Component Of Forests Research Articles

Mineralization Characteristics of Soil Organic Carbon and Its Relationship with Organic Carbon Components in Artificial Robinia pseudoacacia Forest in Loess Hilly Region

In order to explore the characteristics of organic carbon mineralization and the variation law of organic carbon components of an artificial forest in a loess hilly area, an artificial Robinia pseudoacacia forest restored for 13 years and the adjacent slope farmland were selected as the research objects, and indoor culture experiments under three different temperature treatments (15, 25, and 35℃) were carried out. The results indicated that the mineralization rate of soil organic carbon decreased sharply at first and then stabilized. The cumulative release of organic carbon increased rapidly in the initial stage of culture and gradually slowed in the later stage. Soil organic carbon mineralization in sloping farmland was more sensitive to temperature change, and its temperature sensitivity coefficient Q10 was 1.52, whereas that in R. pseudoacacia forest land was only 1.38. According to the fitting of the single reservoir first-order dynamic equation, the soil mineralization potential Cp of R. pseudoacacia forest land and slope farmland was between 2.02-4.32 g·kg-1 and 1.25-3.17 g·kg-1, respectively, that is, the mineralization potential of the R. pseudoacacia forest was higher. During the cultivation period, the content of various active organic carbon components decreased with time, and that in the R. pseudoacacia forest land was greater than that in the slope land. The cumulative carbon release of soil was significantly positively correlated with the contents of MBC and DOC (P<0.05), and Q10 (15-25℃) was negatively correlated with the contents of SOC, EOC, and SWC (P<0.05). These results could provide some reference for the study of soil carbon sequestration in loess hilly regions under climate change.

Spatial distribution of anemophilous pollen and its correlation with the Asian summer monsoon on the southeastern Tibetan Plateau

Previous studies have discovered arboreal pollen in non-forested areas on the Tibetan Plateau, which are mostly anemophilous type and regarded as a result of the Asian summer monsoon. However, the relationship between the spatial distribution of wind-pollinated pollen and monsoon has seldom been illustrated quantitatively. Here, we used 676 surface samples (647 compiled, 29 new samples) to examine the characteristics of the spatial distribution patterns of 13 anemophilous pollen taxa on the southeastern Tibetan Plateau, by employing the spatial interpolation technique. Then, we quantified the correlation between the distributions of these taxa and monsoon wind via Mantel test. The results show that the anemophilous pollen represents at least half percentage of the total pollen assemblages in most areas of the study region. Anemophilous tree pollen mainly distributes in the south and southeastern part, while anemophilous non-tree pollen does in the opposite and perpendicular direction. The distributional pattern of non-anemophilous pollen reflects that their corresponding plants most likely constitute the understory components of different forests or the minorities of non-forests communities. Mantel tests indicate that the anemophilous tree pollen has a highest correlation with the Asian summer monsoon. Anemophilous pollen, overall pollen assemblages and anemophilous pollen with air sacs have higher correlations with summer monsoon. Contrarily, non-anemophilous pollen has relatively weak correlation. Furthermore, we found that the relationships between various pollen groups or separate taxa and the Asian summer monsoon are dependent on sample types. The lake sediment surface samples had the strongest signal of the Asian summer monsoon among the different sample types. Our findings provide the strong evidence of the Asian summer monsoon influencing the pollen distribution patterns. More importantly, the quantification of this correlation between anemophilous tree pollen and the Asian summer monsoon offers the fundamentally theoretical basis of reconstructing paleo-monsoon by the proxy of windborne pollen taxa.

Allometric equations for the estimation of above- and below-ground biomass for Larix sibirica Ledeb. in Northern Mongolia

The accurate estimation of tree above-ground (AGB) and below-ground (BGB) biomass components and their root/shoot ratio play key roles in stand and country-level forest biomass and carbon stock estimation. Nevertheless, site-specific and appropriate biomass equations and root/shoot ratio are hardly available for natural larch (Larix sibirica Ledeb.) forests in Mongolia. The present study aimed (1) to develop allometric equations to estimate the above- and below-ground biomass of L. sibirica trees, and (2) to estimate the root/shoot ratio applicable for estimating the root biomass based on above-ground biomass of natural larch forests in northern Mongolia. A total of 40 trees with DBH ranging from 6.8 to 40.8 cm were sampled for tree biomass analyses. For each biomass component, we calculated the proportion of biomass allocated to different components, and also tested four allometric equations based on diameter at breast height (DBH) and height (H) as independent variables. Our results, based on measurements of oven-dried biomass, revealed that stem biomass on average accounted for 44.5% and followed by branch (28.6%) and root (19.9%) biomass, respectively. Stem and branch biomass proportions were gradually increased with increasing DBH, while a contrary trend was observed for needles. The root/shoot ratio averaged 0.25. A comparison of the allocation of root biomass by diameter fractions showed an ever-growing trend of coarse roots with an increase in stem diameter, which often exceeded more than 50% of the total root biomass. However, biomass equations, which include both DBH and H were more precise than equations that are solely based only on DBH. Consequently, among the proposed allometric regression models for estimating the AGB and BGB, the equation y = aD b H c was selected as the best-fitted equation for estimating each biomass component in Siberian larch forests. These allometric equations are available to be used for the estimation of natural larch forest biomass and carbon stocks in the Khentii Mountains of Mongolia, where extreme continental climate conditions dominate.

The diameter of beech snags is an important factor for saproxylic beetle richness: Implications for forest management and conservation

Snags are an important component of beech forests that promote biodiversity. However, their occurrence is completely marginal in managed stands. Creating snags in these stands would greatly enhance biodiversity. We investigated whether snag dimensions were important for saproxylic beetle richness since they were easily transferable parameters to forest management and assessed the presence of other snag microhabitats affecting beetle communities. Data collection was performed using passive flight traps placed on thirty snags in a recent beech reserve. A total of 6706 adults belonging to 231 saproxylic species (53 Red List species, 23%) were captured. The results showed that the most important snag parameters were the diameter (thickness) and canopy openness of the surrounding stands. The occurrence of Fomes fomentarius, the volume of snag and decay class 3 were marginally significant in terms of the preference of all saproxylic species. Alpha diversity was reduced by an advanced degree of decay and a surprisingly deep stem cavity. After dividing snag thickness into categories (<35 cm; 35–70 cm and >70 ​cm DBH), we found that categories with snag diameter greater than 35 ​cm showed little differences in all saproxylic and Red List species richness and diversity indices and exhibited the highest similarity in beetle communities. Regarding recommendations to forest managers in terms of optimization and simplification of practical procedures, we suggest actively creating high stumps to act as snags greater than 35 ​cm in DBH diameter to promote biodiversity in beech management stands.

Использование лесов для ведения сельского хозяйства в условиях Северо-Запада РФ

The work is devoted to the analysis of the normative and methodological foundations and practices of the use of forests for agriculture in the forest fund of the North-West of the Russian Federation. Constructive interaction between forestry, agriculture and hunting economy is one of the conditions for the successful development of the economy of the Russian Federation, including ensuring its food security. The purpose of this study is to identify the importance of using forests for agriculture as a necessary condition for constructive interaction of the above-mentioned industries. To achieve the purpose of the study, the following tasks were set and solved: to analyze the regulatory and methodological foundations and practice of using forests for agriculture in the forest fund of the North-West of the Russian Federation and to justify the need for wider application in forestry practice of using forests for agriculture, including from the point of view of forest biogeocenology, since it covers knowledge all the properties of the forest components that determine their interaction, and also establishes patterns, managing this interaction and the development of the forest biogeocenosis as a whole. In the NWFD, forests are used for agriculture on an area of 5.4 million hectares, which is almost a third (31.8%) of the total area of forests used for agriculture in the Russian Federation. Therefore, this type of forest use is very important for the forest fund of the North-West of the Russian Federation

Global habitat suitability modeling reveals insufficient habitat protection for mangrove crabs

Mangrove crabs are important components of mangrove forests however their large scale habitat suitability and conservation received little attention. The Metopograpsus thukuhar/cannicci species complex is a mangrove dwelling species occurs in the Indo-Pacific mangrove forests. Since identifying the complex suitable habitat is critical for its conservation, we modeled global habitat suitability of the complex within marine biogeographic realms and estimated representation of the complex suitable habitats within marine protected areas. We found that the complex’ largest and smallest suitable ranges are located in Central Indo-Pacific and Temperate Southern Africa realms, respectively. Only 12.5% of the complex suitable habitat is protected. The highest proportion of the complex’ protected suitable habitat (22.9%) is located in Western Indo-Pacific realm while the lowest proportion of the complex’ protected suitable habitat (1.38%) is located in Central Indo-Pacific realm. Suitable unprotected habitats of the complex identified in this study have high priority for conservation and should be included in marine protected areas to ensure species conservation. Our results show that species distribution models are practical tools to study marine species distribution across large spatial scales and help marine conservation planning.

Climate and forest attributes influence above‐ground biomass of deciduous broadleaf forests in China

Abstract Forests provide a huge carbon pool, a substantial portion of which is stored in above‐ground biomass (AGB). Deciduous broadleaf forests in China are an essential component of global deciduous broadleaf forests, yet the impacts of climate and forest attributes on their AGB are not well understood. Using a comprehensive forest inventory database from 772 plots distributed across temperate and subtropical deciduous broadleaf forests in China (23.51°–42.53°N and 104.24°–128.27°E), we applied variance partitioning analysis, model selection analysis and structural equation models to explore how climate and forest attributes (species diversity, community‐level functional traits and stand structures) affect AGB in different climatic forests (semi‐arid forests, semi‐humid forests and humid forests). Community‐level functional traits and stand structures together explained a great portion of the variance in AGB. The effect of community‐level functional traits was greater than that of stand structures in semi‐arid forests and semi‐humid forests, but smaller in humid forests. Further analyses showed that community‐level maximum tree height, stem density and tree size inequality were important explanatory variables. Although climate and species diversity had minor effects, the direct positive effect of mean annual precipitation (MAP) was still important, especially in semi‐arid forests. Synthesis. Community‐level functional traits but not species diversity were key drivers of AGB, indicating that tree species diversity loss may not impair AGB substantially in deciduous broadleaf forests in China. Moreover, stand structures also had strong effects on AGB in both semi‐arid forests and humid forests, highlighting the importance of structural complexity. In addition, MAP had a direct positive effect on AGB in semi‐arid forests and semi‐humid forests, and a future increase in drought might potentially reduce carbon storage in these forests.

Vulnerability of larch forests to forest fires along a latitudinal gradient in eastern Siberia

The predicted increase in frequency and intensity of boreal forest fires is considered a significant source of carbon dioxide emissions and linked with the degradation of permafrost covering more than half of Russia. Here we analyzed the stand structure and growth of East Siberian larch forests in response to fire severity. We measured 23 sites in the southern part of eastern Siberia along a latitudinal transect with a length of more than 1500 km. Live tree volume differed significantly across geographical regions ( p &lt; 0.05), decreasing from south to north (76–250 m3·ha−1), with higher values in forests burnt with low severity. Similarly, volume of coarse woody debris decreased from south to north. The volume of dead standing trees, on the other hand, increased from south to north. The distribution of trees by diameter class in some areas showed clear evidence of fires, with small trees being absent to rare in forests burnt at high severity. The impact of severe fires on stand volume was negligible at the southern sites, potentially associated with rapid regeneration of birch. Birch is an important component of larch forests near the southern boundary of the permafrost, which may contribute to larch forests in the southern part of the study transect being less vulnerable to wildfires compared to northern larch forests.

Multiple responses of bryophytes in a chronosequence of burnt areas in non-fire prone subtropical cloud forests

In non-fire prone ecosystems, like some subtropical humid forests, fire produces habitat destruction and intensifies land degradation by inducing changes in native species composition, soil properties and erosive processes. Bryophytes are key components of the Macaronesian laurel forests playing an important role in regulating water cycling and microclimate. Ecological and taxonomical bryophytes groups have distinct ecological and physiological requirements and may respond in a different way to the same fire events. Therefore, analysing post fire recovery of bryophyte communities represents a key step towards a better understanding of forest fire drivers and post fire management. We investigated how species richness and composition of different ecological and taxonomical bryophyte groups varied in 1158 samples within a fire chronosequence from 5 to 57 years in the best-preserved laurel forest from Canary Islands (Garajonay National Park) analysing communities in terms of differences with comparable surrounding old growth unburnt stands. Epiphyte, terricolous and saxicolous bryophytes were sampled at each plot and the influence of the time since fire was analyzed together with environmental variables (temperature, precipitation, mist precipitation and elevation) and forest structure variables. Our results indicate that there is no general pattern of post fire recolonization, as recolonization varies depending on the ecological and phylogenetic groups considered. Climate and forest structure play an important role in post-fire recolonization, such that time since fire is not the most important variable influencing richness and composition. The results increase the understanding of the processes that shape compositional patterns in groups with high dispersal capacities and high microclimate dependence, such as mosses and liverworts.

Mapping Soil Organic Carbon Content in Patagonian Forests Based on Climate, Topography and Vegetation Metrics from Satellite Imagery

Soil organic carbon (SOC) content supports several ecosystem services. Quantifying SOC requires: (i) accurate C estimates of forest components, and (ii) soil estimates. However, SOC is difficult to measure, so predictive models are needed. Our objective was to model SOC stocks within 30 cm depth in Patagonian forests based on climatic, topographic and vegetation productivity measures from satellite images, including Dynamic Habitat Indices and Land Surface Temperature derived from Landsat-8. We used data from 1320 stands of different forest types in Patagonia, and random forest regression to map SOC. The model captured SOC variability well (R² = 0.60, RMSE = 22.1%), considering the huge latitudinal extension (36.4° to 55.1° SL) and the great diversity of forest types. Mean SOC was 134.4 ton C ha−1 ± 25.2, totaling 404.2 million ton C across Patagonia. Overall, SOC values were highest in valleys of the Andes mountains and in southern Tierra del Fuego, ranging from 53.5 to 277.8 ton C ha−1 for the whole Patagonia region. Soil organic carbon is a metric relevant to many applications, connecting major issues such as forest management, conservation, and livestock production, and having spatially explicit estimates of SOC enables managers to fulfil the international agreements that Argentina has joined.

Landscape‐scale drivers of liana load across a Southeast Asian forest canopy differ to the Neotropics

Abstract Lianas (woody vines) are a key component of tropical forests, known to reduce forest carbon storage and sequestration and to be increasing in abundance. Analysing how and why lianas are distributed in forest canopies at landscape scales will help us determine the mechanisms driving changes in lianas over time. This will improve our understanding of liana ecology and projections of tropical forest carbon storage now and into the future. Despite competing hypotheses on the mechanisms driving spatial patterning of lianas, few studies have integrated multiple tree‐level biotic and abiotic factors in an analytical framework. None have done so in the Palaeotropics, which are biogeographically and evolutionarily distinct from the Neotropics, where most research on lianas has been conducted. We used an unoccupied aerial system (UAS; drone) to assess liana load in 50‐ha of Palaeotropical forest canopy in Southeast Asia. We obtained data on hypothesised drivers of liana spatial distribution in the forest canopy, including disturbance, tree characteristics, soil chemistry and topography, from the UAS, from airborne LiDAR and from ground surveys. We integrated these in a comprehensive analytical framework to extract variables at an individual‐tree level and evaluated the relative strengths of the hypothesised drivers and their ability to predict liana distributions through boosted regression tree (BRT) modelling. Tree height and distance to canopy gaps were the two most important predictors of liana load, with relative contribution values in BRT models of 34.60%–45.39% and 7.93%–10.19%, respectively. Our results suggest that taller trees were less often and less heavily infested by lianas than shorter trees, opposite to Neotropical findings. Lianas also occurred more often, and to a greater extent, in tree crowns close to canopy gaps and to neighbouring trees with lianas in their crown. Synthesis. Despite their known importance and prevalence in tropical forests, lianas are not well understood, particularly in the Palaeotropics. Examining 2428 trees across 50‐ha of Palaeotropical forest canopy in Southeast Asia, we find support for the hypothesis that canopy gaps promote liana infestation. However, we also found that liana presence and load declined with tree height, which is opposite to well‐established Neotropical findings. This suggests a fundamental difference between Neotropical and Southeast Asian forests. Considering that most liana literature has focused on the Neotropics, this highlights the need for additional studies in other biogeographic regions to clarify potential differences and enable us to better understand liana impacts on tropical forest ecology, carbon storage and sequestration.

Can Intensified Pasture Systems Reduce Enteric Methane Emissions from Beef Cattle in the Atlantic Forest Biome?

The objective of this study was to evaluate the effect of different pasture systems on beef steers’ performance, dry matter intake, enteric methane emission, carcass production, forage quality, and animal production per hectare (ha). The trial was conducted at Embrapa Southeast Livestock, São Carlos/SP, Brazil. Sixty Cachim beef steers (5/8 Charolais × 3/8 Zebu) with initial liveweights of 255 ± 7 kg were evaluated for two years under five different grazing production systems (EXT = Extensive; INT = Intensive; iCL = Integrated crop livestock; iCLF = Integrated crop livestock forest; iLF = Integrated livestock forest). The final liveweight was greater (p &lt; 0.05) for the animals under the INT and iCL systems (484 ± 51 and 466 ± 79 kg, respectively) compared to animals in the iCLF, iLF and EXT systems (416 ± 57, 414 ± 50 and 429 ± 48 kg). The dry matter intake was significantly greater under the EXT system than it was under the iCL system (9.8 ± 2.1 and 7.5 ± 2.9 kg day−1). Regarding the emission intensity in relation to the liveweight gain per unit area (g CH4 kg LWG−1 ha−1 year−1), it differed significantly among the systems (EXT = 1.6; INT = 0.6; iCL = 0.8; ICLF = 1.1; ILF = 0.7). Similarly, the methane emission intensity differed in relation to the carcass production (kg CH4 kg−1 carcass; EXT = 0.496; INT = 0.250; iCL = 0.297; iCLF = 0.345; iLF = 0.286). Beef cattle that are raised in intensive and/or integrated pasture systems have a greater availability of forage mass and nutrients than those that are raised extensively. Pasture systems that undergo soil pH correction and fertilization, rotational grazing and/or integrated with maize cropping produce animals with greater average daily gain and final liveweights, thereby lessening the enteric methane emissions per kg of weight gain. In these systems, the efficiency in terms of the gain per land area is also greater, however, the systems that are integrated with a forest component (iLF and iCLF) are equal to that of the EXT system. The same pattern is observed in the intensity of the methane emission as for the efficiency of the animal gain per unit of land area.

Terrigenous leaf-utilizing life of the tube-bearing annelid Anchinothria cirrobranchiata (Annelida: Onuphidae) in the deep sea

AbstractDeep-sea ecosystems are generally oligotrophic because they lack photosynthesizing producers. On deep-sea slopes near land, however, various terrestrial plant remains flow to and are deposited on near-shore deep bottoms. From a depth of 300 m off the Pacific coast of Owase, central Japan, we collected an onuphid polychaete, Anchinothria cirrobranchiata (Annelida: Onuphidae), which lives in a dorsoventrally flattened portable tube. The polychaete tubes were made of sand, as well as leaves and twigs of terrestrial evergreen trees. The leaves glued on the portable tubes were chartaceous, blackish and tough; they belonged mainly to two genera of Fagaceae, Castanopsis and Quercus, which are dominant components of coastal evergreen oak forests. In aquaria, the polychaetes fed on the leaves on their tubes, as well as autochthonous sedimented leaves, suggesting utilization of terrigenous plant litter as food. As to the evolution of Anchinothria, a molecular phylogenetic analysis suggests that Anchinothria is monophyletic with other Hyalinoeciinae (Nothria, Leptoecia, Hyalinoecia).

Performing as a transformer species? The invasive alien Reynoutria bohemica changes ecosystem properties in a riparian woodland

AbstractInvasive alien plants may profoundly transform ecosystems over wide areas. The study aimed to assess how the invader Reynoutria bohemica could transform ecosystem components of a native riparian forest in Northern Italy, after about 20 years of invasion. We selected 20 forest sites where we set up two 1 × 1 m plots, one in an invaded and one in a non‐invaded patch. Subsequently, we surveyed the properties of litter and mineral soil, soil biological quality (QBS‐ar), diversity of plant and microarthropod communities and light intensity at the ground level. To determine if the invader affected the quality of herb layer, we selected the native herb Allium ursinum as the indicator species of good quality forest stand and measured its traits in the paired plots. Following the application of linear mixed effects models, the invaded and non‐invaded plots showed differences in soil characteristics and plant community: the thickness of the organic horizon, soil C:N and available P were higher in invaded plots, whereas diversity, light intensity, Allium ursinum abundance and its vegetative vigour were found to be lower. Microarthropod communities and QBS‐ar were modestly influenced by R. bohemica. Redundancy analysis of plant community composition indicated that soil C:N and plant richness were the variables most linked to species invasion. This study highlights the ability of R. bohemica to transform certain ecosystem components in native riparian forests, after just a few decades since its first invasion, thereby underlining the need to implement measures to control its spread.

Street Tree Structure, Function, and Value: A Review of Scholarly Research (1997–2020)

Street trees are components of the urban forest that receive considerable attention across academic and professional disciplines. They are also one of the most common types of urban tree that people routinely encounter. A systematic review methodology was used to examine contemporary urban street tree research across natural and social science disciplines. The records collected (n = 429) were published between January 1997 and the mid-2020s and were coded for descriptive information (e.g., publishing journal and geography of study areas) as well as emergent focal research areas (e.g., ecosystem services, economic valuation, and inventory methods). From this sample, there has been considerable growth in street tree literature over time and across research themes, especially following major turning points in the field of urban forestry. Regulating ecosystem functions/services of street trees, especially cooling, has had the greatest attention in the literature, but other robust areas of research also exist, including the utility of pruning waste as construction materials, the benefits and disservices to human health and safety, and indicators of environmental (in)justice. Opportunities for future research and implications for research and practice are also discussed.

Rangewide climatic sensitivities and non-timber values of tall Sequoia sempervirens forests

Heavily exploited for its reddish, decay-resistant heartwood, the tallest conifer, Sequoia sempervirens, is a major component of coastal forests from extreme southwestern Oregon to California’s Santa Lucia Mountains. Primary Sequoia forests are now restricted to < 5 % of their former distribution, and mature secondary forests with trees over 60 m tall are even scarcer due to repeated logging. Leveraging allometric equations recently derived from intensive work in both forest types, we climbed, measured, and core-sampled 235 trees in 45 locations distributed across the species range to examine growth trends and understand how tall Sequoia are responding to recent environmental changes. Paired samples of sapwood and heartwood collected along the height gradient were used to quantify Sequoia investment in decay resistance. During the 20th century, trees in most locations began producing more wood than expected for their size with this growth surge becoming pronounced after 1970 and ending around 2000. Radial increments—ring widths—correlate with climatic variables related to water availability, and these relationships are strengthening as temperatures rise. Sensitivity to drought increased from north to south along a 6° latitudinal gradient of decreasing precipitation and summer fog frequency. Sequoia trees north of 40° were least sensitive to drought, producing similar biomass annually during dry and wet years, whereas trees farther south produced less biomass during individual drought years. Hotter 21st century drought barely affected Sequoia growth efficiency (biomass increment per unit leaf mass) north of 40° until the fourth consecutive year (2015), when growth efficiency dropped precipitously, recovering within two years. South of 40°, Sequoia trees exhibited steadily declining growth efficiency during the multi-year drought followed by recovery, but recovery did not occur south of 37° despite ample precipitation in 2017. Sequoia growth efficiency is currently highest in secondary forests north of 40°, where trees produce relatively small amounts of heartwood with the lowest decay resistance (least fungicide) while receiving the most nocturnal summer fog. Increasing sink limitations, whereby rising temperatures, drier air at night, and extreme tree height collectively lower turgor pressure to inhibit cambial activity, may reduce Sequoia growth efficiency while contributing to more durable biomass production. Heartwood and fungicide increments are higher in primary than secondary forests across the species range. Crown structural complexity promotes development of vascular epiphytes and arboreal soil habitats in Sequoia forests with sufficient moisture availability. These habitats are lacking in secondary forests and rare in primary forests south of 40°. After logging, restoration of tall Sequoia forests can be achieved via silviculture that maximizes height increments during early stand development and then retains some dominant trees in perpetuity, allowing them to gain full stature, produce increasingly decay-resistant heartwood, and support significant arboreal biodiversity.

Linking rhizospheric microbial and fine root C:N:P stoichiometry under long-term forest conversion

The rhizosphere is the microbial hotspot, while fine roots (diameter <2 mm) are the most physiologically active component in forests. However, how rhizospheric microbial carbon (C): nitrogen (N): phosphorus (P) stoichiometry (ESm) is linked with fine root C:N:P stoichiometry (ESfr) in response to long-term forest conversion remains largely unexplored. Using a space-for-time substitution method, we investigated long-term conversion from natural forests (NF) to plantations of Metasequoia glyptostroboides (MG), Cryptomeria fortunei (CF) and Cunninghamia lanceolata (CL). Fine root and rhizospheric soil samples (0–10 cm depth) were collected, and their C, N and P contents were determined. The rhizospheric soil microbial community (SMC) structure, as well as microbial biomass C, N and P, was measured. Both ESm and ESfr present strict homeostasis and ESm did not significantly correlated with the SMC structure or the microenvironment, suggesting that C and nutrient processes via fine roots and rhizospheric microbes return to equilibrium after long-term forest conversion. Moreover, ESm was synergistically and tightly linked with ESfr, indicating that P deficiency was aggravated during NF-to-CF conversion but ameliorated during NF-to-MG and NF-to-CL conversions. The linkage between ESm and ESfr could act as a robust ecological indication of nutrient-use strategies and limitations in forest ecosystems, benefiting our understanding on C and nutrient cycling regarding forest management.

Ground Vegetation in Pinus sylvestris Forests at Different Successional Stages following Clear Cuttings: A Case Study.

The impact of intensive forestry on various components of ecosystems has become the main subject of public and scientific debate in many regions in recent years. Forest ground vegetation is considered one of the most consistent and biodiversity-rich indicators of a certain stage of successional forest development. Therefore, changes in this forest component can potentially show the risks of forest damage due to clear-cutting and recovery trends. This study was carried out to identify the ground vegetation species diversity, including species composition and cover, also ground vegetation species relations with organic layer (forest floor) and upper mineral soil parameters at the different successional stages of the Pinus sylvestris L. stand development, including 1–2-year-old clear-cuts, and 6–130 years old stands. This study identified that the herb and dwarf shrub species were more light-demanding in the 2-year-old clear-cuts, as well as in the 6-year and 10-year old P. sylvestris stands compared to the middle-aged and mature forest stands. The dominant ground vegetation species, characteristic for the Pinetum vaccinio-myrtillosum forest type, were negatively dependent on the forest floor mass; they also had negative correlations with the concentrations of total P, K, Ca, and Mg in the forest floor and upper mineral soil but had positive correlations with the soil pH values and total N. The developed regression models of the percentage cover of mosses, herbs and dwarf shrubs according to the P. sylvestris stand age highlight the stabilization of the increase in the moss cover about 30 years after clear-cutting, with no clear trend for vascular species. The herbs and dwarf shrub species were highly variable during the stand rotation due to the species-specific characteristics and random factors rather than due to the influence of stand age. In this study, relatively short-term changes in ground vegetation species composition and percentage cover were determined after clear-cutting, but an important aspect is that new ground vegetation species appeared in the open areas, creating the potential for increasing species diversity. The clear-cutting system supports different species and numbers of herbs and mosses at different stages of stand development, which potentially increases the overall vegetation species diversity of the ecosystem.

Intensive management enhances mycorrhizal respiration but decreases free-living microbial respiration by affecting microbial abundance and community structure in Moso bamboo forest soils

Intensive management is known to markedly alter soil carbon (C) storage and turnover in Moso bamboo forests compared to extensive treatment regimes. However, the effect of intensive management on soil respiration (R S ) components is still unclear. This study aimed to evaluate the changes in different R S components (root, mycorrhiza, and microbes) in Moso bamboo forests under extensive and intensive management practices. A one-year in-situ microcosm experiment was carried out to quantify the R S components in Moso bamboo forests under the two management approaches using mesh screens of varying sizes. The result showed that total R S and its components exhibited similar seasonal variability between the two groups. Compared to extensive management, intensive management significantly increased cumulative respiration from mycorrhizal fungi by 36.73% while decreasing cumulative respiration from free-living soil microbes by 8.97%. Moreover, the abundance of arbuscular mycorrhizal fungi (AMF) increased by 43.38%. In contrast, bacterial and fungal abundance decreased by 21.65% and 33.30% under intensive management. Both management practices significantly changed the bacterial community composition, which could be mainly explained by soil pH and available K. Mycorrhizal fungi and intensive management affected the co-occurrence interrelationships between bacterial members. Structural equation modeling indicated that intensive management changed the cumulative soil respiration via elevating AMF abundance and lowering bacterial abundance. We conclude that intensive management reduced the microbial respiration-derived C loss and increased the mycorrhizal respiration-derived C loss.

On the inclusion of forest exposure pathways into a stylized lake-farm scenario in a geological repository safety analysis

Geological disposal of radioactive waste has been recognized as the ‘reference solution’ to ensure the safety required for the present and future society and environment. To study the possible exposure pathways from groundwater to humans, radioactive transport modelling is used. One of the ecosystems that may play a significant role when assessing the dose conversion factor (i.e. the dose resulting from a nominal release of 1 Bq/year of each radionuclide) for humans is forest. In this paper we have developed a model of a lake-farm system with a forest component. The biosphere system used in this study represents a typical agricultural scenario in Finland, amended with a typical forest. A lake is assumed to form due to post-glacial land uplift. The main features of this future lake have been obtained from our probabilistic shoreline displacement model. Both deterministic calculations and sensitivity analysis were carried out to simulate the model. The deterministic simulation demonstrates the behaviour of the studied radionuclides (36Cl, 135Cs, 129I, 237Np, 90Sr, 99Tc and 238U) and the proportions of different exposure pathways to humans. Particularly for 135Cs and 129I, forest pathways make a notable contribution to the dose conversion factor. The sensitivity analysis was done using two methods: EFAST and Sobol’. With both methods, the parameters related to the farm contribute the most to the variance of the dose conversion factor for humans. The study demonstrates that the exposure pathways related to forest products may make a considerable contribution to the dose conversion factor in a lake–farm–forest system. It is also confirmed that an advanced sensitivity analysis for a radionuclide transport and dose assessment model on such a landscape scale is feasible even with moderate computational efforts.