Minimum Logging Diameter Research Articles

Growth dynamic and climate signals on abandoned plantation of Pinus elliottii in Southern Brazil: A dendrochronological contribution

Pinus plantation forestry in South America has expanded quickly and assumed a significant portion of land use, including in urban arborization. This invasive alien genus changes the plant community, resulting in a loss of biodiversity, and environmental issues that require public policy actions. Here, we applied dendrochronology to assess ecological growth dynamics and micro and macro scale climate effects on an abandoned Pinus elliottii trees in urban forest fragments, and provide insights into the management for public policies. We constructed a robust 41-year (1978 – 2019) chronology that showed r = 0.63, rbar = 0.47, and EPS = 0.92 with an average annual growth rate of 7.10 mm/year. Modeling tree growth of diameter, height and volume of P. elliottii based on tree-ring analysis, we assessed the average diameter without bark (42.37 cm) and height (19 m). The growth rates in the early years evidence pioneer behavior, representing rapid sexual maturity. The volume growth model indicates an average individual volume of 1.23 m³ , with maximum productivity at 16 years when the current annual volume increment peaks. This age corresponds to a diameter of 32 cm, which would be an appropriate minimum logging diameter to wood destined for a sawmill. Volumetric increment rates highlight the potential trade-in forestry sector and application in public policies that aim to control and manage P. elliotti. We evidence significant climatic signals, but with moderate influence on the variability of growth. For the local climatic variables, there was a positive influence of warm and humid summer and late spring, during the previous and current growth seasons. Furthermore, considering global climatic factors, there was only a positive influence of the Annual Southern Oscillation Index for June, representing a positive correlation for dry and cold early winter, influenced by La Niña events. This work provides an understanding of the biological growth of P. elliotti in urban forest fragments and opens a perspective to assist public policies in managing the invasion of Pinus spp. linked to the forest trade.

Mechanical Behavior of Pericopsis elata Relative to Age during Growth

The assamela (afrormosia) whose scientific name is “Pericopsis elata” (Harms), a large tree of great commercial value, is an exploited species. It is considered “endangered” by the IUCN.” Trees ready for harvesting are scarce because the logging diameter, which has been set at 100 cm, is very big. The studies recommended by the Cameroonian government as part of the ITTO/CITES project activities should be carried out to determine a new minimum logging diameter as the diameter increases with age. No credible solution is provided in the scientific literature to compensate for its scarcity of exploitation. Moreover, little or no information is available for describing the variation of its mechanical properties over time in order to determine the age at which its wood mechanical properties are good enough to be marketable. It is in this context that this work was undertaken. In this study, we adopted an experimental approach to evaluate the mechanical properties of this species exploited in southeast Cameroon. We then studied the variations in these properties as a function of tree age in order to propose leads for their exploitation. Thus, the compression and bending tests allowed us to estimate the relationship between the mechanical properties in three main directions of the log (MOE in compression and bending, failure stress in compression and bending, and creep in compression) and age (or diameter). We also used the 10‐hour creep under low axial compressive loading data to implement the theoretical fractional Maxwell (MF) model, which was compared to the experimental data. For this purpose, after three months of natural drying in the laboratory, we evaluated the above mechanical properties according to age. This study shows that the mechanical properties change as the diameter increases and change very quickly from 70 cm diameter upwards. From the analysis of the experimental data, we deduced that the minimum diameter of exploitable trees should be equal to 80 cm corresponding to the age of about 200 years.

Dynamique des populations d'azobé, Lophira alata Banks ex C. F. Gaertn., et implications pour sa gestion durable au Cameroun

L'impact de l'exploitation forestière sur le renouvellement du stock de bois d'œuvre reste largement méconnu en Afrique centrale du fait du manque de données sur la dynamique des populations d’arbres exploités. C’est en particulier le cas pour l’azobé, Lophira alata, un bois d’œuvre de grande valeur commerciale. L'objectif de cette étude était double : quantifier l'effet du type forestier et de l’exploitation sur la croissance de l’azobé et simuler l'évolution du stock exploitable et du taux de reconstitution après exploitation. Nous avons effectué pendant trois ans un suivi annuel de la croissance et de la mortalité dans trois types forestiers au Cameroun : en forêt sempervirente, en forêt mixte et en forêt semi-caducifoliée. Le recrutement a été étudié uniquement en forêt mixte, sous deux conditions : en milieu exploité et non exploité. Nous avons calibré, avec ces données, un modèle matriciel de Usher. Douze scénarios d’exploitation ont été simulés en faisant varier le diamètre minimum d’exploitation de 60, 70 et 80 cm, et l’intensité de prélèvement des arbres de 100, 80, 60 et 40 %. La croissance de l’azobé est influencée à la fois par le type forestier et l'exploitation. Les arbres de forêt sempervirente ont une croissance plus faible jusqu’à 50 cm de diamètre, alors que la croissance maximale prédite pour ce type forestier est la plus élevée. L'exploitation a par ailleurs stimulé la croissance. Enfin, l’exploitation de l'azobé ne respecte pas le principe du rendement soutenu : ses taux de croissance à long terme varient entre 0,54 et 0,83. Pour garantir la durabilité de son exploitation au Cameroun, une sylviculture dynamisant la croissance des futurs arbres exploitables, ainsi que leur régénération, s’avère indispensable.

Measures for sustainable forest management in the tropics – A tree-ring based case study on tree growth and forest dynamics in a Central Amazonian lowland moist forest

The conservation of tropical forests is recognized as one of the most important challenges for forestry, ecology and politics. Besides strict protection, the sustainable management of natural forests should be enhanced as a key part of the foundation for the maintenance of tropical rain forest ecosystems. Due to methodological reasons it has been complicated to attain reliable growth data to plan sustainable felling cycles and rotation periods. Tree ring analyses enable the estimation of growth rates over the entire life span of trees and their age as well as giving hints from forest dynamics in previous centuries. For tree ring analysis, stem disk samples were taken from three important commercial tree species (Cariniana micrantha, Caryocar villosum and Manilkara huberi) in the upland (terra firme) forests of the Precious Woods Amazon logging company near Itacoatiara, Brazil. Based on radiocarbon estimates of individual growth zones, the annual nature of tree rings was proven for the three species. Tree rings were measured and the results used together with height estimates to model diameter, height and volume growth. The age of the eldest tree, a C. micrantha, was 585 yrs with 165 cm in diameter. The species’ diameter increments range from 0.20±0.12 cm yr-1 to 0.29±0.08 cm yr-1. At first sight, this is considerably lower than increments reported from other Amazonian or African timber species. Considering the respective wood density there is no significant difference in growth performance of dominant timber species across continents. The interpretation of lifetime tree ring curves indicate differences in shadow tolerance among species, the persistence of individuals in the understory for up to 150 years and natural stand dynamics without major disturbances. Management criteria should be adapted for the measured growth rates as they differed considerably from the Brazilian standards fixed by laws (felling cycle of 25–35 years and a common minimum logging diameter of 50 cm). Felling cycles should be increased to 32–51 years and minimum logging diameters to 63–123 cm depending on the species.

Growth models for two commercial tree species in upland forests of the Southern Brazilian Amazon

Despite all efforts to promote sustainable use of timber resources in tropical forests, the current management criteria still require adjustments at a species level, considering specific growth patterns and ecological features. Forest management in upland forests (terra firme) of the Brazilian Amazon region generally applies for all commercial tree species a common minimum logging diameter (MLD) of 50 cm and a felling cycle (FC) varying according to the harvest intensity between 25 and 35 years.. In this study, we define species-specific FCs and MLDs for the two commercial tree species Hymenaea courbaril L. (Fabaceae) and Handroanthus serratifolius (Vahl) S.O. Grose (Bignoniaceae) from the terra firme of the Southern Brazilian Amazon, applying growth models based on the relationships between estimated tree age, diameter, height and volume. A total of 37 transversal cross-sections (20 stem discs from Hymenaea and 17 from Handroanthus) were obtained at a height of 20–60 cm above soil level in a private forest concession close to the municipality of Novo Aripuanã in the southern region of the Amazonas state. The two species are common in terra firme forests and have high wood densities of 0.76–0.96 g cm−3 (H. courbaril) and 0.85–1.08 g cm−3 (H. serratifolius). The mean age of H. courbaril and H. serratifolius, estimated by ring counting, varied from 104 to 241 years and both species had similar mean diameter increments of 3.9 ± 0.5 mm year−1 and 4.1 ± 0.6 mm year−1, respectively. Both species present similar tree growth in diameter, height and volume resulting in a FC of 24.2 years and a MLD of 64.9 cm for H. courbaril, and a FC of 26.0 years and a MLD of 69.5 cm for H. serratifolius. These results demonstrate the need to adjust the selective logging systems practiced in the Brazilian Amazon region towards a species-specific management of timber species to increase the sustainability of selective logging.

Drivers of growth variability of Hymenaea stigonocarpa, a widely distributed tree species in the Brazilian Cerrado

Dendrochronology is a valuable tool to understanding climate-growth and growth-age relationships of native tree species from tropical forests. The information obtained from growth rings can elucidate climate responses of tree-growth under the ongoing environmental changes and support the development of sustainable forest management strategies based on species and site conditions. The Cerrado, which is a vast tropical savannah ecoregion of Brazil, has precipitation seasonality capable of inducing the formation of annual tree rings in moisture sensitive woody species. Hymenaea stigonocarpa is the typical tree species in the Cerrado with proven annual tree rings. It is an important commercial species that has been massively exploited for timber causing the considerable reduction of its natural populations. This study provides information about tree age and growth trajectories as well as climatic-growth signals of H. stigonocarpa in southeastern Brazil. We sampled 13 trees for tree-ring analysis. Tree-ring measurement and analysis were conducted using standard dendrochronological techniques. Sampled trees revealed the young successional stage of the stand, with ages varying from 20 to 35 years old. Nine out of 13 trees were used to build the standard chronology (1981 to 2013) that was positively correlated with precipitation at the end of the growing season (March-April). The chronology was able to capture SST anomalies patterns related to the South American Monsoon System. Growth modeling indicated that minimum logging diameter of 10.4cm is achieved at 24 years of age. The results reported here add valuable contribution to the discussion of sustainable management strategies for Cerrado ecoregion species.

Alternative criteria to achieve sustainable management of Mezilaurus itauba in the Brazilian Amazon

The aims of this study were to evaluate the Brazilian law parameters for tropical forest management regarding forest recovery and to propose alternative criteria to achieve sustainability, using Mezilaurus itauba (Meisn.) Taub. ex Mez as case study. The diameter structure was obtained from a 100% forest inventory of a 500 ha forest compartment. The assessment of M. itauba growth, ingrowth and mortality were carried out in a two sample plot of 50 ha located on the compartment, where all commercial species were measured both before and 7 years after logging. First it was evaluated the species structure and its most productive diameter class. The species recovery of timber volume has been simulated for the minimum logging diameter (MLD) of 50, 60, 70 and 80 cm. The largest volume recover was reached for the 60 cm MLD class. We showed that there is a diametric limit to achieve net timber volume production and that different remnant structures produce different increments.

FOREST MANAGEMENT FOR THE CONSERVATION OF Araucaria angustifolia IN SOUTHERN BRAZIL

Forest management is the legal instrument to propose interventions and conservation of tree species in natural forests; it is a requirement for the management of commercial forest plantations. Considering as objective the conservation with sustainable management and knowledge of the increment rates in forests with Araucaria angustifolia , growth models were fitted with the measures of ring increment data of 587 trees, covering all distribution diameter classes, in four sites in southern Brazil. These fitted models showed the minimum cutting diameter of 40 cm for about 20 years (maximum annual increment in volume), cutting diameter of 55 cm in 37 years (maximum annual mean volume increment) and cutting cycle of 2 to 22.5 years for the diameter classes. The current increment rates in these diameter classes showed the need for approximately 20 years for the species to reach the minimum logging diameter. The lower growth rate in smaller diameter classes indicates that the species requires more time to reach the minimum cutting diameter, which is detrimental to the forest structure. The growth rate variability must be considered in the management of forests with A. angustifolia . The results showed the need and viability of sustainable silvicultural interventions to preserve forest diametric structures; otherwise the forest could compromise the development of larger trees.

Using radiocarbon-calibrated dendrochronology to improve tree-cutting cycle estimates for timber management in southern Amazon forests

Growth rings are investigated in trees harvested in the second cutting cycle in southern Amazonia and have important implications for dendrochronological studies and for forest management. In the southern Brazilian Amazon, upland moist forests have been managed based on a polycyclic system, which cutting cycle (CC) varies from 25 to 35 years, and the minimum logging diameter (MLD) is 50 cm for all species. Many forests logged during the 1970s are being prepared for the second cycle. However, without growth and yield rates information on the remaining forests as well as for individual species, the principles of sustainable management will be jeopardized. For species with annual growth rings, such information can be obtained using dendrochronological techniques. This study investigated the periodicity of rings in Qualea paraensis and Parkia pendula in a forest that had already experienced one cutting cycle. This information was used to estimate growth and yield rates, and adjusting to equations to estimate individual species MLD and CC. Dendrochronological techniques were combined with radiocarbon analyses to confirm whether rings were annual. Rings of Q. paraensis were confirmed to be annual without radiocarbon analysis. However, P. pendula rings were poorly distinguishable; therefore, delimitation and ring counting were systematically underestimated by 10%. Growth and yield rates of managed forests were favored by logging. The MLD should be 53 cm for Q. paraensis, and 42 cm for P. pendula; and the CC must be 11 and 17 years, respectively. It is concluded that MLD and CC legally defined by the Brazilian laws are not adequate for the studied species; in addition, the use of radiocarbon-calibrated dendrochronology technique is essential to produce robust and unbiased estimates of growth and yield rates.

Volume increment modeling and subsidies for the management of the tree Mora paraensis (Ducke) Ducke based on the study of growth rings

First study that demonstrated the formation of annual growth rings in Amazonian Estuary trees. Growth patterns of Mora paraensis and specific management criteria, such as felling cycle, are presented. The aim of the present study was to contribute to increased sustainability in the timber management of Mora paraensis, through the estimation of minimum logging diameter (MLD) and felling cycle, using volume increment models based on tree-ring analysis and allometric relationships. We collected stem discs from 17 trees of five diameter classes. The diameters and heights of the trees were also measured. We estimated tree ages by ring-counting and the radial increment rates by measuring the ring widths with a digital analysis system. We built growth models based on relationships between age, diameter and tree height to estimate volume increment along the tree’s whole life cycle. The maximum current diameter increment in M. paraensis occurs at an age of around 26 years, reaching 4.91 mm year-1. The MLD was 46.4 ± 0.6 cm (standard error), which trees achieve at an age of about 115 years. The felling cycle, estimated by the mean passage time through 10 cm diameter classes until achieving the MLD, was 24.7 ± 1.3 years. These results corroborated the norms of the current Brazilian legislation that regulates forest management of high intensity in the Amazon basin. In future, more specific growth models are needed for other commercial tree species in the Amazonian Estuary to define the optimal harvest rate to maintain sustainable timber resource management practices. Through such practices, the conservation of these ecosystems and their multiple services and functions, as well as the welfare of the forest-dependent human populations can be secured.

Étude de la croissance diamétrique de quatre essences de bois d’oeuvre exploitées à l’Est du Cameroun

Objectives: This article examines the diametric growth of 4 commercial species, with poor natural regeneration, exploited in eastern Cameroon. The species are Erythrophleum suaveolens (tali), Mansonia altissima (bété), Pericopsis elata (assaméla) and Triplochiton scleroxylon (ayous). Methodology and results: For this purpose, permanent monitoring growth devices constituted by permanent circuits were installed. After 3 years of annual measurements of the tree diameter, a periodic diametric medium growth of 0.68 cm / year for E. suaveolens, 0.37 cm / year for M. altissima, 0.32 cm / year for P. elata and 0.70 cm / year for T. scleroxylon was obtained. Considering the periodic medium growth of two diameter classes below the minimum diameter for logging, a new replenishment rate for the 4 species was calculated.Conclusion and application of findings:These replenishment rates were compared to the replenishment rate obtained using the diametric growth set by the Cameroonian government. There is an overestimation of the possibilities by the administration for M. altissima and T. scleroxylon and an underestimation of the possibilities in the case of E. suaveolens. For P. elata, the replenishment rate obtained in this study permanent devices is substantially similar to those calculated with the diametric growth proposed by the Cameroonian state. The results of this study will serve as a reference to the sustainable management of species with low diametric growth by raising their minimum logging diameter. For species with low natural regeneration as those considered in this study, silvicultural measures should be proposed.Keywords: commercial timbers; management plan; diametric growth; permanent devices; replenishment rate.

Growth Rate and Climatic Response ofMachaerium scleroxylonIn a Dry Tropical Forest In Southeastern Santa Cruz, Bolivia

Machaerium scleroxylon (morado) is an important timber species from the lowland tropical dry forests in Bolivia. We followed a dendrochronological approach to (i) evaluate the responses of radial growth to climatic variables and atmospheric circulation patterns, and (ii) quantify the growth rate in order to estimate the Minimum Logging Diameter (MLD), age, and optimal cutting rotation. We measured tree-ring width in wood discs taken from ten randomly selected mature individuals. We used previous histological analyses to distinguish and visually crossdate tree rings. Despite the existence of false rings, lenses and wedging rings, the species showed defined annual ring boundaries, thus enabling a tree-ring chronology analysis. Correlations between residual ring-width indices and monthly climatic variables (temperature and rainfall) and atmospheric circulation patterns (El Niño-Southern Oscillation) index were calculated. Growth showed a significant positive correlation with monthly rainfall and a negative correlation with mean temperature during the late rainy season (i.e. from December up to March). A positive correlation found between the ring width and ENSO indices indicates that the growth of M. scleroxylon was significantly affected by atmospheric circulation patterns. Growth rate is slow in morado, suggesting a MLD of 50 cm and an optimal cutting cycle longer than 40 years depending on each site.

Tree-ring analysis of an African long-lived pioneer species as a tool for sustainable forest management

Improved forest management in the tropics is hampered by the limited availability of quantitative data, especially in tropical Africa. Important management parameters such as the minimum logging diameter (MLD), the associated biological rotation age (BRA) and the timing of silvicultural treatments are too often based on merchantable dimensions and state regulations instead of ecological data and tree growth. This study combines inventory data and bootstrapped tree-ring curves of natural and planted trees of the long-lived pioneer species Terminalia superba Engl. & Diels. A growth-oriented MLD was calculated, and the need and timing of silvicultural treatments was estimated based on the analysis of growth releases and suppressions. Study sites were situated in the Congolese Mayombe forest and western Ivory Coast. Tree rings from 41 natural forest trees (stem discs) and 29 plantation trees (increment cores) were measured, along with diameter and height measurements. Planted and natural forests showed considerable differences in mean growth rate and growth curves. More than 50% of the trees nevertheless reached the canopy without growth releases or suppressions, confirming that T. superba does not require intensive management. The growth-oriented MLD not only differs considerably between sites but bootstrapping revealed large differences within forest regions/types. Furthermore, volume-based MLD and BRA are on average larger than basal area-based calculations. The modified monocyclic management system is suggested, especially for planted forests with light-demanding, fast-growing tree species. One small-scale thinning during the juvenile phase is recommended before a final harvest that includes all trees above the growth-oriented MLD. The introduction of sustainable management for T. superba therefore primarily depends on forest type and cannot be generalized at the species level.

Ecology of Pericopsis elata (Fabaceae), an Endangered Timber Species in Southeastern Cameroon

AbstractPericopsis elata (Fabaceae) is a tall tree of high commercial value of the moist semi‐deciduous African forests. As a result of decades of logging it is now considered as threatened and listed on the IUCN Red List and CITES Appendix II, even though essential biological parameters controlling its population dynamics remain unknown. This study aims at improving the knowledge of the species' ecological parameters, and at assessing the impact of selective logging on its populations in an 118,052 ha forest in Cameroon. After inventorying the species in 1432 ha, mortality and growth were assessed over continuous 5‐ and 2‐yr periods in unlogged and logged areas, respectively. Phenology was monitored in the unlogged forest during 5 yr. The population structure shows high relative abundance of trees in medium size categories. Mean annual diameter increments in both environments did not differ significantly between unlogged and logged areas. P. elata is a deciduous species that flowers at the end of the main dry season. The minimum reproduction and effective flowering diameters were 32 and 37 cm, respectively. Fruit maturation took place during 7 mo. With a minimum logging diameter of 90 cm, the recovery rate computed over a 30‐yr period was > 100 percent. Selective logging harvested only 12.1 percent of the total number of seed trees and had little influence on the species' biological parameters. Securing sufficient regeneration as a post‐logging action is probably the most important consideration for achieving long‐term sustainability.

Growth and population structure of the tree species Malouetia tamaquarina (Aubl.) (Apocynaceae) in the central Amazonian floodplain forests and their implication for management

The long-term success of forest management depends primarily on the sustainability of timber production. In this study we analyse the population structure, tree age and wood increment of Malouetia tamaquarina (Aubl.) (Apocynaceae) to define a species-specific minimum logging diameter (MLD) and felling cycle by modelling volume growth. Contrary to other timber species in the nutrient-rich white-water floodplains forests (várzea), M. tamaquarina grows in the subcanopy of old-growth várzea forests. The wood of this species is utilized by local inhabitants in the floodplains for handicraft. In 35 plots of 25 m × 50 m we measured diameter at breast height (DBH) and tree height of all trees taller than 150 cm height. From 37 individuals with DBH > 15 cm we sampled two cores by increment borers to determine the wood density, tree age and diameter increment rates. In the management area of a várzea settlement with about 150 ha recently harvested trees of M. tamaquarina have been recorded and DBH was measured. The species presents an inverse J-shaped diameter distribution indicating that the species is obviously regenerating in the old-growth forests. Tree-ring analysis indicates a mean age of 74.5 years for a DBH of 22.7 cm for a studied population comprising 37 trees with maximum ages of up to 141 years for an individual with a DBH of 45.7 cm. The tree species has low annual diameter increment rates (3.16 ± 0.6 mm) despite a low wood density (0.36 ± 0.05 g cm −3). The volume growth model indicates a MLD of 25 cm and a felling cycle of 32.4 years. In the management area 35 trees with a mean DBH of 24 cm were recorded, similar to the defined MLD. The abundance of trees above the MLD is 2.7 trees ha −1, or 405 trees, when extrapolated to the whole management area. Considering a felling cycle of 32.4 years (annual production unit of 4.63 ha) this results in total of 12.5 harvestable trees, almost three times less than actually harvested. The actual practice of harvesting M. tamaquarina risks the overexploitation of this slow-growing species.

Critères de gestion dérivés de l’analyse de cernes pour Figus insipida Willd. (Moraceaea) dans des forêts inondables amazoniennes

Ficus insipida Willd. (Moraceae) is a fast growing tree species of early successional stages in the Amazonian nutrient-rich white-water floodplains (varzea). The species is one of the most economically important low-density wood species in the community-based forest management project in the Mamiraua Sustainable Development Reserve (MSDR) in Central Amazonia, where timber species are managed using a polycyclic selection system with a minimum logging diameter (MLD) of 50 cm and a cutting cycle of 25 years. In this study we analyze the floristic composition, stand structure and forest regeneration of a natural 20 year-old stand at an early successional stage and we model tree growth of diameter, height and volume of F. inspida based on tree-ring analysis to define management criteria. The volume growth model indicates that the preferred period for logging should be at a tree age of 17 years when the current annual volume increment peaks. This age corresponds to a diameter of 55 cm, which would be an appropriate MLD.