Damage to Brazil nut trees (Bertholletia excelsa) during selective timber harvesting in Northern Bolivia

The success of multiple forest management systems is contingent on a variety of social, economic, biophysical, and institutional factors, including the integration of timber and non-timber forest product (NTFP) extraction and management. Selective logging for timber is increasingly taking place in forests where the collection of Brazil nuts, a high-value Amazonian NTFP, also occurs. We report on logging damage to Brazil nut trees in three certified timber concessions in Northern Bolivia from which timber is harvested using reduced-impact logging (RIL) guidelines and nuts are gathered yearly from the ground by local people. Observed frequencies of logging damage to Brazil nut trees were low, likely mirroring the low intensity of timber harvesting (∼0.5 trees/ha and ∼5 m³/ha) being currently applied across the study area. Of the trees ≥10 cm in diameter at breast height about 0.1 Brazil nut trees and 0.4 timber species per hectare suffered some degree of logging damage. Crown loss was the predominant damage type for Brazil nut trees accounting for 50% of all damage. In spite of the observed low rates of tree damage, we further recommend that RIL guidelines be amended to include the pre-harvest marking of pre-reproductive Brazil nut trees along with the future crop trees of commercial timber species. Further refining directional felling to reduce crown damage to Brazil nut trees would also serve to help maintain nut yields in the long term.     

Regeneration of commercial tree species in a logged forest in the Selva Maya, Mexico

One of the main threats to the sustainability of community forestry in the Selva Maya is insufficient regeneration of commercial tree species. We evaluated the regeneration status of 22 commercial tree species in a managed semideciduous tropical rain forest in Southern Mexico. The study was carried out in six harvesting areas along a 16-year chronosequence. In each area, 10 transects (1000 m²) were established and all trees >50 cm height and <10 cm diameter were recorded. We evaluated the relationships between seedling and sapling abundance, and canopy cover and disturbance condition (closed forest, canopy gap, log landing, skid road, primary road and secondary road). The area occupied by closed forest canopy increased with age of harvesting area (65–91% of sampled area), while the area occupied by canopy gaps decreased (22–9%). Log landings occupied less than 1% of the sampled area. The predominant canopy cover was 75–80% in all harvesting areas, even in the most recently harvested areas. The highest densities of seedlings and saplings, of both shade tolerant and intolerant species, were found in log landing and skid trails, followed by secondary roads. Even Simarouba glauca, a shade tolerant species, displayed higher densities in sites with ≤65% of canopy cover. Our results support previous findings and indicate that the levels of disturbance caused by existing harvesting procedures may be inadequate to promote sufficient regeneration of not only light demanding desirable species but also for some of the evaluated shade tolerant species of commercial interest. Seedling and sapling densities exhibited by Swietenia macrophylla, for example, are insufficient to support current harvesting rates. The application of a spatial mixed system with patch-cuts of different sizes, a consequence of group felling, could be applied to provide the necessary conditions for the regeneration of the main commercial species.     

Effect of human disturbance on the structure and regeneration of forests in the Nevado de Toluca National Park, Mexico

Sample plots were established in the principal forest types in the the Nevado de Toluca National Park, Mexico including those dominated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. Mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnus jorullensis forests were increasing due to the disturbance of Pinus and Quercus forests, as well abandoned crop lands within the park. A combination of logging, uncontrolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early successional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.     

Detecting large-scale diversity patterns in tropical trees: Can we trust commercial forest inventories?

In this paper we seek to identify the floristic determination biases contained in large-scale commercial inventories conducted by logging companies and to determine whether this impacts on the observed patterns of alpha and beta diversity. The study focused on floristic data recently collected by industrial timber companies in the tropical forests of the Central African Republic (28,229 0.5-ha plots spread over 14,000 km²). A subset of these plots (n = 1107) was later re-sampled for controlling purposes by experienced botanists. The proportion of agreement between the two samplings was assessed for each species and independently for small and large trees, and at genus and family resolutions. Unsurprisingly, large trees and common species were more accurately identified than small trees and rare species. We found that the quality of the floristic determination increased slightly from species to families. We also detected a significant variation between concessions in the quality of the floristic determination that was more dependent on working conditions during forest inventories than on field workers. Contrary to a widespread belief, we did not find a strong bias toward commercial species, showing that commercial inventory data could also be valid for non-commercial species in ecological studies. Finally, we found that both alpha and beta diversity patterns in commercial inventories were highly consistent with those of the re-sampled inventory. This latter result shows that commercial inventories are well suited to detect large-scale patterns of floristic variation. Large-scale commercial inventories could thus play an important role in the identification of large-scale patterns in tropical tree diversity. This could enhance our ability to manage tropical forests by designing representative reserve networks and developing management plans that integrate diversity patterns at the landscape scale.     

Lumber volume modeling of Amazon Brazilian species

Accurate estimates of lumber volume become an important indicator of production and monetary value for a sawmill. However, such estimates are only obtained directly after logging, and no accurate predictions are made for the Amazonian commercial species. In this sense, the objective was to generate equations of lumber volume for commercial species in Amapá (a state in northern Brazil) by adjusting and selecting regression models. The data of 50 logs processed from 10 commercial species were collected, as well as the quantity and volume of sawn products. Sixteen (16) statistical models were adjusted and statistical weights were performed to evaluate the quality of the estimates and to select the best equation by species. In summary, precise estimates of lumber volume can be obtained by the nº16 model for Carapa guianensis, while the models nº13 and nº15 are the most recommended for Dinizia excelsa and Hymenolobium petraeum, respectively. Model 7 presented the best adjustments for Hymenaea courbaril and Vochysia guianensis. Equations using only the log diameter variable suggest less precise estimates. Also, the log volume should be considered as an important predictor variable to obtain the serrated/lumber volume for the different Amazonian commercial species.     

Effect of species and log diameter on the volumetric yield of lumber in northern Brazilian Amazonia: preliminary results

ABSTRACT

Volumetric yield analysis is critical to optimizing performance in the timber industry. In the Amazon and in the Amapá state, this information is still little known and scarce, and therefore this study was developed to obtain and analyze the volumetric yield coefficient of ten commercial tree species and to test the variation by diameter class. We collect data of volumetric yield from for ten commercial species. For each species, the yields in different diameter classes were analyzed, as well as the yield difference between the species. The overall yield obtained for the sawmills (43.95%) and the yield of each species are within the established standards for operations in the industry according to the legal requirements. There were no differences (p ≥ 0.05) in diameter classes for species with the exception of Dinizia excelsa and Handroanthus albus. However, there was no linear increase (p ≥ 0.05) between the diameter and yield of lumber for all species. The species Dinizia excelsa, Hymenolobium petraeum, Ocotea rubra and Vochysia guianensis show a significant difference in yield for the other species due to the higher obtained values, however, they are statistically similar when compared to each other.     

A Natural Forest of Commercial Timber Species: Logging or Not Logging

Most tropical forests outside protected areas have been or will be selectively logged because the timber industry is a main income-generating resource for many developing countries. Therefore, understanding the composition of commercial timber species and logging types is key for sustainable forest management in countries like Vietnam as they move toward fulfilling Reducing Emissions from Deforestation and Forest Degradation (REDD+) agreements. Seven 1-ha plots were surveyed in the Central Highland of Vietnam, and 18 commercial tree species from these plots, whose timber is widely used by local people for housing and furniture making and timber is easily sold at local markets for high prices, were analyzed. In total, 151 tree species with a diameter at breast height (DBH) of ≥?10 cm were recorded. The 18 commercially valuable species assessed in this study accounted for 33.2% of all stems (total of 524 stems ha^?1 for all species), 47.1% of basal area (total of 34.35 m² ha^?1 for all species), and 50.8% of aboveground biomass/AGB (total of 262.68 Mg ha^?1 for all species). Practicing diameter-limit harvesting of all commercially valuable species with DBH of ≥?40 cm, which is widely performed in Vietnam, will reduce the number of stems by 7%, basal area by 31.6%, and AGB by 38.2%. Because such harvesting practices cause severe ecological impacts on the remaining forest, logged forests may require >?40 years to recover the structure status of a pre-logged forest. In addition, the recovery of the 18 commercially valuable species may require a much longer time because they comprised 33.2% of stems. Permission for logging natural forests should be given in Vietnam to sustain lives of local communities, where logging has been prohibited. However, alternative harvesting systems, such as reduced-impact logging systems, should be considered. The systems selected must simultaneously generate economic returns for local people and respect the REDD+ agreements with regard to protecting biodiversity and reducing carbon emissions.     

Impacts of logging residue and stump removal on nitrogen export to a stream: A modelling approach

Abstract

The use of forest chips for energy can decrease net carbon emissions to the atmosphere, but harvesting logging residues and stumps may have adverse effects on the environment, including changes in nutrient export to water-bodies. The aim of this study was, with the aid of a computer model, to simulate the effects of logging residue and stump removal on nitrogen (N) export from a clear-cut area to a stream. A spatially semi-distributed FEMMA ecosystem model (tool for Forestry Environmental Management) was used to simulate N export from a catchment subject to clear-cutting and four different scenarios of logging residue and stump removal. These scenarios were compared with a conventional clear-cutting scenario, where the logging residues were left on site. Simulations suggested that the logging residue recovery does not decrease N export to the stream. In the model this was explained by a decrease in microbial immobilization, which in the case of conventional clear-cutting reduces net release of N in decomposition and mitigates the export of N. The decrease in immobilization is directly related to the removal of the woody debris from the site. Simulations suggested that harvesting of logging residues in low atmospheric N-deposition areas is not an effective strategy for reducing N loads in water-bodies.     

Long-term effects of stump harvesting on soil properties and tree growth in Scots pine and Norway spruce stands

Abstract

Effects of stump harvesting on the properties of surface soil and on the density, structure and growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands were estimated in a field trial in western Finland. The experiment was established in 1977 and measured in 2010. Stems and logging residues were harvested after clear-cutting, and stumps were lifted and removed from half of the experimental area. Sixteen plots were planted with pine seedlings and 16 with spruce. The main effects of stump harvesting were improved survival of planted trees and an increase in natural regeneration. No clearly negative effects were noted in the stand development. Stump harvesting had no or minimal effects on the properties of the organic layer and those of the 0- to 10-cm mineral-soil layer. Soil properties did not differ between tree species. Pine production was higher on plots with stump removal compared to plots without soil treatment.     

Immediate Effects of Logging,Mounding, and Removal of Logging Residues on Epixylic Species in Managed Boreal Norway Spruce Stands in Southern Finland

The immediate effects of bioenergy harvesting methods on epixylic species were studied in mature managed Norway spruce dominated forests in southern Finland. The treatments included logging, residue harvesting, and soil preparation as either mounding or mounding combined with stump harvesting. Altogether, 110 logs and 440 species sample plots on logs were inventoried before and after logging, and after soil preparation treatments. Logging decreased the cover and species richness in all epixylic species groups. The soil preparation decreased the cover of macrolichens, while stump harvesting was significantly most devastating both for cover and richness in bryophytes. We suggest that bioenergy harvesting critically affects the epixylic species, and therefore the use of less devastating methods and compensation for the loss of coarse woody debris is recommended on a landscape level.     

Economic analysis on log damage during logging operation in Caspian Forests

Waste wood was studied in an economic enterprise by logging, function, tree species and log size in four Caspian hardwood sites. Damaged logs were recorded with additional information obtained for the location, dimensions and type of damage. The data were analyzed statistically to determine significant differences of damage during logging process. The results indicated that animal harvesting systems cause more volume (40.5% of log volume) and value loss (89.5 $·m^?3) to logs than mechanized harvesting systems (13.9% and 6.0 $·m^?3), also bucking resulted in significantly more volume (9.9% of log volume) and value loss (5.5 $·m^?3) when compared to skidding (0.2% of log volume and 0.2 $·m^?3), decking (0.4% of log volume and 0.2 $·m^?3) and loading (0.2% of log’s volume and 0.3 $·m^?3) operations. Study showed that the processes of skidding, decking and loading of logs have very little impact on damage levels. Volume and value losses of damaged logs are not sensitive to tree species and log size. The information from the field study is important in creating new guidelines or training to help minimize hardwood log damage during the timber harvesting process.     

Contributions of root and stump sprouts to natural regeneration of a logged tropical dry forest in Bolivia

A major impediment to the sustainable management of tropical dry forests in Bolivia is the scarcity of natural regeneration of commercial timber tree species. Where regeneration is present, true seedlings of many species are outnumbered by vegetative sprouts from roots, broken stems, and the stumps of felled trees. This study evaluates the importance of resprouts promoted by logging operations for the regeneration of commercially important canopy tree species. The objectives of the study were: (1) to characterize stump and root sprouting behaviors of canopy tree species harvested for timber; (2) to quantify the effect of logging on relative abundances and growth rates of stump sprouts, root sprouts, and true seedlings; (3) to relate the species-specific probabilities of stump sprouting to stump diameter and stump height; and (4) to explore how sprouting varies with the ecological requirements of canopy tree species. The study was carried out 1–5 years after logging of a privately owned land in a Bolivian tropical dry forest. Twenty-seven of the 31 species monitored resprouted at least occasionally, among which Centrolobium microchaete (Leguminosae-Fabaceae) and Zeyheria tuberculosa (Bignoniaceae) were the most frequent stump sprouters, and Acosmium cardenasii (Leguminosae-Fabaceae) and C. microchaete were the most frequent root sprouters. In all species the number of sprouts declined with increasing stump diameter and stump height. The probability of stump resprouting differed among species but did not vary consistently with stump diameter, except in Z. tuberculosa in which it declined. Approximately 45% of juveniles <2 m tall of canopy tree species originated from root or stem sprouts. Light-demanding species tended to regenerate more from seeds and root sprouts than from stumps. Seedling densities were higher in microsites opened by logging, while root and stem sprouts were equally common across microsites. Given their abundance and the fact that root and stem sprouts at least initially grew faster than true seedlings, we conclude that vegetative regeneration in this tropical dry forest is an important mode of post-logging regeneration especially for species that regenerate poorly from seed. Resprout management should be considered as a potentially effective strategy for the procurement of regeneration following logging, especially for species that do not readily recruit from seed.     

Beyond reduced-impact logging: Silvicultural treatments to increase growth rates of tropical trees

Use of reduced-impact logging (RIL) techniques has repeatedly been shown to reduce damage caused by logging. Unfortunately, these techniques do not necessarily ameliorate the low growth rates of many commercial species or otherwise assure recovery of the initial volume harvested during the next cutting cycle. In this study, we analyze the effect of logging and application of additional silvicultural treatments (liana cutting and girdling of competing trees) on the growth rates on trees in general and on of future crop trees (FCTs) of 24 commercial timber species. The study was carried out in a moist tropical forest in Bolivia, where we monitored twelve 27-ha plots for 4 years. Plots received one of four treatments in which logging intensity and silvicultural treatments were varied: control (no logging); normal (reduced-impact) logging; normal logging and low-intensity silviculture; and, increased logging intensity and high-intensity silviculture. Tree growth rates increased with intensity of logging and silvicultural treatments. The growth rates of FCTs of commercial species were 50–60% higher in plots that received silvicultural treatments than in the normal logging and control plots. Responses to silvicultural treatments varied among functional groups. The largest increase in growth rates was observed in FCTs belonging to the partially shade-tolerant and the shade-tolerant groups. These results indicate that silvicultural treatments, in addition to the use of RIL techniques, are more likely to result in a higher percentage of timber volume being recovered after the first cutting cycle than RIL alone.     

Silvicultural treatments enhance growth rates of future crop trees in a tropical dry forest

Silvicultural treatments are often needed in selectively logged tropical forest to enhance the growth rates of many commercial tree species and, consequently, for recovering a larger proportion of the initial volume harvested over the next cutting cycle. The available data in the literature suggest, however, that the effect of silvicultural treatments on tree growth is smaller in dry forests than in humid forest tree species. In this study, we analyze the effect of logging and application of additional silvicultural treatments (liana cutting and girdling of competing trees) on the growth rates of future crop trees (FCTs; i.e., trees of current and potentially commercial timber species with adequate form and apparent growth potential). The study was carried out in a tropical dry forest in Bolivia where a set of 21.25-ha plots were monitored for 4 years post-logging. Plots received one of four treatments that varied in intensity of both logging and silvicultural treatments as follows: normal (reduced-impact) logging; normal logging and low-intensity silviculture; increased logging intensity and high-intensity silviculture; and, unlogged controls. The silvicultural treatments applied to FCTs involved liberation from lianas and overtopping trees. Results showed that rates of FCT stem diameter growth increased with light availability, logging intensity, and intensity of silvicultural treatments, and decrease with liana infestation degree. Growth rate increment was larger in the light and intensive silvicultural treatment (22–27%). Long-lived pioneer species showed the strongest response to intensive silviculture (50% increase) followed by total shade-tolerant species (24%) and partial shade-tolerant species (10%). While reduced-impact logging is often not sufficient to guarantee the sustainability of timber yields, application of silvicultural treatments that substantially enhanced the growth rates of FCTs will help move the management of these forests closer to the goal of sustained yield.     

“十二五”期间露水河林业局东升林场商品林合理年伐量测算

对传统的模拟测算法进行改进,以露水河林业局东升林场森林资源小班数据库为基础,测算了"十二五"期间商品林的合理采伐量,并模拟了在此采伐影响下森林资源动态变化。结果表明:经过30年的采伐,成熟林和过熟林面积之和占商品林的比例由41.62%调整到42.02%,成熟林面积大幅度增加,过熟林面积大幅度减少,森林资源结构得到优化;经过前5年的采伐,商品林蓄积由189.14万m3增为193.29万m3,森林资源消耗量低于生长量;每公顷蓄积由起初的134.85m3增加到137.80 m3;前5年合理年均采伐面积为182.42hm2,年均合理采伐蓄积为3.59万m3,可作为"十二五"期间调整采伐限额的依据。     

Inter-specific variation in foliar nutritional responses to disturbance by small coupe harvesting varies with landscape position

The effects of small coupe harvesting on the foliar nutritional characteristics of four indigenous plant species were investigated in a New Zealand Nothofagus truncata forest. The coupes were established in 1994, and installed in replicated logged and unlogged pairs of plots on the ridge line, face and gully of a valley, allowing variation with landscape position to be assessed. Foliar sampling occurred in March 2006. Logging significantly increased foliar nitrogen and phosphorous concentrations. Logging increased foliar δ¹⁵nitrogen, attributed to increased rates of mineralisation and nitrification, and decreased nutrient demand. Foliar calcium, magnesium and strontium concentrations were significantly decreased by logging, and this was considered the result of increased leaching in the logged coupes. The effect of the harvest treatment varied considerably with plant species, and it was determined that the examination of multiple plant species is critical to accurately assessing the effect of logging on nutrient availability. Foliar nitrogen, calcium and strontium concentrations decreased significantly from ridge line to gully coupes, and this was attributed to water movement. The effect of logging on foliar calcium and strontium concentrations also varied significantly with landscape position. It was concluded that small coupe harvesting in N. truncata forests causes substantial long term disturbances to nutrient dynamics, which may alter the relative diversity of the regenerating plants in the coupes.     

Impacts of selective logging on above-ground forest biomass in the Monts de Cristal in Gabon

Selective logging is an important socio-economic activity in the Congo Basin but one with associated environmental costs, some of which are avoidable through the use of reduced-impact logging (RIL) practices. With increased global concerns about biodiversity losses and emissions of carbon from forest in the region, more information is needed about the effects of logging on forest structure, composition, and carbon balance. We assessed the consequences of low-intensity RIL on above-ground biomass and tree species richness in a 50 ha area in northwestern Gabon. We assessed logging impacts principally in 10 randomly located 1-ha plots in which all trees ?10 cm dbh were measured, identified to species, marked, and tagged prior to harvesting. After logging, damage to these trees was recorded as being due to felling or skidding (i.e., log yarding) and skid trails were mapped in the entire 50-ha study area. Allometric equations based on tree diameter and wood density were used to transform tree diameter into biomass.Logging was light with only 0.82 trees (8.11 m³) per hectare extracted. For each tree felled, an average of 11 trees ?10 cm dbh suffered crown, bole, or root damage. Skid trails covered 2.8% of the soil surface and skidding logs to the roadside caused damage to an average of 15.6 trees ?10 cm dbh per hectare. No effect of logging was observed on tree species richness and pre-logging above-ground forest biomass (420.4 Mg ha⁻¹) declined by only 8.1% (34.2 Mg ha⁻¹). We conclude from these data that with harvest planning, worker training in RIL techniques, and low logging intensities, substantial carbon stocks and tree species richness were retained in this selectively logged forest in Gabon.     

Modelling moisture content and dry matter loss during storage of logging residues for energy

Abstract

To achieve optimal utilisation of logging residues for energy, it is important to know how different handling and storage methods affect fuel properties. The aim of this study was to model how the moisture content and dry matter losses of logging residues develop during storage. Logging residues were collected from five different stands of spruce and pine during different seasons of the year and stored in the same location. The logging residues were stored in covered piles of bundled residues and loose residues. Only minor differences were found in the moisture content profiles between piles of bundles and loose residues. Logging residues located in the centre of both types of piles had considerably lower moisture content than the outer parts. The moisture content significantly affected dry matter loss, with the highest dry matter losses being found in the samples with the least favourable drying conditions. The dry matter losses varied between 1 and 3% per month. Significantly higher dry matter losses were found in the spruce bundles than in the pine bundles. Seasoned logging residues had the lowest dry matter loss, while the logging residues harvested and piled in the autumn had the highest loss.     

Private native forest policies in New South Wales,Queensland, Victoria and Tasmania

Private native forests in Australia perform a dual production and conservation role, providing an important source of timber, and complementing formal conservation reserves. A comparison of policies for private native forests in New South Wales, Queensland, Victoria and Tasmania illustrates the scope for timber harvesting, the provision for environmental values, and initiatives for responsible and sustainable forest management. The sustainable management of Australia’s forests requires initiatives by both government and landowners to accommodate changes in community attitudes, new management strategies, integrated catchment management principles and both commercial and non-commercial opportunities for forest use. Of all of the Australian states, New South Wales has the most restrictive laws in terms of forest management and harvesting. Queensland and Victorian legislation have a more commercial focus, while Tasmania has a balance of both environmental and commercial objectives. The duty of care for private native forests is a responsibility that falls to the landholder, and while this should be enforced by legislation, the private provision of community benefits requires both recognition and reward. The presence or absence of incentives potentially determines the effectiveness of forest codes of practice.     

Impacts of bucking and delimbing alternatives on pulpwood and energy wood yields in young thinning stands in Finland

The supply of energy wood from young forests could be enhanced by altering the harvesting methods in integrated pulpwood and energy wood thinnings. In this study, effects of different bucking and delimbing options on the biomass division into energy wood, pulpwood and logging residue were estimated in integrated thinnings of young stands dominated by Scots pine (Pinus sylvestris), Norway spruce (Picea abies) or birches (Betula spp.) in Finland. Thinning options were simulated in the harvestings of model stands created on the basis of forest inventory data. Increasing the minimum top diameter of pulpwood (MTDP) expectedly increased energy wood and decreased pulpwood yields. Depending on tree species, energy wood yield increased by 36–65% when the top diameter was increased from the regular level (6 or 7 cm) to 8 cm in whole-tree harvesting, and was more than doubled when the top diameter was increased to 10 cm. Delimbed energy wood yield was increased by 240–280% when the top diameter was increased to 10 cm. Total harvesting yield in whole-tree thinnings was slightly increased by increasing top diameter. These increments in harvesting yields and reallocations of tree biomass could have an impact on large-scale forest energy potentials.