A review of the roles of forest canopy gaps

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question： how do gaps influence forest structure？ From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.     

Abundance and diversity of soil invertebrates in annual crops, agroforestry and forest ecosystems in the Nilgiri biosphere reserve of Western Ghats, India

Biologically mediated soil processes rely on soil biota to provide vital ecosystem services in natural and managed ecosystems. However, land use changes continue to impact on assemblages of soil biota and the ecosystem services they provide. The objective of the present study was to assess the effect of land use intensification on the distribution and abundance of soil invertebrate communities in the Nilgiri, a human-dominated biosphere reserve of international importance. Soil invertebrates were sampled in 15 land use practices ranging from simple and intensively managed annual crop fields and monoculture tree plantations through less intensively managed agroforestry and pristine forest ecosystems. The lowest taxonomic richness was found in annual crops and coconut monoculture plantations, while the highest was in moist-deciduous and semi-evergreen forests. With 21 ant species, agroforestry systems had the highest diversity of ants followed by forest ecosystems (12 species). Earthworms and millipedes were significantly more abundant in agroforestry systems, plantations and forest ecosystems than in annual crop fields. Ants, termites, beetles, centipedes, crickets and spiders were more abundant in forest ecosystems than in other ecosystems. It is concluded that annual cropping systems have lower diversity and abundance of soil invertebrates than agroforestry and natural forest ecosystems. These results and the literature from other regions highlight the potential role that agroforestry practices can play in biodiversity conservation in an era of ever-increasing land use intensification and habitat loss.     

Advances of study on atmospheric methane oxidation （consumption） in forest soil

Next to CO2, methane (CH4) is the second important contributor to global warming in the atmosphere and global atmospheric CH4 budget depends on both CH4 sources and sinks. Unsaturated soil is known as a unique sink for atmospheric CH4 in terrestrial ecosystem. Many comparison studies proved that forest soil had the biggest capacity of oxidizing atmospheric CH4 in various unsaturated soils. However, up to now, there is not an overall review in the aspect of atmospheric CH4 oxidation (consumption) in forest soil. This paper analyzed advances of studies on the mechanism of atmospheric CH4 oxidation, and related natural factors (Soil physical and chemical characters, temperature and moisture, ambient main greenhouse gases concentrations, tree species, and forest fire) and anthropogenic factors (forest clear-cutting and thinning, fertilization, exogenou saluminum salts and atmospheric deposition, adding biocides, and switch of forest land use) in forest soils. It was believed that OH4 consumption rate by forest soil was limited by diffusion and sensitive to changes in water status and temperature of soil.CH4 oxidation was also particularly sensitive to soil C/N, Ambient CO2, CH4 and N2O concentrations, tree species and forest fire.In most cases, anthropogenic disturbances will decrease atmospheric CH4 oxidation, thus resulting in the elevating of atmos-pheric CH4. Finally, the author pointed out that our knowledge of atmospheric CH4 oxidation (consumption) in forest soil was insufficient. In order to evaluate the contribution of forest soils to atmospheric CH4 oxidation and the role of forest played in the process of global environmental change, and to forecast the trends of global warming exactly, more researchers need to studiesfurther on CH4 oxidation in various forest soils of different areas.     

Seasonal variation of soil respiration rates in a secondary forest and agroforestry systems

Agroforestry systems are widely practiced in tropical forests to recover degraded and deforested areas and also to balance the global carbon budget. However, our understanding of difference in soil respiration rates between agroforestry and natural forest systems is very limited. This study compared the seasonal variations in soil respiration rates in relation to fine root biomass, microbial biomass, and soil organic carbon between a secondary forest and two agroforestry systems dominated by Gmelina arborea and Dipterocarps in the Philippines during the dry and the wet seasons. The secondary forest had significantly higher (p < 0.05) soil respiration rate, fine root biomass and soil organic matter than the agroforestry systems in the dry season. However, in the wet season, soil respiration and soil organic matter in the G. arborea dominated agroforestry system were as high as in the secondary forest. Whereas soil respiration was generally higher in the wet than in the dry season, there were no differences in fine root biomass, microbial biomass and soil organic matter between the two seasons. Soil respiration rate correlated positively and significantly with fine root biomass, microbial biomass, and soil organic C in all three sites. The results of this study indicate, to some degree, that different land use management practices have different effects on fine root biomass, microbial biomass and soil organic C which may affect soil respiration as well. Therefore, when introducing agroforestry system, a proper choice of species and management techniques which are similar to natural forest is recommended.     

Lack of natural control mechanisms increases wildlife–forestry conflict in managed temperate European forest systems

Across Europe, ungulate numbers have greatly increased over the past decades, leading to increasing concerns about the ecological and economical impacts and pleas for stronger population control. However, focussing on population control only ignores other underlying factors which may enhance the wildlife–forestry conflict. I reviewed factors which shape herbivore top-down effects in natural temperate forest systems aiming at understanding how these interactions are altered in managed forests. Carnivores are important in modifying ungulate–plant interactions. They can directly influence the numbers of ungulates, but this effect is dependent on productivity and predicted to be smallest in highly productive temperate forest. Indirectly, they modify herbivore top-down effects by creating a landscape of fear. Despite the abundance of knowledge from American systems, there is a lack of knowledge on how this process might work in European systems. Next to carnivores, abiotic conditions interact with herbivory by influencing forage quality and availability. Forest gaps lead to concentration of ungulates and their effects, due to increased forage supply. Abiotic conditions also influence the response of plants following herbivory, which can be tolerated by showing increased regrowth or resistance due to chemical or physical defence. In typical managed forest systems, carnivores and abiotic conditions which shape ungulate top-down effects in natural forests are altered or absent. Human hunting might replace the direct effects of carnivores, but does not replace their indirect effects. Forestry practices also have modified herbivore–plant interactions in several ways, creating a forest with lower ungulate carrying capacity and higher sensitivity for ungulate browsing. These changes logically increase the strength of herbivore top-down effects in managed forests and increase the wildlife–forestry conflict. To reduce this conflict, aiming only at reducing wildlife numbers is predicted to have little effects when they do not coincide with habitat ameliorations. Forestry practices may therefore greatly enhance the conflict that exists between wildlife and forestry but can also be an important tool to reduce this conflict by adapting management practices that allow more natural functioning of forests systems.     

Greenhouse gas balance of harvesting stumps and logging residues for energy in Sweden

Abstract

In this case study, forest fuel procurement chains of stumps and logging residues were evaluated using a Life Cycle Assessment perspective. Direct emissions from combustion were not included, but soil organic carbon change was included as changes in carbon stocks in litter and soil. The results showed that primary forest biomass for energy has a climate impact which is time dependent. However, in long-time perspectives, there are large greenhouse gas (GHG) savings. In a short-term (20 years), there were no GHG savings when natural gas or coal was replaced. This is due to the fact that the harvest lead to decreased input of organic matter to the soil which is compared to a reference where biomass are left to decompose. The reduction in soil organic carbon may have been underestimated in the stump harvest systems studied, as the effect of soil disturbance per se was not included. Important factors when assessing GHG balance of forest fuels, besides the time horizon used, were site productivity, geographical position and forest fuel resource (stumps or logging residues). When assessing the greenhouse gas savings, efficiency of the end-use, allocation method between heat and power and type of fossil fuel replaced were also important.     

Review of state-of-the-art decision support systems (DSSs) for prevention and suppression of forest fires

Forest ecosystems are our priceless natural resource and are a key component of the global carbon budget. Forest fires can be a hazard to the viability and sustainable management of forests with consequences for natural and cultural environments, economies, and the life quality of local and regional populations. Thus, the selection of strategies to manage forest fires, while considering both functional and economic efficiency, is of primary importance. The use of decision support systems (DSSs) by managers of forest fires has rapidly increased. This has strengthened capacity to prevent and suppress forest fires while protecting human lives and property. DSSs are a tool that can benefit incident management and decision making and policy, especially for emergencies such as natural disasters. In this study we reviewed state-of-the-art DSSs that use: database management systems and mathematical/economic algorithms for spatial optimization of firefighting forces; forest fire simulators and satellite technology for immediate detection and prediction of evolution of forest fires; GIS platforms that incorporate several tools to manipulate, process and analyze geographic data and develop strategic and operational plans.     

Effects of the clear-cutting of a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation on chemical soil fertility

? Stand harvesting and regeneration were usually considered to be a critical phase for the sustainability of forest soils. The present study concerned the effects on soil chemical fertility of the clear-cutting of a highly productive Douglas-fir stand aged 67 years that was clear-cut with no disturbance.

? Results showed that soil changes were rapid in the three-year period following the cutting. The forest floor mass considerably decreased and the mineral soil showed a limited but real acidification. Soil losses represented 4% of the available nutrients over a depth of 60 cm for N, 22% for K, 25% for Ca and 32% for Mg. Only P increased by 11%. Due to the spatial variability of forest soils, and despite regular re-sampling, confidence intervals were large and difficult to reduce.

? The reversibility of the effects of the clear-cutting and its consequences on soil functions depend on the element: it should not be a problem for C, N and K, which would recover when the biological cycle is re-established once again in the young stand. Phosphorus is not at issue since it changes form in the soil. The depletion of Ca, and to a lesser extent of Mg, is of some concern as a result of limited soil reserves, the limited flux of cations from the mineral changes in the soil, the relatively large part of Ca and Mg in the forest floor, and the negative input-output budgets for those elements.

? The duration of the impact of the clear-cutting on soil requires medium-term observations because it cannot be deduced from the current knowledge of this ecosystem.

     

Modern forestry vehicles and their impact on soil physical properties

Mechanized harvesting procedures for typical forest vehicles were analysed to examine soil stresses and displacements occurring in soil profiles and to reveal changes in physical properties of forest soils. All field experiments were carried out under traffic lanes of standard forest vehicles in forest stands of the southern Black Forest. The soil stresses were determined using stress state transducers (SST) and displacement transducer systems (DTS) at depths of 20 and 40 cm. Complete harvesting and trunk-logging processes with a total time span of 9 min were observed. The maximum vertical stresses for all experiments exceeded 200 kPa; some experiments showed maximum vertical stresses up to 500 kPa or more at a depth of 20 cm. To evaluate the impact of soil stresses on soil structure, the internal soil strength was determined by predicting the precompression stress. Comparison of soil stress data with the natural bearing capacity of the natural forest soil proves that sustainable traffic is not possible, irrespective of the vehicle type and the working process. Topsoil and subsoil compaction, an increase in the precompression stresses, deep rutting and vertical as well as horizontal soil displacement associated with shearing effects took place and affected the mechanical strength and the physical properties of forest soils. Considering these results, heavy forest machinery has a severe impact on soil physical properties such as air, heat, water fluxes and rootability. In order to sustain the present undamaged soil condition, a change in harvest logistics and organisation is necessary. This can be achieved with a permanent skid-trail system which has already been designed to implement new guidelines in Baden-Württemberg, Germany (Ministerium für Ernährung und ländlichen Raum, Baden-Württemberg 2003, p 27).     

Forest types for biodiversity assessment at regional level: the case study of Sicily (Italy)

Within Europe the question of plant coenosis is attracting growing interest. The quality and quantity of collected information on forest resources at a global level largely depends on the capacity to collect and analyse data at national and sub-national scale in a way compatible with those at global or continental levels. In Italy the acceptance of all the international agreements and protocols on the protection of the environment and management of natural resources, requires a standardization of collected information and statistics, with the aim to produce homogeneous and integrative data at global level. This need is reflected in the following points: (1) the adoption of a classification system of land use and forest cover compatible with international hierarchical systems and definitions; (2) the identification of standard procedures in data collection and data elaboration. To classify natural resources and, in this case study, forest resources, implies to order natural and semi natural coenosis, forest and pre-forest communities, in a systematic way, according to the applied variables and to the scale detail. The solution proposed in this case study is organised according to forest management, through the adoption of the habitat approach, describing forest and pre-forest types in a synoptic way and performing a system of nomenclature in agreement with the international standards initiatives. In this way, the characterization of forest types at community level is related to the environmental planning for the protection of biodiversity.     

筇竹不同林分类型土壤酶活性的垂直分布特征

在云南省大关县木杆镇选择4种筇竹林分类型：天然筇竹—阔叶树混交林、天然筇竹—山茶混交林、天然筇竹—人工黄皮树混交林、人工筇竹—黄皮树混交林等，研究不同筇竹林分类型、不同土层深度(0~20、20~40和40~60 cm)的土壤过氧化氢酶、蔗糖酶、酸性磷酸酶和脲酶活性。结果表明：1)天然筇竹—阔叶树混交林的土壤过氧化氢酶、酸性磷酸酶和脲酶活性高于其他3种林分类型，人工筇竹—黄皮树混交林的土壤蔗糖酶活性高于其他3种林分类型，说明人工施肥处理对提高蔗糖酶活性有一定的作用；2)除天然筇竹—阔叶树混交林的蔗糖酶外，4种林分类型的土壤酶活性在土层0~20 cm达到最大值，并且随着土壤土层深度的增加而降低；3)除天然筇竹—人工黄皮树混交林的蔗糖酶和脲酶与过氧化氢酶、人工筇竹—黄皮树混交林和天然筇竹—山茶混交林的酸性磷酸酶与过氧化氢酶、天然筇竹—阔叶树混交林的酸性磷酸酶与蔗糖酶无显著相关外，其他酶活性之间均存在显著或极显著相关(P＜0.05或P＜0.01)。研究表明林分类型和土层深度是影响土壤酶活性的重要因素。     

火干扰对森林水文的影响

在森林生态系统中 ,火是一种相当普遍的自然现象 ,森林火灾和森林水文二者有着密切的关系。森林火灾对水的影响是间接的 ,主要表现为火烧后植被、地被物、土壤以及生态环境的改变影响水分循环过程、水质、水生生物等方面。火对水文的影响有大有小 ,它取决于火强度和频度。轻度野火或计划火烧对水文可能不产生明显影响 ,但是 ,频繁的或严重的野火却可以导致乱砍滥伐所造成的类似水文变化     

人工林和天然林的比较评价

对人工林和天然林的生态学和林学特性进行了比较和分析。指出天然林对病虫害的抵抗能力强,能持久地生产木材和发挥多重效益,并与很多物种的生存有密切关系。因人工林多样性低,稳定性差,轮伐期短,集约栽培的工业人工林尽管速生,但对地力消耗大,若没有优越的土地条件和额外的施肥,生产力将不能持久。提出我国应实行人工林和天然林并重的方针,要对大量发展工业人工林可能产生的隐患给予重视,要对已保存不多的原始林实行不改变林相的经营方式,避免将它们大面积地改变为人工林的作法。     

Soil and litter fauna of cacao agroforestry systems in Bahia,Brazil

Agroforestry systems deposit great amounts of plant residues on soil and this leads to high levels of soil organic matter content and has increased soil biodiversity and improved its conservation. This study compares the distribution of meso and macrofaunal communities in soil and litter under cacao agroforestry systems and in a natural forest in the southern Bahia state of Brazil. Soil and litter samples were obtained in September 2003, February 2004, and August 2004 in five cacao agroforestry systems. The systems evaluated included: cacao renewed under Erythrina sp. (Erythrina poeppigiana) (CRE); cacao renewed under natural forest (Cabruca, CRF); an old cacao system under Erythrina sp. (OCE); an old cacao system under a natural forest system (Cabruca, OCF) and a cacao germplasm collection area (CGC). As a reference soil and litter under a natural forest (NF) was included. Organisms were collected over a 15-day period with a Berlese–Tullgren apparatus. The density and richness of total fauna varied distinctly according to sites, sampling time and material sampled (soil and litter). 16,409 of fauna were recovered from soil and litter samples and the density of total fauna was 2,094 individuals m⁻² in the litter and 641 individuals m⁻² in the soil. The richness was 11.8 in the litter and 7.5 in the soil. The cacao agroforestry systems adopted for growing cacao in the southern Bahia region of Brazil have beneficial effects on the soil and litter faunal communities, and such systems of cacao cultivation could be considered as a conservation system for soil fauna. The development of a litter layer resulted in higher abundance and diversity of soil fauna.     

Interspecific interactions of ungulates in European forests: an overview

Mammalian herbivores vary in the degree to which they browse, graze and cause physical disturbance, and so vary in the effects they have on the structure and composition of forest ecosystems. To create predictive models of the interactions of forest ecosystems with herbivore communities, an appreciation of the interactions between the species of herbivore themselves is necessary. This paper reviews interspecific interactions of ungulates, methods used in studying them, and seeks to identify areas to which future research should be directed in the context of European forest systems. Methods that have been used to provide information on interactions include: comparative resource studies, niche theory, physiological and anatomical analyses, modeling and foraging theory, and population studies. The most commonly reported types of interactions appear to be competition and facilitation. Behavioural and social interactions between species are potentially important, but evidence for these is scarce and often anecdotal. It is suggested that there may be considerable potential for ungulates to interact in European forests which are often significantly altered from their natural state. Future research should aim at refining the theoretical understanding of interspecific interactions, particularly between ungulates with different feeding ecologies. The roe deer (Capreolus capreolus) has a major impact on forest ecosystems and is increasing its range throughout Europe. However, there is evidence that it may be displaced or out-competed by a number of ungulate species, and it is suggested as being research priority to quantify these effects.     

Integrating natural woodland with pig production in the United Kingdom:an investigation of potential performance and interactions

Although silvopastoral systems involving pigs were once widespread in Britain, the practice has largely died out. However, recent changes in pig production techniques, consumer demands and the economic climate within which farmers operate, have led to renewed interest in both traditional and novel tree-pig systems. This paper describes a financial spreadsheet model (MAST) that was developed to: provide a means of determining financial performance of integrating finishing pigs with natural woodland; identify the likely importance of different as yet largely unresearched animal-tree interactions; and, determine which interactions warrant attention in research and management. Preliminary analysis suggests that the financial performance of this agroforestry enterprise could be superior to that of a pasture-based enterprise. The most important factors in determining incremental performance are identified as sales premia for ‘forest-reared’ pork, changes to feed conversion ratios arising from the provision of a heterogeneous microclimate, and the availability of cheaper land rents.     

Seasonal soil CO2 efflux dynamics after land use change from a natural forest to Moso bamboo plantations in subtropical China

Moso bamboo plantations (Phyllostachys pubescens) are one of the most important forest types in southern China, but there is little information on the effects of their establishment and silvicultural practices on soil CO₂ efflux. The objectives of this study were to evaluate the effect of land use change from a natural broadleaf evergreen forest to Moso bamboo plantations and their management practices on soil CO₂ efflux in a subtropical region of China using static closed chamber method. Regardless of the land uses or management practices, the effluxes over a 12-month period had a seasonal pattern, with the maximum effluxes observed in summer and the minimum in winter. Whereas there was no significant difference in the total annual soil CO₂ efflux between the natural broadleaf evergreen forest (BL) and the conventionally managed bamboo forests (CM), soil CO₂ efflux in the intensively managed bamboo forest (IM) was significantly higher. Soil temperature was the most important environmental factor affecting soil CO₂ efflux rates for all three land uses. Soil moisture also had a significant positive correlation with soil CO₂ efflux rates. Soil temperature and moisture had greater influence on soil CO₂ efflux rate in the IM than the CM and BL forests. Soil dissolved organic C had a positive correlation with soil CO₂ efflux rate in the CM, but had no significant correlation with that in the IM or the BL forests. Our study for the first time demonstrated that conversion of the natural subtropical broadleaf evergreen forest to Moso bamboo does not increase soil CO₂ efflux. However, when bamboo forests are under intensive management with regular tillage, fertiliser application and weeding, significantly more soil CO₂ emission occurs. Therefore, best management practices should be developed to reduce soil CO₂ efflux in Moso bamboo plantations in the subtropical regions of China.     

Single-tree influences on soil properties in agroforestry: lessons from natural forest and savanna ecosystems

Climate, organisms, topographic relief, and parent material interacting through time are the dominant factors that control processes of soil formation and determine soil properties. In both forest and savanna ecosystems, trees affect soil properties through several pathways. Trees alter inputs to the soil system by increasing capture of wetfall and dryfall and by adding to soil N via N₂-fixation. They affect the morphology and chemical conditions of the soil as a result of the characteristics of above- and below-ground litter inputs. The chemical and physical nature of leaf, bark, branch, and roots alter decomposition and nutrient availability via controls on soil water and the soil fauna involved in litter breakdown. Extensive lateral root systems scavenge soil nutrients and redistribute them beneath tree canopies. In general, trees represent both conduits through which nutrients cycle and sites for the accumulation of nutrients within a landscape. From an ecological perspective, the soil patches found beneath tree canopies are important local and regional nutrient reserves that influence community structure and ecosystem function. Understanding species-specific differences in tree-soil interactions has important and immediate interest to farmers and agroforesters concerned with maintaining or increasing site productivity. Lessons from natural plant-soil systems provide a guide for predicting the direction and magnitude of tree influences on soil in agroforestry settings. The challenge for agroforesters is to determine under what conditions positive tree effects will accumulate simultaneously within active farming systems and which require rotation of cropping and forest fallows.     

A review of belowground interactions in agroforestry, focussing on mechanisms and management options

This review summarises current knowledge on root interactions in agroforestry systems, discussing cases from temperate and tropical ecosystems and drawing on experiences from natural plant communities where data from agroforestry systems are lacking. There is an inherent conflict in agroforestry between expected favourable effects of tree root systems, e.g. on soil fertility and nutrient cycling, and competition between tree and crop roots. Root management attempts to optimise root functions and to stimulate facilitative and complementary interactions. It makes use of the plasticity of root systems to respond to environmental factors, including other root systems, with altered growth and physiology. Root management tools include species selection, spacing, nutrient distribution, and shoot pruning, among others. Root distribution determines potential zones of root interactions in the soil, but are also a result of such interactions. Plants tend to avoid excessive root competition both at the root system level and at the single-root level by spatial segregation. As a consequence, associated plant species develop vertically stratified root systems under certain conditions, leading to complementarity in the use of soil resources. Parameters of root competitiveness, such as root length density, mycorrhization and flexibility in response to water and nutrient patches in the soil, have to be considered for predicting the outcome of interspecific root interactions. The patterns of root activity around individual plants differ between species; knowing these may help to avoid excessive competition and unproductive nutrient losses in agroforestry systems through suitable spacing and fertiliser placement. The possibility of alleviating root competition by supplying limiting growth factors is critically assessed. A wide range of physical, chemical and biological interactions occurs not only in spatial agroforestry, but also in rotational systems. In a final part, the reviewed information is applied to different types of agroforestry systems: associations of trees with annual crops; associations of trees with grasses or perennial fodder and cover crops; associations of different tree and shrub species; and improved fallows. This revised version was published online in June 2006 with corrections to the Cover Date.     

Comparison of depth- and mass-based approaches for estimating changes in forest soil carbon stocks: A case study in young plantations and secondary forests in West Java, Indonesia

Soil carbon (C) stocks in forest ecosystems have been widely estimated to a fixed soil depth (i.e., 0-30 cm) to clarify temporal changes in the C pool. However, surface elevations change as a result of compaction or expansion of the soil under forest management and land use. On the other hand, the calculation of soil C stocks based on “equivalent soil mass” is not affected by compaction or expansion of forest soil. To contribute to the development of a forest C accounting methodology, we compared changes in soil C stocks over 4 years between depth- and mass-based approaches using original soil data collected at 0-30 cm depths in young plantations and secondary forests in West Java, Indonesia. Our methodology expanded on the mass-based approach; rather than using one representative value for the mass-based calculation of soil C stocks, we adjusted individual values, maintaining the coefficient of variance in soil mass. We also considered the effect of an increase or decrease in soil organic matter on equivalent soil mass. Both increasing and decreasing trends in soil C stocks became clearer when the mass-based approach was used rather than the depth-based approach. The trends in soil C stocks based on equivalent soil mass were particularly evident in the surface soil layers (0-5 cm) and in plantation sites, compared with those for soil profiles including subsurface soil layers (0-30 cm) and in secondary forests. These trends in soil C stocks corresponded with temporal trends in litter stocks. We suggest that equivalent mass-basis soil C stock for the upper 30 cm of soil be calculated based on multiple soil layers to reduce estimation errors. Changes in soil organic matter mass had little effect on the estimation of soil C stock on an equivalent mass basis. For the development of a forest C accounting system, the mass-based approach should be used to characterize temporal trends in soil C stocks and to improve C cycle models, rather than simpler methods of calculating soil C stocks. These improvements will help to increase the tier level of country-specific forest C accounting systems.