Thinnings Research Articles

Substantiating optimum parameters and efficiency of rotary brush cutters

The problem of untimely forest thinning is quite common in today's society. It leads to the emergence of the underbrush, which negatively impacts the growth and development of young trees. Therefore, this work aims to estimate the feasibility of applying a new rotary brush cutter model to eliminate excessive vegetation. The dependence of the tractor's speed when removing underbrush with different diameters of tree trunks was established by performing mathematical modeling to optimize the brush cutter parameters. Three types of flexible inertia cutting devices were investigated: flat knives, sprocket chains, and knife chains. Knife chains are the most optimal choice as they cut plants most efficiently (94.61% and 92.5% for two-year and three-year underbrush, respectively). They also show the lowest energy consumption for underbrush with a trunk between 1 and 2.4 cm in diameter. Further experiments are required to determine if the developed mathematical model can be used for more neglected forestry stands.

Long-term effects of forest management on post-drought growth resilience: An analytical framework

There is great interest in determining the effects of forest thinning as a tool to improve growth recovery from drought in different tree species and climatic conditions. However, we lack a robust framework to determine how transient are post-drought growth resilience and enhancement, and if such growth improvement involves an uncoupling with climate conditions. We used regression analysis to determine differences in growth, sensitivity to drought and previous-year growth, and long-term growth in five plantations of three pine species (Pinus halepensis Mill., Pinus nigra Arn. and Pinus sylvestris L.) under different thinning intensities. Then, we simulated post-drought and post-thinning growth trajectories based on fitted models, and we computed drought resistance, resilience and recovery indices based on these trajectories. Moreover, the simulation allowed us to calculate the time to recovery after a drought. Using this analytical framework, we found that thinning enhanced radial growth (between 85 and 150%, significant in all sites with p < 0.05), and reduced previous-year growth dependence (between −13 and −26%, significant in two out of five sites) and climatic dependence of growth (−23 to −49%, significant in two sites). We interpret these effects as a result of competition reduction by thinning and a transitory alleviation of growth climatic constraints. Thinning consistently improved drought resistance (+4 to +20%) and resilience (+1 to +4%). Recovery, on the contrary, was reduced (−1 to −15%). Since the growth loss during the drought was reduced due to higher drought resistance, the recovery was proportionally lower. Thinning reduced the time to recovery by one to two years. The thinning legacy effect persisted up to 15 to 20 years after thinning. Taken together, these findings enhance the benefits of adaptive silviculture in making pine plantations less vulnerable to unfavourable extreme climate events such as droughts. We present a novel and robust analytical framework to assess drought-thinning interactive effects on tree growth.

Innovative wood use can enable carbon-beneficial forest management in California

Responsible stewardship of temperate forests can address key challenges posed by climate change through sequestering carbon, producing low-carbon products, and mitigating climate risks. Forest thinning and fuel reduction can mitigate climate-related risks like catastrophic wildfire. These treatments are often cost prohibitive, though, in part because of low demand for low-value wood "residues." Where treatment occurs, this low-value wood is often burned or left to decay, releasing carbon. In this study, we demonstrate that innovative use of low-value wood, with improved potential revenues and carbon benefits, can support economical, carbon-beneficial forest management outcomes in California. With increased demand for wood residues, forest health-oriented thinning could produce up to 7.3 million (M) oven-dry tonnes of forest residues per year, an eightfold increase over current levels. Increased management and wood use could yield net climate benefits between 6.4 and 16.9 million tonnes of carbon dioxide equivalent (M tCO2e) per year when considering impacts from management, wildfire, carbon storage in products, and displacement of fossil carbon-intensive alternatives over a 40-y period. We find that products with durable carbon storage confer the greatest benefits, as well as products that reduce emissions in hard-to-decarbonize sectors like industrial heat. Concurrently, treatment could reduce wildfire hazard on 4.9 M ha (12.1 M ac), a quarter of which could experience stand-replacing effects without treatment. Our results suggest that innovative wood use can support widespread fire hazard mitigation and reduce net CO2 emissions in California.

Conservation easement landowners' willingness to accept for forest thinning and the impact of information

After being subject to several decades of degradation, the bottomland hardwood (BLH) forests within the Lower Mississippi Alluvial Valley have undergone landscape-scale restoration regimes through conservation easement programs, such as the Wetland Reserve Program (WRP). Reforested easements offer an opportunity for landowners' adoption of forest management practices to fulfill the program's long-term conservation goals. Using the contingent valuation approach, we examine easement landowners' willingness to accept (WTA) to thin their forest subject to an easement to enhance forest health and wildlife habitat quality, and we test the effect of providing information about the benefits of thinning on WTA estimates. Results from an interval regression model suggest that ownership characteristics like years of ownership, involvement in non-timber activities like hiking and walking, and management characteristics like having past intention to thin, significantly decreased WTA while being an original easement grantor and ownership objectives like legacy increased WTA. The mean monetary compensation required to induce thinning adoption is $11.41 per ton of pulpwood. There is some evidence that the information intervention influences the WTA estimates downward, representing a potential policy instrument to achieve thinning objectives in the conservation easements efficiently.

Seasonal and temporal variation in the effects of forest thinning on headwater stream benthic organisms in coastal British Columbia

Removal of riparian trees can alter aquatic ecosystem structure and function by influencing factors such as light availability, sediment input, and stream temperature. Contemporary forest practices such as variable retention harvest are used to mitigate the effects of clear-cut forest harvest on stream communities, but few studies have examined the effects of these techniques on aquatic ecosystems. We examined the effects of variable retention harvest on light, temperature, biofilm biomass and macroinvertebrate consumers in three coastal headwater streams in British Columbia, Canada and compared them to three nearby reference streams with unlogged riparian stands. Variable retention harvest increased light and stream temperature variability. Harvested catchments had higher stream biofilm biomass in all seasons except winter and higher invertebrate abundance in summer. Variable retention harvest altered invertebrate community composition, largely driven by increasing Chironomidae abundance and decreasing Simuliidae abundance. In conclusion, we found that variable retention harvest modified stream benthic communities, but responses varied seasonally and among taxa. This is one of few studies to investigate the impacts of variable retention harvest on multiple trophic levels over multiple seasons and years. Understanding the cascading effects of forest harvest over multi-year time scales is important for management decisions.

Impact of forest thinning on aboveground macrofungal community composition and diversity in Mediterranean pine stands

Fungal communities are especially relevant in Mediterranean regions, a ‘hotspot’ of fungal diversity, and where the value of edible commercial sporocarps may be much higher than the income from timber products. Assessing the effects of forest management practices together with the modulating role of climate on sporocarp community composition and diversity is crucial for understanding their impacts on fungal-related ecosystem services. Yet, previous research on forest management impacts on aboveground fungal diversity and community composition is scant, sometimes contradictory and mainly focused on rather short-term impacts. We quantified the long-term response of the sporocarp community composition and diversity to different forest thinning intensities in Mediterranean Pinus pinaster forest stands, and the interactions with weather conditions in modulating the fungal response. We relied on 28 permanent plots representing a thinning intensity gradient, monitored for sporocarp diversity on a weekly basis during eleven consecutive years. Weather conditions of each plot were obtained through interpolation from different meteorological stations. Overall, the fungal sporocarp community composition showed short-term (<2 years) changes mainly under both heavy and light thinning intensities compared to unthinned plots. The unexpected compositional change caused by light thinning intensities affected only certain ectomycorrhizal fungi (Lactarius group deliciosus). Climatic factors, mostly the mean temperature of September and October, contributed to enhancing or diminishing the compositional response of macrofungi to forest thinning. Moreover, there was no effect of forest thinning on sporocarp species diversity (i.e., richness and evenness). Both ectomycorrhizal and saprotrophic species richness and ectomycorrhizal species evenness increased over time. Our results indicate that the post-treatment conditions following forest thinning may cause short-term successional changes in both ectomycorrhizal and saprotrophic fungal assemblages, benefiting, in turn, particular fungal species of socioeconomic interest by producing large amount of sporocarps. Furthermore, forest thinning with careful and low-impact removal of trees does not jeopardize sporocarp diversity.

Importance of environmental factors on plantings of wild-simulated American Ginseng

American ginseng (Panax quinquefolius L.) is an herbaceous perennial plant native to the forests of eastern North America with a long history of use and harvest, and with a significant international market. To supply international demand, the plant is grown in the USA and Canada under artificial shade cloth. However, wild and wild-appearing ginseng roots command prices up to 100 times greater than roots cultivated in a field: $550–2200 (US$ dry kg) vs. $20–70 (US$ dry kg). Growing ginseng in a forested environment using a “wild-simulated” forest farming approach, where growers introduce ginseng into a forested environment and then let it grow with little to no intervention, allows forest farmers to access these higher prices and meet international demand. As climate change shifts growing conditions globally, there will be increasing opportunities for the forest farming of American ginseng internationally. In this study, we examined the main drivers of ginseng growth and development in a wild-simulated ginseng forest farm. We measured the range of environmental conditions and built statistical models to examine which factors were most important for ginseng vigor. We found that the amount of sunlight, even under highly shaded conditions, was the most important driver of ginseng establishment on the landscape, as well as ginseng plant size and development. Prior research indicates that additional factors including soil nutrient levels, moisture, and texture are important for the survival, growth, and development of wild and planted American ginseng, but our study did not show significant patterns of importance at this site. Our findings suggest that integrating silvicultural techniques such as forest thinning may enhance the productivity of wild-simulated ginseng operations while providing additional forest-based income with minimal impact on natural forest ecosystems.

Mid-Term Effects of Forest Thinning on N Mineralization in a Semi-Arid Aleppo Pine Forest

In order to assess the sustainability of silvicultural treatments in semiarid forests, it is necessary to know how they affect the nutrient dynamics in the forest. The objective of this paper is to study the effects of silvicultural treatments on the net N mineralization and the available mineral N content in the soil after 13 years following forest clearings. The treatments were carried out following a randomized block design, with four treatments and two blocks. The distance between the two blocks was less than 3 km; they were located in Chelva (CH) and Tuéjar (TU) in Valencia, Spain. Within each block, four experimental clearing treatments were carried out in 1998: T0 control; and T60, T75 and T100 where 60%, 75% and 100 of basal area was eliminated, respectively. Nitrogen dynamics were measured using the resin tube technique, with disturbed samples due to the high stoniness of the plots. Thirteen years after the experimental clearings, T100, T75 and T60 treatments showed a twofold increase in the net mineralization and nitrification rates with respect to T0 in both blocks (TU and CH). Within the plots, the highest mineralization was found in sites with no plant cover followed by those covered by undergrowth. These results can be explained in terms of the different litterfall qualities, which in turn are the result of the proportion of material originating from Pinus halepensis Mill. vs. more decomposable undergrowth residues.

Adapting western North American forests to climate change and wildfires: 10 common questions.

We review science‐based adaptation strategies for western North American (wNA) forests that include restoring active fire regimes and fostering resilient structure and composition of forested landscapes. As part of the review, we address common questions associated with climate adaptation and realignment treatments that run counter to a broad consensus in the literature. These include the following: (1) Are the effects of fire exclusion overstated? If so, are treatments unwarranted and even counterproductive? (2) Is forest thinning alone sufficient to mitigate wildfire hazard? (3) Can forest thinning and prescribed burning solve the problem? (4) Should active forest management, including forest thinning, be concentrated in the wildland urban interface (WUI)? (5) Can wildfires on their own do the work of fuel treatments? (6) Is the primary objective of fuel reduction treatments to assist in future firefighting response and containment? (7) Do fuel treatments work under extreme fire weather? (8) Is the scale of the problem too great? Can we ever catch up? (9) Will planting more trees mitigate climate change in wNA forests? And (10) is post‐fire management needed or even ecologically justified? Based on our review of the scientific evidence, a range of proactive management actions are justified and necessary to keep pace with changing climatic and wildfire regimes and declining forest heterogeneity after severe wildfires. Science‐based adaptation options include the use of managed wildfire, prescribed burning, and coupled mechanical thinning and prescribed burning as is consistent with land management allocations and forest conditions. Although some current models of fire management in wNA are averse to short‐term risks and uncertainties, the long‐term environmental, social, and cultural consequences of wildfire management primarily grounded in fire suppression are well documented, highlighting an urgency to invest in intentional forest management and restoration of active fire regimes.

A riverscape approach reveals downstream propagation of stream thermal responses to riparian thinning at multiple scales

AbstractHydrological connectivity in river networks influences their response to environmental changes as local effects may extend downstream via flowing water. For example, localized changes in riparian forest conditions can affect stream temperatures, and these effects may propagate downstream. However, studies evaluating stream temperature responses to riparian forest management have not considered cumulative effects across entire watersheds. Improved understanding at these scales is needed because land managers are increasingly required to consider broad‐scale consequences of their actions. To address this question, we deployed a high‐density network of sensors across watersheds to examine stream temperature responses to experimental thinning of riparian forests. A riverscape approach that combined high‐resolution data throughout the study watersheds made it possible to examine local and downstream patterns of stream temperature at multiple spatial and temporal scales. We found that local responses of temperature to thinning varied widely depending on the intensity of thinning treatments. Downstream propagation of local responses extended from 100 m to over 1000 m and depended on the magnitude of the local response. We characterized these responses as a series of waveforms. In the watersheds with more intensive thinning, thermal responses occurred most often as an extended pulse where downstream increases in temperature attenuated gradually at variable distances. Although we observed no evidence of cumulative effects associated with thinning at the downstream extent of stream networks, effects emerged where thinning treatments were closely spaced (&lt;400 m apart) and local warming did not dissipate with downstream distance. In a watershed with less intensive thinning, there was either no response or a localized pulse with no downstream propagation. Collectively, these patterns suggest that riparian forest thinning influenced downstream thermal conditions to varying extents depending on the intensity, scale, and spatial proximity of treatments. We found that a multiscale riverscape approach and conceptual framework based on contrasting waveforms provided a foundation for understanding the cumulative watershed effects of riparian thinning. The approach developed here can be adapted more broadly when evaluating downstream propagation of local changes in river networks and has direct implications for guiding restoration in riparian ecosystems.

Effects of variable-density thinning on non-native understory plants in coniferous forests of the Pacific Northwest

Old-growth forests serve as critical habitat for many sensitive species, but management practices have diminished their prevalence, and former regions of old-growth are now dominated by second-growth stands lacking the structural heterogeneity, diversity, and species richness that these older forests possess.In western Washington state in the Pacific Northwest of the United States, the Olympic Habitat Development Study was designed to address this issue and hasten the development of specific old-growth features in second-growth stands using variable-density thinning. One concern with such methods, however, is the potential to introduce non-native plants, which can have negative ecological and economic impacts. Here, we examine how variable-density thinning influences desirable forest characteristics, such as increased plant species diversity, versus the less desirable effects of non-native plant species introduction. We test two hypotheses regarding plant invasions. First, thinning would promote establishment of non-native, shade-intolerant species, but their abundance would gradually decline over time. Second, thinning disturbance and increased heterogeneity of canopy cover would initially promote understory richness of all species, although richness would decline over time with canopy closure and increased cover of shrubs and regenerating trees. We found that the number and cover of non-native species initially increased after thinning, peaking at 16 species present in variable-density thinned treatments in year three. By year 17, 11 species remained throughout the seven 6.5 ha treatment plots sampled, and cover was negligible. As predicted, species richness increased following thinning, however, native species richness remained elevated through year 17, contrary to our hypothesis. Furthermore, native species diversity also increased following thinning and remained higher in thinned treatments than controls through year 17. Our results show that variable-density thinning in temperate coniferous forests can enhance native, but not exotic, plant richness and diversity in the long term.

Tree species identity and composition shape the epiphytic lichen community of structurally simple boreal forests over vast areas.

Greatly simplified ecosystems are often neglected for biodiversity studies. However, these simplified systems dominate in many regions of the world, and a lack of understanding of what shapes species occurrence in these systems can have consequences for biodiversity and ecosystem services at a massive scale. In Fennoscandia, ~90% of the boreal forest (~21Mha) is structurally simplified with little knowledge of how forest structural elements shape the occurrence and diversity of for example epiphytic lichens in these managed forests. One form of structural simplification is the reduction of the number and frequency of different tree species. As many lichen species have host tree preferences, it is particularly likely that this simplification has a huge effect on the lichen community in managed forests. In a 40-70 years old boreal forest in Sweden, we therefore related the occurrence and richness of all observed epiphytic lichens to the host tree species and beta and gamma lichen diversity at the forest stand level to the stand's tree species composition and stem diameter. Picea abies hosted the highest lichen richness followed by Pinus sylvestris, Quercus robur, Alnus glutinosa, Betula spp., and Populus tremula. However, P. tremula hosted twice as many uncommon species as any of the other tree species. Stand level beta and gamma diversity was twice as high on stands with four compared to one tree species, and was highest when either coniferous or deciduous trees made up 40-50% of the trees. The stem diameter was positively related to lichen richness at the tree and stand level, but negatively to beta diversity. For biodiversity, these findings imply that leaving a few trees of a different species during forest thinning is unlikely as effective as combining life-boat trees for endangered species with an even tree species mixture.

A global synthesis reveals increases in soil greenhouse gas emissions under forest thinning

Forest thinning is a major forest management practice worldwide and may lead to profound alterations in the fluxes of soil greenhouse gases (GHGs). However, the global patterns and underlying mechanisms of soil GHG fluxes in response to forest thinning remain poorly understood. Here, we conducted a global meta-analysis of 106 studies to assess the effects of forest thinning on soil GHG fluxes and the underpinning mechanisms. The results showed that forest thinning significantly increased soil CO2 emission (mean lnRR: 0.07, 95% CI: 0.03–0.11), N2O emission (mean lnRR: 0.39, 95% CI: 0.16–0.61) and decreased CH4 uptake (mean Hedges’ d: 0.98, 95% CI: 0.32–1.64). Furthermore, the negative response of soil CH4 uptake was amplified by thinning intensity, and the positive response of soil N2O emission decreased with recovery time after thinning. The response of soil CO2 emission was mainly correlated with changes in fine root biomass and soil nitrogen content, and the response of soil CH4 uptake was related to the changes in soil moisture and litterfall. Moreover, the response of soil N2O emission was associated with changes in soil temperature and soil nitrate nitrogen content. Thinning also increased the total balance of the three greenhouse gas fluxes in combination, which decreased with recovery time. Our findings highlight that thinning significantly increases soil GHG emissions, which is crucial to understanding and predicting ecosystem-climate feedbacks in managed forests.

Model analysis of forest thinning impacts on the water resources during hydrological drought periods

In Japan, there has recently been an increasing call for forest thinning to conserve water resources from forested mountain catchments in terms of runoff during prolonged drought periods of the year. How their water balance and the resultant runoff are altered by forest thinning is examined using a combination of 8-year hydrological observations, 100-year meteorological data output that is generated using a stochastic model, and a semi-process-based rainfall-runoff model. The rainfall-runoff model is developed based on TOPMODEL assuming that forest thinning has an impact on runoff primarily through an alteration in canopy interception. The main novelty in this analysis is that the availability of the generated 100-year meteorological data allows the investigations of the forest thinning impacts on mountain catchment water resources under the most severe drought conditions. The model is validated against runoff observations conducted at a forested mountain catchment in the Kanto region of Japan for the period 2010–2017. It is demonstrated that the model reproduces temporal variations in runoff and evapotranspiration at inter- and intra-annual time scales, and the flow duration curves were well reproduced. On the basis of projected flow duration curves for the 100-year, despite the increase in an annual total runoff with thinning, low flow rates (the flows within the range of >70% time exceedance) in both dry and normal years (the years in which low flow are the lowest and 50th the lowest) were impacted by the forest thinning to a lesser extent. Simulations also showed that low flows would increase more with higher catchment water retention capacity, and higher catchment water retention capacity would enhance the forest thinning effect on increasing available water resources. This study would be helpful in planning for better forest management considering runoff from forested catchments.

Effect of thinning intensity on understory herbaceous diversity and biomass in mixed coniferous and broad-leaved forests of Changbai Mountain

BackgroundHerbs are an important part of the forest ecosystem, and their diversity and biomass can reflect the restoration of vegetation after forest thinning disturbances. Based on the near-mature secondary coniferous and broad-leaved mixed forest in Jilin Province Forestry Experimental Zone, this study analyzed seasonal changes of species diversity and biomass of the understory herb layer after different intensities of thinning.ResultsThe results showed that although the composition of herbaceous species and the ranking of importance values were affected by thinning intensity, they were mainly determined by seasonal changes. Across the entire growing season, the species with the highest importance values in thinning treatments included Carex pilosa, Aegopodium alpestre, Meehania urticifolia, and Filipendula palmata, which dominated the herb layer of the coniferous and broad-leaved mixed forest. The number of species, Margalef index, Shannon-Wiener index and Simpson index all had their highest values in May, and gradually decreased with months. Pielou index was roughly inverted “N” throughout the growing season. Thinning did not increase the species diversity. Thinning can promote the total biomass, above- and below-ground biomass. The number of plants per unit area and coverage were related to the total biomass, above- and below-ground biomass. The average height had a significantly positive correlation with herb biomass in May but not in July. However, it exerted a significantly negative correlation with herb biomass in September. The biomass in the same month increased with increasing thinning intensity. Total herb biomass, above- and below-ground biomass showed positive correlations with Shannon-Winner index, Simpson index and Pielou evenness index in May.ConclusionsThinning mainly changed the light environment in the forest, which would improve the plant diversity and biomass of herb layer in a short time. And different thinning intensity had different effects on the diversity of understory herb layer. The findings provide theoretical basis and reference for reasonable thinning and tending in coniferous and broad-leaved mixed forests.

Past and future prediction of land cover land use change based on earth observation data by the CA–Markov model: a case study from Duhok governorate, Iraq

Understanding land use land cover change (LULCC) dynamics is crucial for sustaining the integrity of structure and function of ecosystems. As such, frequent measuring and monitoring of LULCC are necessary. Over the last four decades, Duhok governorate in the north of Iraq has undergone sweeping changes caused mainly by anthropogenic factors (e.g. population growth). This study used geospatial techniques and the synergy Cellular Automata (CA)–Markov approach to quantify past, current and model the future changes of LULC. The maximum likelihood classifier (MLC) was employed to conduct classification for three consecutive-year Landsat imagery (i.e. 1988, 2008 and 2017). From the classified imageries, three LULC maps with several classes were created and then, change detection analysis was implied. The classified (1988–2008) and (2008–2017) LULC maps were incorporated into the hybrid model to predict LULC maps for 2017 and 2060, respectively. The classified 2017 LULC maps were used as a reference to validate the model output for 2017. Relatively high accuracy agreements were achieved between the classified and the modelled maps (Kno= 0.8315, Klocation= 0.8267, Kstandard = 0.7978). The model classes estimated for 2060 compared to the classified 2017 LULC classes revealed that dense forest, sparse forest, agricultural land and barren area would decrease by −26.26% (from 327.08 to 241.08 km2), −0.76% (from 2372.29 to 2355.82 km2), −5.86% (from 973.21 to 916.27 km2) and −10.03% (from 2918.9–2626.19 km2), respectively. In contrast, the urban area would significantly increase by 271.19%, (from 161.99 to 602.19.8 km2). Dense forest in Duhok governorate has seen remarkable decline from 1988 to 2017, and future predictions demonstrated that the declining trend would continue. Dense forest would predominantly convert to sparse forest and barren areas, suggesting forest thinning and clearing. Urban areas were the most dynamic cover types that increased significantly between 1998 and 2017. This trend would continue to increase from 2.36% (2017) to 8.76% (2060). Urbanization would be predominantly at the cost of agricultural land and barren area. Information on spatiotemporal dynamics of LULCC has been proved as an effective measure for maintaining the integrity of the ecosystem components through sustainable planning and management actions.

Applying the stress‐gradient hypothesis to curb the spread of invasive bamboo

AbstractThe stress‐gradient hypothesis (SGH) provides a conceptual framework for explaining how environmental context determines the nature of biotic interactions. It may be also useful for predicting geographic variability in the effect of management interventions on biological invasions. We aimed to test hypotheses consistent with the SGH to explain context dependency in bamboo invasion of secondary forests in Japan, and establish a predictive understanding of forest management impacts on invasion.We use a priori physiological knowledge of invasive giant bamboo,Phyllostachys bambusoides, to generate hypotheses consistent with the SGH. We modelled variation in giant bamboo occupancy within 810 secondary forest plots across the broad environmental gradients of Japan using a national vegetation database.Consistent with the SGH, we find that the effect of tree canopy cover on bamboo occupancy depends on interactions between solar radiation and mean annual temperature. In cool regions with high solar radiation—stressful conditions for bamboo—shade cast by dense canopies facilitates invasion. However, in warmer regions that are more benign, dense canopies tend to inhibit spread via competition for light, space and other resources.Synthesis and applications. We provide evidence that the stress‐gradient hypothesis can inform practical recommendations for invasive species control. We characterised geographic variability in the effect of forest thinning, a widespread management intervention used to enhance forest biodiversity, on the risk of bamboo spread into secondary forests in Japan. Thinning forest canopies to increase understorey light radiation should limit bamboo spread in cooler regions, while tree planting to increase canopy shade should limit bamboo spread in warmer regions.

Forest thinning in the seaward fringe speeds up surface elevation increment and carbon accumulation in managed mangrove forests

Abstract Mangroves are significant carbon (C) sinks and ecological engineers as they accumulate sediments and increase soil surface elevation. Thus, the forest management practice of thinning may not only alter forest structure, but also facilitate new biogeomorphological processes that affect soil development. Thinning may create additional opportunity for understorey species, such as the light‐demanding Acanthus ilicifolius, to become a more prominent vegetation component of mangroves, which may further alter soil surface elevation trajectories. Forest structure and soil surface elevation change (SEC) were monitored along transects from the landward edge (upper intertidal) to seaward fringe before and after thinning of non‐native Sonneratia apetala plantations along the seaward edge of a mangrove site in China. Soil C accumulation was also evaluated. Acanthus individuals colonized the forest gaps created by Sonneratia thinning in the seaward forest edge of the intertidal zones. In the absence of other pioneer species or other mangrove propagules/seeds, Acanthus pioneers occupied the areas rapidly (from 33.6 to 72.6 stems/m2), and were successful opportunists. Newly colonizing Acanthus vegetation significantly increased SEC from 25.1 mm/year before Sonneratia was thinned to 46.5 mm/year after thinning‐induced Acanthus occupation. Furthermore, Acanthus occupation enhanced soil C accumulation at the seaward edge to 49.9 MgC ha−1 year−1; a rate twofold higher than in the Sonneratia plantation before thinning. Synthesis and applications. Prolific Acanthus growth formed small elevation mounds on the seaward forest edge, which was suspected as a positive effect induced by thinning Sonneratia plantations that further facilitated colonization of Acanthus clones. Thinning non‐native Sonneratia disturbed the established zonation, altered SEC, and is facilitating further succession of these mangrove forests into un‐occupied aquatic areas. Higher elevations created by Acanthus expansion (vertically and horizontally) may further promote a greater percentage of landward edge mangrove species to colonize at these more favourable intertidal elevations yielding at least short‐term gains in soil carbon accumulation by altering ecosystem function. Silvicultural activity should consider unintended influences on sedimentation patterns both in situ and in adjacent habitats in tidal forests, where small elevation changes affect mangrove species habitat preferences.

Capital Return Rate and Carbon Storage on Forest Estates of Three Boreal Tree Species

In this study, the capital return rate and carbon storage on forest estates with three boreal tree species are discussed. A growth model is applied, along with verified yield models of sawlogs and veneer logs. Using the normal forest principle, thinning schedules and rotation ages maximizing the estate-level capital return rate are clarified. Regeneration expenses are amortized at the end of any rotation. Capitalizations are greater and rotations longer than in recent studies. The capital return rate is a weak function of initial stem count and rotation age but differs by tree species. The initial stem count strongly contributes to biomass stored in trees. Omission of thinnings increases carbon storage very effectively but requires financial compensation. The most promising way of increasing the capital return rate is the reduction of regeneration expenses. Thinnings are triggered by stand volumes of at least 200 m3/ha. The average commercial trunk volume of trees removed in thinnings always exceeds 200 L. Risk aversion theory proposes short rotations and low stem count in seedling planting unless carbon storage compensation exists. Even a small carbon storage compensation justifies increased seedling counts and extended rotations.

Land use and social-ecological legacies of Rio de Janeiro's Atlantic urban forests: from charcoal production to novel ecosystems.

Historical ecology is an important tool in deciphering human–environment interactions imprinted on landscapes throughout time. However, gaps of knowledge still remain regarding the land use legacies hidden in the current Atlantic Forest landscape; and also regarding how this information can help management of the remaining forest cover. The social-ecological systems framework was applied to understand charcoal production in the urban forests of Rio de Janeiro, from the nineteenth to mid-twentieth century, and their current social-ecological legacies. Charcoal production carried out by former enslaved populations, allowed for rapid forest regeneration. Forest thinning instead of forest felling was carried out by small groups in these urban remnant forests, sparing large native trees and facilitating natural regeneration. Currently, more than one thousand former charcoal production sites are accounted for hidden underneath the forest cover. The forest landscape of today is a result of novel forest successional trajectories that recovered structural and functional attributes of the forest ecosystem. However, this came at the cost of social invisibility and marginalization of these populations. The management practices of charcoal production dispersed in the landscape is one of Rio de Janeiro's most important, albeit hidden, land use legacies. Currently, the forested landscape is comprised of regenerated forests, both structurally and functionally sound, though with significant changes in species composition including the introduction of exotic species throughout recent centuries. These urban forests are today a complex mosaic of novel ecosystems, with rich biocultural diversity, and together with managed lands and well conserved forest tracts, provide not only livelihood and sustenance for forest dwelling families, but also important ecosystem services for the entire population of Rio de Janeiro. We believe that these concepts and frameworks can offer practical solutions for urban forest management, taking into account the biocultural diversity of Rio de Janeiro, increasing awareness of sustainability and promoting food security.