The choice of definition has a large effect on reported quantities of dead wood in boreal forest

A survey was conducted to assess the impact of the choice of definition on reported quantities of dead wood in Swedish forests, which to more than 90% are located in the boreal zone. The data collection was made on a subsample of the permanent plots of the Swedish national forest inventory. The objects included were standing dead trees and snags down to 5-cm diameter at breast height, dead lying stems and branches down to a threshold diameter of 1 cm and stumps down to a threshold diameter of 5-cm at normal stump height. Standing trees, snags and stumps were inventoried on 10-m radius circular plots while the downed objects were inventoried using both circular plots and line intersect sampling; thin objects (diameter 1–5 cm) were assessed only through line intersect sampling. The results showed that the estimated volume of dead wood was as high as 25 m³ ha^?1 when all components were included. With the standard Swedish definition, the corresponding estimate was only 10.9 m³ ha^?1, or 43% of the total value. Since definitions of dead wood vary greatly between countries we conclude that great caution must be exercised when figures are compared in connection with international reporting. For example, adding stumps to the Swedish definition would increase the amounts of dead wood from 10.9 to 15.7 m³ ha^?1, i.e. with 44%.     

Afforestation of savannah with cocoa agroforestry systems: a small-farmer innovation in central Cameroon

Cocoa cultivation is generally considered to foster deforestation. Contrary to this view, in the forest–savannah interface area in Cameroon, farmers have planted cocoa agroforestry systems on Imperata cylindrica grasslands, a soil-climate zone generally considered unsuitable for cocoa cultivation. We undertook a survey to understand the agricultural and ecological bases of this innovation. Age, cropping history and marketable cocoa yield were assessed in a sample of 157 cocoa plantations established on grasslands and 182 cocoa plantations established in gallery forests. In a sub-sample of 47 grassland cocoa plantations, we inventoried tree species associated with cocoa trees and measured soil organic matter levels. Marketable cocoa yields were similar for the two types of cocoa plantations, regardless of their age: 321?kg?ha^?1 in cocoa plantations on grasslands and 354?kg?ha^?1 in cocoa plantations in gallery forests. Two strategies were used by farmers to eliminate I. cylindrica prior to the establishment of cocoa plantations, i.e., cropping oil palms in dense stands and planting annual crops. Farmers then planted cocoa trees and fruit tree species, while preserving specific forest trees. The fruit tree and forest tree densities respectively averaged 223 and 68 trees?ha^?1 in plantations under 10?years old, and 44 and 27 trees?ha^?1 in plantations over 40?years old, whereas the cocoa tree density remained stable at 1,315 trees?ha^?1. The Shannon–Weaver index increased from 1.97 to 2.26 over the same period although the difference was not statistically significant. The soil organic matter level was 3.13?% in old cocoa plantations, as compared to 1.7?% in grasslands. In conclusion, our results show that the occupation of grasslands by cocoa agroforestry systems is both an important example of ecological intensification and a significant farmer innovation in the history of cocoa growing.     

Logging activity and tree regeneration in an Amazonian forest

We studied the effect of experimental logging of 4 ha plots on the regeneration of tree species in a forest 90 km north of Manaus, Amazonas, Brazil. Logging resulted in a total reduction in live wood volume of 44–107 m³ ha⁻¹, although only 63% of this volume was felled, and only 43% removed from the plots. The density of established regeneration (trees and shrubs with diameter at breast height ≤10 cm, and height ≥200 cm) was greater in logged plots than in control plots when measured 3 and 7–8 years after logging. Species richness was also significantly higher in logged plots than in controls. We registered 139 species per 1000 stems, 7–8 years after logging, 143 species per 1000 stems, 3 years after logging, and 136 species per 1000 stems in control plots. Overall species composition was significantly affected by the intensity of logging damage in the plots after 7–8 years, and control plots were significantly different from plots logged 3 years previously. However, changes were not great in relation to natural variation within the forest. Most species increased in density after logging (mean=17%), and the number of individuals belonging to species with commercial value on the local market was 15% greater in logged plots than in control plots. The total potential value of the regeneration, based on the value of wood per m³ (when adult) of the individuals, was 23% higher in logged plots than in control plots, though this difference was not statistically significant. Therefore, enrichment planting is not necessary to maintain either the biodiversity, or potential economic value for wood production, of this forest.     

Structure of a Central-European mountain spruce old-growth forest with respect to historical development

This study examines the structural characteristics of the tree layer, dead wood, canopy openings, and regeneration patterns of a spruce old-growth forest in the Bohemian Forest, Czech Republic. An old-growth stand with minor human influence and a stand that was presumably logged about 200 years ago were analyzed and compared, as some forest managers considered the presumable human impact as a reason for salvage logging. Even though the stands differed in tree density, height and DBH structure, it was not possible to conclude whether it was due to management history or the environmental differences. The volume of dead wood also differed between the stands. There was about 142 and 83 m³ ha⁻¹ of dead wood in the old-growth stand and presumably logged stand, respectively. The amount of dead wood found in the old-growth stand was comparable with values reported from spruce old-growth stands across Central Europe. In both stands, many canopy trees were arranged in linear patterns, which was a result of spruce regeneration on nurse logs. This suggests that the origin and development of the stands were characterized by natural processes and during the past 200 years typical old-growth structural characteristics have already evolved.     

Canopy dynamics in unlogged and logged forest stands in the eastern Amazon

Selective logging of tropical forests damages residual trees and creates canopy openings throughout the stand. In the Amazon, reduced-impact logging results in significantly less damage than conventional unplanned logging; yet either logging method leads to substantial fragmentation of the forest canopy. Increased mortality rates of trees damaged in logging have been documented. In this paper, we investigate the effect of logging disturbance on treefall rates.Using repeat inventories of canopy trees (≥35 cm dbh) in six large (≥50-ha) forest stands at two sites in the eastern Amazon, we measured mortality rates in three treatment classes: unlogged, conventionally logged (CL) and logged using reduced-impact methods (RIL). At least 3000 trees were mapped and inventoried per stand prior to timber harvests. In the second inventory, 3 years after harvests in the logged stands, all trees were located and scored as living, standing dead, uprooted or broken.We found significantly higher overall mortality rates for trees in logged forest (both CL and RIL stands) than in adjacent unlogged forest. This effect was largely due to higher rates of treefall (i.e., stems uprooted or broken from natural causes). Moreover, significantly higher treefall rates were recorded for trees in logged forest that were not damaged in the logging than for trees in unlogged stands. Treefall rates were nearly twice as high in conventionally logged forest as in forest logged using reduced-impact methods. We found indirect support for the hypothesis that increased treefall rates in logged forest are related to increased canopy opening and fragmentation through analysis of the locations of fallen trees in relation to canopy disturbance.     

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

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

Natural development and regeneration of a Central European montane spruce forest

Montane Norway spruce forests of Central Europe have a very long tradition of use for timber production; however, recently there has been increasing concern for their role in maintaining biological diversity. This concern, coupled with recent severe windstorms that led to wide-spread bark beetle outbreaks, has brought the management of montane spruce forests to the forefront of public policy discussions in Central Europe. In order to shed light on the natural development and current structure of mature montane spruce forests, we established four 0.25 ha research plots in a semi-natural montane spruce forest in the Šumava Mountains (The Bohemian Forest), Czech Republic. We mapped all trees, extracted increment cores for age and growth-pattern analyses, and inventoried all current tree regeneration, including the substrates on which it was found. Stands were characterized by uni-modal tree diameter distributions and high basal areas (56.6 m² ha⁻¹ on average), indicating a natural transition from the stem exclusion phase towards the understory reinitiation phase. The stands showed largely single-cohort recruitment age structures, however, with recruitment spanning seven decades. Our analyses suggest that this cohort existed as advance regeneration prior to major disturbances in the late 1800s, which included post-bark beetle salvage logging. Spatial pattern analyses of living and dead stems combined, showed an increase in uniformity of living trees, pointing to the role of natural density-dependent mortality. However, past growth patterns and historical documentation suggest that low intensity canopy disturbances (wind and snow) also caused mortality and diversified canopy structure. Because the stands developed naturally over the past 120+ years and thus escaped thinning operations, high volumes of coarse woody debris (94 m³ ha⁻¹) and snag densities (546 stems ha⁻¹) have accrued. Advance spruce regeneration was quite abundant and existed primarily on deadwood substrates, even though these occupied only a small percent of stand area. Because of salvage logging in the late 1880s, these stands do not qualify, according to the traditional paradigm, as natural spruce forests. As a result, they are recently subject to active management practices including salvage logging that remove dead and dying trees. Given the importance of deadwood for forest regeneration and recovery from disturbance, as demonstrated in this study, we argue that dead wood removal may limit future natural regeneration in these stands. Thus, the purported benefits of removing dead and dying trees from semi-natural forests must be carefully weighed against the potential detrimental impacts on natural spruce forest regeneration and biodiversity.     

Effect of tree spacing on growth and wood density of 38-year-old Cariniana legalis trees in Brazil

Average wood density of 38-year-old Cariniana legalis (Mart.) Kuntze, a Brazilian native forest species, was found to increase with faster growth and lower stocking, while decreasing from pith to bark. A complete randomised block design was planted with five blocks. Ten trees were harvested in each of three spacing treatments. We hypothesised that the stand stemwood production would not significantly differ depending on tree spacing. However, tree growth would be higher in the wider spacing and wood density would be higher in the narrower spacing. The diameter growth of trees was higher at 3 m × 2.5 m than at 3 m × 2 m and 3 m × 1.5 m. Nevertheless, this higher individual tree growth at 3 m × 2.5 m did not compensate for the greater tree stock density at 3 m × 1.5 m with stand stemwood production at 38 years of 530 m3 ha^?1 and 649 m³ ha^?1, respectively. These results suggest that C. legalis, which can produce up to 17 m³ ha^?1 y^?1 of medium-to high-density timber – about 800 kg m^?3 – is a promising native species for forest plantations in Brazil.     

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

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

Liberation: Acceptable production of tropical forest timber

Reduced impact logging in an eastern Amazonian terra firme forest left more than half of the next crop trees growing at a rate corresponding to a rotation of more than a century to attain 60-cm dbh. Two years after the logging, in 20 ha of the logged forest, tree competitors around crop trees were eliminated. Competitors were defined as trees whose crowns overtopped crop trees, those within 2 m of them, and trees as tall as or taller than the crop trees closer than indicated by a basal area of 15–25 m²/ha, depending on their summed diameters. During the subsequent 5.7 years, increment of the liberated crop trees was 20% greater than that of comparable crop trees left in another 20 ha of the same logged forest without liberation. Had the competing trees been identified at the time of the logging the 5.8/ha that were merchantable could have increased the yield from 25 m³/ha to as much as 43 m³/ha. This added harvest should have more than paid the entire cost of the liberation, including the elimination of the remaining unmerchantable trees. Additionally, a prospective reduction of 25% in the wait for the next harvest, as compared with logging only, would have been created. Where the economical sustainability of tropical wood productivity and quality is a goal, the wisdom of neglect of liberation is questioned.     

Carbon pools and sequestration in forest ecosystems in Britain

British vegetation is estimated to contain 113.8 million tC,80 per cent of which is in forests and woodlands (91.9 milliontC). Sitka spruce plantations, although covering 21.4 per centof the forest/woodland area, contain only 8.2 per cent of theforest/woodland carbon, because the plantations are young andhave an average of only 14.1 tC ha^–1. Broadleaved woodlandsin Britain have an average of 61.9 tC ha^–1 and contain46.8 per cent of the total carbon in all vegetation. A breakdownis given of the carbon density (tC ha^–1) and content ofdifferent tree species. A carbon density map of Britain highlightsthe concentration of carbon in the broadleaved woodlands insouthern England and in the large conifer plantations in southernScotland and northern England. Carbon storage in the trees, products, litter and soil can beevaluated in terms of long-term equilibrium storage or short-termrate of storage. These two components vary among forest typesin Britain and globally. Plantations harvested at the time ofmaximum mean annual increment (MAI) will not store as much carbonas mature, old-growth forests on the same site unless they havelong-lasting products and/or are very fast growing. Maximumequilibrium carbon storage is generally achieved by harvestingat the time of maximum MAI when the lifetime of products exceedsthe time to maximum MAI. Undisturbed peatlands sequester CO₂and emit CH₄, and may be greenhouse neutral. When peatlandsare drained and planted with trees, they stop emitting CH₄ andstore carbon in the trees, forest litter, forest soil and woodproducts. However, these greenhouse gas ‘gains’are offset by the oxidation to CO₂ of the peat, and the gainsare exceeded by CO₂ losses when 20–40 cm depth of peathas been oxidized. Forests in Britain are currently sequestering1.5–1.7 million tC a^–1 in trees, 0.3–0.5 tCa^–1 in litter and 0.5 million tC a^–1 in wood products,totalling about 2.5 million tC, equivalent to about 1.5 percent of the carbon currently emitted by burning fossil fuelsin the UK. In order to maintain the current forest carbon sink,the forest area needs to continue to expand at about 25 000ha a^–1 of upland conifers or 10 000 ha a^–1 of poplarson good land.     

Necromass in undisturbed and logged forests in the Brazilian Amazon

Necromass is an important stock of carbon in tropical forests. We estimated volume, density, and mass of fallen and standing necromass in undisturbed and selectively logged forests at Juruena, Mato Grosso, Brazil (10.48°S, 58.47°W). We also measured standing dead trees at the Tapajos National Forest, Para, Brazil (3.08°S, 54.94°W) complementing our earlier study there on fallen necromass. We compared forest that was selectively logged using reduced-impact logging methods and undisturbed forest. We estimated necromass density accounting for void volume for necromass greater than 10 cm diameter at Juruena for five decay classes that ranged from freshly fallen (class 1) to highly decayed material (class 5). Average necromass density adjusted for void space (±S.E.) was 0.71 (0.02), 0.69 (0.04), 0.60 (0.04), 0.59 (0.06), and 0.33 (0.05) Mg m⁻³ for classes 1 through 5, respectively. Small (2–5 cm) and medium (5–10 cm) size classes had densities of 0.52 (0.02) and 0.50 (0.04) Mg m⁻³, respectively. The average dry mass (±S.E.) of fallen necromass at Juruena was 44.9 (0.2) and 67.0 (10.1) Mg ha⁻¹ for duplicate undisturbed and reduced impact logging sites, respectively. Small and medium sized material together accounted for 12–21% of the total fallen necromass at Juruena. At Juruena, the average mass of standing dead was 5.3 (1.0) Mg ha⁻¹ for undisturbed forest and 8.8 (2.3) Mg ha⁻¹ for forest logged with reduced impact methods. At Tapajos, standing dead average mass was 7.7 (2.0) Mg ha⁻¹ for undisturbed forest and 12.9 (4.6) Mg ha⁻¹ for logged forest. The proportion of standing dead to total fallen necromass was 12–17%. Even with reduced impact harvest management, logged forests had approximately 50% more total necromass than undisturbed forests.     

Growth and yield models for Eucalyptus grandis grown in Swaziland

The aim of this study was to develop a stand-level growth and yield model for short-rotation Eucalyptus grandis grown for pulp wood production at Piggs Peak in Swaziland. The data were derived from a Nelder 1a spacing trial established with E. grandis clonal cuttings in 1998 and terminated in 2005. Planting density ranged from almost free-growing trees established at 161 trees ha^?1 to extremely dense stands at 6 809 trees ha^?1. Functions were fitted to describe stand density, dominant height and basal area development over time. The functions performed well when scrutinised for their goodness of fit. They were also found to be consistent with forest growth theory when their logical behaviour was tested over the range of planting densities.     

Impact of Community Forest Management on Biomass Carbon Stocks in the Uatumã Sustainable Development Reserve,Amazonas, Brazil

Forest management can result in net losses of carbon stock. To quantify the impact of the management it is important to assess losses or gains of carbon, as well as the sustainability of the management system. This study quantified the impact management under a Small-Scale Sustainable Forest Management Plan, which is a recently created category of authorized management for small managers in the state of Amazonas, Brazil. Impact was quantified on the number of individuals, the biomass of natural regeneration, and the damage to the remaining trees 2 months after logging. The impact of these changes on carbon stock was estimated. The study was carried out in the Uatumã Sustainable Development Reserve, Amazonas, Brazil, where two areas of small-scale forest management and one control were evaluated. Average total carbon stock previous to logging was estimated at 161.25 ± 9.66 MgC ha^?1. Two months after logging, reductions were found of 3% in one managed area (MA1) and 8.3% in the other (MA3), including the carbon stock from the harvested timber. For each harvested tree, the logging caused damage to 12 trees in MA1 and four trees in MA3. The reductions in carbon stock and number of trees damaged per harvested tree were less than the reductions found for higher impact forest management and other experiences in community forest management. No significant alteration was found in the carbon stock of natural regeneration. However, there was an increase in the number of individuals, both in the logged areas and in their respective control areas.     

Harvesting intensity versus sustainability in Indonesia

In East Kalimantan (Indonesia), impacts of conventional (CNV) and reduced-impact logging (RIL) on forest ecosystems were compared on the basis of pre- and post-harvesting stand inventories. There was a positive and significant correlation between the proportion of trees damaged by felling and the density of trees felled. Logging intensity ranged from 1 to 17 trees ha⁻¹(9–247 m³ ha⁻¹) and averaged 9 trees ha⁻¹ (86.9 m³ ha⁻¹). The study has shown that with RIL techniques, logging damage on the original stand can be significantly reduced by 50% compared with conventional logging. However, this 50% reduction in logging damage, was dependent on the felling intensity. With a felling intensity of 8 stems ha⁻¹ or less, RIL techniques only damaged 25% of the original tree population whereas 48% were damaged with conventional techniques. Above this felling intensity (i.e. 8 stems ha⁻¹), the effectiveness of RIL in limiting forest damage was significantly reduced, mainly because of the increasing felling damage. Moreover, the removal of all harvestable timber trees, leaving only few potential crop trees, will result in a seriously depleted residual stand. Because of the high damage involved by high felling intensity, leaving few potential crop trees, and the yield capacity of the remaining stand, acceptable harvesting volume will not be reached within the felling rotation of 35 years. It is concluded that silvicultural system based on diameter limit alone, as is the Indonesian system (TPTI), cannot be compatible with sustainability and more sophisticated harvested-selection rules are needed.     

Above-ground biomass dynamics after reduced-impact logging in the Eastern Amazon

Changes in above-ground biomass (AGB) of 17 1 ha logged plots of terra firme rain forest in the eastern Amazon (Brazil, Paragominas) were monitored for four years (2004–2008) after reduced-impact logging. Over the same time period, we also monitored two 0.5 ha plots in adjacent unlogged forest. While AGB in the control plots changed little over the observation period (increased on average 1.4 Mg ha⁻¹), logging resulted in immediate reductions in ABG that averaged 94.5 Mg ha⁻¹ (±42.0), which represented 23% of the 410 Mg ha⁻¹ (±64.9) present just prior to harvesting. Felled trees (dbh > 55 cm) accounted for 73% (±15) of these immediate losses but only 18.9 Mg ha⁻¹ (±8.1) of biomass was removed in the extracted logs. During the first year after logging, the annual AGB balance (annual AGB gain by recruitment and growth − annual AGB loss by mortality) remained negative (−31.1 Mg ha⁻¹ year⁻¹; ±16.7), mainly due to continued high mortality rates of damaged trees. During the following three years (2005–2008), average net AGB accumulation in the logged plots was 2.6 Mg ha⁻¹ year⁻¹ (±4.6). Post-logging biomass recovery was mostly through growth (4.3 ± 1.5 Mg ha⁻¹ year⁻¹ for 2004–2005 and 6.8 ± 0.9 Mg ha⁻¹ year⁻¹ for 2005–2008), particularly of large trees. In contrast, tree recruitment contributed little to the observed increases in AGB (1.1 ± 0.6 Mg ha⁻¹ year⁻¹ for 2004–2005 and 3.1 ± 1.3 Mg ha⁻¹ year⁻¹ for 2005–2008). Plots with the lowest residual basal area after logging generally continued to lose more large trees (dbh ≥70 cm), and consequently showed the greatest AGB losses and the slowest overall AGB gains. If 100% AGB recovery is desired and the 30-year minimum cutting cycle defined by Brazilian law is adhered to, current logging intensities (6 trees ha⁻¹) need to be reduced by 40–50%. Such a reduction in logging intensity will reduce financial incomes to loggers, but might be compensated for by the payment of environmental services through the proposed REDD (reduced emissions from deforestation and forest degradation) mechanism of the United Nations Framework Convention on Climate Change.     

Timing and intensity of precommercial thinning in Pinus sylvestris stands

The effects of timing and intensity of precommercial thinning were studied in three Scots pine artificially regenerated stands on Vaccinium forest sites in southern Finland. A two-level factorial design (3×3) was used in each stand: thinning at dominant height of 3, 6 and 9 m to 1000, 1600 and 2200 stems ha^?1. The effects of the treatments were analysed after a period of 23–25 yrs when the dominant height was 14–15 m. Early thinning resulted in the highest standing volume and amount of merchantable wood, and also in slightly accelerated height development. Thinning to 1000 stems ha^?1 caused a considerable production loss, but there were no differences between the densities of 1600 and 2200 stems ha^?1. Branches became thicker after early thinning, but the differences between the treatments were negligible for crop trees. Crown ratio was lowest as the result of early or moderate thinning (2200 stems ha^?1).     

Initial impact of supervised logging and pre-logging climber cutting compared with conventional logging in a dipterocarp rainforest in Sabah,Malaysia

Pre-marked skid trails, directional felling and climber cutting when logging in tropical rainforests may be important ways of reducing damage to the forest, thus creating a healthier stand and improving future yields.This study, carried out in a virgin dipterocarp rainforest in the south of Sabah, Malaysia, compared two types of logging (both with and without pre-cutting climbers): conventional selective logging (CL) and supervised logging (SL). The latter is a selective logging system in which both pre-marked skid trails and directional felling were implemented. The pre-marked skid trails were aligned parallel to each other, spaced 62 m apart. A randomised complete block 2 × 2 factorial design was used in the experiment, consisting of 16 gross treatment plots, each of 5.76 ha with a 1 ha net plot in the centre.Fewer trees tended (0.050 < P ≤ 0.100) to be logged in SL plots than in CL plots (on average 9.4 and 13.0 trees ≥60 cm diameter breast height ha⁻¹). Pre-felling of climbers resulted in four more dipterocarp trees being logged ha⁻¹, compared with no climber cutting: a statistically significant difference (P ≤ 0.050). The basal areas lost of both large trees (≥ 60 cm dbh) and small dipterocarp trees (10–29 cm dbh) tended to differ between the logging systems, with CL leading to greater losses.There were significant differences in the residual stands left by the logging systems, with respect to the number of dipterocarps and their basal area in the diameter class 10–29 cm; ca 30% more stems being found after SL. No significant differences (or tendencies) in these variables were found in the residual stands in other diameter classes, or when trees of all species were considered.     

Carbon stocks and net ecosystem production changes with time in two Italian forest chronosequences

Forest management influences several ecosystem processes, including carbon exchange between forest ecosystem and atmosphere. The aim of this paper was to study the carbon cycle over different age classes of two managed forests in the Italian Alps through direct measurements and modelling. For this purpose, ecosystem carbon dynamics of a beech forest (Fagus sylvatica L.) and of a spruce forest (Picea abies (L.) Karst.) were investigated using a chronosequence approach. In both forests, five forest development stages were identified (thicket, pole wood, young forest, mature forest and the regeneration phase) with an age spanning from 42 to 163?years for the beech forest and from 35 to 161?years for the spruce forest. Measured total ecosystem carbon stock increased up to 80–100?years, with a mean of 232?MgC?ha^?1 in the beech forest and of 299?MgC?ha^?1 in the spruce forest. Calculated net ecosystem production (NEP) was found to decrease linearly with age and had an average value of 2.2 and 4.4?MgC?ha^?1?year^?1 for beech and spruce forest, respectively. Model simulations reported an increase in NEP till 50–60?years followed by a decrease thereafter. The model also predicted a negative NEP for a short period (8–11?years) after the seed cut. Aboveground biomass was the main driver of carbon accumulation while soil carbon was not significantly influenced by both age and management system. Moreover, measured data and model showed that the applied shelterwood system allowed for a rapid recovery of the ecosystem after the disturbance (i.e. seed cut), bringing back forest to act as C sink in few years.     

A silvicultural strategy for managing uneven-aged beech-dominated forests in Thuringia,Germany: a new approach to an old problem

Maintaining a permanent forest canopy cover and eventually harvesting wood in a final harvest according to predefined dimensions is often considered as prototype for future management of deciduous forests. An uneven-aged structure is considered by the public to resemble “natural” conditions, and by forest engineers it is considered as being more resilient to disturbances. In the Hainich-Dün region of Thuringia, Germany, beech-dominated selection forests covering about 10,000?ha have been managed for almost 1000 years, initially by irregular use, but as regular selection system since about 200 years. Managing these stands remains difficult, due to the lack of yield tables and a quantification of harvest of uneven-aged stands considering differences in site conditions and handling of over-sized trees. It is the objective of the present study to develop tables of target stand volumes, increments, and harvest for different diameter ranges of uneven-aged stands according to site conditions. The present study is based on repeated grid-based inventories of about 2150 plots, which were partly re-inventoried 3 times over the past 20 years. The recommended target wood volumes vary between 296 and 388 m³ ha^?1. Stand growth rates of different yield classes were estimated to range between 6.7 and 7.7 m³ ha^?1 yr^?1 which is 30% lower than for age class forest. Nevertheless, the economic returns are higher. Thus, selective cutting with single tree selection remains a viable silvicultural system, but it may change over time into small-scale shelter-woods for improving growth of regeneration.