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Effects of permanent (i.e., maintained) and temporary edges with north- and south-facing exposures were studied in sand pine (Pinus clausa var. clausa (Chapm. ex Engelm.) Vasey ex Sarg.) scrub, an open-canopied forest type in Ocala National Forest, Florida. On edges and interiors of four stands of each type, we measured canopy tree architecture in 5 m × 100 m plots and stand density and basal area in 5 m × 200 m plots. Edge effects were modest but often stronger on south- than north-facing edges and along permanent forest roads than temporary edges of clearcuts that were allowed to regrow. Compared with interior trees, those on edges were typically shorter, retained branches lower on their boles, oriented their first branches more towards the edge, and produced more asymmetrical crowns with the long axis extending into the opening; these trends were greater on south- than north-facing edges and along permanent than temporary edges. Contrary to expectations, there were no edge effects on total basal area, dead tree densities, proportions of sand pine trees with leaning trunks, directions of lean, or angles of lean. Instead of an edge effect, most trees leaned towards the southwest, which seems related to the northeastern origin of prevailing winds and wind gusts.

PREMISE To support large leaves, many woody plant species evolved a cost-effective way to thicken twigs. As an extension of E. J. H. Corner's rule that twig diameter increases with leaf size, we hypothesized that pith width also increases with leaf size. The benefit to the plant from the proposed relationship is that pith is a low-cost tissue that reduces the metabolic cost of large diameter twig production. METHODS Leaf sizes and cross-sectional areas of bark, xylem, and pith of 81 species of trees and shrubs growing in Gainesville, Florida were measured and compared with standardized major axis regressions of pairwise species trait values and phylogenetically independent contrasts. RESULTS Pith area increases with leaf size with or without accounting for phylogenetic relationships. In agreement with Corner's rule, overall twig diameter as well as bark and wood thickness also increase with leaf size. Thicker twigs showed more variation in relative pith, wood, and bark cross-sectional areas compared to thinner twigs. CONCLUSIONS Investments in pith, a tissue of low density found in the centers of twigs, provides a low-cost way to increase twig circumference and thereby space for attachment of large leaves while increasing the overall second moment of area of twigs, which increases their ability to biomechanically support large leaves.

Community involvement is critical for the success of many interventions designed to promote reforestation. To secure this involvement, it helps to recognize that communities are heterogenous both within and among themselves and possess diverse mixes of livelihood assets required to implement reforestation. We explore the relationship between livelihood assets and reforestation success and outline a conceptual model that we call the community capacity curve (CCC) applied to reforestation. We argue that the shape of the CCC is sigmoidal. Importantly, communities at the lower end of the CCC have limited capacity to implement reforestation projects without substantial and ongoing capacity building and other sorts of support, including through livelihood projects that improve food security and provide cash benefits. Communities at the higher part of the CCC have greater capacity to implement reforestation projects, especially projects focused on biodiversity and environmental services. The CCC can help design, implement, monitor and assess reforestation projects, select appropriate livelihood activities and types of reforestation, select communities suited to a reforestation project, guide implementation and understand projects' successes and failure. The CCC also provides a framework to engage with policy makers and funding bodies to explore the types of support for communities to reforest successfully. This article is part of the theme issue ‘Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration’.

Pocket gophers (Geomys spp.) are solitary, root-eating fossorial rodents native to North and Central American grasslands and are presumed to acquire most of their food through excavation of tunnels maintained as part of tunnel systems up to 160 m long

Based on recent insights about intensive soil husbandry by some Neolithic farmers combined with the required techniques for efficient use of stone tools, this research questions the emphasis in the experimental archaeology literature on felling of large trees by stone-axe-wielding males working alone. To reflect conditions after the short fallows now thought to have been favored by farmers using stone tools, young (8–12 years) and small (3.5–5.6 cm diameter) Quercus hemisphaerica (laurel oak) trees were felled in this study by both male and female participants. Felling with a stone axe required an average of 75 more strokes than for felling a similar sized tree with a steel axe. One novel finding in this study is that when the Quercus hemisphaerica (laurel oak) saplings were bent over/tensioned by a co-worker, the predicted numbers of felling strokes declined by 123 (73%) for stone axes and by 15 (72%) for steel axes. We also observed no effect of sex on felling efficiency with stone axes. These results suggest that stone-tool wielding farmers of both sexes worked together to clear trees from their fallowed fields.

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.

Lianas (woody climbing plants) often abound in tropical forests after selective logging and other disturbances. Liana cutting is an often-prescribed but seldom applied silvicultural treatment designed to foster the growth of future crop trees (hereafter: FCTs). Small-scale studies indicate that this treatment is effective, but little is known about its efficiency (i.e., proportions of lianas missed) or financial cost effectiveness at operational scales. To fill these gaps, we worked in a commercial forest concession in Belize where FCTs and trees to be felled were liberated from lianas in 500–1000 ha annual timber harvest blocks. We found that field crews assigned this and inventory-related tasks spent 11.8% of their time cutting lianas from FCTs at a cost of $0.11 per tree. Workers failed to cut 31.9% of the lianas that infested the 701 FCTs they were supposed to liberate; most of the missed lianas grew into the FCT crowns from neighbors or hung down far from the bole [an additional 48 FCTs (6%) were completely missed]. In a logging block treated 9-years prior to this study, 39% of the liberated Swietenia macrophylla FCTs 29–56 cm DBH were still liana-free whereas in an untreated stand, 94% of similar-sized conspecific control FCTs were liana-infested. Based on tree ring data for the same 9-year period, the liberated FCTs grew 38–63% faster than control FCTs. If the mean growth benefit is sustained over the entire 40-year cutting cycle, each liberated FCT will yield an average of 1.51 m3 (639 board feet) more roundwood than comparable FCTs in unliberated forest. Over this 40-year period with an annual discount rate of 4.5%, this added volume gives the $0.11 investment per tree a net present value of US $161.38 and a profitability index of 1467 for export quality timber. These results argue for the application of this inexpensive and effective treatment in managed forests where lianas abound.

On the Yucatan Peninsula in Mexico, communities (ejidos) that selectively log their forests help reduce deforestation and are an important source of timber for national and international markets. If carried out without proper planning and reduced-impact logging (RIL) practices, forest disturbances and carbon emissions from these harvests can be substantial. To assess variation in logging-induced emissions and to estimate potential reductions in those emissions, we estimated carbon impacts from damage to trees > 5 cm DBH in the annual cutting areas of ten forest-managing ejidos. Baselines were developed for emissions from felling, skidding and transport of timber and then ejidos were compared with respect to whether they were Forest Stewardship Council (FSC) certified, size of annual cutting area, logging intensity, and implementation of RIL practices, particularly directional felling, skid trail planning, and the use of small modified agricultural tractors instead of large forestry skidders. The carbon impacts of enrichment planting in multiple-tree felling gaps (400–1800 m2) were also evaluated. Carbon emissions from selective logging averaged 1.52 Mg m−3 but ranged 1.19–2.55 Mg m−3 among the 10 ejidos. Most emissions were from the remnants of trees felled for their timber (73%), followed by skidding (11%), transport infrastructure (i.e. logging roads and landings; 8%), and collateral damage from felling (7%). Our analyses indicate that FSC certification was not associated with any difference in carbon emissions from selective logging but that employment of RIL practices resulted in fewer damaged trees and lower carbon emissions even in ejidos with high logging intensities. Use of modified agricultural tractors for log yarding (i.e., skidding) reduced C emissions by 0.15 Mg m−3 or 5 Mg km−1 of skid trail. Greater collateral damage was found in multiple felling gaps but the increased emissions were offset by reductions in the remnants of harvest trees. Adoption of RIL-C practices by all community forestry ejidos in the region would contribute substantially to the Mexican forest sector’s efforts to mitigate climate change.

Selective logging causes at least half of the emissions from tropical forest degradation. Reduced-impact logging for climate (RIL-C) is proposed as a way to maintain timber production while minimizing forest damage. Here we synthesize data from 61 coordinated field-based surveys of logging impacts in seven countries across the tropics. We estimate that tropical selective logging emitted 834 Tg CO2 in 2015, 6% of total tropical greenhouse gas emissions. Felling, hauling, and skidding caused 59%, 31%, and 10% of these emissions, respectively. We suggest that RIL-C incentive programs consider a feasible target carbon impact factor of 2.3 Mg emitted per Mg of timber extracted. Operational modifications are needed to achieve this target, such as reduced wood waste, narrower haul roads, and lower impact skidding equipment. Full implementation would reduce logging emissions by 44% (366 Tg CO2 year−1) and deliver 4% of the nationally determined contributions to the Paris Climate Agreement from tropical countries, while maintaining timber supplies.

To estimate carbon emissions from selective logging in Central Africa, we employed the reduced-impact logging for carbon emissions reductions (RIL-C) protocol to quantify baseline carbon emissions from legal timber harvests by source (i.e., hauling, skidding, and felling). We modeled the relationships between emissions and biophysical conditions, logging practices, and forest policies and then used these models to estimate potential emission reductions from full implementation of RIL-C practices. We applied the method in 8 forest management enterprises (FMEs; i.e., concessions) in the Democratic Republic of Congo (DRC), 9 in Gabon, and 6 in the Republic of Congo (RoC). Committed logging emissions expressed per cubic meter of timber harvested (to control for differences in logging intensities) ranged from 0.63 Mg C m−3 in a FME in RoC to 4.8 Mg C m−3 in a FME in Gabon, with an overall average of 2.1 Mg C m−3. Logging emissions were dominated by damage caused by road and log landing construction (i.e., hauling; 50%) and felling (43%; includes carbon in extracted logs). Total emissions represented only about 9% of unlogged forest biomass carbon stocks. Average emissions were highest in Gabon (2.65 Mg C m−3) followed by DRC (1.84 Mg C m−3) and RoC (1.54 Mg C m−3). Emissions from concessions certified by the Forest Stewardship Council (FSC, N = 6) and those that were not certified (N = 17) did not differ. Nearly half (51%) of logging emissions could be avoided without reducing timber yields if all best examples of RIL-C logging practices observed were applied in the same FME. At the country level, if all FMEs were to utilize these practices, emissions reductions would be 34% in RoC, 45% in DRC, and 62% in Gabon. When combined with country-level logging statistics, emissions from selective logging as currently practiced in the six countries of the Congo Basin are equivalent to 40% of the region’s total emissions from deforestation.

We define two implementation levels for reduced-impact logging for climate mitigation (RIL-C) practices for felling, skidding, and hauling in dipterocarp forest concessions of East and North Kalimantan. Each implementation level reduces logging emissions by a consistent proportion below the business-as-usual emissions baseline, which varies with harvest intensity. Level 1 reflects the best recorded emissions performance for each type of practice. Level 2 is more ambitious but feasible based on workshop feedback from concession managers and forestry experts, and confirmed by a recent demonstration. At Level 1 emissions can be reduced by 33%, avoiding emissions of 64.9 ± 22.2 MgCO2 per ha harvested, on average. At Level 2 emissions can be reduced by 46%, avoiding 88.6 ± 22.7 MgCO2 ha−1. The greatest emissions reductions derive from (i) not felling trees that will be left in the forest due to commercial defects, and (ii) use of long-line cable winching to avoid bulldozer impacts. We also quantify the potential to avoid logging steep slopes and riparian habitats, while holding to our RIL-C accounting assumption that timber yields are maintained to avoid problems of leakage and product substitution. Logging damage to riparian areas 40% could similarly be avoided. The combined areas of these sensitive habitats (steep slopes and riparian buffers) represented 16% of each cutting block on average. Implementation of RIL-C practices would deliver 8% (Level 1) and 11% (Level 2) of Indonesia’s pledged reductions to their forest reference emissions level as a nationally determined contribution to the Paris Climate Agreement. In concert with RIL-C practices, 30% of logging concession areas could be permanently protected from logging and conversion to minimize impacts on biodiversity, soils, and water quality, thereby expanding Indonesia’s protected areas by one third and achieving 93% of Indonesia’s Aichi Target 11 (the effective conservation of at least 17% of lands). Both these Paris Climate Agreement and Aichi outcomes could be delivered with no reductions in timber yields and substantial improvements in worker safety and sustainability of the natural forest timber sector.

Premise Many perennial herbaceous plants develop underground storage organs (USOs) that store carbohydrates, water, and minerals. The resprouting ability of plants is influenced by the availability of these materials and by the type of underground organ and number of viable buds. In this study, we illustrate the diversity of longleaf pine savanna species and their nonstructural carbohydrate (NSC) pools and concentrations. We also determined whether NSC concentrations by USO are good predictors of NSC pools in species with different types of underground structures. Methods We excavated in their entirety 1-4 individuals of each of 100 ground-layer pine savanna species, classified their USO types, and measured their NSC concentrations and NSC pools. Results The NSC concentrations in underground organs varied widely among the 100 species sampled. Surprisingly, the fibrous roots of Pityopsis graminifolia stored higher concentrations of NSCs than many species with USOs. The relationship between NSC concentrations and NSC pools was strong after controlling for underground biomass. Conclusions Our results revealed the high diversity of underground organs in pine savannas. It also showed that NSC concentrations in species with USOs reach high levels. Predictions of NSC pool sizes from NSC concentrations are interpretable, when corrections for underground biomass are considered. Research on underground organs would benefit from inclusion of morphological-anatomical analyses and phylogenetic controls to promote use of the data in broad-scale analyses.

We used corrective action requests (CARs) issued by conformity assessment bodies (CABs) working under the Forest Stewardship Council (FSC) certification in Indonesia to explore differences among audited natural forest management units (FMUs). Specifically, we evaluate how FMU characteristics influenced the classes of CARs issued and the time elapsed before their closure. We analyzed 933 CARs from 22 FSC-certified FMUs reported by six CABs in 99 public summaries. The average number of CARs issued did not vary with type of audit or CAB, most focused on social and environmental issues, and most represented minor infractions that were rectified with procedural changes (i.e., improvements in planning, record keeping, and reporting). None of the measured characteristics of Indonesian FMUs helped explain the foci of assigned CARs. The elapsed time before CAR closure differed among CABs and type of audit, but decreased over time. Large FMUs established before 1998 that employed many workers and subcontracted logging took longer to close CARs than FMUs with the opposite characteristics. Finally, conclusions based on this analysis should be made in light of the limitations of analyses based on reports from auditors rather than on direct observations.

Widespread degradation of tropical forests is caused by a variety of disturbances that interact in ways that are not well understood. To explore potential synergies between edge effects, fire and windstorm damage as causes of Amazonian forest degradation, we quantified vegetation responses to a 30‐min, high‐intensity windstorm that in 2012, swept through a large‐scale fire experiment that borders an agricultural field. Our pre‐ and postwindstorm measurements include tree mortality rates and modes of death, above‐ground biomass, and airborne LiDAR‐based estimates of tree heights and canopy disturbance (i.e., number and size of gaps). The experimental area in the southeastern Amazonia includes three 50‐ha plots established in 2004 that were unburned (Control), burned annually (B1yr), or burned at 3‐year intervals (B3yr). The windstorm caused greater damage to trees (>10 cm DBH) in the burned plots (B1yr: 13 ± 9% of 785 trees; B3yr: 17 ± 13% of 433) than in the Control plot (8 ± 4% of 2,300; ± CI). It substantially reduced vegetation height by 14% in B1yr, 20% in B3yr and 12% in the Control plots, while it reduced above‐ground biomass by 18% of 77.7 Mg/ha (B1yr), 31% of 56.6 (B3yr), and 15% of 120 (Control). Tree damage was greatest near the agricultural field edge in all three plots, especially among large trees and in B3yr. Trunk snapping (70%) and uprooting (20%) were the most common modes of tree damage and mortality, with the height of trunk failure on the burned plots often corresponding with the height of historical fire scars. Of the windstorm‐damaged trees, 80% (B1yr), 90% (B3yr), and 57% (Control) were dead 4 years later. Trees that had crown damage experienced the least mortality (22%–60%), followed by those that were snapped (55%–94%) and uprooted (88%–94%). Synthesis. We demonstrate the synergistic effects of three kinds of disturbances on a tropical forest. Our results show that the effects of windstorms are exacerbated by prior degradation by fire and fragmentation. We highlight that understorey fires can produce long‐lasting effects on tropical forests not only by directly killing trees but also by increasing tree vulnerability to wind damage due to fire scars and a more open canopy.

We used a hybrid optimization-agent-based model to simulate REDD+ (Reduced Emissions from Deforestation and forest Degradation in combination with conservation, sustainable forest management, and enhancement of forest carbon stocks) payment scenarios to farm households in the old deforestation frontier of Rondonia, Brazil. Payments varied from $5 to $30 per ton of net CO2 either not emitted or removed from the atmosphere relative to a baseline scenario. The impacts of REDD+ were assessed as changes in land use/cover, net CO2 emissions, program costs, community welfare, and agricultural production. Our results suggest that interventions aimed at zero gross deforestation would require unrealistically large annual disbursements. In contrast, zero net carbon emissions can be achieved at approximately two-thirds the cost with reduced impacts on food production. Overall, simulated payments increased inequality among households, which conflicts with desired REDD+ outcomes. Results suggest that REDD+ might be more successful solely as a climate change mitigation mechanism as opposed to a complex multi-objective development program.

Much of the tropical forest that will escape conversion is on steep slopes. Land uses in steep areas disproportionately affect environmental processes, especially hydrology (e.g., peak flows, suspended sediment loads). We use data from East Kalimantan, Indonesia, to demonstrate why slope measurements used for planning and regulatory purposes should be based on digital elevation models (DEMs) constructed with small pixel data and ground-based or canopy-penetrating remote sensing, and not just mean slopes calculated for large areas with passive remote sensing. For five logging concessions, the proportion of the forest on slopes >40% (21.8°) ranged 35–85% with crown penetrating airborne lidar pixels of 1 m, but only 13–69% when pixel size was increased to 30 m. With passive satellite-based remotely sensed 30 m pixels, estimates of land on slopes >40% were even lower (11–56%). Policies based on DEMs with underestimated slopes contribute to the misuses of steep areas and the consequent deleterious in-forest and downstream impacts. The energy costs of forest operations increase with slope, which decreases the financial costs of compliance with environmentally motivated policies for the protection of steep terrain.

REDD+ was initially conceived of as a multi-level carbon-based payment for environmental services (PES). It is still often assumed to be a cost-effective climate change mitigation strategy, but this assumption is mostly based on theoretical studies and static opportunity cost calculations. We used spatial and socioeconomic datasets from an Amazonian deforestation frontier in Brazil to construct a simulation model of REDD + payments to households that can be used to assess REDD + interventions. Our SimREDD + model consists of dynamic optimization and land-use/cover change allocation submodels built into an agent-based model platform. The model assumes that households maximize profit under perfect market conditions and calculates the optimal household land-use/cover configuration at equilibrium under a given REDD + PES scenario. These scenarios include PES based on (1) forest area and (2) carbon stocks. Insights gained from simulations under different conditions can assist in the design of more effective, efficient, and equitable REDD + programs.

Made available in DSpace on 2022-04-29T08:32:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) When an ecosystem undergoing restoration does not follow the desired trajectory, management interventions may be warranted. Where the initial steps towards restoration include tree planting at high densities, reduction of stand basal area (BA) by overstory thinning is a potential adaptive management tool to stimulate natural regeneration, although it can also damage young plants. We ask how tree regeneration in a restored tropical forest responds to different intensities of thinning. We applied two intensities of thinning to a 22-yr-old restored forest in southeastern Brazil and then sampled seedlings and saplings before and over an eight year period after thinning; unthinned plots were retained as controls. Thinning impacts on the woody understory were negligible, far below annual mortality in control plots. Positive responses to thinning were stronger in the treatment with low remaining basal area (ca. 30% below the reference forests), with increases in seedling density, numbers of recruits, and seedling-to-sapling and sapling-to-tree transitions. Understory dynamics were clearly intensified by gap opening, with a pulse of natural regeneration in the first years after thinning. These changes, however, were not simultaneous and did not usually persist over time. Rarefied richness of the understory increased over time after all treatments and changes in species composition of saplings were enhanced by thinning. Our study gives support to selective timber harvests from restored tropical forests insofar as thinning did not threaten the understory and stimulated natural regeneration. Frequency and intensity of thinning operations, however, should be locally adjusted based on monitoring data. Departamento de Ciência Florestal Solos e Ambiente Faculdade de Ciências Agronômicas Universidade Estadual Paulista “Júlio de Mesquita Filho”, Avenida Universitária, 3780, Altos do Paraíso Floresta Estadual de Assis Instituto de Pesquisas Ambientais, Caixa Postal 104 Department of Biology University of Florida, P.O. Box 118526 Departamento de Ciência Florestal Solos e Ambiente Faculdade de Ciências Agronômicas Universidade Estadual Paulista “Júlio de Mesquita Filho”, Avenida Universitária, 3780, Altos do Paraíso CNPq: #303402/2012 CNPq: #561771/2010-3 CAPES: 001

In 2006, the Brazilian Forest Service (SFB) started an ambitious program to establish forest concessions so as to provide a legal framework for long-term sustainable timber production in Amazonian forests. Forest concessions in the Brazilian Amazon currently cover only 1.6 million ha (Mha) but we estimate the area of all potential concessions as 35 Mha. This paper assessed the conditions under which the present and potential concession system can ensure an annual production of 11 Mm3. yr−1 to meet the estimated present timber demand. For this we used the volume dynamics with differential equations model (VDDE) calibrated for the Amazon Basin with a Bayesian framework with data from 3500 ha of forest plots monitored for as long as 30 years after selective logging. Predictions of commercial volume recovery rates vary with location. We tested 27 different scenarios by using combinations of initial proportion of commercial volume, logging intensity and cutting cycle length. These scenarios were then applied to the current area of concessions and to the area of all potential concessions (35 Mha). Under current logging regulations and the current concession area (mean logging intensity of 15–20 m3.ha−1, a harvest cycle of 35 years and an initial commercial timber volume proportion of 20%), timber production can be maintained only for a single cutting cycle (35 years). Only the scenario with a logging intensity of 10 m3ha−1 every 60 years with a 90% initial proportion of commercial timber species can be considered as sustainable. Under this scenario, the maximum annual production with the present concession areas is 159,000 m3 (157–159), or less than 2% of the present annual production of 11 Mm3. When considering all potential concession areas (35 Mha), under current rules, the total annual production is 10 Mm3yr−1 (2–17 Mm3yr−1, 95% credibility interval) but is not maintained after the first logging cycle. Under the most sustainable scenario (see above) and a concession area of 35 Mha, the long-term sustainable annual production of timber reaches only 3.4 Mm3yr−1. Based on these results we argue that the concession system will not be able to supply the timber demand without substantial reforms in natural forest management practices and in the wood industry sector. We argue that alternative sources of timber, including plantations linked with forest restoration initiatives, must be promoted.

After more than 20 years and substantial investments of time and money, Forest Stewardship Council (FSC) certification of tropical forest management is due for a stringent impact evaluation. For any social, ecological, and economic outcomes to be attributed to FSC certification, rival explanations need to be ruled out. We recognize that different types of knowledge about FSC impacts derived from information gathered through a range of methods can satisfy the evidence-needs of different stakeholders. But this paper describes a roadmap based on rigorous methods to assess whether FSC certification delivers on its expected outcomes and the underlying mechanisms through which changes can be attributable to FSC. To this end, background studies that provide contextual knowledge related to implementation of FSC certification are proposed to account for any positive self-selection biases and to capture the temporal dynamics of certification including changes in the sociopolitical and economic contexts that influence certification decisions. (Resume d'auteur)

To sustain timber yields from selectively logged tropical forests, silvicultural treatments beyond reduced-impact logging are often recommended but seldom implemented outside of research areas. To determine the extent to which financial constraints justify the reluctance of Indonesian forest industries to intensify their silviculture at operational scales, we develop a series of scenarios to compare the financial viability of enrichment planting along cleared lines through twice logged forest (TPTJ) with the common practice of selective logging alone (TPTI). Because TPTJ also increases carbon stocks relative to the logged-only option, we consider carbon payments in some scenarios. With a discount rate of 6% and a cutting cycle of 30 years, TPTJ yields higher net present values (NPVs) than TPTI (US$442 vs $145/ha, respectively). TPTJ still provides higher NPVs than TPTI with discount rates up to 8% and cutting cycles of 25–30 years. With carbon payments of US$9.6/Mg CO 2e , TPTJ maintains a positive NPV with discount rates up to 13%. In contrast, TPTI has positive NPVs with discount rates up to 12% with cutting cycles of 25–30 years. At all discount rates with positive NPVs, TPTJ yields higher NPVs than TPTI for all comparisons with equal cutting cycle durations (US$69–3,370/ha vs. US$68–393/ha). Given its substantial impacts on forest structure and composition, the more intensive TPTJ treatment should be implemented in only small and appropriately selected portions of managed landscapes.

An individual-tree-based growth-and-yield model (SILFOR) was developed to evaluate the long-term effects of silvicultural treatments beyond logging in a tropical forest is described. Here we focus on the model’s approach to prediction of the magnitude and duration of silvicultural treatment effects on growth of the residual trees that will contribute most of the timber available to the next planned harvest in 25–40 years. Data from 30 1-ha permanent sample plots monitored for up to 20 years in dipterocarp forest in Kalimantan, Indonesia were used to develop the model. The treatments were different logging intensities with or without post-logging silvicultural treatments. Each species was assigned to one of five groups based on their ecological traits and the merchantability of their timber. A mixed-effects model was used to account for the spatially and temporally autocorrelated permanent plot data. The mixed-effects approach improved model performance substantially compared to a fixed-effects approach; specification of the variance function and correlation structure of the error term further improved model fit. Patterns and rates of tree diameter increment varied substantially, as indicated by the large differences among species groups in terms of the level of random-effects, number of parameters assigned as mixed-effects, and the covariates that define the best model. Similarly, silvicultural treatment effects also varied among species groups, as indicated by differences in the treatment dummy variables in the final model. Among-treatment differences diminished over time. We also found that species group representation is effected differentially by the silvicultural treatments. Overall, the study presents a novel and hopefully useful approach to the analysis of growth-and-yield data from tropical forests under intensified management for timber.

This viewpoint paper presents a reaction to the article by Brandt et al. (2016). It highlights the complexities inherent to the attribution of deforestation impacts to policy interventions when using remote-sensing data. This critique argues that in the context of the Congo a suite of factors (i.e., population density in particular) other than those considered by Brandt et al. (e.g., type of forest, distance from roads and markets) play essential roles in determining the fates of forests. It also contends that care is needed when making decisions regarding which units will be included in the comparison group so that contextual factors and on-the-ground information are properly considered (e.g., when logging operations are inactive or when a concession is used for 'conservation' purposes). Finally, it proposes that a focus on an analysis of deforestation rates for a given level of timber production might be a metric that more accurately represents one aspect of the consequences of forest management, which should also consider the appraisal of trade-offs associated with a larger set of social, financial and ecological objectives.

Areas allocated for industrial logging and community-owned forests account for over 50% of all remaining tropical forests. Landscape-scale conservation strategies that include these forests are expected to have substantial benefits for biodiversity, especially for large mammals and birds that require extensive habitat but that are susceptible to extirpation due to synergies between logging and hunting. In addition, their responses to logging alone are poorly understood due to their cryptic behavior and low densities. In this study, we assessed the effects of logging and hunting on detection and occupancy rates of large vertebrates in a multiple-use forest on the Guiana Shield. Our study site was certified as being responsibly managed for timber production and indigenous communities are legally guaranteed use-rights to the forest. We coupled camera-trap data for wildlife detection with a spatially explicit dataset on indigenous hunting. A multi-species occupancy model found a weak positive effect of logging on occupancy and detection rates, while hunting had a weak negative effect. Model predictions of species richness were also higher in logged forest sites compared to unlogged forest sites. Density estimates for jaguars and ocelots in our multiple-use area were similar to estimates reported for fully protected areas. Involvement of local communities in forest management, control of forest access, and nesting production forests in a landscape that includes protected areas seemed important for these positive biodiversity outcomes. The maintenance of vertebrate species bodes well for both biodiversity and the humans that depend on multiple-use forests.

The inclusion of managed tropical forests in climate change mitigation has made it important to find the sustainable sweet-spot for timber production, carbon retention, and the quick recovery of both. Here we focus on recovery of aboveground carbon and timber stocks over the first 32 years after selective logging with the CELOS Harvest System in Suriname. Our data are from twelve 1-ha permanent sample plots in which growth, survival, and recruitment of trees ≥15 cm diameter were monitored between 1978 and 2012. We evaluate plot-level changes in basal area, stem density, aboveground carbon, and timber stock in response to average timber harvests of 15, 23, and 46 m3 ha−1. We use a linear mixed-effects model in a Bayesian framework to quantify recovery time for aboveground carbon and timber stock, as well as annualized increments for both. Our statistical models accounted for the uncertainty associated with the height and biomass allometries used to estimate aboveground carbon and increased precision of annualized aboveground carbon increments by including data from forty-one plots located elsewhere on the Guiana Shield. The probabilities of aboveground carbon recovery to pre-logging levels 32 years after harvests of 15, 23 and 46 m3 ha−1 were 45%, 40%, and 24%, respectively. Net aboveground carbon increment for logged forests across all harvest intensities was 0.64 Mg C ha−1 yr−1, more than twice the rate observed in unlogged forests (0.26 Mg C ha−1 yr−1). The probabilities of timber stock recovery at the end of the 32-year period were highest after harvest intensities of 15 and 23 m3 ha−1 (with 80% probability) and lowest after the harvest of 46 m3 ha−1 (with 70% probability). Timber stock recovery across all harvest intensities was driven primarily by residual tree growth. Application of the legal cutting limit of 25 m3 ha−1 will require more than 70 and 40 years to recover aboveground carbon and timber stocks, respectively, with 90% probability. Based on the low recruitment rates of the twelve species harvested, the 25 year cutting cycle currently implemented in Suriname is too short for long-term timber stock sustainability. We highlight the value of propagating uncertainty from individual tree measurements to statistical predictions of carbon stock recovery. Ultimately, our study reveals the trade-offs that must be made between timber and carbon services as well as the opportunity to use carbon payments to enable longer cutting rotations to capture carbon from forest regrowth.

We evaluated the impacts of selective logging on tree regeneration one, four, and eight years after harvests in Antimary State Forest in the State of Acre, Brazil. We inventoried tree seedlings, saplings, and poles (>50 cm tall to

Nature conservation through sustainable forest management is challenged in the tropics by unnecessarily destructive but selective logging and diminishing timber yields. Silvicultural treatments beyond reduced-impact logging are often recommended to increase timber stocking, tree growth, and profits. Despite lack of large-scale and long-term scientific support, Indonesia has embarked on large-scale silvicultural intensification. To fill this information gap, we assessed the timber, carbon, and tree species composition consequences of different silvicultural practices in dipterocarp forests in Kalimantan, Indonesia. With data from 30 1-ha sample plots monitored for up to 20 years after silvicultural intervention coupled with a new forest growth and yield model simulation (SILFOR), we evaluated the long–term consequences of the following silvicultural practices: once logged with a minimum cutting diameter (MCD) of 60 cm (L60); once logged followed by under-planting with seedlings of commercial timber species (L60UP); twice logged with MCDs of 60 cm and then 40 cm (L60L40); and, twice logged followed by strip planting along cleared lines (L60L40SP). The results indicate that timber yields will not be sustained by L60 or L60L40 even if cutting cycles are extended from the current minimum of 30 years to 60 years. In contrast, yields from enrichment planted logged-over forests will recover to levels higher than the first cut if cutting cycles are extended to 50 years for L60UP and to 40 years for L60L40SP. Under these intensive silvicultural regimes, biomass carbon stocks also recover to primary forests levels, but with increased representation of commercial species. Although silviculturally successful, the financial consequences of these approaches to management intensification remain to be scrutinized.

The selective logging that characterizes most timber extraction operations in the tropics leaves large patches of logging blocks (i.e., areas allocated for harvesting) intact, without evidence of direct impacts. For example, in ~10,000 ha sampled in 48 forest management enterprises in Africa (Gabon, Republic of Congo, and the Democratic Republic of Congo), Indonesia, Suriname, and Mexico, an average of 69% (range 20–97%) of the area in logging blocks was not directly affected by timber harvests. The proportion of intact forest within logging blocks decreased very slightly with increases in harvest intensity in the accessed portion of the logging blocks (9–86 m3 ha−1) but decreased strongly with harvest intensity in entire logging blocks (0.3–48.2 m3 ha−1). More forest was left intact in areas farther from roads, on slopes >40%, and within 25 m of perennial streams, but the effect sizes of each of these variables was small (~8%). It is less clear how much of the intact forest left after one harvest will remain intact through the next. Conservation benefits without reductions in timber yields will derive from better management planning so that sensitive and ecologically critical areas, such as steep slopes and riparian buffers, constitute large and permanent proportions of the intact forest in selectively logged landscapes in the tropics.

Concerns about the sustainability of tropical forestry motivated this study on post-logging timber and carbon dynamics over a 20-year period in Paragominas, Para, Brazil. Previously unlogged forest was subjected to conventional logging (CL), reduced-impact logging (RIL), or was set aside as an unlogged control. All trees ⩾25 cm DBH and all trees of commercial species ⩾10 cm DBH were monitored in a 24.5 ha plot in each treatment, with a 5.25 ha subplot in each for monitoring all trees ⩾10 cm 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 211 Mg ha−1, and 78, 80, and 70 m3 ha−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 (⩾50 cm 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 (0.72 m3 ha−1 year−1) than in the CL plot (0.08 m3 ha−1 year−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.

To assess the impacts of a low-intensity selective timber harvest on a palm community in Belize, we mapped logging infrastructure (i.e., roads, log landings, skid trails, and stumps) and measured palm regeneration 1 year after a timber harvest carried out using reduced-impact logging (RIL) practices. We sampled palms across a gradient of increasing harvest impact severity from areas not directly affected by logging, in felling gaps, on secondary and primary skid trails, and on log landings. We used generalised linear mixed-effect models fitted in a Bayesian framework and applied a non-metric multi-dimensional scaling of the ecological distances between sites to evaluate differences in palm seedling regeneration density and species composition, respectively. The harvest of an average of 2.5 trees ha−1 caused 0.4% of the forest to be converted to log landings, 0.7% and 3.6% to roads and skid trails, and 2.3% to felling gaps, which left 93.0% of the 350 ha harvest block with no direct impacts of logging. The difference in abundance and species composition of palm regeneration in unlogged areas compared to felling gaps and skid trails was small, but log landings had markedly lower densities. These results highlight that the impacts of selective logging are minor at least where harvest intensities are low and RIL practices are employed. If further reductions in canopy opening and soil disturbance are desired, we recommend that logs be cable-yarded (i.e., winched) the final 20 m to skid trails instead of driving to the tree stumps. We estimate that implementation of this practice would reduce total skid trail coverage from 3.6% to 2.9% and overall forest disturbance from 7.0% to 6.3%. However, further reductions in disturbance might be inimical to the maintenance of palms and will certainly not favour regeneration of light-demanding commercial timber species (e.g., Swietenia macrophylla).

Tropical forests are crucial in terms of biodiversity and ecosystem services, but at the same time, they are major sources of revenue and provide livelihoods for forest-dependent people. Hopes for the simultaneous achievement of conservation goals and poverty alleviation are therefore increasingly placed on forests used for timber extraction. Most timber exploitation is carried out unsustainably, which causes forest degradation. Two important mechanisms have emerged to promote sustainable forest management: certification and community-based forest management (CFM). We synthesize the published information about how forest certification and CFM perform in terms of environmental, social, and economic variables. With the caveat that very few published studies meet the standards for formal impact evaluation, we found that certification has substantial environmental benefits, typically achieved at a cost of reduced short-term financial profit, and accompanied by some improvement to the welfare of neighboring communities. We found that the economic and environmental benefits of CFM are understudied, but that the social impacts are controversial, with both positive and negative changes reported. We identify the trade-offs that likely caused these conflicting results and that, if addressed, would help both CFM and certification deliver the hoped-for benefits. (Resume d'auteur)

Tropical dry forests (TDF) are highly threatened ecosystems that are often fragmented due to land-cover change. Using plot inventories, we analyzed tree species diversity, community composition and aboveground biomass patterns across mature (MF) and secondary forests of about 25 years since cattle ranching ceased (SF), 10–20-year-old plantations (PL), and pastures in a TDF landscape in Ecuador. Tree diversity was highest in MF followed by SF, pastures and PL, but many endemic and endangered species occurred in both MF and SF, which demonstrates the importance of SF for species conservation. Stem density was higher in PL, followed by SF, MF and pastures. Community composition differed between MF and SF due to the presence of different specialist species. Some SF specialists also occurred in pastures, and all species found in pastures were also recorded in SF indicating a resemblance between these two land-cover types even after 25 years of succession. Aboveground biomass was highest in MF, but SF and Tectona grandis PL exhibited similar numbers followed by Schizolobium parahyba PL, Ochroma pyramidale PL and pastures. These findings indicate that although species-poor, some PL equal or surpass SF in aboveground biomass, which highlights the critical importance of incorporating biodiversity, among other ecosystem services, to carbon sequestration initiatives. This research contributes to understanding biodiversity conservation across a mosaic of land-cover types in a TDF landscape.

Attempts to restore savannas are often thwarted by the resprouting of unwanted woody plants after they are top-killed by fire or mechanical treatments. In an effort to reduce stump sprouting of native to the region but invasive Quercus hemisphaerica (laurel oak) and Q. nigra (water oak) in an area being restored to longleaf pine (Pinus palustris) savanna, we treated 5–19 cm diameter stumps in ways opposite to the recommended practices for coppice management. Specifically, we created high stumps (1 m) and split half longitudinally (1 m-split); we also cut a sample at ground level (0 m), as recommended for coppice management. Over the 9-year observation period about 45% of the stumps died, with no treatment or species effects. Survival of individual sprouts was higher for Q. nigra than Q. hemisphaerica. In both species, sprouts from the 1 m stumps suffered the highest mortality rates, followed by the 0 m and 1 m-split treatments; number of sprouts per stump followed the same pattern (1 m > 0 m > 1 m-split). Root collar sprouts were more likely to survive than those that emerged higher on the stump or from rhizomes, and sprout mortality decreased with stump diameter in Q. nigra but not Q. hemisphaerica. Sprout survival decreased but sprout growth increased with canopy openness. About 40% of all sprouts were from rhizomes. Contrary to our expectation, wood decay was rare in all sprouts, regardless of their diameter or the height from which they emerged. These results confirm the benefits of treating stumps with herbicides to reduce unwanted trees in savannas undergoing restoration.

We compared stump sprouting by three common timber species in Suriname on the basis of sprout origins on stumps, sprout densities, and sprout height:diameter ratios. We then compared some leaf and stem functional traits of 15&ndash, 18-month-old resprouts and nearby conspecific saplings of the same height (0.5&ndash, 3.5 m) but unknown age. Stumps of Dicorynia guianensis Amsh. (29&ndash, 103 cm in diameter) produced the most sprouts (x = 9.2/stump), followed by the 50&ndash, 71 cm diameter stumps of Eperua falcata Amsh. (10.6/stump), and the 30&ndash, 78 cm diameter Qualea rosea Amsh. (5.9/stump), sprout density did not vary with stump diameter. Sprouts emerged from the lower, middle, and upper thirds of the stumps of all three species, but not from the vicinity of the exposed vascular cambium in Qualea. With increased resprout density, heights of the tallest sprout per stump tended to increase but height:diameter ratios increased only in Dicorynia. Compared to conspecific saplings, sprouts displayed higher height-diameter ratios, higher leaf-to-wood mass ratios (LWR), and lower wood densities, but did not differ in leaf mass per unit area (LMA) or leaf water contents. These acquisitive functional traits may reflect increased resprout access to water and nutrients via the extensive root system of the stump. That we did not encounter live stump sprouts from the previous round of selective logging, approximately 25 years before our study, suggests that stump sprouts in our study area grow rapidly but do not live long.

We evaluate the effects of “Water and Forest Producers” (PAF), a payment for ecosystem services project, on forest cover outcomes in a watershed serving the Rio de Janeiro region of Brazil. We apply propensity score matching and regression to 81 beneficiary properties on 8848 ha and 398 control properties on 33,748 ha. We estimate the average treatment effect on the treated for changes in rates of reforestation and deforestation, and the resulting change in forest cover. Over the first 7 years of PAF (2010–2016), our results indicate that the project increased forest cover on participating properties by only 136 ha (95% confidence intervals of 8–265 hectares), or 1.5% relative to our estimate of the counterfactual scenario without PAF. Impacts on forest cover were caused mostly by reduced deforestation rather than reforestation. “Placebo” impact tests estimated using pre-intervention data indicate that our results are robust. The observed forest cover benefit came at the per-hectare cost of $32,963 ($16,917-$560,367) paid mostly with off-site mitigation funds. Semi-structured interviews with PAF beneficiaries suggest that the limited impacts of PAF may be the result of mostly enrolling properties that likely would have remained forested even without the project.

Large trees in the tropics are reportedly more vulnerable to droughts than their smaller neighbours. This pattern is of interest due to what it portends for forest structure, timber production, carbon sequestration and multiple other values given that intensified El Niño Southern Oscillation (ENSO) events are expected to increase the frequency and intensity of droughts in the Amazon region. What remains unclear is what characteristics of large trees render them especially vulnerable to drought-induced mortality and how this vulnerability changes with forest degradation. Using a large-scale, long-term silvicultural experiment in a transitional Amazonian forest in Bolivia, we disentangle the effects of stem diameter, tree height, crown exposure and logging-induced degradation on risks of drought-induced mortality during the 2004/2005 ENSO event. Overall, tree mortality increased in response to drought in both logged and unlogged plots. Tree height was a much stronger predictor of mortality than stem diameter. In unlogged plots, tree height but not crown exposure was positively associated with drought-induced mortality, whereas in logged plots, neither tree height nor crown exposure was associated with drought-induced mortality. Our results suggest that, at the scale of a site, hydraulic factors related to tree height, not air humidity, are a cause of elevated drought-induced mortality of large trees in unlogged plots. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

When 2 Mha of Amazonian forests are disturbed by selective logging each year, more than 90 Tg of carbon (C) is emitted to the atmosphere. Emissions are then counterbalanced by forest regrowth. With an original modelling approach, calibrated on a network of 133 permanent forest plots (175 ha total) across Amazonia, we link regional differences in climate, soil and initial biomass with survivors’ and recruits’ C fluxes to provide Amazon-wide predictions of post-logging C recovery. We show that net aboveground C recovery over 10 years is higher in the Guiana Shield and in the west (21 ±3 Mg C ha-1) than in the south (12 ±3 Mg C ha-1) where environmental stress is high (low rainfall, high seasonality). We highlight the key role of survivors in the forest regrowth and elaborate a comprehensive map of post-disturbance C recovery potential in Amazonia. DOI: http://dx.doi.org/10.7554/eLife.21394.001, eLife digest The Amazon rainforest in South America is the largest tropical forest in the world. Along with being home to a huge variety of plants and wildlife, rainforests also play an important role in storing an element called carbon, which is a core component of all life on Earth. Certain forms of carbon, such as the gas carbon dioxide, contribute to climate change so researchers want to understand what factors affect how much carbon is stored in rainforests. Trees and other plants absorb carbon dioxide from the atmosphere and then incorporate the carbon into carbohydrates and other biological molecules. The Amazon rainforest alone holds around 30% of the total carbon stored in land-based ecosystems. Humans selectively harvest certain species of tree that produce wood with commercial value from the Amazon rainforest. This “selective logging” results in the loss of stored carbon from the rainforest, but the loss can be compensated for in the medium to long term if the forest is left to regrow. New trees and trees that survived the logging grow to fill the gaps left by the felled trees. However, it is not clear how differences in the forest (for example, forest maturity), environmental factors (such as climate or soil) and the degree of the disturbance caused by the logging affect the ability of the forest ecosystem to recover the lost carbon. Piponiot et al. used computer modeling to analyze data from over a hundred different forest plots across the Amazon rainforest. The models show that the forest’s ability to recover carbon after selective logging greatly differs between regions. For example, the overall amount of carbon recovered in the first ten years is predicted to be higher in a region in the north known as the Guiana Shield than in the south of the Amazonian basin where the climate is less favorable. The findings of Piponiot et al. highlight the key role the trees that survive selective logging play in carbon recovery. The next step would be to couple this model to historical maps of logging to estimate how the areas of the rainforest that are managed by selective logging shape the overall carbon balance of the Amazon rainforest. DOI: http://dx.doi.org/10.7554/eLife.21394.002

Better stewardship of land is needed to achieve the Paris Climate Agreement goal of holding warming to below 2 °C; however, confusion persists about the specific set of land stewardship options available and their mitigation potential. To address this, we identify and quantify "natural climate solutions" (NCS): 20 conservation, restoration, and improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We find that the maximum potential of NCS-when constrained by food security, fiber security, and biodiversity conservation-is 23.8 petagrams of CO2 equivalent (PgCO2e) y-1 (95% CI 20.3-37.4). This is ≥30% higher than prior estimates, which did not include the full range of options and safeguards considered here. About half of this maximum (11.3 PgCO2e y-1) represents cost-effective climate mitigation, assuming the social cost of CO2 pollution is ≥100 USD MgCO2e-1 by 2030. Natural climate solutions can provide 37% of cost-effective CO2 mitigation needed through 2030 for a >66% chance of holding warming to below 2 °C. One-third of this cost-effective NCS mitigation can be delivered at or below 10 USD MgCO2-1 Most NCS actions-if effectively implemented-also offer water filtration, flood buffering, soil health, biodiversity habitat, and enhanced climate resilience. Work remains to better constrain uncertainty of NCS mitigation estimates. Nevertheless, existing knowledge reported here provides a robust basis for immediate global action to improve ecosystem stewardship as a major solution to climate change.