Reduced-impact Logging Techniques Research Articles

KERUSAKAN TEGAKAN TINGGAL PADA TEKNIK REDUCED IMPACT LOGGING DI INDONESIA: TINJAUAN SISTEMATIS

Forest harvesting in the natural production forest management in Indonesia is mostly carried out using conventional logging techniques and causes serious damage to residual stands and soil resources. One of the efforts made to reduce this environmental damage is the application of reduced impact logging (RIL) techniques. This study aimed to collect and analyze research results related to the damage to residual stands caused by RIL in the natural production forest management in Indonesia. This study used a systematic review method. A systematic literature search was carried out at data sources such as Google Scholar, Research Gate, Science Direct, and SINTA, which were published between 1996-2021. All studies reported that applying RIL techniques can reduce the damage to the residual stands.

The recovery of logged forests proves that a viable management is possible in the Venezuelan Guayana Shield

Aim of study: To compare the diversity and biomass of logged forests, with different ages after harvesting and the risk of their degradation to liana forests.
 Area of study: We studied 18 plots at the central zone of the Imataca Forest Reserve (Guayana shield), Venezuela.
 Material and methods: We used 1-ha plots, to measure individuals with dbh > 10 cm in control plots (0 years) and in logged plots with 3, 9, 12, 15 and 18 years after logging. The main variables evaluated were enlarge importance index (EII), richness (R), Shannon-Weaner index (H´), Alpha Fischer (α), basal area for commercial species (BA_comm), above-ground carbon (C) and lianas abundance at the understory (Lianas_%Au).
 Main results: Diversity variables (R: 62-77 spp ha-1, p: 0.117-0.838; H´: 2.8-3.4, p: 0.181-0.677; α: 18.6-25.4, p: 0.293-0.922) and biomass (89.6-180.2 MgC ha-1, p: 0.171-0.895) did not have significant differences between control and most of the logged plots. Only the 18 years-old forests had statistically higher values of diversity (R: 81-94 spp ha-1, p: 0.000; H´: 3.8-3.9, p: 0.000; α: 26.8-31.7, p: 0.000), perhaps due to a high impact skidding operation. Commercial species were not recovering after logging.
 Research highlights: Forest management can be viable in this area, but it requires reduced impact logging techniques and better silvicultural systems to guarantee future harvest of high value commercial timber.

Above-ground biomass storage potential in primary rain forests managed for timber production in Costa Rica

Tropical forests play a fundamental role in mitigating climate change through storage of carbon in above- and below- ground biomass. Their mitigation potential is, however, affected by significant greenhouse gas emissions through tropical deforestation or forest degradation. Mitigating degradation caused by conventional logging is therefore an important challenge for silvicultural management, and various reduced impact logging techniques seek to reduce biomass loss and other logging impacts during forest logging activities.Little knowledge exists about the potential of sustainable management for maintaining and restoring the climate change mitigation capacity of tropical forests. Our research contributes to knowledge about this potential, as our aim is to evaluate the above-ground biomass (AGB) stock of tropical forests managed for sustainable timber production and compare it with that of intact primary forests. We also determine the environmental and spatial factors that influence AGB.We estimated the AGB of 141 permanent sampling plots in Costa Rican tropical forests (71 plots set up in areas managed for timber production forests and 70 plots set up in areas with intact primary forests) using data for the 2000–2015 period. We compared the AGB of timber production forests with that of primary forest using linear mixed models and examined the relationship between forest AGB and climate, soil fertility and spatial variables (PCNM eigenvalues) using variation partitioning (VARPART) and multiple linear regression in the mixed model framework.Mean AGB was higher in forest plots set up in areas managed for timber production than in plots set up in areas with intact primary forests. In VARPART, spatial variables had the strongest effect on AGB with a small but significant effect of soil fertility. Regression showed potassium levels in the soil to be positively related to AGB. There was no significant effect of climate, probably because of the short temperature and precipitation gradients.Sustainable forest management in these Costa Rican forests managed for timber production has enabled them to store as much carbon in biomass as primary forests, due to the low intensity logging and sustainability criteria stipulated by the country’s forestry legislation. As a result, sustainable forest management, in addition to providing a sustainable timber ecosystem service, is also a natural climate solution, maintaining the mitigation potential of Costa Rica’s tropical forests in the current climate context.

Influence of logging on nest density and nesting microsites of cavity-nesting birds in the subtropical forests of the Andes

Abstract Birds select nesting sites with certain characteristics associated with tree age and species that help to prevent or reduce the risk of clutch loss due to predation or unfavourable weather conditions. Logging may reduce the availability of trees and their related features that may be important for cavity nesters. Thus, the aim of this study is to evaluate the effect of logging on nest density, nesting microsite and nest success of cavity nesting birds at Piedmont forests of northwestern Argentina. We monitored these variables at different logged and unlogged sites during four consecutive reproductive seasons and analysed them using univariate analysis and generalized linear models. The main results indicate that logging reduces nest density and changes the characteristics of the nesting microsites. We found that nest success was greater in cavities located higher above the ground and found no evidence of lower nest success at logged sites. This study suggests the need for forest management actions aimed at increasing nesting sites for cavity-nesting birds. For this purpose, management should be focused on the retention of old trees with a diameter >50 cm (both living and dead). The use of reduced-impact logging techniques or forest certifications (e.g. Forest Stewardship Council) could provide alternatives in subtropical forests, as these forestry practices can ensure tree abundance and richness, providing features suitable for cavity-nesting birds (e.g. tree diameter, cavity size and height).

Mammal responses to reduced-impact logging in Amazonian forest concessions

Production forests are a dominant feature of most tropical forest landscapes and it is therefore important to understand the effects of timber extraction on the resident fauna. Here we investigate the effects of reduced-impact logging (RIL) on medium- to large-sized terrestrial mammals in two Jamari National Forest logging concessions, south-western Brazilian Amazonia. We used camera traps to survey the terrestrial mammal fauna. Bayesian multi-species occupancy models (MSOMs) were performed to assess the effect of logging intensity and density of logging roads on site-level species richness, occupancy and detection rates. Species richness was negatively affected by logging status and by increasing logging intensity, and positively affected by road density. Occupancy and detection rates of individual species were largely unrelated to model predictors, although responses across species tended to be consistent with that observed for species richness. Despite negative effects of logging on species richness, no individual species were lost at the landscape level, suggesting that concessions managed under RIL techniques may be a reasonable compromise between economic and conservation interests.

Sustainable forest management is vital for the persistence of sun bear Helarctos malayanus populations in Sabah, Malaysian Borneo

With large mammals in Southeast Asia facing a host of threats such as forest loss and poaching, one important strategy in supporting conservation interventions is to understand local trends in species distributions. In Sabah, Malaysian Borneo, selective logging has both historically (conventional selective logging) and currently (reduced impact logging) impacted large areas of forest. Furthermore, the impact of poaching remains difficult to assess, potentially leading forest managers to underestimate its effects on large mammals. Our study focused on the sun bear (Helarctos malayanus), a forest dependent species threatened by poaching across its range. We used camera trap data collected in 2014 and 2018 from 127 camera trap stations in two adjacent forest blocks in Sabah. One of these blocks is a complex of degraded protected areas (formerly logged using conventional selective logging), interspersed with two areas of forest plantations (Tangkulap), while the other block is an active production forest logged using reduced impact logging techniques (Deramakot). We ran single-season occupancy models using covariates representing both habitat quality and poaching pressure to understand what factors most influenced sun bear habitat use and projected their distribution over the study area. We found that sun bear habitat selection was most strongly influenced by a dynamic covariate representing habitat quality, Normalised Difference Moisture Index (NDMI) from Landsat satellite data. Sun bear occupancy marginally increased from 2014 to 2018, in response to forest regeneration in Deramakot and Tangkulap. Overall, sun bear distribution was higher in the reduced impact logged and sustainably managed Deramakot compared to Tangkulap. Our proxies for poaching pressure had very minor effects on sun bear occupancy, suggesting that the population in this study area may not be subject to intense poaching. We highlight that sun bear populations can in fact better persist in well-managed production forests as compared to degraded protected areas.

Assessing habitat quality on alpha and beta diversity of Odonata larvae (Insect) in logging areas in Amazon forest

The present study evaluated the effects of habitat quality on the alpha and beta diversity of odonate larvae under conditions of reduced impact and conventional logging. We hypothesized that the variation in the abiotic conditions found in areas of conventional logging would result in a greater loss of alpha and beta diversity in these areas in comparison with areas of reduced-impact logging and native forest. The study area was located in northeastern Para state, in northern Brazil. We analyzed data from 10 control streams, located in areas of preserved native forest, 11 streams in forest harvested by reduced-impact logging, and nine streams in areas that had been logged conventionally. Environmental factors such as dissolved oxygen, woody debris, water temperature, sediments, and canopy cover were the principal predictors of the diversity of the Odonata. Our results showed that turnover was the principal component structuring beta diversity in the three areas (native forest, reduced impact and conventional logging). The results of the present study indicate that management initiatives based on reduced-impact logging techniques could be adopted to guarantee socio-economic benefits while minimizing the impacts of logging on local biodiversity.

The reasons great ape populations are still abundant in logged concessions: Environmental drivers and the influence of management plans

Negative short-term impact of logging on great ape distribution has been investigated but very little information is available on the long-term impacts of selective logging and management plans on ape habitats at a broader scale. We carried out a habitat suitability analysis using the presence data of great apes to identify the spatial relationships between their locations, logging activities patterns, and other human impacts (due to activities in rural communities) in an FSC-certified forestry concession (388,949 ha) in Cameroon. First, field data showed that the two great ape species, gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes troglodytes), did not differ in habitat type selection and they particularly appreciated highly dense rainforests which also lie within selectively logged zones. Second, we used MAXENT software to relate ape presence data to a set of predictor variables which represent environmental conditions and human disturbance factors (poaching, farming, trees felled to collect honey, logging roads). The model predicted that half of the whole concession may be suitable for the two primate species. Disturbances stemming from rural communities mainly correspond to poaching in the framework or not of usage rights. Road density was the strongest predictor of habitat choice by the great apes. Whereas the great apes tend to avoid zones with high road density, their population abundance increases in areas with a certain level of old logging roads. The vast majority of the predicted suitable habitats corresponds to areas logged less than 17 years ago (46.8% of the whole suitable area) where sustainable management practices have begun to be implemented, and unlogged areas (34.30%). Unsuitable habitats were mostly located in areas exploited before 2003 (45.46% of the unsuitable zones) with no reduced-impact logging practices, and in unlogged forests (41.51%). Our findings tend to confirm that selective logging combined with reduced-impact logging techniques which were more prevalent in FSC-certified concessions, may maintain or increase the spatial distribution of great ape habitats.

Impact Assessment of Timber Harvesting Operations for Enhancing Sustainable Management in a Secondary Atlantic Forest

Conservation and management of forest ecosystems are currently largely conflicting goals in the Brazilian Atlantic Forest biome. At present, all parts of the Atlantic Forest are protected and commercial logging is highly restricted. However, sustainable forest management systems can offer significant income opportunities for landholders, and thereby actively support the process of ecosystem rehabilitation and protection of the Atlantic Forest. This research is intended to contribute to enhancing the development of environmentally sound forest management alternatives in the Atlantic Forest biome. Through a case study, the harvesting impact of a conventional harvesting method (CM) was evaluated and compared with an alternative and improved harvesting method (AM), performed by a well-trained professional chainsaw operator experienced in reduced impact logging techniques, and included the use of a snatch block and a skidding cone. Following a full pre-harvest inventory, 110 different tree species were identified. The harvesting impact on the residual stand was classified and evaluated through a successive post-harvest inventory. Damage maps were developed based on interpolation of tree damage intensities with the triangular irregular networks (TIN) methodology. Our results showed noticeable high rates of tree hang-ups, observed for both harvesting methods. Furthermore, the harvesting damaged trees mainly in the lower diameter at breast height (DBH) classes. In comparison to winching, the felling process caused most of the damage to remnant trees for both methods, at 87% (CM) and 88% (AM). The number of damaged trees (above 11.9 cm DBH) per harvested tree, for CM, ranged from 0.8 trees to 2.5 trees and, for AM, ranged from 0.6 trees to 2.2 trees. Improvements of the AM method (operator skills, skidding cone and snatch block) over CM allowed for a reduction of the damaged basal area, a reduction of the “high damaged area” per plot, and a reduction of the winching disturbed ground area. Nonetheless, a suitable harvesting system should consider further improvements in the felling technique, and additionally integrate the local knowledge of CM regarding forest and tree species with the technical improvements of AM.

English

Worldwide understorey nesting bird species such as bulbuls can also be highly vulnerable to nest predation in disturbed landscapes because they breed mainly on the lower stage of the forest. We test the following hypotheses: the transformation of forests into alternative land use systems and the vegetation’s variables at the nesting sites will affect the understorey nest predation rates. The nests of 12 understorey bird species were surveyed and vegetation variables were measured within five types of habitats along a gradient of increasing forest destruction in the north-eastern peripheral zone of the Korup National Park in Cameroon. Only the open-cup nest type suffers from predation, mostly egg predation. The general linear mixed model analysis suggests that the types of habitat do not affect nest daily predation rate which decreases with increasing trees and understorey plant density. The most deleterious impact of deforestation in this study area is the reduction of nesting sites whose characteristics remain unchanged across the landscape. These results underscore the need to give understorey nesting species, as well as other particularly sensitive groups, special consideration within conservation strategies such as the reduced-impact logging techniques.   Key words: Cameroon, deforestation, land-use system, nest predation, understorey birds.

Key drivers of ecosystem recovery after disturbance in a neotropical forest

BackgroundNatural disturbance is a fundamental component of the functioning of tropical rainforests let to natural dynamics, with tree mortality the driving force of forest renewal. With ongoing global (i.e. land-use and climate) changes, tropical forests are currently facing deep and rapid modifications in disturbance regimes that may hamper their recovering capacity so that developing robust predictive model able to predict ecosystem resilience and recovery becomes of primary importance for decision-making: (i) Do regenerating forests recover faster than mature forests given the same level of disturbance? (ii) Is the local topography an important predictor of the post-disturbance forest trajectories? (iii) Is the community functional composition, assessed with community weighted-mean functional traits, a good predictor of carbon stock recovery? (iv) How important is the climate stress (seasonal drought and/or soil water saturation) in shaping the recovery trajectory?MethodsParacou is a large scale forest disturbance experiment set up in 1984 with nine 6.25 ha plots spanning on a large disturbance gradient where 15 to 60% of the initial forest ecosystem biomass were removed. More than 70,000 trees belonging to ca. 700 tree species have then been censused every 2 years up today. Using this unique dataset, we aim at deciphering the endogenous (forest structure and composition) and exogenous (local environment and climate stress) drivers of ecosystem recovery in time. To do so, we disentangle carbon recovery into demographic processes (recruitment, growth, mortality fluxes) and cohorts (recruited trees, survivors).ResultsVariations in the pre-disturbance forest structure or in local environment do not shape significantly the ecosystem recovery rates. Variations in the pre-disturbance forest composition and in the post-disturbance climate significantly change the forest recovery trajectory. Pioneer-rich forests have slower recovery rates than assemblages of late-successional species. Soil water saturation during the wet season strongly impedes ecosystem recovery but not seasonal drought. From a sensitivity analysis, we highlight the pre-disturbance forest composition and the post-disturbance climate conditions as the primary factors controlling the recovery trajectory.ConclusionsHighly-disturbed forests and secondary forests because they are composed of a lot of pioneer species will be less able to cope with new disturbance. In the context of increasing tree mortality due to both (i) severe droughts imputable to climate change and (ii) human-induced perturbations, tropical forest management should focus on reducing disturbances by developing Reduced Impact Logging techniques.

Productivity assessment of timber harvesting techniques for supporting sustainable forest management of secondary Atlantic Forests in southern Brazil

The Atlantic Forest in southern Brazil has been subject to overexploitation in the past prompting the formulation of a rigorous conservation orientated policy by the government including a strict ban of timber harvesting. In the region, the forestland is owned by farmers. The economic value of the forest is rather limited for those farmers, because of the prohibition of commercial timber harvesting as a source of income. Sustainable forest management systems can offer great potential as new income opportunities for land holders, and further actively support the process of ecosystem rehabilitation and protection for these ecosystems. Yet, successful implementation of such sustainable management systems requires feasible and adapted timber harvesting systems. In order to develop such harvesting systems, a regional comparative case study was conducted at a typical smallholder forestry venture with the objective to analyze and evaluate harvesting methods supporting sustainable management of the Atlantic Forest. This study assessed production rates and associated costs of a common conventional timber harvesting method (CM) and a proposed alternative method (AM). CM was performed by a selected, typical forest landowner who had only basic training in chainsaw operations, but 20 years of experience at the wood yard of his small sawmill. In contrast, the AM employed a professional chainsaw operator from the Amazon forest, trained and experienced in reduced impact logging techniques using state of the art equipment, supplemented by a snatch block and a skidding cone for improved extraction. Time study based models identified tree volume, winching distance and skidding distance to the landing as the most significant independent variables affecting productivity. Total net productivity ranged from 4.9 m³ PMH0-1 for CM to 3.1 m³ PMH0-1 for AM. Corresponding gross-productivity ranged from 3.0 m³ SMH-1 to 1.9 m³ SMH-1 with an overall mean utilization rate of 60.8 % and 60.9 %, respectively for CM and AM. Associated harvesting costs ranged from 12.05 € m-3 to 20.94 € m-3 with an estimated annual production of 4000 m³ and 2700 m³, respectively. Although AM showed overall lower productivity and higher costs, it represented an important improvement in terms of occupational health and safety. In conclusion, a suitable harvesting system should integrate local experiences of CM and proposed technical improvements of AM.

Enforcing the rules in timber concessions: Performance bonding in the presence of corruption risk

Performance bonding is a common method to enforce logging standards and timber contract rules, yet their applications in tropical concessions are still uncommon, with prohibitively high cost of capital, imperfect enforcement, risk of corruption, and long payback periods cited as reasons. In the face of these factors, we derive conditions for a feasible bond scheme and the amount of additional insurance a landowner can ask from a harvester in the form of a higher than strictly needed bond payment. We then determine the effect of confiscation risk on the feasibility of bond schemes, with this risk stemming from the presence of a corrupt inspector and taking the form of either collusive or non-collusive corruption. We show that confiscation risk can seriously limit the range of possible bond payments and the effects differ between the corruption types. An empirical example evaluates these results in the context of enforcement of reduced impact logging techniques in tropical concession management. The results will help governments better apply bond schemes and in particular adjust them in the presence of risks and external constraints.

Limited effects of low-intensity forest management on ant assemblages in southwestern Amazonian forests

One important strategy to conciliate forest conservation and economic development is the use of reduced-impact logging techniques. Here we evaluated the effects of low-intensity forest management on ant assemblages and vegetation structure in a managed area in the southeast of Acre State, Brazil. Ground-dwelling and arboreal ants, and several forest-structure descriptors were sampled in nine paired areas located in control (unlogged) and logged areas in 2005, 2007 and 2009. None of the forest structure predictors were related with either the treatment or the time since logging. However, some ant assemblage’ descriptors were related with logging activities. Arboreal and ground-dwelling ant species richness was similar between unlogged and logged areas, but more ground-dwelling ant species were found in areas logged in 2005 compared with areas logged in 2009. Ground-dwelling ant assemblage composition differed between treatments (logged and unlogged) and year of logging, but species composition heterogeneity was similar between areas. Arboreal ant assemblage composition was not related with treatment and year of logging, but assemblage composition was more heterogeneous in managed areas, suggesting that species that forage on the understory vegetation may be more resilient than ground-dwelling species. The general results of functional group approach suggest that changes of species composition between control and managed areas are more related with differences in ant species occurrence than ant species richness. Selective logging had limited effect on both vegetation descriptors and ant assemblage structure, suggesting that the conciliation of impact reduction techniques with low intensity extraction seems a promising alternative for sustainable logging activity in tropical forests.

Spatially explicit estimates of forest carbon emissions, mitigation costs and REDD+ opportunities in Indonesia

Carbon emissions from the conversion and degradation of tropical forests contribute to anthropogenic climate change. Implementing programs to reduce emissions from tropical forest loss in Southeast Asia are perceived to be expensive due to high opportunity costs of avoided deforestation. However, these costs are not representative of all REDD+ opportunities as they are typically based on average costs across large land areas and are primarily for reducing deforestation from oil palm or pulp concessions. As mitigation costs and carbon benefits can vary according to site characteristics, spatially-explicit information should be used to assess cost-effectiveness and to guide the allocation of scarce REDD+ resources. We analyzed the cost-effectiveness of the following REDD+ strategies in Indonesia, one of the world’s largest sources of carbon emissions from deforestation: halting additional deforestation in protected areas, timber and oil palm concessions, reforesting degraded land and employing reduced-impact logging techniques in logging concessions. We discover that when spatial variation in costs and benefits is considered, low-cost options emerged even for the two most expensive strategies: protecting forests from conversion to oil palm and timber plantations. To achieve a low emissions reduction target of 25%, we suggest funding should target deforestation in protected areas, and oil palm and timber concessions to maximize emissions reductions at the lowest cumulative cost. Low-cost opportunities for reducing emissions from oil palm are where concessions have been granted on deep peat deposits or unproductive land. To achieve a high emissions reduction target of 75%, funding is allocated across all strategies, emphasizing that no single strategy can reduce emissions cost-effectively across all of Indonesia. These findings demonstrate that by using a spatially-targeted approach to identify high priority locations for reducing emissions from deforestation and forest degradation, REDD+ resources can be allocated cost-effectively across Indonesia.

Body condition scoring of Bornean banteng in logged forests

The Bornean banteng (Bos javanicus lowi) is an endangered subspecies that often inhabits logged forest; however very little is known about the effects of logging on their ecology, despite the differing effects this has on other ungulate species. A body condition scoring system was created for the Bornean banteng using camera trap photographs from five forests in Sabah, Malaysia, with various past and present management combinations to establish if banteng nutrition suffered as a result of forest disturbance. One hundred and eleven individuals were photographed over 38,009 camera trap nights from April 2011 to June 2014 in five forests. Banteng within forests that had a recent history of reduced-impact logging had higher body condition scores than banteng within conventionally logged forest. Conversely, when past logging was conducted using a conventional technique and the period of forest regeneration was relatively long; the banteng had higher body condition scores. The body condition scoring system is appropriate for monitoring the long-term nutrition of the Bornean banteng and for evaluating the extent of the impact caused by present-day reduced-impact logging methods. Reduced-impact logging techniques give rise to individuals with the higher body condition scores in the shorter term, which then decline over time. In contrast the trend is opposite for conventional logging, which demonstrates the complex effects of logging on banteng body condition scores. This is likely to be due to differences in regeneration between forests that have been previously logged using differing methods.

The Potential of REDD+ for Carbon Sequestration in Tropical Forests: Supply Curves for Carbon Storage for Kalimantan, Indonesia

Abstract We study the potential of tropical multi-age multi-species forests for sequestering carbon in response to financial incentives from REDD+. Following existing carbon crediting schemes, the use of reduced impact logging techniques (RIL) allows a forest manager to apply for carbon credits whereas conventional logging (CL) does not. This paper is the first to develop a Hartman model with selective cutting in this setting that takes additionality of carbon sequestration explicitly into account. We apply the model using data for Kalimantan, Indonesia, for both private and government forest managers. The latter have a lower discount rate and are exempt from taxes. RIL leads to less damages on the residual stand than CL and has lower variable but higher fixed costs. We find that a system of carbon credits through REDD+ can increase carbon stored per hectare by 15.8% if the forest is privately managed and by 22% under government management if the carbon price equals the average 2015 price in the European Union's Emission Trading Scheme. Interestingly, awarding carbon credits to carbon stored in end-use wood products does not increase the amount of carbon stored, nor Land Expectation Value.

The potential of REDD+ for carbon sequestration in tropical forests: Supply curves for carbon storage for Kalimantan, Indonesia

We study the potential of tropical multi-age multi-species forests for sequestering carbon in response to financial incentives from REDD+. Following existing carbon crediting schemes, the use of reduced impact logging techniques (RIL) allows a forest manager to apply for carbon credits whereas conventional logging (CL) does not. This paper is the first to develop a Hartman model with selective cutting in this setting that takes additionality of carbon sequestration explicitly into account. We apply the model using data for Kalimantan, Indonesia, for both private and government forest managers. The latter have a lower discount rate and are exempt from taxes. RIL leads to less damages on the residual stand than CL and has lower variable but higher fixed costs. We find that a system of carbon credits through REDD+ can increase carbon stored per hectare by 15.8% if the forest is privately managed and by 22% under government management if the carbon price equals the average 2015 price in the European Union's Emission Trading Scheme. Interestingly, awarding carbon credits to carbon stored in end-use wood products does not increase the amount of carbon stored, nor Land Expectation Value.

Recovery of biomass and merchantable timber volumes twenty years after conventional and reduced-impact logging in Amazonian Brazil

Concerns about the sustainability of tropical forestry motivated this study on post-logging timber and carbon dynamics over a 20-year period in Paragominas, Pará, Brazil. Previously unlogged forest was subjected to conventional logging (CL), reduced-impact logging (RIL), or was set aside as an unlogged control. All trees ⩾25cm DBH and all trees of commercial species ⩾10cm DBH were monitored in a 24.5ha plot in each treatment, with a 5.25ha subplot in each for monitoring all trees ⩾10cm DBH. Above-ground biomass and bole volumes of merchantable species were tracked based on 10 inventories made between 1993 and 2014. Pre-logging biomass and bole volumes of commercial species were estimated as 237, 231, and 211Mgha−1, and 78, 80, and 70m3ha−1, in the RIL, CL, and unlogged plots, respectively. One year after logging, biomass was reduced 14% by RIL and 24% by CL with corresponding merchantable species volume reductions of 21% and 31%. By 2014, biomass and bole volumes of commercial species had recovered 95% and 98% of their pre-logging stocks in the RIL plot but only 76% and 72% in the CL plot, respectively; timber volumes from large trees (⩾50cm DBH) were only recovered to 81% in the RIL plot and to 53% in the CL plot. Over the first twenty years after logging, average volume increments from commercial species were substantially higher in the RIL plot (0.72m3ha−1year−1) than in the CL plot (0.08m3ha−1year−1). Recovery of both biomass and timber volumes were temporarily reversed between 2009 and 2014 due to a 4-fold increase in annual mortality rates in the RIL plot and a 5.5-fold increase in the CL plot (as well as a 3-fold increase in the control plot), all presumably related to the extreme drought of 2010. Our findings support the claim that use of RIL techniques accelerates rates of biomass and timber stock recovery after selective logging.

On volume recovery index and implications for sustainable logging in Congo Basin

We introduce a volume recovery index (VRI), the fraction of inventoried (alternatively felled) tree volume that can be recovered and commercialized. The new index improves on the traditional marketing coefficient used in the Congo Basin, through a systematic assessment of wastage at logging and preprocessing stages. Statistically, the new index is more reliable: its two proposed versions are both accurate (absence of bias) and precise (small mean square error). Practically, VRI gauges the ATO/ITTO indicator 2.3.4 stating that “[wastage should be] minimized at all stages of production and processing”. VRI actually encapsulates three sub-indicators of that indicator and complements a fourth sub-indicator on using “felling methods [that] optimize the volume of usable timber”. Thus, VRI is useful in assessing the ecological and socioeconomic sustainability of timber production of all forest types, with particular relevance for reduced-impact logging (RIL) and carbon (or biomass) storage. We examine the qualities of VRI as sustainability indicator, set forth a principle for sustainable logging, and discuss the limitation effects of (i) ecology (species growth conditions, spatial distribution, and stand structure), (ii) management (polycyclic logging, species selection and diversification, logging operations, logging intensity, and conservation constraints) and (iii) policy (legislation on timber processing and export products, incentive allocation, property rights definition and enforcement) on volume recovery, together with possible remedies. We recommend: (i) using the spatialized VRI jointly with other pressure indicators in discriminating between genuine environmental limitations and mining exploitation; (ii) adopting RIL techniques to their fullest potential, given current low logging intensities in Congo Basin; (iii) allowing transfer of user rights in salving damaged trees and low quality timber; (iv) promoting recovery and utilization of residue to increase timber transformation rate, curb resource dissipation, reduce the rate of desertification, improve distribution of forest benefits, and contribute to poverty alleviation.