Timber Growth Research Articles

Bilateral Defect Cutting Strategy for Sawn Timber Based on Artificial Intelligence Defect Detection Model.

Solid wood is renowned as a superior material for construction and furniture applications. However, characteristics such as dead knots, live knots, piths, and cracks are easily formed during timber's growth and processing stages. These features and defects significantly undermine the mechanical characteristics of sawn timber, rendering it unsuitable for specific applications. This study introduces BDCS-YOLO (Bilateral Defect Cutting Strategy based on You Only Look Once), an artificial intelligence bilateral sawing strategy to advance the automation of timber processing. Grounded on a dual-sided image acquisition platform, BDCS-YOLO achieves a commendable mean average feature detection precision of 0.94 when evaluated on a meticulously curated dataset comprising 450 images. Furthermore, a dual-side processing optimization module is deployed to enhance the accuracy of defect detection bounding boxes and establish refined processing coordinates. This innovative approach yields a notable 12.3% increase in the volume yield of sawn timber compared to present production, signifying a substantial leap toward efficiently utilizing solid wood resources in the lumber processing industry.

Research Hotspots and Trends of Large-Diameter Trees Based on Bibliometric Data

The current challenges facing large-diameter timber forests include low yield and low eco-economic benefit. As a result, the development of large-diameter timber forests has become one of the most important strategies for the development of forestry in China. The present study employed bibliometric analysis and Citespace software v.6.1.R3 to examine the literature from CNKI and WOS databases spanning 2002–2021. This analysis aimed to identify the research hotspots and trends in large-diameter timber trees while providing theoretical support and guidance for developing large-diameter timber forests. The research results showed the following data. (1) The number of articles published increased year by year, approximately 4.8 times in 20 years. (2) The journal “Forest Ecology and Management”, where the number of papers is up to 53, has a significant impact on the field of large-diameter timber research. The Tropical Forestry Experimental Center of the Chinese Academy of Forestry and the Wageningen University and Research in the Netherlands possess strong research capabilities, with average citation frequencies of the articles of 26.8 and 51.5, respectively. (3) Research on large-diameter trees focuses on “large-diameter timber cultivation technology and cultivation measures”, “forest conservation management”, “large-diameter timber stand structure”, and “dynamic monitoring of large-diameter timber growth”. “Selection of suitable seed sources”, “Innovation of large-diameter timber cultivation technology”, and “improvement of large-diameter timber forest management mode” are the future research trends of large-diameter trees. In the future, it will be a challenge to realize the sustainable development of large-diameter timber resources. Concurrently, long-term monitoring and scientific management of large-diameter timber forests will be a key issue in promoting the development of large-diameter timber forests.

Deep neural network-based plant protection strategy in rural garden landscape construction

Rural landscaping enhances the quality of the environment in rural areas by planting trees and flowers and plants and at the same time can contribute to the protection of plants in rural areas. The occurrence and development of landscape plant diseases are very insidious, which may lead to poor tree growth and affect the annual growth of timber, or even lead to the death of the whole forest and the reverse succession of the forest. Plant leaf disease lesion location is random, and plant leaf image shooting is susceptible to light, background, angle and other objective factors can only rely on artificial identification, but the traditional artificial identification and physiological information extraction methods such as low accuracy, low efficiency and cumbersome. The rapid development of deep neural networks provides an effective solution for plant leaf recognition based on image analysis. In this paper, a DCA-ResNet model is constructed based on ResNet101 to recognize plant leaves by introducing the attention mechanism and optimizing the model structure. The validation of the DCA-ResNet model using public datasets on three species of plant leaves and plant leaf diseases achieved accuracy rates of 96.79%, 96.64%, and 96.44%, respectively.

Comprehensive Time-Course Transcriptome Reveals the Crucial Biological Pathways Involved in the Seasonal Branch Growth in Siberian Elm (Ulmus pumila).

Timber, the most prevalent organic material on this planet, is the result of a secondary xylem emerging from vascular cambium. Yet, the intricate processes governing its seasonal generation are largely a mystery. To better understand the cyclic growth of vascular tissues in elm, we undertook an extensive study examining the anatomy, physiology, and genetic expressions in Ulmus pumila. We chose three robust 15-year-old elm trees for our study. The cultivars used in this study were collected from the Inner Mongolia Autonomous Region in China and nurtured in the tree farm of Shandong Normal University. Monthly samples of 2-year-old elm branches were taken from the tree from February to September. Marked seasonal shifts in elm branch vascular tissues were observed by phenotypic observation: In February, the cambium of the branch emerged from dormancy, spurring growth. By May, elms began generating secondary xylem, or latewood, recognized by its tiny pores and dense cell structure. From June to August, there was a marked increase in the thickness of the secondary xylem. Transcriptome sequencing provides a potential molecular mechanism for the thickening of elm branches and their response to stress. In February, the tree enhanced its genetic responses to cold and drought stress. The amplified expression of CDKB, CYCB, WOX4, and ARF5 in the months of February and March reinforced their essential role in the development of the vascular cambium in elm. Starting in May, the elm deployed carbohydrates as a carbon resource to synthesize the abundant cellulose and lignin necessary for the formation of the secondary wall. Major genes participating in cellulose (SUC and CESA homologs), xylan (UGD, UXS, IRX9, IRX10, and IRX14), and lignin (PAL, C4H, 4CL, HCT, C3H, COMT, and CAD) biosynthetic pathways for secondary wall formation were up-regulated by May or/and June. In conclusion, our findings provided a foundation for an in-depth exploration of the molecular processes dictating the seasonal growth of elm timber.

Natural durability of mid-rotation plantation Gympie messmate and red mahogany in a 13-year aboveground field test

ABSTRACT Compared with the same species from native forests, faster growth and earlier harvesting of plantation timber may cause reductions in heartwood extractive levels, density and decay resistance due to the immaturity of wood tissues. The aim of this study was to evaluate the decay resistance of mid-rotation plantation Gympie messmate and red mahogany heartwood in ground proximity and L-joint aboveground field tests at three sites in Queensland, Australia. After 12–13 years in both tests, the inner heartwood of each plantation species generally had more decay than the middle and outer heartwood. Middle heartwood was significantly less durable than outer heartwood for each plantation species in the ground-proximity test at the tropical South Johnstone site. Plantation Gympie messmate outer heartwood performed similarly to native-forest spotted gum, the high-durability reference species. Plantation red mahogany had more decay than Gympie messmate. Given the need for plantation timber to supplement supplies from sustainable native forest resources, substantial research is recommended to fully characterise the durability of key plantation hardwood species, including investigation of protective treatment supplementation and communication of design requirements.

A framework of payments for water-related ecosystem services (PWES) based on green water management

Green water describes precipitation that infiltrates into the unsaturated soil layer and returns to the atmosphere via plant transpiration and soil evaporation, which are two functions of the hydrological cycle. Green water provides the basis for timber growth, crop production, and ecosystem services. However, it has not been adequately accounted for in traditional payments for water-related ecosystem services (PWES), which predominantly consider on blue water and hence underestimate the availability of all water resources. In this study, a new framework of payments for green water-related ecosystem services (PGWES) is proposed based on green water management (GWM) and green water compensation (GWC). This framework is constructed with game theory modelling, hydrological simulation and scenario evaluation. Then, the Xiangjiang River Basin (XRB) is used as a case study to test and evaluate the feasibility of the framework. The results of this study are as follows: (a) the framework of PGWES and its game payoff matrix and optimal payoff function are improved by adding the GWM scenarios. This approach can identify the GWC standard and Pareto optimal solution in different GWM scenarios, thereby optimizing the spatial allocation of blue and green water in the river basin and coordinating conflicts of interest between the upstream and downstream. (b) The average Pareto optimal payoffs of the XRB are increased by 4390 million CNY/year under different GWM and GWC scenarios compared to the baseline scenario, and the average GWC standard is 2.41 CNY/m3 or 1305.98 CNY/hm2. The case study indicates that the socioeconomic and ecological benefits for the whole XRB are expected to significantly improve under this framework. (c) Three aspects of managing water resources and conflict of interest issues noted during the study include “broadening water sources”, “saving water resources” and “coordinating water conflict”. Green water resources are an important component in broadening water sources; green water management provides a basic measurement tool for saving water resources; and green water compensation based on game theory offers a possible way to coordinate water conflicts and should be given more attention. In general, the PGWES framework provides a referenced methodology for the efficient development and equitable allocation of blue and green water resources in the river basin; furthermore, this study provides a scientific basis for the theory and methods of PWES, thus enriching this field of research.

Long-term effects of planting density and site quality on timber assortment structure based on a 41-year plantation trial of Chinese fir

Stand density control coupled with site control is a key technique for cultivating large-diameter timber of Chinese fir trees, whose yield can be effectively increased by the optimal density and site management mode employed. This study aimed to evaluate the dynamic changes in timber assortment structure under differing initial planting densities and site quality based on growth data of a 41-year trial of Chinese fir plantations. Our results showed that the total timber yield and both large-diameter timber outturn and the outturn rate all increased with better site quality under the same initial planting density. Further, the outturn peak as well as outturn rate peak for both medium- and small-diameter timber was reached sooner with improved site quality. For the same site class, a lower initial planting density augmented the total timber outturn rate, and also resulted in less time required for the total timber outturn rate to reach a constant or maximum value. Finally, the total timber outturn rate of all density plots tended to be nearly identical. Using a high planting density increased the outturn of small-diameter timber, whose outturn peak was delayed in the denser plots. The bolstering effect of low density upon the growth of large-diameter timber was enhanced by higher site quality, with density-induced differences in large-diameter timber more pronounced; conversely, that promoting effect weakened under poor site quality conditions. The interaction between planting density and site index significantly influenced the growth of any timber assortment of Chinese fir in the early stage following its formation. Notably, the significant effect of site index on large-diameter timber lasted longer than that of other timber assortments. The optimal site conditions for cultivating large-diameter timber trees of Chinese fir consist of a site class ≥ 20 with a planting density limited to no more than 1667 trees/ha, whose stand rotation period must be over 26 years, so as to maximize the output of large-diameter timber yield. Our empirical findings will be helpful for the construction of an optimal cultivation mode for the density, site, and rotation age of large-diameter timber in Chinese fir plantations.

Determining optimal forest rotation ages and carbon offset credits: Accounting for post‐harvest carbon storehouses

AbstractSequestering carbon in forest ecosystems is important for mitigating climate change. A major policy concern is whether forests should be left unharvested to avoid carbon dioxide (CO2) emissions and store carbon, or harvested to take advantage of potential carbon storage in post‐harvest wood product sinks and removal of CO2 from the atmosphere by new growth. The issue is addressed in this paper by examining carbon rotation ages that consider commercial timber as well as carbon values. A discrete‐time optimal rotation age model is developed that employs data on carbon fluxes stored in both living and dead biomass as opposed to carbon as a function of timber growth. Carbon is allocated to several ecosystem and post‐harvest product pools that decay over time at different rates. In addition, the timing of carbon fluxes is taken into account by weighting future carbon fluxes as less important than current ones. Using simple formulae for determining optimal rotation ages, we find that: (1) Reducing the price of timber while increasing the price of carbon will increase rotation age, perhaps to infinity (stand remains unharvested). (2) An increase in the rate used to discount physical carbon generally reduces the rotation age, but not in all cases. (3) As a corollary, an increase in the price of carbon increases or reduces rotation age depending on the weight chosen to discount future carbon fluxes. (4) Site characteristics and the mix of species on the site affect conclusions (2) and (3). (5) A large variety of carbon offset credits from forestry activities could be justified, which makes it difficult to accept any.

The effect of pests and pathogens on forest harvesting regimes: A bioeconomic model

Pests and diseases are an existential threat to trees in forests and woodlands. There is, therefore, a pressing need to use ecological and bioeconomic models to inform forest managers on control and mitigation strategies. For example, the incidence of Dothistroma needle blight in the UK has increased rapidly since the 1990s, and it is a significant threat to the productivity of commercial forestry. Climatic changes are expected to exacerbate this problem further. Control of the disease in the UK primarily focuses on good stand management through pre-commercial thinning; similar practices are widely used in commercial forests worldwide. Forest managers would benefit from evidence on the effectiveness of this precautionary strategy (in comparison to its alternatives) to reduce disease impacts and increase the value extracted from timber. In this paper, we develop a bioeconomic model to determine the economically optimal harvesting regime – in terms of thinning and rotation – of an even-aged plantation under the risk of an invading pest. We extend a Schaefer–Faustmann model to include a compartmental epidemiological system that governs timber growth and disease spread. We analyse a set of management regimes, including the timing of the final clear-felling of the forest and the timing and level of earlier thinning. Thus, in our approach, forest managers decide whether and when to thin and must balance (i) harvesting before infection destroys the timber’s value and (ii) exploiting the forest’s density-dependent growth. We use a sensitivity analysis with respect to the disease spread and impact on the tree dynamics to demonstrate that, in the presence of disease, thinning can significantly improve the net present value of the plantation if applied correctly. Furthermore, if thinning reduces the transmission rate significantly, the priority is to protect the final harvest, and rotations extend while the thinning time shortens. Our study provides a framework to help design appropriate forest management strategies in the presence of disease.

Understanding Nonindustrial Private Forest Landowners’ Perspectives on the Benefits Associated with Sustainable Forest Management Certification

Sustainable forest management provides ecological, economic, and social benefits to society. Sustaining these benefits in Arkansas relies on 345,000 nonindustrial private forest (NIPF) landowners who own 4.2 million hectares (10.4 million acres) of forests. Forest certification is a voluntary and market-based mechanism aimed to enhance such societal benefits while providing incentives or benefits for the landowners. Understanding NIPF landowners’ perspectives on the benefits associated with adopting forest certification programs would be useful in identifying potential participants and in designing outreach and communication programs to elevate the interests of less interested landowners in participating in certification programs. Using data collected from a mixed mode of mail and online (Qualtrics) survey of NIPF landowners in Arkansas, this study examined the potential factors that influence landowners’ perspectives on different benefits associated with adopting sustainable forest management certification by employing binary logistic regression. Results revealed that ownership and forestland characteristics (i.e., ownership size, whether having a harvesting plan), as well as ownership motivations (biodiversity protection, financial investment, hunting), were significantly associated with landowners’ agreement on the benefits of increasing timber growth and health, expanding markets, having a price premium for certified timber, enhancing public recognition, more environmental-friendly harvesting, and better management practices. These findings improve the understanding of landowners’ expectations after certifying their forestland and provide baseline information for improving certification program design to attract more adoption among private and family landowners.

Quantitative analysis of Saharanpur wood carving handicraft industry on the specific issues of wood and wood product certification

The study was undertaken with the objective to develop strategies for certification of wood and woodcraft products for Saharanpur District of Uttar Pradesh, India. The primary data was collected through a preliminary survey, from the various stakeholder including manufacturers and exporters commission agents /brokers traders, and artisans.The data analysis relates to the awareness regarding wood certification among stakeholders, which indicates a very low level of that awareness among all stakeholders. Only 16.67% Commission agents, 11.28% manufactures and traders, 4.26% of traders are aware of the wood certification 79.17% commission agents/brokers, 97.74% manufacturers and exporters,95.74% traders and100.0%craft sman responded that they are not very much aware of the procedure and practices of wood certification. The majority of stakeholders are of the view that the role of non-government organization for wood certification which would work as a bridge between government and stakeholders. The share 97.74% of manufactures and exporters answered that non-government organization creates awareness for wood certification and sustainable forest management. It was also revealed that the timber growers (Forest department and Farmers) should take initiative for certifying their wood rather than other stakeholders of the woodcraft industry.

Timber growth, cacao yields, and financial revenues in a long-term experiment of cacao agroforestry systems in northern Honduras

Cacao in Honduras is cultivated under traditional shade tree species (Inga sp., Erythrina sp., Gliricidia sp.), fruit and timber species deliberately planted or selected and managed from natural regeneration. Typically, the shade canopy of these cacao plantations is poorly managed resulting in high tree density and heavy shading, thus affecting cacao yield performance overtime. We assessed 12 cacao plots made up of 15–35 useful timber shade trees with varying spacing 6 × 9, 9 × 9, 8 × 10, and 10 × 12 m. Initially, each plot consisted of three shade components plus cacao. Plantain (Musa x paradisiaca) and madreado (Gliricidia sepium) were used as temporary shade and timber species, were selected as permanent shade. Dasometric data were retrieved to assess growth rates of timber species and cacao yield per plant were recorded to explore the effects of shade cover yield performance and the incidence of main diseases. Specifically, we: a) calculated growth rates and build curves for diameter (DBH), total height (Ht), and commercial volume (Vc) and compared the growing performance with ANOVA and DGC tests; b) run a correlation analysis between shade cover, timber basal area, cocoa yields, and the incidence of monilia and black pod. Statistical differences were found in terms of growth rates among timber species evaluated. Mean annual growth rates were 2.25 cm in DBH, 1 m in Ht, and the standing commercial timber gained was 4.2 m3ha−1year−1. Cocoa yields ranged between 950 and 1,365 kg ha1year1 and were negatively affected by both increased tree cover and timber basal area. Cacao yields were reduced up to 25% when tree cover and tree basal area were over 40% and 10 m2ha−1, respectively. Regardless of timber tree species, no significant effect of tree cover was found on the incidence of cacao diseases. After 22 years, total revenues were determined by the proportion of incomes provided by each component of the agroforestry systems assessed. Five out of 12 timber-based cacao plantations accumulated more than U$95,000 of combined revenues, equivalent to incomes of US$3775 ha−1 year−1. Timber-based cacao plantations are a promising alternative for farm diversification in northern Honduras.

Modelling the response of larch growth to age, density, and elevation and the implications for multifunctional management in northwest China

Plantations of Rupprecht’s larch (Larix principis-rupprechtii) have been widely established in the drylands of northwest and north China under traditional fast-growing plantation management strategies. These strategies and the long-term logging ban have led to over-populated stands with lower structural and functional stability, less economic benefit and higher water consumption. To guide the sustainable management of larch plantations, field surveys and historical data compilation were undertaken in the Liupan Mountains of northwest China. The main influencing factors (stand structure and site condition) and their effects on mean tree height, mean DBH and timber volumes were determined based on up-boundary line analysis. Tree growth models coupling the effects of tree age, stand density, and elevation were established. Both height and DBH markedly increased initially and then slowly with tree age, decreased with stand density, and showed unimodal change with elevation. The coupled growth models accounted for 72–78% of the variations in tree height, DBH and timber growth. Recommendations for future plantation management are: (1) prolong the rotation to at least 60 years to produce large-diameter, high-quality timber and maintain greater carbon stocks; (2) zone the target functions of stands by elevation; and, (3) reduce stand density for balanced supply of multiple ecosystem services. The growth models developed can predict growth response of larch plantations to density alteration under given ages and elevations, and assist the transformation from traditional management for maximum timber production to site-specific and multifunctional management with longer rotations and moderate tree density.

Productivity-Based Land Suitability and Management Sensitivity Analysis: The Eucalyptus E. urophylla × E. grandis Case

Eucalyptus plantations are productive and short rotation forests prevalent in tropical areas that experience fast expansion and face controversies in ecological issues. In this study, we perform a systematic analysis of factors influencing eucalyptus growth through plot records from the National Forest Inventories and satellite images. We find primary restricting factors for eucalyptus growth via machine learning algorithms with random forests and accumulated local effects plots, as conventional forest growth models are inadequate to calculate the causal effect with the large number of environmental and socioeconomic factors. As a result, despite common belief that temperature affects eucalyptus growth the most, we find that precipitation is the most evident restricting factor for eucalyptus growth. We then identify and rank key factors that affect timber growth, such as tree density, rotation period, and wood ownership. Finally, we suggest optimal management and planting strategies for local farmers and policymakers to facilitate eucalyptus growth.

Improving Communications to Increase Nonindustrial Private Forest Landowner (NIPF) Participation in Forest Certification Programs: A Case Study in Arkansas, USA

Despite the socioeconomic and ecological significance of the 10.4 million acres of forestland owned by nonindustrial private forest (NIPF) landowners across Arkansas (approximately 58% of forestland in the state), only 5% of this land is certified through the American Tree Farm System. As such, understanding how to improve the reach and content of communications to NIPF landowners is vital for expanding certification participation and subsequent improvement of forest management in Arkansas and throughout the southern United States. To explore current and optimal communications to increase NIPF participation, we employed Berlo’s source–message–channel–receiver (SMCR, 1960) model to analyze survey data collected from Arkansas NIPF landowners regarding their familiarity with, interest in, and information sources for forest certification programs. Our results indicate that NIPF landowners have a relatively low familiarity with certification programs and a low interest in adopting a certification program regardless of personal involvement throughout the certification process, the transparency of on-sight inspections to the public, and the requirements of forest management plans. However, positive correlations were found between self-reported familiarity with certification programs and the perceived usefulness of various information sources, indicating that communications to NIPF landowners have the ability to be influential. Furthermore, the results showed that the greatest perceived benefits to landowners were improved timber growth and health, better management actions, and environmentally-friendly timber harvesting, whereas the most concerning perceived drawbacks were increased record-keeping and paperwork as well as management costs. These findings will offer actionable insights into future messaging campaigns and provide directions for new approaches of reaching NIPF landowners to increase their participation in forest certification.

Increasing Mass Timber Consumption in the U.S. and Sustainable Timber Supply

Mass timber products are growing in popularity as a substitute for steel and concrete, reducing embodied carbon in the built environment. This trend has raised questions about the sustainability of the U.S. timber supply. Our research addresses concerns that rising demand for mass timber products may result in unsustainable levels of harvesting in coniferous forests in the United States. Using U.S. Department of Agriculture U.S. Forest Service Forest Inventory and Analysis (FIA) data, incremental U.S. softwood (coniferous) timber harvests were projected to supply a high-volume estimate of mass timber and dimensional lumber consumption in 2035. Growth in reserve forests and riparian zones was excluded, and low confidence intervals were used for timber growth estimates, compared with high confidence intervals for harvest and consumption estimates. Results were considered for the U.S. in total and by three geographic regions (North, South, and West). In total, forest inventory growth in America exceeds timber harvests including incremental mass timber volumes. Even the most optimistic projections of mass timber growth will not exceed the lowest expected annual increases in the nation’s harvestable coniferous timber inventory.

Evaluation of Low-Grade Yellow-Poplar (Liriodendron tulipifera) as Raw Material for Cross-Laminated Timber Panel Production

Abstract Utilization of low-grade yellow-poplar (Liriodendron tulipifera) lumber would provide for alternative structural lumber sources and promote the growth of cross-laminated timber (CLT) manufacturing facilities within the Appalachian Region. A significant amount of low-grade yellow-poplar lumber (i.e., National Hardwood Lumber Association [NHLA] No. 2A and Below Grade) is utilized for wood pallets. In practice, this material is not graded for structural purposes. Additionally, research on yellow-poplar for structural use has focused on grading lumber from a small population of selected logs, not by regrading NHLA lumber from manufacturing facilities. Therefore, the research's objective was to investigate the structural grades of a typical population of NHLA graded No. 2 and lower lumber and evaluate their potential to meet structural grades necessary for CLT panels. NHLA graded lumber was regraded and assigned to visual structural grades following Northeastern Lumber Manufacturers Association rules and evaluated for flatwise bending modulus of elasticity (MOEb) by nondestructive proof loading. The results of the study indicated that 54.6 percent of the boards possessed a minimal structural visual grade required for CLT panels according to American National Standards Institutes/The Engineered Wood Association (ANSI/APA) PRG 320-2019 (2020). Splits were the most common limiting defect that downgraded boards to nonstructural grades. Also, 96.6 percent of the boards evaluated had a MOEb above the required minimal board value of 1.2 ×106 psi (8,274 MPa) listed in ANSI/APA PRG 320-2019 (2020). The results of the study indicated that a majority of NHLA low-grade yellow-poplar, when regraded for structural purposes, meets or exceeds minimum lumber grade values necessary for use in CLT panel production.

Contribution of Small-Scale Acacia Hybrid Timber Production and Commercialization for Livelihood Development in Central Vietnam

Forming a backbone of the wood supply in Vietnam, approximately 50% of plantation areas are managed by individual households. Of the planted species, the Acacia (Acacia auriculiformis A. Cunn. ex Benth. × Acacia mangium Willd) hybrid is one of the most preferred by timber growers. Yet, information on the potential of this timber species for rural livelihoods is lacking. Taking Nam Dong and Phu Loc districts in Thua Thien Hue province as case studies, this paper aimed to explore the (i) characteristics of small-scale Acacia hybrid timber producers; (ii) contribution of Acacia hybrid timber production and commercialization to rural livelihoods; and (iii) socio-economic and contextual factors which determine the income from Acacia hybrid timber. We applied a mixed-methods approach including review of secondary data, interviews of 26 key informants, eight focus group discussions, direct observations and a survey of 300 Acacia hybrid producer households selected through multistage and purposive sampling. Qualitative and quantitative data were analyzed using thematic, descriptive and inferential statistics, such as variance analysis, correlation analysis and Bayesian model average (BMA) analysis. The results demonstrated the diversity of socio-economic characteristics, resource access and management as well as determinants of timber income of small-scale timber producers between the cases. Accounting for 33–56% of total household income, Acacia hybrid timber plantations played a crucial role in the current livelihood system. Nevertheless, timber income was skewed toward the wealth status of timber producers and ranged between 327 USD/household and 3387 USD/household in Nam Dong and between 397 USD/household and 9460 USD/household in Phu Loc district. Despite the substantial contribution the income from Acacia hybrid plantations could make to local poverty reduction, it was the main contributor to the overall income inequality. While this income source reduced the Gini coefficient by 1% in Nam Dong, it increased the Gini coefficient by 18% in Phu Loc district. Our study can be of interest for further policy interventions focusing on sustainable reforestation and livelihood development in Vietnam.

Continuous timber harvest — Costly restriction or profitable solution?

In timber production, sustainability means maintaining resources by balancing timber harvest with timber growth. In forest management, sustainability also refers to a constant and steady flow of income. The aim of this study is to resolve the contradiction, whether a sustainable/continuous flow of timber income is a costly (income-reducing) restriction, or a comparatively profitable (income-increasing) solution. For that we relax the common assumption of a perfect capital market and consider differing borrowing and lending rates to incorporate the aspect of financial viability into forest management decisions.Based on an established forest production model, we construct a synchronized “normal” forest enterprise and confront it with an interest rate on a perfect capital market and transform the forest enterprise to be optimal under the Faustmann-Pressler-Ohlin rule (FPO-rule). We do this by strictly following the FPO-harvesting-pattern, which immediately yields a perpetual non-constant (intermittent) flow of timber income. Alternatively, we simulate a long-term continuous forest enterprise transition, which ultimately results in a new normal forest structure with constant timber income. In a second step, we re-run the forest enterprise transitions under varying borrowing and lending rates, that differ as a function of capital availability within an imperfect capital market model. In both approaches, we derive and compare the maximum annual payout of the two alternative transition paths for an infinite time-horizon.Our results show, that the normal forest enterprise structure no longer holds when the rotation age is adjusted to be optimal under the FPO-rule when capital markets are perfect. We highlight why the normal forest structure is often referred to as a costly restriction towards the question of the optimal harvesting age due to inefficient investment and financing costs. In an imperfect capital market, with differing borrowing and lending rates, creating a new normal forest stand structure appears to be economically favorable compared to a stand structure which yields non-constant income.While our analysis does not provide universally valid evidence for the optimality of a normal forest, we are able to show that a constant flow of income can be favorable compared to non-constant income when the assumption of a perfect capital market is relaxed.

Site Quality for Mahogany (Swietenia macrophylla King) in Natural Forests in Quintana Roo

ABSTRACT The concept of site quality was developed to project the expected production of timber species in even-aged stands in order to produce standardized site index curves. This concept can also be used in a more ecological sense to discern the spatial growth patterns of timber species in natural forests. We used the height-diameter relationship to evaluate a method to determine site quality for Swietenia macrophylla King in natural forests in Quintana Roo, Mexico. Using linear models and analysis of covariance, we detected significant and notable differences in mahogany development (p < .001), with some trees exceeding the predicted height by more than one meter. These differences were related to micro-topographic and edaphic factors and to the spectral response of the vegetation. Using a predictive model of site quality to develop a site quality map, we also determined that 86% of the production forest in the study area fit in the low productivity category, with mahogany growing below the predicted height for the area. These results suggest that site quality maps can contribute to effective forest management where forest aptitude is not homogeneous for timber growth. Concentrating management practices on high quality sites has the potential to conserve investment resources and increase production.