return rate are clarified. Regeneration expenses are amortized at the end of any rotation. Capitalizations are greater and rotations longer than in recent studies. The capital return rate is a weak function of initial stem count and rotation age but differs by tree species. The initial stem count strongly contributes to biomass stored in trees. Omission of thinnings increases carbon storage very effectively but requires financial compensation. The most promising way of increasing the capital return rate is the reduction of regeneration expenses. Thinnings are triggered by stand volumes of at least 200 m3/ha. The average commercial trunk volume of trees removed in thinnings always exceeds 200 L. Risk aversion theory proposes short rotations and low stem count in seedling planting unless carbon storage compensation exists. Even a small carbon storage compensation justifies increased seedling counts and extended rotations.

Net Revenue of Forest Carbon Offset Projects: Application of the Korean Emission Trading System in the Forestry Sector

Under the Korean Emission Trading System in The Forestry Sector (KETSF) initiative, the Korean government has developed several greenhouse gas (GHG) emissions reduction programs that include forestry activities as cornerstones of the initiative. Forest management is deemed to be a major strategy to implement KETSF; this has been confirmed by most participants in the program, who have shown their preference for forest management projects as the most effective and encouraging strategy to participate in the KETSF program. For a successful implementation of KETSF projects, it is essential to explore methods that optimize the positive impacts of such strategies, thereby maximizing the economic returns and carbon stocks that result from the implementation of forest management activities. Thus, this study investigated the economic returns of several KETSF projects in Korea, which included simulated scenarios under two main forest management strategies, one based on an extension of the rotation age, and a second one based on reforestation with new species. Five forest management scenarios were examined and evaluated in their ability to maximize carbon stocks and economic returns. Based on the results, two scenarios were identified as the best KETSF projects in terms of carbon stock increments. Additionally, the results indicated that projects including reforestation with new species added more economic value than projects that considered an extension of the rotation age. The study also revealed that KETSF projects generated revenue in both scenarios, by either extending the rotation age or by implementing reforestation with new species.

Structure of black walnut (Juglans nigra L.) stands on sandy soils in Hungary

Understanding the various processes and relationships that take place in forest ecosystems is generally possible only through long-term observations. This is especially true of the biological production of forests, through the in-depth exploration of their structure. In Hungary the black walnut (Juglans nigra L.) is one of the most valuable exotic tree species, mainly because of its very valuable wood, with fine tissues and unique colour, for furniture industry. Generally, the species is established by manual seeding, and can also be regenerated well by coppice shoots, but not by natural seeding. Black walnut regularly produces seeds from the age of 25–30 years and its rotation age is 70–80 years. It is also used outside forests due to the very decorative stem and crown shapes. In this paper, out of the stand structure factors, the relationships between age and height (r² = 0.7205), age and diameter (r² = 0.7719), age and number of stems per ha (r² = 0.3485) as well as between diameter and number of stems per ha (r² = 0.4595), all considered important for cultivation technology, were examined (based on the data collected in 34 black walnut stands, age of 7 to 67 years). We also analysed the diameter distributions in two black walnut stands with tending operations, reporting them as a case study. Its future role may be increased mainly on sandy soils of better quality, therefore the more accurate exploration of the structure of black walnut stands growing under such conditions can be considered as gap-filling.

Value-Added Forest Carbon Offset Projects: Application of the South Korean Emission Trading System in the Forestry Sector

Under the &ldquo;Korean emission trading system in the forestry sector (KETSF)&rdquo; initiative, the South Korean government has developed several greenhouse gas (GHG) emissions reduction programs that include forestry activities as the cornerstones of the initiative. Forest management is deemed to be a major strategy to implement KETSF; this has been confirmed by most participants in the program, who have shown their preference for forest management projects as the most effective and encouraging strategy to participate in the KETSF program. For a successful implementation of KETSF projects is essential to explore methods that optimize the positive impacts of such strategies, thereby maximizing the economic returns and carbon stocks that result from the implementation of forest management activities. Thus, this study investigated several value-added KETSF projects in South Korea, which included simulated scenarios under two main forest management strategies: one based on an extension of the rotation age, and a second one based on reforestation with new species. Five forest management scenarios were examined and evaluated in their ability to maximize carbon stocks and economic returns. Based on the results, Scenarios 2 and 4 were identified as the best KETSF projects in terms of carbon stock increments. Additionally, the results indicated that projects including reforestation with new species added more economic value than projects that considered an extension of the rotation age. The study also revealed that KETSF projects generated revenue in both scenarios, by either extending the rotation age or by implementing reforestation with new species.

Additive predictions of aboveground stand biomass in commercial logs and harvest residues for rotation age Pinus radiata plantations in New South Wales, Australia

Two systems of additive equations were developed to predict aboveground stand level biomass in log products and harvest residue from routinely measured or predicted stand variables for Pinus radiata plantations in New South Wales, Australia. These plantations were managed under three thinning regimes or stand types before clear-felling at rotation age by cut-to-length harvesters to produce sawlogs and pulpwood. The residue material following a clear-fell operation mainly consisted of stumps, branches and treetops, short off-cut and waste sections due to stem deformity, defects, damage and breakage. One system of equations did not include dummy variables for stand types in the model specification and was intended for more general use in plantations where stand density management regimes were not the same as the stand types in our study. The other system that incorporated dummy variables was for stand type-specific applications. Both systems of equations were estimated using 61 plot-based estimates of biomass in commercial logs and residue components that were derived from systems of equations developed in situ for predicting the product and residue biomass of individual trees. To cater for all practical applications, two sets of parameters were estimated for each system of equations for predicting component and total aboveground stand biomass in fresh and dry weight respectively. The two sets of parameters for the system of equations without dummy variables were jointly estimated to improve statistical efficiency in parameter estimation. The predictive performances of the two systems of equations were benchmarked through a leave-one-plot-out cross validation procedure. They were generally superior to the performance of an alternative two-stage approach that combined an additive system for major components with an allocative system for sub-components. As using forest harvest residue biomass for bioenergy has increasingly become an integrated part of forestry, reliable estimates of product and residue biomass will assist harvest and management planning for clear-fell operations that integrate cut-to-length log production with residue harvesting.

OPTIMIZATION AND ECONOMIC ANALYSIS OF MULTIPRODUCTS OBTAINED FROM WOOD OF EUCALYPTUS STANDS UNDER DIFFERENT PRODUCTIVE CAPACITY CLASSES AND ROTATION AGES

The present study aimed to analyze the yield and economic viability of the destination, for lumber and energy, of the wood from non-thinned stands of the hybrid Eucalyptus urophylla x Eucalyptus grandis under different productive capacity class and whose production was projected by individual tree growth model to different ages. The simulation of the growth of individual trees was performed by applying the height and diameter growth, and mortality sub-models for three productive capacity classes: high, medium and low. The Kozak model was adjusted to study the stem taper and, in addition, used to optimize patterns for sawing logs and to produce lumber. The economic viability of the projects was evaluated by Net Present Value, Equivalent Periodic Benefit and risk analysis using the Monte Carlo method. It was observed that in areas with less productive capacity the volume of wood destined for energy was greater than 80% and, in areas with greater productive capacity the volume of lumber was greater than 26%. Economic indicators showed that the lumber production was viable at any of the studied rotation age. The risk analysis using the Monte Carlo method did not indicate the possibility of the project being unfeasible under the conditions analyzed. The quantity of different types of products obtained and the wood yield depends on the productive capacity class and age of the stand. The destination of the wood for multiproducts is the most viable option, regardless of the productive capacity class.