In northeastern Japan, an area of high precipitation and mountains, beech (Fagus creanata Blume), larch (Larix kaempferi Lamb.), cedar (Cryptomeria japonica D. Don) and black locust (Robinia pseudoacacia L.) were evaluated for N resorption and N isotope fractionation in pre- and post-abscission leaves in comparison to green leaves. The highest leaf N concentration in summer corresponded to the N-fixing black locust, followed in decreasing order by the deciduous beech and larch and evergreen cedar. On the other hand, the lowest N resorption efficiency corresponded to black locust and the highest to beech, in increasing order by larch and cedar. All tree species returned significant amounts of N before leaf abscission; however, N isotope fractionation during leaf N resorption was only found for beech, with a depleted N isotope value from green to pre-abscission leaf. The most N, however, was resorbed from pre-abscission to post-abscission. This result may indicate that δ¹⁵N fractionation took place during N transformation processes, such as protein hydrolysis, when the concentration of free amino acids increased sharply. The difference in the type of amino acid produced by each species could have influenced the N isotope ratio in beech but not in the other tree species. The results of this study showed that it is possible to infer the type and timing of processes relevant to N resorption by analyzing leaf δ¹⁵N variation during senescence.

We assessed the effects of arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis inoculation on salt stress tolerance in roots of the drought-tolerant plant Elaeagnus angustifolia. We studied a plant growth index, spore density and hyphal length density of AMF, the Na⁺ contents and ultrastructure of root cells, as well as rhizosphere soil enzyme activities of mycorrhizal and non-mycorrhizal E. angustifolia seedlings under different salt stress. Under salt stress, growth of E. angustifolia with mycorrhizal inoculation was higher than that of non-inoculated treatments. The spore density and hyphal length density decreased significantly under salt stress in rhizosphere soil of mycorrhizal E. angustifolia seedlings (p < 0.05). The root cells of E. angustifolia seedlings inoculated with R. irregularis at 300 mmol L⁻¹ salt had more organelles, greater integrity, and lower root Na⁺ contents than those of non-inoculated seedlings. In addition, the results showed notably higher activities of catalase, phosphatase, urease and saccharase in rhizosphere soil of the mycorrhizal seedlings in response to salinity compared to those of the non-mycorrhizal seedlings. Therefore, AMF inoculation could enhance salt stress tolerance in roots of E. angustifolia.

Cerrado soils are acidic and nutrient-poor, with high content of solubilized Al³⁺. Plants growing in these conditions may display adaptations to cope with high aluminum concentrations especially during early developmental stages. We investigated leaf nutritional status, and photosynthetic and growth characteristics during the initial establishment of Handroanthus impetiginosus (Mart. Ex Dc.) Mattos, a secondary tree species distributed in the Brazilian Cerrado. Our goal was to understand leaf-level traits related to different aluminum concentrations. H. impetiginosus plants were cultivated in four different aluminum sulfate concentrations: 0, 1, 2, and 4 mM Al, for 40 days. We performed analyses of growth, leaf gas exchange, chloroplast pigment content, and leaf mineral nutrients. We observed a linear increase of Al leaf content as a function of Al concentration in the nutrient solution. Plants grown in 1 mM Al showed a remarkable increase of K leaf content, net photosynthesis, stomatal conductance, and transpiration, while in 4 mM Al there were reductions of N, P, and K contents, gas exchange characteristics, and height. H. impetiginosus did not have mechanisms of avoidance, compartmentalization, or resistance to high Al concentrations. Indeed, this species showed a hormetic response, with low Al concentrations stimulating and high Al concentrations inhibiting plant responses.

Estimating stand transpiration of natural forests using traditional methods through up-scaling of sap flux density from sample trees based on stand sapwood area only is difficult because of the complexity of species, ages, and hierarchical structure of natural forests. To improve stand transpiration estimation, we developed an up-scaling method by considering the tree dominance effect based on the assumption that individual tree transpiration is affected by crown dominance and species, in addition to factors previously considered such as meteorological conditions, sapwood area, and soil moisture. In this study, the meteorological factors, soil moisture, and sap flux density of 15 sample trees of different species and dominance in a natural evergreen and deciduous broadleaved mixed forest were simultaneously monitored from March 2012 to February 2014 in the Karst mountain region in southwestern China. After establishing a single tree transpiration model which considers the effects of dominance and species, an up-scaling method was explored to estimate stand transpiration. The results show that the transpiration intensity increased exponentially with increasing tree dominance. The contribution to annual stand transpiration from a few dominant trees (5.4% of trees, 28.2% of basal area) was up to 65.0%. The corresponding contribution was 16.2% from sub-dominant trees (7.6% of trees, 16.2% of basal area) and 22.8% from middle- and lower-layer trees (87.0% of trees, 55.6% of basal area). The variation of individual tree transpiration was mainly (97.9%) explained by tree dominance, but very weakly by tree species. The estimated annual stand transpiration was 300.2 mm when using the newly developed method which considers tree dominance, 52.5 mm (14.9%) lower than the estimation (352.7 mm) of traditional method which considers only the sapwood area effect, and 8.5 mm (2.7%) lower than the estimation (308.6 mm) which considers the effects of both species composition and sapwood area. The main tree characteristics affecting stand transpiration are tree size (sapwood area) and dominance. Consideration of tree dominance will significantly improve stand transpiration estimation and provide a more solid basis for guiding integrated forest–water management at stand scale.

Proteome analysis of embryo and endosperm of Givotia moluccana, a promising angiosperm tree species was carried out using two-dimensional electrophoresis combined with matrix-assisted laser desorption/ionization time of flight to identify differentially abundant proteins and their possible functions. The study revealed the presence of 492 protein spots in the embryo and 432 in the endosperm, and the relative abundance of 44 spots varied significantly between the two. Of the 21 functionally characterized protein spots, 14.3% were involved in metabolism and energy, 28.6% in protein destination and storage, 14.3% in defense and stress and 19% in cell growth and division. The embryo-specific protein ATP-dependent zinc metalloprotease FtsH is predicted to be involved in chloroplast biogenesis and the endosperm-specific protein hydroxyacyl-ACP dehydratase in fatty acid synthesis. These results suggested that the seeds have proteins required for germination and for stress responses.

The objective of this study was to compare eco-physiological and morphological parameters of a regionally endangered orchid species, Epipactis atrorubens (Hoffm. ex Bernh.) Bess., growing in two forest communities (on serpentine and granite outcrops) of the Middle Urals, Russia. Biodiversity, dominance, and phytocoenosis studies showed the colonization of a wide range of plant species on both sites. The physicochemical properties of the soil, chemical composition and morphological features of E. atrorubens, growing under technogenic conditions (asbestos deposits), on serpentine outcrops and in the natural environment of the granite massif were studied for the first time. The serpentine substrate differed from the granite one by its greater stoniness, circumneutral pH and lower contents of available nitrogen and phosphorus. Extremely high concentrations of magnesium were found in the serpentine soil, some 79 times higher than in the granite substrate. High concentrations of nickel (94 times), chromium (59 times), cobalt (17 times), and iron (4 times) were found in the serpentine substrate, higher than in the granite substrate. The differences between the sites for available metal contents and for root and shoot metal contents were significantly less. Concentrations of most of the metals in the roots were higher than in the shoots. Despite higher metal concentrations and lower nitrogen and phosphorus levels in serpentine soils, E. atrorubens had a larger population and greater viability compared to those growing on granite. Plants on serpentine outcrops were characterized by the formation of a larger number of fruits, greater root lengths and thicker leaf blades, compared to plants on granites. The well-developed orchid mycorrhizae contributed to the survival of this species under unfavorable serpentine conditions. Hence, serpentine outcrops formed due to the mining of asbestos could be a suitable substrate for the light-demanding E. atrorubens due to its capacity to adapt to dry, rocky, nutrient-depleted soils and limited competition from other plants.

Restoration activities in semi-arid Mediterranean areas like Greece face many obstacles, such as summer droughts that are becoming more intense with climate change, that pose limitations to transplanting success. Seedlings for restoration must be of high quality; a vigorous root system is critical to enable seedlings to tolerate adverse conditions. Here we investigated the effects of altitude and source parent for seeds on the growth of subsequent seedlings to determine the best seed sources for obtaining highest-quality, most-tolerant seedlings for restoration efforts. Seeds of Quercus coccifera L. were collected on an altitudinal gradient of 50 m (200, 250 and 300 m a.s.l.) and from specific parents at each altitude. Subsequent seedlings were grown for 3 months in a greenhouse with controlled irrigation. The results indicated a strong altitudinal and parental seed effect on seedling characteristics. As altitude decreased, biomass of the seedlings increased, and they developed more vigorous roots and more photosynthetic leaf tissue. Thus, altitude and parent are critical factors to consider when producing seed-derived seedling. By collecting seeds from a specific altitude and parent, more vigorous and stress-tolerant seedlings can be obtained to enhance transplanting success.

This study quantified the effect of weeding frequency and weeding schedules on weeding operation time in a sugi (Cryptomeria japonica) plantation stand. A weeding operation time estimation model was developed; then the cumulative weeding operation time after six growing seasons was simulated using the developed model. The developed model included weed height, relative height of weeds to sugi, and initial planting density. The simulated cumulative weeding operation time decreased approximately 6% for each one-treatment decrease in weeding frequency. Under a three-treatment weeding frequency scenario, the simulated cumulative operation time when weeding was conducted during non-consecutive years was longer than that when weeding was conducted during three consecutive years. The results suggest that carrying out weeding treatment during consecutive years is the more effective for reduction of weeding costs. We conclude that weeding schedule as well as weeding frequency must be considered for reduction of weeding operation time.

Rubber [Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg.] plantations are the largest cultivated forest type in tropical China. Returning organic materials to the soil will help to maintain the quality and growth of rubber trees. Although many studies have demonstrated that organic waste materials can be used to improve soil fertility and structure to promote root growth, few studies have studied the effects of organic amendments on soil fertility and root growth in rubber tree plantations. Here, bagasse, coconut husk or biochar were applied with a chemical fertilizer to test their effects on soil properties after 6 months and compared with the effects of only the chemical fertilizer. Results showed that the soil organic matter content, total nitrogen, available phosphorus and available potassium after the chemical fertilizer (F) treatment were all significantly lower than after the chemical fertilizer + bagasse (Fba), chemical fertilizer + coconut husk (Fco) or chemical fertilizer + biochar (Fbi) (p < 0.05). Soil pH in all organic amendments was higher than in the F treatment, but was only significantly higher in the Fbi treatment. In contrast, soil bulk density in the F treatment was significantly higher than in treatments with the organic amendments (p < 0.05). When compared with the F treatment, soil root dry mass increased significantly by 190%, 176% and 33% in Fba, Fco and Fbi treatments, respectively (p < 0.05). Similar results were found for root activity, number of root tips, root length, root surface area and root volume. Conclusively, the application of bagasse, coconut husk and biochar increased soil fertility and promoted root growth of rubber trees in the short term. However, bagasse and coconut husk were more effective than biochar in improving root growth of rubber trees.

Clonal propagation of eucalypts has considerable importance due to the increasing demands for short rotation tree crops. Rooting quality is important as it governs the soil exploitation capacity of the plant and the anchorage of trees which are susceptible to wind damage. This study assesses the quality of adventitious rooting by coppice cuttings of commercially important Eucalyptus clones using multiple attribute ranking of the differences in parameters of root growth. The effects of different concentrations of indole-3-butyric acid (IBA) on root development were observed. Cuttings were treated with 500, 1000, 4000, 6000 mg L⁻¹ IBA and tannic acid for 10 s, 2 h and 24 h. Total length of root systems, number of roots, shoot to root ratios, number of root segments, extent of forking, rooting percentage, average root diameters, and number of root tips were measured. Grey relational analysis was used to create a comparability sequence to rank treatments. Reducing the concentration of auxin (IBA) and increasing the length of exposure produced better quality roots in Eucalyptus camaldulensis and interspecific hybrids (reciprocal hybrids of E. tereticornis and E. camaldulensis), while the opposite was observed with E. tereticornis clones. A root quality index was proposed, based on the Dickson quality index for the assessment of root system characteristics and considered total mass, shoot: root ratios, total length of root systems, and average root diameters. It has the advantage of implementation convenience. A positive correlation was obtained between grey relational analysis grades and root quality index. Rooting dynamics were studied by evaluating the total length of the root system at seven-day intervals and plotting daily current and medium increments using regression analysis. The curves showed the variation in growth rates among the different clones, and their intersection gave the optimal time of permanence (time at which further growth is restricted) which varied considerably. The highest daily current increment was 35–40 days for all clones.

Nutrient loading in the fall is a practical way to improve seedling quality and has been proven to increase nutrient accumulation, translocation and utilization. Few studies have reported on the variation in free amino acids as a result of fall fertilization, especially for different seasonal needle habits (evergreen, deciduous). Therefore, a balanced two-factor factorial design with one fall fertilization treatment (10 mg N/seedling) and Chinese pine (Pinus tabulaeformis Carr.) and Prince Rupprecht’s larch (Larix principis-rupprechtii Mayr.) seedlings was used to examine growth response over one nursery season. Associated changes between fall fertilization, N storage and free amino acids were analyzed. Results showed that: (1) stem height, diameter and biomass for both species were similar between controls and fall fertilization treatments; (2) compared to controls, fall fertilization increased Chinese pine needle and root N by 17.7% and 36.9%, respectively. For Prince Rupprecht’s larch, fall fertilization resulted in 26.3% and 34.54% more N in stem and roots, respectively, than controls; (3) the three main amino acids in control and fertilization treatments in Prince Rupprecht’s larch seedlings were glutamine, arginine and proline, and in Chinese pine seedlings were glutamine, arginine and γ-amino butyric acid; (4) total amino acid contents were not significantly increased by fall fertilization, but glutamine in Chinese pine and Prince Rupprecht’s larch increased by 64.2% and 35.2%, respectively. Aboveground biomass of Prince Rupprecht’s larch had higher proline contents than Chinese pine, which suggests that the stress resistance of the aboveground tissue may be higher for Prince Rupprecht’s larch. The results indicate that different plant organs with various response are well adapted to nitrogen loading for nutrient storage in evergreen and deciduous conifer seedlings.

High-elevation, snow-dependent, semiarid ecosystems across southwestern United States are expected to be vulnerable to climate change, including drought and fire, with implications for various aspects of the water cycle. To that end, much less is known about the dynamics of transpiration, an important component of the water cycle across this region. At the individual-tree scale, transpiration is estimated by scaling mean sap flux density by the hydroactive sapwood area (SA). SA also remains a key factor in effectively scaling individual tree water-use to stand level. SA across large spatial scales is normally established by relating SA of a few trees to primary size measures, e.g., diameter at breast height (DBH), tree height (H), or canopy diameter (CD). Considering the importance of SA in scaling transpiration, the primary objective of this study was therefore to establish six species-specific (aspen, maple, white fir, ponderosa pine, Douglas fir, Englemann spruce) allometric relationships between SA and three primary size measures (DBH, CD, or H) across two high-elevation, snow-dependent, semiarid ecosystems in New Mexico and Arizona. Based on multiple statistical criteria (coefficient of determination, index of agreement, Nash–Sutcliffe efficiency) and ease of measurement in the forest, we identified DBH as the primary independent variable for estimating SA across all sites. Based on group regression analysis, we found allometric relationships to be significantly (p < 0.05) different for the same species (ponderosa pine, Douglas-fir) across different sites. Overall, our allometric relationships provide a valuable database for estimating transpiration at different spatial scales from sap flow data in some of our most vulnerable ecosystems.

Little is known of the tree and stand dynamics of varied species of planted Paulownia left unmanaged until harvest in the southeastern United States. We sought to remedy this lack of information needed by land managers to make informed decisions by investigating differences in survivorship, attained diameter breast height (DBH), diameter at ground level, total height, tree volume and stand-level volume yields of planted P. elongata, P. fortunei, and P. tomentosa in the cool-moist environment of the southern Appalachian Mountains. After 9 years, combined-species survivorship was only 27.3%. Low survivorship was likely related to several inclement weather events. P. fortunei was significantly smaller in DBH and total height. Three combined-species stem (bole) volume models were developed as functions of (1) DBH squared, (2) the product DBH squared and total height, and (3) the product diameter ground line squared and total height. Mean total volume production of unmanaged stands was greatest for P. elongata and P. fortunei 4 years after planting; by the 9th year, total volume of P. elongata was greater than the other two species. Results of our study provide managers information on productivity of three species of Paulownia that can be used for estimating plantation yields.

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is an important exotic tree species that was planted across a large part of Europe during the last century. In both experimental trials and conventional forest plantations, the trees grow at a high rate and produce high-quality timber. The present study investigated climate-growth relationships of Douglas-fir at two Italian sites that contrast in climate: a Mediterranean area in southern Italy (Mercurella site) and a cooler, moister site in the northern Apennines without summer aridity (Acquerino). The relationship between tree-ring chronologies and monthly climatic variables was evaluated by a moving average and correlation analysis. Results showed that the minimum temperature in February and in March play a key role for Douglas-fir at both sites, with a positive effect on growth. At the northern site, it is also highly sensitive to late summer temperatures (negative correlation) and spring–summer precipitation (positive correlation). Growth rates in southern latitudes were high even in Europe and in the Mediterranean environment, with low sensitivity to climatic fluctuation. On the basis of our results, further common garden experiments should test adaptation and the interaction between genetics and environment of second- or third-generation seeds from old stands across Europe such as done by the old International Union of Forest Research Organizations (IUFRO) or the European Douglas-fir Improvement Research Cooperative (EUDIREC) experimentation programmes.

Phenology is a valuable attribute of vegetation to assess the biological impacts from climate change. A challenge of phenological research is to obtain information on both high temporal resolution and fine spatial scale observations. Here, we constructed an air temperature map based on temporal merging and spatial interpolation algorithms to overcome the cloud-related problem from the MODIS LST product. Then, we derived the accumulated growing degree days (AGDD) from the constructed mean air temperature map to use as a meteorological indicator. Further, we verified the indicator with the seasonal mean air temperature and the green-up date of a Quercus mongolica forest determined from the field-based measurements. The AGDD threshold for each Q. mongolica forest when the first leaf has unfolded was detected from the EXG trajectory extracted from digital camera images. A comparison between meteorological and MODIS-derived AGDD showed good agreement between them. There was also high consistency between DoYs extracted from AGDD and EVI based on curvature K for Q. mongolica forests of 30 sampling sites throughout South Korea. The results prove that microclimatic factors such as elevation, waterbody, and land-use intensity were faithfully reflected in the reconstructed images. Therefore, the results of this study could be applied effectively in areas where microclimatic variation is very severe and for monitoring phenology of undergrowth, which is difficult to detect from reflectance imaging.

Long tree-ring chronologies can be developed by overlapping data from living trees with data from fossil trees through cross-dating. However, low-frequency climate signals are lost when standardizing tree-ring series due to the “segment length curse”. To alleviate the segment length curse and thus improve the standardization method for developing long tree-ring chronologies, here we first calculated a mean value for all the tree ring series by overlapping all of the tree ring series. The growth trend of the mean tree ring width (i.e., cumulated average growth trend of all the series) was determined using ensemble empirical mode decomposition. Then the chronology was developed by dividing the mean value by the growth trend of the mean value. Our improved method alleviated the problem of trend distortion. Long-term signals were better preserved using the improved method than in previous detrending methods. The chronologies developed using the improved method were better correlated with climate than those developed using conservative methods. The improved standardization method alleviates trend distortion and retains more of the low-frequency climate signals.

The distribution, quantification and fluxes of Pb were examined in an evergreen broadleaved forest in western Greece for three hydrological years. More specifically, concentrations and annual fluxes of Pb were determined in bulk and throughfall deposition as well as litterfall. The Pb concentrations were also measured in forest floor and mineral soil up to 80 cm and the isotopic ratios of ²⁰⁶Pb/²⁰⁷Pb were determined in soil layers and the parent rock material. High variability in the fluxes of the metal among the three hydrological years were found, evidence of the variability of Pb deposition in time. Litterfall fractions with a large surface area, like holm oak flowers, had high Pb concentrations. Applying a steady state model and considering the Pb amounts in throughfall and litterfall as inputs on the forest floor, the mean residence time of Pb in the forest floor was 94 years with a coefficient of variation equal to 41%. More observations are needed to lower the variability of the mean residence time. The isotopic ratio in the rock material was defined as the lithogenic ratio. The statistical tests showed that the petrol derived Pb migrated to the depth of 20 cm and its percentages in the soil pedon was in the range of 62% in the L horizon to 11% in the 10–20 cm layer. In higher depths (> 40 cm) preindustrial anthropogenic Pb affected the isotopic ratio. As the forest under consideration is remote from industrial activities, the results can serve as a baseline for future studies on Pb distribution and quantification.

The present study examines the extent of negative effects of traditional multiple land-use systems on oak coppices, from a forest management point of view. The study area was located in approximately 10,000 ha of hilly Brant’s oak (Quercus brantii Lindl.) woodlands in the central Zagros Mountains. In the same site-quality class, three land-use systems were compared: simple coppice (Co), coppice in conjunction with small ruminant grazing (CoG), and coppice with understory rain-fed wheat cultivation plus grazing (CoCG). Data on total wood volume of trunk and major branches, and annual ring growth, were collected and analyzed from 74 stands in 15 coppiced woodland patches. The results showed the advantage of Co over CoG and CoCG land-uses by 43 and 60 m³ of mean accumulated wood volume per hectare, respectively. The diameter growth analysis also revealed an annual increase in wood production of trees in Co land-uses over 43 years, with an exception of the recent decade, when growth coincided with a severe drought. Using a back-extrapolation method, the minimum rotation age of woodlands in Co land-use was found to be 23.6 years, 5 and 7 years shorter than those of CoG and CoCG land-uses, respectively. Unlike CoCG, woodlands located in Co and CoG land-use systems demonstrated a high level of agreement with self-thinning rule of − 3/2. Values for the stand density index for coppiced oak woodlands were between more than 1000 for the least disturbed (Co) and less than 400 for the most disturbed woodlands (CoCG). The structure and growth rate of the coppiced oak woodlands were irreversibly disrupted by understory tillage plus grazing and in less extent by grazing alone. It was concluded that ending undergrowth cultivation in semi-arid oak coppices should be addressed as a priority by adopting minimum regulations.

The Himalayas are characterized by a broad gradient of bioclimatic zones along their elevation. However, less is known how forest growth responds to climatic change along elevation. In this study, four standard tree-ring width chronologies of Himalayan fir (Abies spectabilis) were developed, spanning 142–649 years along an elevation gradient of 3076–3900 m a.s.l. Principal component analysis classified the four chronologies into two groups; the ones at lower elevations (M1 and M2) and higher elevations (M3 and M4) show two distinct growth trends. Radial growth is limited by summer (June–August) precipitation at M3, and by precipitation during spring (March–May) and summer at M4. It is limited by spring temperatures and winter precipitation (December–February) at M1. Tree-ring width chronologies also significantly correlate with winter and spring Palmer Drought Severity Index (PDSI) at M1, and with summer PDSI at M3 and M4. Thus, Himalayan fir growth at high elevations is mainly limited by moisture stress rather than by low temperatures. Furthermore, the occurrence of missing rings coincides with dry periods, providing additional evidence for moisture limitation of Himalayan fir growth.

Taxus wallichiana Zucc. (Himalayan yew) is subject to international and national conservation measures because of its over-exploitation and decline over the last 30 years. Predicting the impact of climate change on T. wallichiana’s distribution might help protect the wild populations and plan effective ex situ measures or cultivate successfully. Considering the complexity of climates and the uncertainty inherent in climate modeling for mountainous regions, we integrated three Representative Concentration Pathways (RCPs) (i.e., RCP2.6, RCP4.5, RCP8.5) based on datasets from 14 Global Climate Models of Coupled Model Intercomparison Project, Phase 5 to: (1) predict the potential distribution of T. wallichiana under recent past (1960–1990, hereafter “current”) and future (2050s and 2070s) scenarios with the species distribution model MaxEnt.; and (2) quantify the climatic factors influencing the distribution. In respond to the future warming climate scenarios, (1) highly suitable areas for T. wallichiana would decrease by 31–55% at a rate of 3–7%/10a; (2) moderately suitable areas would decrease by 20–30% at a rate of 2–4%/10a; (3) the average elevation of potential suitable sites for T. wallichiana would shift up-slope by 390 m (15%) to 948 m (36%) at a rate of 42–100 m/10a. Average annual temperature (contribution rate ca. 61%), isothermality and temperature seasonality (20%), and annual precipitation (17%) were the main climatic variables affecting T. wallichiana habitats. Prior protected areas and suitable planting areas must be delimited from the future potential distributions, especially the intersection areas at different suitability levels. It is helpful to promote the sustainable utilization of this precious resource by prohibiting exploitation and ex situ restoring wild resources, as well as artificially planting considering climate suitability.

Climate warming is expected to influence forest growth, composition and distribution. However, accurately estimating and predicting forest biomass, potential productivity or forest growth is still a challenge for forest managers dealing with land-use at the stand to regional levels. In the present study, we predicted the potential productivity (PP) of forest under current and future climate scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) in Jilin province, northeastern China by using Paterson’s Climate Vegetation and Productivity (CVP) index model. The PP was validated by comparing it with the mean and maximum net primary production calculated from light energy utilization (GLM_PEM). Our results indicated that using the CVP index model is partially valid for predicting the potential forest productivity in northeastern China. PP exhibited obvious spatial heterogeneity varying from 4.6 to 8.9 m³ ha⁻¹ year⁻¹ with an increasing tendency from northwest to southeast driven by the precipitation across the region. The number of vegetation-active months, precipitation and insolation coefficient were identified as the primary factors affecting PP, but no significant relationship was found for warmest temperature or temperature fluctuation. Under future climate scenarios, PP across the Jilin Province is expected to increase from 1.38% (RCP2.6 in 2050) to 15.30% (RCP8.5 in 2070), especially in the eastern Songnen Plain (SE) for the RCP8.5 scenarios.

The primary challenge of mineland revegetation is the establishment of species able to cope with low availability of nutrients, especially in steep slopes such as of mine pits. We evaluated plant growth response and nutrient use efficiency (NUE) of two promising native Fabaceae species (Dioclea apurensis—liana from metalliferous savannas; Bauhinia longipedicellata—tree from Amazon rainforest) from the Carajás Mineral Province, eastern Amazon-Brazil. Plants were grown separately in 2-kg pots filled with mining waste. Substrates were fertilized with nitrogen, phosphorus, potassium (NPK), lime, and micronutrients. The results showed increments on growth of both species when nutrients were applied to the mining waste. D. apurensis showed increases in leaf area, plant height, stem diameter, and shoot dry mass production when NPK or NPK + micronutrients were applied, while B. longipedicelata was responsive to application of NPK + lime or NPK + lime + micronutrients. Further, D. apurensis showed higher NUE than B. longipedicelata, especially at the lowest doses of N, P and K. These findings may indicate a substantial advantage of D. apurensis for mineland revegetation, as this species may require lower nutrient inputs, being, therefore, a more sustainable way to revegetate degraded areas.

The interactive effects of ozone, soil nutrient availability and root microorganisms on physiological, growth, and productivity traits were studied for the first time for Japanese larch (Larix kaempferi) seedlings grown in containers over a growing season, using a free air ozone-concentration enrichment exposure system. High nutrient availability altered leaf and root nutrient dynamics and enhanced plant growth; however, it also enhanced seedling susceptibility to damping-off disease compared to low nutrient availability. Negative effects of elevated ozone, as compared with ambient ozone, on leaf gas exchange and plant stem form were neither offset nor exacerbated by soil nutrient availability and root colonizers. Such negative effects suggest that elevated ozone may have implications for ecological health even when plant vigor is limited by factors other than ozone. Inoculation of roots with ectomycorrhizae had negligible influence on the effects of either soil nutrient availability or ozone. However, this lack of effect may be upon impeded formation of complete mycorrhizal root tips due to factors other than the manipulated variables. B and Na appeared to have an important role in stress responses, so further studies to examine their link with physiological mechanisms as a function of time. This study provides an important perspective for designing forestry practices to enhance seedling health.

Forest soils have high carbon densities compared to other land-uses. Soil carbon sequestration is important to reduce CO₂ concentrations in the atmosphere. An effective climate change mitigation strategy involves limiting the emissions of greenhouse gases from soils. Khyber Pakhtunkhwa is the most forested province of Pakistan, hosting about one-third of the country’s 4.5 × 10⁶ ha forest area. Soil organic carbon in the province’s forests was estimated through a field-based study carried out during 2014–17 covering the whole province. Data was collected from 373 sample plots laid out in different forest types using a stratified cluster sampling technique. The total quantity of soil organic carbon was estimated at 59.4 × 10⁶ t with an average of 52.4 ± 5.3 t/ha. About 69% of the total soil carbon is present in temperate forests. Subtropical broad-leaved and subtropical pine forests constitute 11.4% and 8.8% of the soil carbon stock respectively. Similarly, subalpine and oak forests have respective shares of 5.1% and 5.7% in the soil carbon pool. The lowest carbon stock (0.1%) was found in dry-tropical thorn forests. The highest soil carbon density was found in subalpine forests (69.5 ± 7.2 t/ha) followed by moist temperate forests (68.5 ± 6.7 t/ha) and dry temperate forests (60.7 ± 6.5 t/ha). Oak forests have carbon density of 43.4 ± 7.1 t/ha. Subtropical pine, subtropical broad-leaved and dry tropical thorn forests have soil carbon densities of 36.3 ± 3.7, 32.8 ± 6.2 and 31.5 ± 3.5 t/ha, respectively. The forests of the Khyber Pakhtunkhwa province have substantial amounts of soil carbon which must be conserved for climate change mitigation and maintenance of sound forest health.

Understanding the dynamics of soil carbon is crucial for assessing the soil carbon storage and predicting the potential of mitigating carbon dioxide from the atmosphere to the biomass and soil. The present study evaluated variations of soil carbon stock in semi-arid forests in India under different moisture regimes. Soil organic carbon (SOC) and soil inorganic carbon (SIC) stocks were determined in different moisture regimes i.e. monsoon, post-monsoon, winter and pre-monsoon seasons at 0–10 and > 10–20 cm depths. SOC stock showed significant variations under different moisture regimes. The highest SOC stock was during winter (22.81 Mg C ha⁻¹) and lowest during the monsoon season (2.34 Mg C ha⁻¹) among all the ridge forests under study. SOC and SIC stock under different moisture regimes showed significant negative correlation with soil moisture (p < 0.05), as a sudden increase in soil moisture after rainfall results in an increase in carbon loss due to microbial decomposition of accumulated carbon during the dry period. There was an increase in annual SOC stock and a decrease (or no change in some cases), in SIC stock at both the depths during the study period. The SOC and SIC sequestration rates were estimated as any increase/decrease in the respective stock during each successive year. SOC sequestered ranged between 0.046 and 0.741 Mg C ha⁻¹ y⁻¹. Similarly, SIC sequestration ranged between 0.013 and 0.023 Mg C ha⁻¹ y⁻¹ over all ridge forests up to 20 cm depth. The Delhi ridge forests, which accounts to 0.007% of the semi-arid regions of India, contribute 0.25–0.32% of the national potential (semi-arid region) for SOC sequestration up to 20 cm depth. The estimates of the rate of C sequestration in this study provide a realistic image of carbon dynamics under present climatic conditions of semi-arid forests, and could be used in developing a database and formulating new strategies for carbon dioxide mitigation by enhancing soil C sequestration rates.

A total of 900 soil samples were collected from five habitats, including primary coniferous broad-leaved mixed forests, secondary coniferous broad-leaved mixed forests, secondary broad-leaved forests, secondary shrub forests, and cutover lands in spring, summer, and autumn to quantify responses of soil Collembolans (springtails) to the restoration of vegetation of temperate coniferous and broad-leaved mixed forests. The results reveal that the taxonomic composition of Collembolans varied in the different stages of vegetation restoration. Seasonal variations were in regard to their abundance and richness. High similarities existed in Collembola communities at different stages of vegetation restoration, and distribution patterns of Collembola taxa displayed an evenness throughout all habitats. Soil Collembolans tended to gather on litter layers and soil surface; the highest abundance was found in the upper 5 cm soil layer during the initial stages of vegetation recovery. Tomocerus, Proisotoma, and Folsomia genera responded positively to the restoration of vegetation. However, responses of Ceratophysella and Parisotoma genera were negative. In addition, the Onychiuridae family did not respond to the vegetation restoration process. It was concluded that restoration of vegetative cover can increase the abundance of soil Collembolans, but different genera respond differently.

Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver, increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest (SDTF) tree community. We evaluated the relationship between microscale edaphic variations and floristic–structural patterns of tree communities in a SDTF fragment located in the southern end of the Brazilian Caatinga domain. Vegetation and soil data were obtained through 27 sample units of 400 m² (20 m × 20 m), within each one we measured and identified at species level all arboreal individuals with Circumference at the Breast Height greater or equal to 10 cm, and also collected the soil samples. Through the data we evaluated soil variation influence on the tree community structural and floristic patterns trough generalized linear models.Soil explained the small-scale structural and floristic variations, contributing significantly to biomass, sprouting and to floristic relationships between sample units. It was also observed a possible relation of the result with the Caatinga domain biogeographic history, due the presence of Sedimentary Caatinga species, which are not expected for the study region. Soil plays an important role in driving small-scale complexity and diversity of SDTF, but we also suggest that Caatinga biogeographic events have influence on the high heterogeneity patterns.

Root activity has an important impact on soil development but we have little knowledge of the interaction of the root zone and soil genetic horizons. The aim of this investigation was to study the interactions between soil chemical characteristics and root zone processes in a declining Persian oak forest (Quercus brantii Lindl.). A randomized complete block design was used to investigate the long-term effect of Persian oak on soil horizons, and the chemical and biological properties in two soil zones (under and outside the canopy). Results indicate that the rhizosphere zone had significantly higher total organic carbon (TOC) than outside the canopy soil in the upper soil horizons. In subsurface horizons, water-extractable organic carbon values were significantly higher in rhizosphere than in non-rhizospheric zone. Microbial biomass carbon (MBC) values in the rhizospheric zone decreased from the first to the second horizon. The MBC/TOC ratio indicated significant differences between the rhizosphere and soils outside of the canopy, with the exception of the subsurface horizon. In the subsurface horizon of the rhizosphere, there was greater respiration of organic carbon (∑CO₂/TOC) than in outside of canopy soil. In addition, root processes influenced pH, nitrogen fractions, and availability of phosphorus, potassium, iron, zinc and manganese. Differences in soil characteristics between rhizospheric and non-rhizospheric zones were significant in surface horizons due to higher root density than in deeper soil layers. The findings indicate that Persian oak (Quercus brantii Lindl.) roots influenced the main soil chemical properties, even in calcareous soils.

Deforestation or clear-cut logging affects forest ecosystems, including soil microbial communities. The purpose of this study was to investigate the effects of clear-cut logging on the soil bacterial community in a temperate deciduous broad-leaved forest on Mt. Sambong, South Korea. We investigated the physicochemical characteristics and bacterial diversity of the soil in clear-cut logging and control sites. The available phosphorus (AP) level in soil was significantly lower in the clear-cut sites than in the control; however, the other physicochemical properties of soil were similar at the two sites. By examining the bacterial 16S rRNA gene using next-generation sequencing, we found that the number of bacterial taxa at the species and phylum level were similar at the control and clear-cut sites. Consistent with the high resilience of bacterial communities and absence of change in the soil physicochemical properties—with the exception of AP—we found similar levels of bacterial diversity at the two sites. Although most taxa showed similar composition ratios at the control and the clear-cut sites, some taxa such as Deltaproteobacteria, Ktedonobacteriales, Myxocccales, Polyangiaceae, Pedosphaera_f, and Solibacter showed differences after clear-cut logging. We conclude that AP was significantly associated with those bacterial taxa that showed differences in their composition ratios following clear-cut logging.

Soil microbial biomass is an important indicator to measure the dynamic changes of soil carbon pool. It is of great significance to understand the dynamics of soil microbial biomass in plantation for rational management and cultivation of plantation. In order to explore the temporal dynamics and influencing factors of soil microbial biomass of Keteleeria fortunei var. cyclolepis at different stand ages, the plantation of different ages (young forest, 5 years; middle-aged forest, 22 years; mature forest, 40 years) at the Guangxi Daguishan forest station of China were studied to examine the seasonal variation of their microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) by chloroform fumigation extraction method. It was found that among the forests of different age, MBC and MBN differed significantly in the 0–10 cm soil layer, and MBN differed significantly in the 10–20 cm soil layer, but there was no significant difference in MBC for the 10–20 cm soil layer or in either MBC or MBN for the 20–40 cm soil layer. With increasing maturity of the forest, MBC gradually decreased in the 0–10 cm soil layer and increased firstly and then decreased in the 10–20 cm and 20–40 cm soil layers, and MBN increased firstly and then decreased in all three soil layers. As the soil depth increased, both MBC and MBN gradually decreased for all three forests. The MBC and MBN basically had the same seasonal variation in all three soil layers of all three forests, i.e., high in the summer and low in the winter. Correlation analysis showed that MBC was significantly positively correlated with soil organic matter, total nitrogen, and soil moisture, whereas MBN was significantly positively correlated with soil total nitrogen. It showed that soil moisture content was the main factor determining the variation of soil microbial biomass by Redundancy analysis. The results showed that the soil properties changed continuously as the young forest grew into the middle-aged forest, which increased soil microbial biomass and enriched the soil nutrients. However, the soil microbial biomass declined as the middle-age forest continued to grow, and the soil nutrients were reduced in the mature forest.

To obtain accurate spatial distribution maps of soil organic carbon (SOC) and total nitrogen (TN) in the Hetian Town in Fujian Province, China, soil samples from three depths (0–20, 20–40, and 40–60 cm) at 59 sampling sites were sampled by using traditional analysis and geostatistical approach. The SOC and TN ranged from 2.26 to 47.54 g kg⁻¹, and from 0.28 to 2.71 g kg⁻¹, respectively. The coefficient of variation for SOC and TN was moderate at 49.02–55.87% for all depths. According to the nugget-to-sill ratio values, a moderate spatial dependence of SOC content and a strong spatial dependence of TN content were found in different soil depths, demonstrating that SOC content was affected by both extrinsic and intrinsic factors while TN content was mainly influenced by intrinsic factors. Indices of cross-validation, such as mean error, mean standardized error, were close to zero, indicating that ordinary kriging interpolation is a reliable method to predict the spatial distribution of SOC and TN in different soil depths. Interpolation using ordinary kriging indicated the spatial pattern of SOC and TN were characterized by higher in the periphery and lower in the middle. To improve the accuracy of spatial interpolation for soil properties, it is necessary and important to incorporate a probabilistic and machine learning methods in the future study.

Compacted soil has an adverse effect on plant roots and affects water and nutrient availability. However, different degrees of soil compaction may be suitable for growth and development of different understory species. This study determined whether soil compaction could explain characteristics of 10 different Dahurian larch (Larix gmelinii Rupr.) forest types in the Daxing’anling area. The relationship of soil compaction to soil depth was also studied. Forty-five tests were conducted on soil compaction of the 10 forest types with multiple comparisons, of which five showed no significant differences. At different soil depths, there were significant differences in soil compaction among forest types. The correlation between the degree of soil compaction and depth was positive and significant. The Larix gmelinii—shrub forest type, L. gmelinii—herb forest type, and L. gmelinii—swamp forest type were significantly different in soil compaction according to soil depth. This research indicates that, as a physical property, soil compaction may be used to explain forest distribution spatial variabilities.

Prunus africana is an endangered medicinal species and has been classified as a priority for domestication in Cameroon. However, the seeds rapidly lose their viability during storage at room temperature after 2–3 months. This study aimed to improve seed germination of P. africana by germinating at different temperatures (4 °C, 28 °C) using different concentrations of growth stimulators (sodium nitrate and gibberellic acid) and different concentrations of salts. P. africana seeds had 91.7% germination at 4 °C after 1 month of storage. Growth regulators considerably influenced germination after 6 months and reached 66.0% with 10 mM gibberellic acid and 100% with 10 mM sodium nitrate. Approximately three shoots per seed were developed, an indication of polyembryony. Histochemical analyses revealed the presence of protein-like bodies close to the embryo axis and accumulations of starch after 7 days of germination. After 14 days, amyloplasts and dark protein bodies of various sizes were observed. The outcome of this study will contribute to improve the germination of P. africana for better domestication and conservation.

Araucaria angustifolia (Bertol.) Kuntze is a representative species of the Mixed Ombrophilous Forest in the Atlantic Forest Biome of Brazil. The development of a germplasm conservation protocol for long-term seed bank storage is compromised for this species, as it is sensitive to desiccation. Furthermore, in situ establishment of a soil seed bank in its natural habitat may be limited. This study evaluates the storability of two provenances of A. angustifolia seeds and their behavior in an artificial soil seed bank in two forest environments (understory and edge). Results show that both seed provenances may be stored at 5 °C for approximately 12 months, retaining high viability. The subsequent decrease in germination was associated with a reduction and an increase in seed water content, as well as with increased electrical conductivity. In the understory environment, seed viability was above 85% for the first 60 days, and at the end of the experiment (270 days), seedlings emerged. However, at the forest edge, there was a total loss of seed viability after 120 days associated with a reduction in water content and high predation. It is concluded, therefore, that short-term storage of A. angustifolia seeds is possible in a cold room, which is fundamental to supply seed demand outside the production period. Forest cover conservation is important for regeneration and conservation of the species.

Primary dormancy of seeds of Korean pine (Pinus koraiensis Sieb. et Zucc.) after dispersal in the autumn and the induction of secondary dormancy the first summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China. This study was to determine how changes in the levels of abscisic acid (ABA) and gibberellic acid (GA) maintain primary and secondary dormancy of Korean pine seeds under germination conditions. We transferred seeds with one of five primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA, GA₁₊₃ (GA₁ and GA₃) and GA₄₊₇ (GA₄ and GA₇) in the seed coat, megagametophyte and embryo during incubation. Seed coat ABA levels in primary dormant seeds (PDS) and ABA levels in various parts of secondary dormant seeds (SDS) gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released. GA₄₊₇ and GA₁₊₃ levels in embryos greatly decreased 35% and 24%, respectively, during incubation of SDS, and thus, the ratio of ABA to GA₄₊₇ in embryos and megagametophytes significantly increased. The ratio of ABA to GA₁₊₃ in various parts of SDS increased slightly during incubation. In contrast, in seeds for which secondary dormancy was already released, GA₄₊₇ and GA₁₊₃ levels in the embryo, GA₄₊₇/ABA ratio in the embryo and seed coat, and the GA₁₊₃/ABA in the embryo and megagametophyte significantly increased during incubation. There was no trend in the changes in the levels of ABA, GA₄₊₇ or GA₁₊₃ in embryos and megagametophytes of PDS or the levels of GA₄₊₇ or GA₁₊₃ in megagametophytes of SDS during incubation. The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds. Maintenance of secondary dormancy involves a reduction of GA₄₊₇, GA₁₊₃, GA₄₊₇/ABA, and GA₁₊₃/ABA and the retention of high ABA levels.

Seed distribution and deposition patterns around parent trees are strongly affected by functional traits and therefore influence the development of plant communities. To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain, we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a temperate forest in the Changbai Mountain. Among 480,598 seeds belonging to 12 families, 17 genera, and 26 species were identified, only 54% of the species with mature trees in the community were represented in seeds collected over the 9 years, indicating a limitation in seed dispersal. Understory species were most limited; overstory species were least limited. Species with wind-dispersed seed had the least limitation, while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species; fleshy-fruited species had stronger dispersal limitations than dry-fruited species. Generalized linear mixed models showed that relative basal area had a significant positive effect on seed abundance in traps, while the contribution of diaspore traits was low for nearly all groups. These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here. These findings strengthen the knowledge that tree traits are key in explaining seed deposition patterns, at least at the primary dispersal stage. This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in temperate forests.

This study was conducted to determine the parent–offspring genetic structure of the pedunculate oak (Quercus robur L.), sessile oak (Q. petraea [Matt.] Liebl.) and their hybrids. Forty half-sib Quercus families and their maternal trees originating from one tree stand in southern Lithuania were analyzed using SSR and RAPD markers. Based on a preliminary study of leaf morphological traits, the individuals separated into six groups. The studied half-sib oak families were also compared for allelic diversity, including group variations; genotypic structure; genetic diversity; and the degree of genetic subdivision and differentiation. The level of genetic variation and subdivision was lower in the hybrid families than in the families of the parental species. Genotypic analysis of the half-sibling offspring showed the asymmetric nature of interspecific hybridization processes of pedunculate and sessile oaks in mixed stands.

Larix olgensis A.Henry is a fast-growing tree used for afforestation in northeastern China and has great ecological and economic value. For studying developmental genes in the xylem of this species, we investigated the Myb transcription factor family, one of the largest families of transcription factors in plants, which plays an important role in the regulation of lignification in plant secondary walls. By sequencing a L. olgensis cDNA library using the Illumina HiSeq2500 high-throughput sequencing platform, we obtained 58,683 unigene sequences, of which 16,554 unigenes were longer than 1000 bp, accounting for 28.2% of the total database. The alignment of these genes with the GO, COG, KEGG, Swiss-Prot and NR databases resulted in annotated 29,350 unigenes. We obtained a total of 1460 differentially expressed genes, of which 453 were upregulated and 1007 were downregulated at the two developmental stages analyzed. The gene annotations showed a wide range of biological functions and metabolic pathways. The 10 Myb transcription factors that were obtained from the differentially expressed genes were analyzed by real-time quantitative PCR (qRT-PCR). The results showed that four Myb transcription factors may be associated with xylem development in L. olgensis. Due to the large genome size of conifers, genomics research on these species has lagged behind that for other plant groups. Our data provide the basis for further studies on xylem development in L. olgensis.

Idesia polycarpa Maxim. var vestita Diels. is a dioecious tree species native to eastern Asia. There are difficulties associated with distinguishing the sex of the plant at the seedling stage. In order to explore the mechanism of sex differentiation in flower development, we conducted the transcriptome profiles of male and female flowers at early, metaphase and late developmental stages. Approximately 123,335 unigenes with a total length of 83,996 Mb and an average length of 168 bp were assembled. The unigenes were blasted into Nr, Nt, Pfam, KOG/COG, Swiss-prot, KEGG, GO databases. Homology analysis demonstrated that I. polycarpa and black cottonwood had the highest homology with the alignment of 92,871 sequences. This study identified 80 groups of transcription factor families with a total of 1475 unigenes, mainly including MYB, WRKY, AP2 and bHLH transcription factor families. KEGG pathway analysis showed that the expression of numerous plant hormones (cytokinin, gibberellin and ethylene) and flavonoid biosynthesis pathway were different at various stages of female and male flower development. In addition, a number of unigenes associated with flowering were identified which were key genes associated with photoperiodic, vernalization, thermosensory, gibberellin, and autonomic pathways. The results show that I. polycarpa floral organ development was in accordance with the ABCDE model, in which the down-regulation of the B gene family might affect stamen fertility in late stages of female flower development. qRT-PCR experiments validated that the expression patterns of 15 unigenes were consistent with those in RNA-seq results. The results highlight a central role for plant sex identification in seedling production and a sex-determining mechanism for dioecious plants. In addition, the transcriptome data provided a theoretical basis for I. polycarpa genetic diversity analysis and molecular- assisted breeding.

Changes in forest biomass and soil organic carbon reserves have strong links to atmospheric carbon dioxide concentration. Human activities such as livestock grazing, forest fires, selective logging and firewood extraction are the common disturbances that affect the carbon dynamics of the forest ecosystems. Here, we hypothesized that such anthropogenic activities significantly reduce the carbon stocks and accumulation rates in the tropical highland forests of the Sierra Madre de Chiapas in Southern Mexico. We sampled the Pinus oocarpa Scheide dominated forests within the elevation range of 900 to 1100 m above sea level in 2010, 2014 and 2017. We measured the stand structural properties and used the reported allometric equations to calculate the tree carbon stocks. Stock change approach was used to calculate carbon accumulation rates. The results showed a gradual increase in carbon storage over the 7-year period from 2010 to 2017, but the rate of increase varied significantly between the study sites. The aboveground carbon stock was 107.25 ± 11.77 Mg ha⁻¹ for the site with lower anthropogenic intensity, compared to 74.29 ± 16.85 Mg ha⁻¹ for the site with higher intensity. The current annual increment for the forest with lower anthropogenic intensity was 7.81 ± 0.65 Mg ha⁻¹ a⁻¹, compared to 3.87 ± 1.03 Mg ha⁻¹ a⁻¹ in the site with high anthropogenic intensity. Although at varying rates, these forests are functioning as important carbon sinks. The results on carbon accumulation rates have important implications in greenhouse gas mitigations and forest change modelling in the context of changing global climate.

In order to understand the management of regional vegetation, numerical classification and ordination are widely used to investigate community distribution and vegetation features. In particular, two-way indicator-species analysis programs (TWINSPAN) classifies plots and species into different groups. De-trended correspondence analysis (DCA) and canonical correspondence analysis (CCA) reflects the relationship between community and site conditions. Afforestation with Larix olgensis Herry. Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains. The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process. Twenty-eight L. olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method. Species composition, community structure attributes of diversity, and site conditions were analyzed. Communities were classified by TWINSPAN into five successional stages: immature, juvenile, mid-aged, near-mature and mature. Classifications were validated by DCA and CCA analysis. Site conditions such as soil and litter thickness, soil organic matter, soil density, and pH were measured. Successional stages varied in community composition and species population, accompanied by time from afforestation and a gradient of site conditions. This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions. The study showed that L. olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.

Forest fuel investigations in central and southern Siberian taiga of Scots pine forest stands dominated by lichen and feather moss ground vegetation cover revealed that total aboveground biomass varied from 13.1 to 21.0 kg/m². Stand biomass was higher in plots in the southern taiga, while ground fuel loads were higher in the central taiga. We developed equations for fuel biomass (both aerial and ground) that could be applicable to similar pine forest sites of Central Siberia. Fuel loading variability found among plots is related to the impact and recovery time since the last wildfire and the mosaic distribution of living vegetation. Fuel consumption due to surface fires of low to high-intensities ranged from 0.95 to 3.08 kg/m², that is, 18–74% from prefire values. The total amount of fuels available to burn in case of fire was up to 4.5–6.5 kg/m². Moisture content of fuels (litter, lichen, feather moss) was related to weather conditions characterized by the Russian Fire Danger Index (PV-1) and FWI code of the Canadian Forest Fire Weather Index System. The data obtained provide a strong foundation for understanding and modeling fire behavior, emissions, and fire effects on ecosystem processes and carbon stocks and could be used to improve existing global and regional models that incorporate biomass and fuel characteristics.

Fire-induced forest loss has substantially increased worldwide over the last decade. In China, the connection between forest loss and frequent fires on a national scale remains largely unexplored. In this study, we used a data set for a time-series of forest loss from the Global Forest Watch and for a MODIS-derived burned area for 2003–2015 to ascertain variations in forest loss and to explore its relationship with forest fires (represented by burned areas) at the country- and forest-zone levels. We quantified trends in forest loss during 2003–2015 using linear regression analysis and assessed the relation between forest loss and burned areas using Spearman’s correlation. Forest loss increased significantly (264.8 km² a⁻¹; R ² = 0.54, p < 0.01) throughout China, with an average annual increase of 11.4% during 2003–2015. However, the forest loss trend had extensive spatial heterogeneity. Forest loss increased mainly in the subtropical evergreen broadleaf forest zone (315.0 km² a⁻¹; R ² = 0.69, p < 0.01) and tropical rainforest zone (38.8 km² a⁻¹; R ² = 0.66, p < 0.01), but the loss of forest decreased in the cold temperate deciduous coniferous forest zone (− 70.8 km² year⁻¹; R ² = 0.75, p < 0.01) and the temperate deciduous mixed broadleaf and coniferous forest zone (− 14.4 km² a⁻¹; R ² = 0.45, p < 0.05). We found that 1.0% of China’s area had a significant positive correlation (r ≥ 0.55, p < 0.05) with burned areas and 0.3% had a significant negative correlation (r ≤ − 0.55, p < 0.05). In particular, forest loss had a significant positive relationship with the burned area in the cold temperate deciduous coniferous forest zone (16.9% of the lands) and the subtropical evergreen broadleaf forest zone (7.8%). These results provide a basis for future predictions of fire-induced forest loss in China.

Negative air ions (NAIs) benefit the mental and physical health of humans, but rapid urbanization can decrease the abundance of NAIs. Quantifying the spatial and seasonal distribution of NAIs and determining the factors that influence the concentration during urbanization is thus essential. In the present study of a typical developing urban district in southern China, negative air ion concentrations (NAICs) in 60 forests sites and 30 urban green spaces were quantified on seven consecutive days in each of the four seasons. Large seasonal variations in NAIC were revealed in forests and urban green spaces with trough values in summer. NAIC progressively decreased from forests to urban green spaces and was influenced by local land morphology, vegetation characteristics, and climatic factors. The vast, heavily vegetated northeastern region was the richest area for NAIs, whereas the narrow central region (urbanized area) was the poorest, implying dramatic impacts of urbanization on the spatial distribution of NAIs. The relationship between air temperature and NAIC was better fitted with a quadratic equation than a linear equation. Moreover, the NAIC was more sensitive to local morphology in urban green spaces than in urban forests, indicating the vulnerability of NAIs in urbanized areas. Therefore, the appropriate design of local urban morphology is critical.

Ophiostomatalean fungi may facilitate bark beetle colonization and reproduction. In the present study of the fungal community associated with bark beetle species belonging to Tomicus in Yunnan, China, six ophiostomatalean fungi (Ophiostoma canum, O. ips, O. tingens, Leptographium yunnanense, Leptographium sp. 1 and Leptographium sp. 2) were isolated from the beetles or their galleries; O. canum was the most common fungal species. The distribution of O. canum was associated with stands heavily damaged by Tomicus species and a higher percentage of valid galleries of Tomicus yunnanensis and T. minor in Yunnan pine (Pinus yunnanensis). After inoculation of Yunnan pine with the fungus, a phloem reaction zone formed and monoterpenes accumulated in the phloem. These results suggested that O. canum was pathogenic to Yunnan pine and that the wide distribution of the fungus might be beneficial to reproduction of pine shoot beetles in Yunnan pine. However, because the reaction zone and monoterpene accumulation were mild, fungal damage of Yunnan pine might be limited. A more integrated study considering all the fungal species should be done to better understand the interactions among bark beetles, blue-stain fungi, and the tree hosts in the region.

The critical antioxidant catalase (CAT) breaks down hydrogen peroxide induced by environmental stresses. Here we cloned full length catalase cDNA from Lymantria dispar asiatic (LdCAT). Bioinformatic analyses showed that open reading frames of LdCAT contains 1524 bp, encoding 507 amino acids with molecular weight of 126.99 kDa, theoretical pI of 5.00, aliphatic index of 29.92, grand average of hydropathicity of 0.764, and instability index (II) of 46.56. Protein BLAST and multiple sequence alignment indicated that LdCAT had high identity with CAT from other insects, especially lepidopterans. In a phylogenetic analysis, LdCAT was most similar to CAT from Spodoptera litura and S. exigua. Quantitative real-time polymerase chain reaction showed that LdCAT transcripts in all instar larvae and the five tissues tested, verifying the ubiquity of LdCAT in L. disapr. Moreover, LdCAT of third instar larvae was significantly upregulated after they fed on avermectin at sublethal and LC₁₀ doses. The highest relative transcript levels were found 2 h after an avermectin spray at LC₉₀, and in the cuticula, rather than heads, fat bodies, malpighian tubes, and midguts after a spray avermectin at a sublethal concentration. The expression level of LdCAT under pesticide stresses here suggested that CAT is an important antioxidant enzyme of L. disapr defensing against pesticide stress and may be a good target for controlling this pest.

Chinese hackberry (Celtis sinensis Pers.) is an adaptable species widely growing in southern China. The symptoms of canker on stems of seedlings were discovered mid-July 2017 in Shuyang, Jiangsu Province. The diseased portions of the stems were dark brown due to discoloured xylem. Some seedlings showed symptoms of wilting, leaf fall, twig dieback, and tissue discolouration. The outbreak period was concentrated in July and August, suggesting that the disease spread during summer months. Possible fungal causal agents were isolated from naturally infected canker tissue and discoloured xylem. The isolate from xylem tissue with a high frequency (> 50%) was named Ls7 type. Pathogenicity tests were carried out on 4-year-old seedlings. The symptoms of canker began to develop 20 days after inoculation with Ls7 isolate and by day 35, there were dark, enlarged longitudinal lesions. A phylogenetic tree of the isolate was developed using the internal transcribed spacer, elongation factor-1α (tef1-α), β-tubulin gene (TUB) and RNA polymerase II subunit primer genes (RPB2). Based on morphological features and phylogenetic information, the pathogen was identified as Lasiodiplodia pseudotheobromae. This is the first report of L. pseudotheobromae causing canker on Chinese hackberry stems in China.

During a helminthological study of waterfowl in China, a new species (Cloacotaenia cygnimorbus sp. nov.) of hymenolepidid cestodes (tapeworm) was found in the small intestine of whooper swan (Cygnus cygnus, Linnaeus, 1758). The rudimentary rostellum and four unarmed muscular suckers, proglottids with distinct craspedote and three spherical testes were coincident with the characters of Cloacotaenia or Hymenolepis, but phylogenetic analysis of 28S rRNA and cox1 gene revealed that the new species is Cloacotaenia rather than Hymenolepis. Its morphology was also clearly differentiated from C. megalops in the arrangement of its testes in a triangle instead of in line and the cirrus unarmed rather than spined. Compared with C. megalops, the new species has more elongated neck, much larger mature proglottids and much smaller testes, cirrus sac, ovary, vitellarium and uterine proglottid. In addition, it infected the host intestine not the cloacae. Phylogenetic analysis of cox1 gene of the new species shows that it had a level of sequence variation (10.52–23.06%) with the sequences of C. megalops. The considerable morphological and molecular differences between those two parasites support C. cygnimorbus sp. nov. as a new species.

This study evaluated boron diffusion from raw boron minerals ulexite and colemanite with low water solubility in comparison to disodium octaborate tetrahydrate (DOT). Tests were conducted using sugi (Cryptomeria japonica (L.) f. D. Don) sapwood and heartwood blocks conditioned to 30, 60, and 90% target moisture content. The blocks were filled with the boron compounds through treatment holes and diffusion was observed at three assay zones across the blocks after 7, 30, 60 or 90-day incubation period at room temperatures. For comparison, ethylene glycol was also introduced into the holes to elevate boron diffusion. As expected, diffusion increased with increased moisture content and levels were higher at the 60% and 90% moisture levels compared to the 30% level. With some exceptions, boron levels did not follow consistent gradients with distance away from the treatment hole. Incorporation of ethylene glycol helped increase boron levels, even in heartwood blocks. Boron levels were higher from the ulexite source than from colemanite; however, DOT treatments resulted in the highest boron diffusion rates as a result of greater water solubility compared to both raw boron minerals. The results suggest that ulexite together with ethylene glycol may be useful in both sapwood and heartwood materials when kept at high moisture levels for extended periods.

Larch wood is structurally classified in many countries as one of conifers with the highest load-bearing capacity (strength class of C30). The Spanish visual classification regulation only assigns a strength class to 4 pine woods: Laricio pine (Pinus nigra Arn. var. Salzmannii), Silvestre pine (Pinus sylvestris L.), Radiata pine (Pinus radiata D. Don), and Pinaster pine (Pinus pinaster Ait.). This work adds to the number of structurally characterised species by creating a visual classification table for Japanese larch wood (Larix kaempferi (Lamb.) Carr.) which differentiates between 2 visual classes, MEG-1 and MEG-2. Characteristic strength values were calculated for each class (f _k,MEG-1 = 31.80 MPa, f _k,MEG-2 = 24.55 MPa), mean module of elasticity (E _0,mean,MEG-1 = 13,082 MPA, E _0,mean,MEG-2 = 12,320 MPA) and density (ρ _k,MEG-1 = 456.6 kg m⁻³, ρ _k,MEG-2 = 469.1 kg m⁻³), before finally assigning a strength class of C30 to visual class MEG-1, and a strength class of C24 to visual class MEG-2.