High-value Timber Species Research Articles

Mapping the Distribution of High-Value Broadleaf Tree Crowns through Unmanned Aerial Vehicle Image Analysis Using Deep Learning

High-value timber species with economic and ecological importance are usually distributed at very low densities, such that accurate knowledge of the location of these trees within a forest is critical for forest management practices. Recent technological developments integrating unmanned aerial vehicle (UAV) imagery and deep learning provide an efficient method for mapping forest attributes. In this study, we explored the applicability of high-resolution UAV imagery and a deep learning algorithm to predict the distribution of high-value deciduous broadleaf tree crowns of Japanese oak (Quercus crispula) in an uneven-aged mixed forest in Hokkaido, northern Japan. UAV images were collected in September and October 2022 before and after the color change of the leaves of Japanese oak to identify the optimal timing of UAV image collection. RGB information extracted from the UAV images was analyzed using a ResU-Net model (U-Net model with a Residual Network 101 (ResNet101), pre-trained on large ImageNet datasets, as backbone). Our results, confirmed using validation data, showed that reliable F1 scores (>0.80) could be obtained with both UAV datasets. According to the overlay analyses of the segmentation results and all the annotated ground truth data, the best performance was that of the model with the October UAV dataset (F1 score of 0.95). Our case study highlights a potential methodology to offer a transferable approach to the management of high-value timber species in other regions.

Understanding Diospyros rumphii Bakh from North Sulawesi through Long-read sequences analysis using MinION Oxford Nanopore Technologies

Diospyros rumphii (Ebony) is a high-value timber species native to Indonesia, which is listed as a Data Deficient species by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Therefore, additional data to enrich knowledge on the distribution, ecology, and genetics of this species is urgently needed. Furthermore, this study aimed to generate whole-genome sequencing data, including the low-coverage data for D. rumphii using MinION Oxford Nanopore Technologies (ONT). The sequence data generated from leaf and cambium genomic DNA was assembled to result in a draft of the chloroplast genome and constructed the phylogenetic tree based on partial nucleotide sequences of the rbcL gene. The results showed that DNA sequencing of D. rumphii generated a 3.25 Gb of long-read sequences data and a draft of a partial chloroplast genome with a size of 150,578 bp. Genetic relationship analysis using the rbcL gene showed that D. rumphii was positioned in one clade with Diospyros oblonga, which has a bootstrap value of 87% suggesting that the rbcL gene can be considered as recommended molecular marker for genetic analysis of D. rumphii in the future.

Effect of changes in forest water balance and inferred root reinforcement on landslide occurrence and sediment generation following Pinus radiata harvest on Tertiary terrain, eastern North Island, New Zealand

Background: The frequent occurrence of storm-initiated landslides following harvesting of Pinus radiata D.Don in steep, Tertiary terrain, East Coast region, North Island, New Zealand, is of increasing concern. This paper documents the influence of tree removal and of replacement plantings on the canopy water balance and soil moisture regime when slopes are at their most vulnerable to landslide occurrence. Methods: At a previously established study site, rainfall, throughfall, and soil moisture data were collected before a mature stand of P. radiata was harvested. After harvesting, part of the study site was replanted with P. radiata at 1000 stems ha-1 and part with 500 stems ha-1. Relationships between hydrological changes and landslide occurrence are discussed in relation to planting density, site factors, root system development, silvicultural regimes, and alternative land use options for mitigating erosion in highly erodible hill country. Results: Following harvesting, soil moisture levels remained higher for longer than under a mature forest until rainfall interception and evapotranspiration returned to pre-harvest levels. This coincided with canopy closure, irrespective of planting density. After thinning, interception and evapotranspiration decreased, then regained the equivalent of a closed canopy 2 years later. Landslide occurrence was highest on slopes >25° and with a NE aspect. Sediment generation rates were highest in 2─4-year-old plantings, then decreased markedly with increasing tree age. Conclusions: Irrespective of planting density, P. radiata had little influence on the soil-water regime until canopy interception, evapotranspiration rates, soil-drying and recharge cycles returned to pre-harvest levels, coinciding with canopy closure. During this period, pore-water pressures at times of heavy or prolonged rainfall likely result in soil saturation and an increase in landslides. The progressive loss of root strength of the harvested trees had a secondary influence. The duration of the post-harvest period of heightened slope vulnerability to landslide initiation is a function of the combined influences of site factors on rates of tree growth and survival, and of the planting density regime on the canopy water balance and soil water content until the development of an effective live soil-root reinforcement system. For areas identified as high risk, the targeting of high-value timber species with longer rotation length, including consideration of coppicing species, would minimise the risk of slope failure at harvest. Very high-risk areas unsuited to rotational harvesting will ultimately require transitioning to a permanent indigenous forest cover.

Enrichment of Logging Gaps with High-Value Timber Species: How Far Fertilizer, Biochar and Mammal Predation Affect Performances of Cylicodiscus gabunensis Harms Seedlings

Many commercial species are light-demanding and regenerate with difficulty in natural forest, which compromises the sustainability of logging. Okan, Cylicodiscus gabunensis Harms is one of the most exploited species in Central Africa and its regeneration is deficient in evergreen forest. In forest concessions, the enrichment of logging gaps with commercial species has already been tested but only for a few species. Mixed results have been obtained because the ability of seedlings to emerge from competing vegetation depends on the species, the environment and the silvicultural techniques adopted. This paper aims to determine the performance of C. gabunensis when planted in felling gaps. The impact of fertilization and biochar application on the performance of the seedlings was examined, as well as the role of predation played by large mammals. In 30 gaps, whose light levels were quantified, we planted nine seedlings and applied three treatments (fertilizer and biochar, fertilizer, control). The performance of the seedlings (survival, mammal damage and growth) was followed for 18 months. In another 30 gaps, the preferential consumption of C. gabunensis seedlings was quantified using camera traps. Seedlings had moderate and highly variable growth (1.84 cm to 2.50 cm in height and 0.201 mm to 0.267 mm in basal diameter per month, all treatments combined). Gap size and initial fertilization significantly boosted growth in diameter and survival rate. Elephants preferentially sought out C. gabunensis seedlings and after 18 months they destroyed 35% of the plants. Enrichment of logging gaps with C. gabunensis should therefore be limited to the largest gaps in forests with low elephant densities. Initial fertilization is recommended but not allowed under the sustainable management certification guidelines. We suggest that these standards should be adapted to maximize the chances of success.

Genetic parameters in a clonal test of Tectona grandis in Mato Grosso, Brazil

Teak (Tectona grandis) is a high-value timber species in tropical regions. In Brazil, although teak has a high productivity, there are few studies related to its genetic improvement. This work aimed to estimate genetic parameters and evaluate potential gains of selection in a clonal test of teak installed in the state of Mato Grosso, Brazil. The experimente is in a randomized block design, with five replications, 3x3 m spacing, 22 treatments, and plots with six individuals. At five years, the genotypes were evaluated for survival (S), tree total height (H) and girth at breast height (GBH). There was significance and feasibility of selection for S and GBH. For H, the result was not significant, indicating few gains with the selection. The genetic parameters of clonal mean heritabilities and accuracy were of moderate magnitude for S and GBH and low for H. To best of our knowledge, this is the first work that estimates genetic parameters in a clonal teak test in the field in Brazil.

Supervivencia y crecimiento de plantines de ciprés de la cordillera durante siete años en dos sitios contrastantes de Patagonia norte

Native forestry species enable forest restoration and are a sustainable productive alternative. In any forest plantation —among them, those in which native tree species are used— knowledge on seedling dynamics is highly relevant for planning and management. We describe the seedling dynamics —survival and height growth— of planted ‘ciprés de la cordillera’, a high-value timber species of the Andean-Patagonian forests, in northern Patagonia shrublands. We carried out a 7-years planting experiment (275 seedlings) in two contrasting sites (a valley bottom and a northern-exposure hillside), and each spring we recorded the survival and height of the seedlings. In addition, we evaluated the effect of protecting the seedlings from herbivores and modeled the browsing dynamics. Survival and browsing were evaluated with generalized linear models while height was modeled with a non-linear mixed-effects model from which we quantified the growth rate per seedling. At the valley bottom, survival decreased to <15% at the end of the experiment. Survival was higher in the hillside with north exposure and remained relatively stable. At this site, the values of survival (~70% at year 7) and height growth (rates greater than 15%; MAI ~8 cm/year) were comparable with those of seedlings planted in forests of ‘ciprés de la cordillera’, suggesting that the species could be used for restoration or production in northern hillsides like the one assayed. Seedling protectors reduced browsing, increased survival although not significantly, and diminished growth. Therefore, it is not clear whether seedlings should be protected using the protector type tested in this study. We hope our results contribute to the sustainable management of shrublands and forests of northern Patagonia.

Technical and financial evaluation of enrichment planting in logging gaps with the high-value species Swietenia macrophylla and Handroanthus serratifolius in the Eastern Amazon

Enrichment planting in logging gaps is an important silvicultural treatment to ensure long-term wood production in tropical forests. Knowledge on environmental and economic aspects of enrichment planting with high commercial value timber species in logging gaps is scarce, which creates uncertainty for decision makers about the method effectiveness. To contribute to the debate, this work aimed to evaluate technically and financially enrichment planting of Swietenia macrophylla and Handroanthus serratifolius in logging gaps to serve as a model in the recovery and production increase of these species in future cutting cycles. An experiment on enrichment planting was established in 46 logging gaps in 2009 and measurements of planted individuals were done in 2011, 2014, and 2017. A cost-benefit analysis using net present value (NPV) and a sensitivity analysis were carried out on different interest rates for the production of roundwood and sawnwood. Eight years after planting, individuals of Swietenia and Handroanthus presented a diameter at breast height of 7.88 ± 1.41 cm and 5.20 ± 1.00 cm, and a Periodic Annual Increment (PAI) of 0.98 ± 0.38 cm year−1 and 0.65 ± 0.22 cm year−1, respectively. At the last measurement, Swietenia and Handroanthus individuals had a survival percentage of 51% and 24% and a mortality rate of 8% and 16% year−1, respectively. NPV was positive for Swietenia in roundwood and sawnwood harvested at 60 and 90 years after planting (2nd and 3rd cutting cycles) and for Handroanthus in sawnwood harvested 90 years after planting. Once increasing PAI in 10% and 20%, Swietenia presented the highest NPVs and Handroanthus was profitable with harvest in 60 years and PAI increasing 20%. Based on these results, a model of Swietenia and Handroanthus production and conservation through enrichment planting in logging gaps was built.

Tree regeneration in active and passive cloud forest restoration: Functional groups and timber species

Tree regeneration of late-successional, animal-dispersed and/or timber species in restored forests is key to the recovery of ecological functions and interactions, as well as ecosystem services. We assessed whether active restoration is more effective than passive restoration at increasing the recovery of these groups in the tree seedling community. We analysed tree seedlings (>0.3 m to 1.5 m in height) over four years under three conditions in a tropical montane cloud forest landscape in Mexico: mature cloud forest (MF) as the reference system, active restoration (AR; mixed plantation with native species) and passive restoration (PR; natural succession). The AR and PR were 24 years old and were originally established in abandoned grazing land located at similar distances to the MF (709 ± 67 m and 906 ± 66 m, respectively). We recorded ~ 488 seedlings/year belonging to 51 tree species. Seedling density was higher in AR than in PR, but no differences were found in recruitment or survival rates between these restoration conditions. The density of late-successional, barochorous-synzoochorous and timber species was much higher in MF than in the restoration conditions. Seedling density of timber species was similar in AR and PR. Our results support higher recovery of the richness and density of late-successional and barochorous-synzoochorous functional groups in the tree seedling community in AR than in that of PR. However, the overall low seedling density and recruitment found in both restoration conditions highlight the need for additional intervention, even after 24 years, in order to overcome barriers to tree regeneration. Direct seeding and enrichment plantings of late-successional, barochorous-synzoochorous and high-value timber species could contribute towards more ecologically and economically valuable forests.

Veneering and sawing performance of plantation-grown Eucalyptus pellita, aged 7–23 years, in Borneo Malaysia

ABSTRAC Plantation-grown, high-value timber species producing high-value end products are key to optimising land utilisation in Sabah and Sarawak states in Borneo, Malaysia, while meeting the demand for downstream processing. Eucalyptus pellita is one such species suitable for the tropical climatic conditions and exhibits considerable potential for solid wood and veneer production. The characteristics of E. pellita grown in Sabah, demonstrate the need for an appropriate silviculture management and downstream processing strategy to optimise the quality and quantity of veneer and sawn board. Recovery from E. pellita resources has demonstrated the average volume recovery of dry-graded veneer ranged from 38.1 to 49.5%, whereas the average dried board volume ranged from 48.5 to 57.9%. If E. pellita is to be grown on short rotations as a peeler resource, an appropriate pruning regime is needed to maximise the volume of clearwood. The greatest cause of volume loss was end-splitting in the recovery of veneer and solid timber.

Application of UAV Photogrammetry with LiDAR Data to Facilitate the Estimation of Tree Locations and DBH Values for High-Value Timber Species in Northern Japanese Mixed-Wood Forests

High-value timber species play an important economic role in forest management. The individual tree information for such species is necessary for practical forest management and for conservation purposes. Digital aerial photogrammetry derived from an unmanned aerial vehicle (UAV-DAP) can provide fine spatial and spectral information, as well as information on the three-dimensional (3D) structure of a forest canopy. Light detection and ranging (LiDAR) data enable area-wide 3D tree mapping and provide accurate forest floor terrain information. In this study, we evaluated the potential use of UAV-DAP and LiDAR data for the estimation of individual tree location and diameter at breast height (DBH) values of large-size high-value timber species in northern Japanese mixed-wood forests. We performed multiresolution segmentation of UAV-DAP orthophotographs to derive individual tree crown. We used object-based image analysis and random forest algorithm to classify the forest canopy into five categories: three high-value timber species, other broadleaf species, and conifer species. The UAV-DAP technique produced overall accuracy values of 73% and 63% for classification of the forest canopy in two forest management sub-compartments. In addition, we estimated individual tree DBH Values of high-value timber species through field survey, LiDAR, and UAV-DAP data. The results indicated that UAV-DAP can predict individual tree DBH Values, with comparable accuracy to DBH prediction using field and LiDAR data. The results of this study are useful for forest managers when searching for high-value timber trees and estimating tree size in large mixed-wood forests and can be applied in single-tree management systems for high-value timber species.

Genetic diversity of Fusarium pseudocircinatum in the central western region of Mexico: the case of big-leaf mahogany malformation disease

Fusarium pseudocircinatum is the main causal agent of big-leaf mahogany malformation disease (BLMMD) of mahogany (Swietenia macrophylla) in Mexico. Although, BLMMD is the most important disease for this high-value timber species, there is a lack of information on the genetic variation present in geographically diverse isolates of F. pseudocircinatum. The objective of this study was to determine the genetic diversity of populations of F. pseudocircinatum causing BLMMD in the central western region of Mexico. A total of 611 big-leaf mahogany trees were inspected at eight sites in four states (Colima, Guerrero, Jalisco and Michoacán); of these, 42.7% showed malformation symptoms similar to those of BLMMD. Of 374 Fusarium isolates that were recovered, 277 were identified as F. pseudocircinatum, 56 were F. mexicanum, and 41 were Fusarium spp. An ISSR analysis of the F. pseudocircinatum isolates generated 51 bands of which 38 were polymorphic (76.8%) with a mean of 17 bands per primer. A total of 87 multilocus genotypes (MLGs) were identified. Nei's genetic diversity analysis showed that the isolates had a high genetic diversity average (0.147), with values ranging from 0.070 to 0.365 depending of the geographical location. An analysis of molecular variance revealed that the variation within the populations was low (27.36%), while the variation within MLGs was significant (72.64%), indicating genetic flow. Overall, the genetic variability of F. pseudocircinatum populations was high and the MLGs from Colima (Colima) and Gabriel Zamora (Michoacán) were placed centrally, which possibly is evidence of ancestry and indicates its dispersion routes in the central western region of Mexico.

Predicting individual tree growth of high-value timber species in mixed conifer-broadleaf forests in northern Japan using long-term forest measurement data

ABSTRACT Quantifying individual tree growth of economically high-value timber species is important for the simulation and development of forest management options. Long-term permanent plot data provides crucial information of forest stand dynamics that can be used to predict individual tree growth. In this study, we developed individual tree basal area growth models of three high-value timber species: monarch birch (Betula maximowicziana), castor aralia (Kalopanax septemlobus), and Japanese oak (Quercus crispula) in a cool temperate mixed forest in northern Japan using long-term measurement data (1968–2016) collected in permanent plots. Data included species, diameter at breast height, and survival status, and stand management history. We applied linear mixed-effects modelling to predict the individual tree basal area growth as a function of individual tree size, competition, and forest management. Model prediction followed by leave-one-out cross validation revealed a correlation between predicted and observed basal area increments with r values of 0.62, 0.73, and 0.70 and root mean square errors values of 10.44, 7.91, and 11.62 cm2/year for monarch birch, castor aralia, and Japanese oak, respectively. The individual tree growth models developed in this study will provide valuable information for species-specific forest management of economically high-value timber species.

Early indications of success rehabilitating an underperforming teak (Tectona grandis) plantation in Panama through enrichment planting

Enrichment planting can be an effective strategy for increasing the ecological and economic value of timber plantations, but success depends on appropriate matching of under- and overstory species and site conditions. This case study in the Panama Canal Watershed explores the viability of enrichment planting for rehabilitating underperforming teak (Tectonia grandis) plantations, which are common in the area. Two high-value timber species native to the neotropics, Dalbergia retusa and Terminalia amazonia, were underplanted in an established teak plantation at the Agua Salud research site in the province of Colon, Panama. Seedling survival, basal diameter, height, total biomass and relative growth rate were assessed for the two years following planting. In contrast with the widespread belief that teak is a poor nurse tree, both species achieved promising early growth with low mortality in plantation understory conditions. Neither understory light availability nor combined above- and below-ground effects of crowding pressure from teak strongly predicted growth of either species. D. retusa, thought to be more shade-tolerant, performed equally across a range of intermediate light levels whereas T. amazonia, thought to be more heliotropic, performed best at the highest light levels, though light relationships explained little variation in seedling growth. These early findings support the suitability of either species for use in enrichment plantings in established, underperforming teak plantations in the Panama Canal Watershed. Longer-term research is needed to evaluate the potential of enrichment planting to increase profitability and ecosystem services such as carbon sequestration and water resource management in these plantations.

Forestry in Vietnam: The potential role for native timber species

Vietnam is bucking the global tropical deforestation trend through government-led reforestation programs and strict controls on harvesting of natural forest. However, most reforestation in Vietnam has been via plantations of a few exotic species, mainly in the genus Acacia. Vietnam's plantation estate, while financially profitable, is characterised by low biodiversity, and there are concerns about disease risk and resilience to disturbances. The continuing demand for high-grade timber to supply Vietnam's successful timber processing industry, and increasing pressure for environmentally responsible forest practices (especially for production of furniture for export) has led to the opportunity for change in Vietnam's forestry industry. Increased plantation diversity is associated with increased resilience and improvement in resource utilisation, while diverse plantations of native species can yield environmental and biodiversity benefits. Highlighting the potential for native species in forestry in Vietnam, we provide the details of 16 Vietnamese tree species, which are known to perform well in plantation forestry to produce timber (and other products), and which have not yet been widely planted. A significant challenge to increasing the area of plantations of high-value timber species is maintaining the income of smallholders while the trees grow to harvestable size. Potential solutions include incentive payments (including payments for environmental services), and encouraging smallholders to grow diverse plantations with short- and long-rotation species.

Sustainability of High-Value Timber Species in Mixed Conifer–Broadleaf Forest Managed under Selection System in Northern Japan

Understanding the sustainability of high-value timber species in managed forests provides useful information for the management of these species in the long-run. Using nearly 50 years of census data in long-term permanent plots, we investigated the sustainability of three high-value timber species—monarch birch (Betula maximowicziana Regel), castor aralia (Kalopanax septemlobus (Thunb.) Koidz), and Japanese oak (Quercus crispula Blume)—in cool-temperate mixed forest under a selection system in northern Japan. We used stocking, demographic parameters, and species proportions of these species as measures of sustainability. Results showed that the tree density and basal area of the three high-value timber species increased during the study period. Moreover, the basal area increment of these species showed an increasing trend across census periods. However, while no significant differences in the tree mortality of these species were observed, the numbers of in-growth fluctuated across census periods. Increasing trends in species proportions of monarch birch and Japanese oak were observed. Even though there were some fluctuations across census periods, especially in smaller diameter classes, diameter distribution curves of high-value timber species followed a reversed J-shaped pattern. The results revealed that the sustainability measures of high-value timber species can be achieved in forest stands managed under single-tree selection system. In addition, the results also indicated the changing structure and composition of the forest stand. The stocking and basal area increment of conifers decreased while those of broadleaves increased. The proportion of conifers decreased to 33.01% in 2008–2016 from 48.35% in 1968–1978. The results of this study would be useful for adapting silvicultural practices and harvesting practices as well as for simulating various silvicultural and management options for high-value timber species.

Comparing Individual Tree Height Information Derived from Field Surveys, LiDAR and UAV-DAP for High-Value Timber Species in Northern Japan

High-value timber species such as monarch birch (Betula maximowicziana Regel), castor aralia (Kalopanax septemlobus (Thunb.) Koidz), and Japanese oak (Quercus crispula Blume) play important ecological and economic roles in forest management in the cool temperate mixed forests in northern Japan. The accurate measurement of their tree height is necessary for both practical management and scientific reasons such as estimation of biomass and site index. In this study, we investigated the similarity of individual tree heights derived from conventional field survey, digital aerial photographs derived from unmanned aerial vehicle (UAV-DAP) data and light detection and ranging (LiDAR) data. We aimed to assess the applicability of UAV-DAP in obtaining individual tree height information for large-sized high-value broadleaf species. The spatial position, tree height, and diameter at breast height (DBH) were measured in the field for 178 trees of high-value broadleaf species. In addition, we manually derived individual tree height information from UAV-DAP and LiDAR data with the aid of spatial position data and high resolution orthophotographs. Tree heights from three different sources were cross-compared statistically through paired sample t-test, correlation coefficient, and height-diameter model. We found that UAV-DAP derived tree heights were highly correlated with LiDAR tree height and field measured tree height. The performance of individual tree height measurement using traditional field survey is likely to be influenced by individual species. Overall mean height difference between LiDAR and UAV-DAP derived tree height indicates that UAV-DAP could underestimate individual tree height for target high-value timber species. The height-diameter models revealed that tree height derived from LiDAR and UAV-DAP could be better explained by DBH with lower prediction errors than field measured tree height. We confirmed the applicability of UAV-DAP data for obtaining the individual tree height of large-size high-value broadleaf species with comparable accuracy to LiDAR and field survey. The result of this study will be useful for the species-specific forest management of economically high-value timber species.

Forensic validation of a SNP and INDEL panel for individualisation of timber from bigleaf maple (Acer macrophyllum Pursch)

Illegal logging is one of the largest illicit trades in the world, with high profits and generally low risks of detection and prosecution. Timber identification presents problems for law enforcement as traditionally used forensic methods such as wood anatomy and dendrochronology are often unable to confidently match wood evidence to the remains of illegally felled trees. Here we have developed and validated a set of genetic markers for individualisation in bigleaf maple (Acer macrophyllum), a high value timber species often felled illegally in the USA. Using 128 single nucleotide polymorphisms and three insertion/deletion markers developed through massively parallel sequencing, 394 individuals were genotyped on the MassARRAY® iPLEX™ platform (Agena Bio-science™, San Diego, USA) to produce a population reference database for the species. We demonstrate that the resulting DNA assay is reliable, species specific, effective at low DNA concentrations (<1 ng/μL) and suitable for application to timber samples. The PID for the most common profile, calculated using an overall dataset level FST-correction factor, was 1.785 × 10−25 and PID-SIB across all individuals (treated as a single population) was 2.496 × 10-22. The further development of forensic identification assays for timber species has the potential to deliver robust tools for improved detection and prosecution of illegal logging crimes as well as for the verification of legality in reputable supply chains.

Logging impact on Amazonian white-sand forests: perspectives from a sustainable development reserve

ABSTRACT Overexploitation is one of the main causes of biodiversity loss and local extinction. In the Brazilian Amazon, the intensive use of high-value timber species is leading to a decline in their populations. When in decline, these species can be replaced by less valuable and more common ones that are more feasible to exploit. We conducted interviews with residents of two communities in a sustainable development reserve in central Amazonia, and used free lists and the cognitive salience index (S) to assess the perceptions of residents regarding the occurrence and purpose of timber exploitation, and to identify possible endangered species in white-sand and terra-firme forests. In addition, to infer possible consequences of logging, we assessed the current population status of timber species cited by residents in forest-plot inventories carried out within the reserve. S-index values and interviewee reports suggested an intensive use of terra-firme timber species and an apparently recent increase in the exploitation of white-sand species, which did not use to be exploited because of their relatively low commercial value. The inventories showed that the white-sand timber species have high relative densities and low S values in contrast to the terra-firme species, which mostly have low relative densities and high S values. Our results highlight the need to identify and monitor relevant timber species in both terra-firme and white-sand forests, and to increase the involvement of the local community in the development of logging management practices.

Establishment and management of leucaena in Latin America

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Leucaena leucocephala (leucaena) is native to Mexico and Central America and is currently naturalized in the majority of Latin American countries. Over the last 2 decades, considerable research and promotion of leucaena have been carried out in Colombia, Mexico, Cuba, Brazil, Paraguay and Argentina. Research focused on the agronomic and management options for feeding beef, dairy or dual-purpose animals, with some studies on germplasm, weediness issues, toxicity, organic fertilizer application and environmental services.Over the past 10‒15 years, establishment and management of leucaena feeding systems in Latin America have varied according to country. For instance, intensive Silvopastoral Systems (iSPS) models are widely promoted and successfully adopted in Colombia, Mexico, Cuba, Venezuela and Northeast Brazil. In ISS, leucaena is planted at high density (&gt;10,000 trees/ha), in combination with improved tropical grass and high-value timber species (200‒400 trees/ha), and intensively managed employing rotational grazing.In Paraguay and Argentina, leucaena is planted in single or double hedgerows with inter-row alleys of 6‒8 m, following the configuration used in Australia and mainly focused on beef production. In Mexico, leucaena is also cultivated with Tithonia diversifolia or lemon trees. Meanwhile, in other countries such as Cuba, leucaena has been established as protein banks using single/twin rows with inter-row spacing of 2‒4 m for feeding beef, dairy or dual-purpose animals. Overall, paddock sizes for protein banks and ISS range between 0.3 and 50 ha, while single and twin hedgerow systems are generally established over larger areas (20‒500 ha). Despite the significant benefits demonstrated by research on leucaena feeding systems over the past 2 decades, coupled with successful outcomes for farmers who have adopted these systems, total area sown remains low across Latin America. This review provides a comparison between Latin American and Australian leucaena pasture systems, and recommendations for future collaborative research between countries.

Carbon emissions and potential emissions reductions from low-intensity selective logging in southwestern Amazonia

Forests in southwestern Amazonia are increasingly being converted for agriculture, mining, and infrastructure development; subjected to low-intensity selective logging of high value timber species; and designated as conservation areas and indigenous reserves. To understand the impacts of forestry in this region, we evaluated carbon emissions from felling, skidding, and hauling in five FSC-certified concessions where workers were trained in reduced-impact logging (RIL) and in four non-certified concessions where workers were not trained in RIL in Madre de Dios, Peru. Emissions estimates did not differ by certification status, so we established a single baseline for selective logging emissions. Total carbon emissions from selective logging were low per hectare (4.9–11.6 Mg ha−1) due to low logging intensities (2.9–8.1 m3 ha−1). Despite the unique architecture of trees in the southwestern Amazon (short stems and large crowns), emissions per volume and per ton carbon in the extracted timber were also relatively low (1.55 Mg m−3 and 4.04 Mg Mg−1, respectively). Only emissions per area scaled with logging intensity. Emissions were dominated by the felled tree itself (in extracted logs and residuals), whereas hauling infrastructure (roads and log landings) contributed comparatively little. Unintended emissions could be reduced by 46% if concessions were able to achieve the best demonstrated outcomes in each source category and by 54% with additional improvements. Less than 5% of timber was lost due to hollow sections. We determined that it would be overly cautious to avoid cutting all trees with any hollow sections, and it would actually increase emissions per unit timber extracted if no other trees were cut in place of the hollow trees. At the tree level, certified concessions had higher log recovery and damaged fewer commercial species during felling, which should increase their current and future timber yields. It is important to both understand and improve carbon dynamics in managed forests in this emerging hotspot for greenhouse gas emissions from deforestation and forest degradation.