Black locust (Robinia pseudoacacia L.) was the first North-American tree species imported to Europe at the beginning of the seventeenth century. It is commonly planted worldwide because of its adaptability to environmental stresses, its valuable wood, easy propagation, frequent and abundant seed production, excellent coppicing, high seedling survival, and relatively high wood yield. In Europe, Romania and Hungary have the most highly-developed black locust growing techniques and experiences. As a result of increasing interest in black locust in many countries, this review aims to provide a comprehensive overview of state-of-the-art site requirements, propagation, improvement and management (including growth and yield as well as use in energy plantations).

The taiga coniferous forests of the Siberian region are the main carbon sinks in the forest ecosystems. Quantitatively, the size of the carbon accumulation is determined by the photosynthetic productivity, which is strongly influenced by environmental factors. As a result, an assessment of the relationship between environmental factors and photosynthetic productivity makes it possible to calculate and even predict carbon sinks in coniferous forests at the regional level. However, at various stages of the vegetative period, the force of the connection between environmental conditions and the productivity of photosynthesis may change. In this research, correlations between the photosynthetic activity of Scots pine (Pinus sylvestris L.) with the environmental conditions were compared in spring and in autumn. In spring, close positive correlation of the maximum daily net photosynthesis was identified with only one environmental factor. For different years, correlations were for soil temperature (r _s = 0.655, p = 0.00315) or available soil water supply (r _s = 0.892, p = 0.0068). In autumn within different years, significant correlation was shown with two (temperature of air and soil; r _s = 0.789 and 0.896, p = 0.00045 and 0.000006, respectively) and four factors: temperature of air (r _s = 0.749, p = 0.00129) and soil (r _s = 0.84, p = 0.00000), available soil water supply (r _s = 0.846, p = 0.00013) and irradiance (r _s = 0.826, p = 0.000001). Photosynthetic activity has a weaker connection with changes in environmental factors in the spring, as compared to autumn. This is explained by the multidirectional influence of environmental conditions on photosynthesis in this period and by the necessity of earlier photosynthesis onset, despite the unfavorable conditions. This data may be useful for predicting the flow of carbon in dependence on environmental factors in this region in spring and in autumn.

The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 × 5 × 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation—E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g⁻¹ of the residue for H. courbaril and 0.27 mmol g⁻¹ of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.

Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under future global climate change. In this study, the ecophysiological parameters of saplings and trees of Fraxinus mandshurica Rupr. were measured at different levels of nitrogen addition in a temperate forest. The results show that ecophysiological parameters maximum net photosynthetic rate (P _max), apparent quantum efficiency (α), dark respiration (R _d), light saturation point (L _sp), photosynthetic nitrogen use efficiency (PNUE), specific leaf area (SLA) and stomatal conductance under saturated light intensity (G _smax) were higher in saplings than in trees. These physiological parameters and not N _leaf (leaf nitrogen content) led to relatively lower P _max and R _d in trees. For both saplings and trees, low and median nitrogen addition (23 and 46 kg ha⁻¹a⁻¹) resulted in significant increases in P _max, R _d, L _sp, Chl, PNUE, SLA and G _smax. These parameters tended to decline under high additions of nitrogen (69 kg ha⁻¹a⁻¹), whereas N _leaf was always enhanced with increasing nitrogen. Variations in P _max and R _d with increasing nitrogen were attributed to variations in the strongly related parameters of, L _sp, Chl, PNUE, SLA and G _smax. Overall, the response sensitivity of physiological parameters to enhanced nitrogen levels was lower in trees compared with saplings.

Araucaria angustifolia (Bertol.) O. Kuntze exhibits dimorphism in its stem structure, where the trunk is orthotropic and branches and branchlets (primary and secondary branches) are plagiotropic. These stems exhibit different behavior when used for vegetative propagation, and only segments of trunk can form a complete plant. The physiological and biochemical mechanisms that characterize these stems are still little known. The aim of this study was to describe the free amino acid profiles in trunks, branches, and branchlets of A. angustifolia. Segments of 5 cm in length were excised from young individuals below the stem apex. The needles were removed and samples were frozen and lyophilized. The determinations were made by high-performance liquid chromatography, and the results were expressed as µg/g fresh weight (FW). The trunks and branches had the highest content of total amino acids, which were 112.23 ± 20.57 µg/g FW and 111.97 ± 27.78 µg/g FW, respectively. The amino acids—glutamine, aspartate and γ-aminobutyric acid and tyrosine—were noticeably higher in the three types of stems. In the trunk, a higher amount of asparagine and tryptophan, was also detected. Glutamic acid and glutamine were found in higher quantities in the branches. The branchlets had very low total amino acid content (30.79 ± 4.19 µg/g FW), wherein asparagine is the only amino acid not detected. Thus, it was observed that the profile of the free amino acid differs among trunks, branches, and branchlets in A. angustifolia, indicating that they perform different functions.

Larix olgensis A. Henry (Changbai larch) is a productive commercial species and good candidate for afforestation in northeast China. It is widely planted in lead-stressed soils which can induce oxidative damage in this plant. Increasing tolerance to lead (Pb) stress is therefore of keen interest. A greenhouse experiment was conducted to identify the biomass, physiological responses and Pb accumulation of L. olgensis seedlings to Pb stress under succinic acid (SA) application and to explore the interaction of exogenous SA applications and stress resistance. L. olgensis seedlings were planted in Pb-stressed or unstressed haplic cambisols in pots. In Pb-contaminated soils the seedlings were treated daily with concentrations of SA solutions at a rate approximately equivalent to 0, 0.04, 0.2, 1.0, or 2.0 mmol kg⁻¹ of soil for 10, 20, and 30 days, respectively. Pb treatment induced damage in the seedlings and led to the inhibition of biomass accumulation in roots, stems and leaves, and a rise in Pb accumulation in fine roots and leaves. Malondialdehyde (MDA) content and electrolyte leakage in leaves significantly increased while peroxidase (POD) activities, soluble protein and photosynthetic pigment contents in leaves were all reduced. Physiological toxicity was promoted with increasing Pb treatment times. When Pb-stressed seedlings were exposed to SA (especially 10.0 mmol L⁻¹ over 20 days), the physiological responses for Pb-only were reversed and the biomass of roots, stems, and leaves dramatically increased. SA facilitated Pb uptake in fine roots and leaves but more Pb accumulated in fine roots. The results demonstrate that exogenous SA alleviates Pb-induced oxidative injuries and improves the tolerance of L. olgensis seedlings to Pb stress.

The impacts of elevated temperature and CO₂ on young silver birch (Betula pendula Roth) saplings after 0, 25, 50 or 75% artificial defoliation were assessed by measuring plant height and dry mass of aboveground compartments and roots and various morphological and physiological variables. Defoliation either increased or decreased plant growth depending on the severity of damage and the climatic treatment. At 21 °C and 400 mg L⁻¹ CO₂, defoliated plants were not able to compensate for the lost foliage, but growth compensation and adaptation to the changed conditions were greater; growth of young defoliated silver birch saplings increased, which led to increased height and a tendency to enhance final aboveground and root biomass and leaf nitrogen and carbon content compared to the nondefoliated controls. Nevertheless, the short-term effect of the different climatic conditions did not result in a significant overgrowth of defoliated plants. A slight increase in temperature and CO₂ were the most acceptable conditions for defoliated plants; however, a 4 °C increase with correspondingly higher CO₂ was more stressful as shown by less growth in height and biomass allocation to leaves, stems and roots. The findings from the pilot experiment are more applicable to young birch trees, but stress on young trees may be reflected in future tree growth.

Tree improvement programs on loblolly pine (Pinus taeda) in the southeastern USA has focused primarily on improving growth, form, and disease tolerance. However, due to the recent reduction of design values for visually graded southern yellow pine lumber (including loblolly pine), attention has been drawn to the material quality of genetically improved loblolly pine. In this study, we used the time-of-flight (TOF) acoustic tool to assess the effect of genetic families on diameter, slenderness, fiber length, microfibril angle (MFA), velocity and dynamic stiffness estimated using green density (DMOE_G) and basic density (DMOE_B) of 14-year-old loblolly pine stands selected from two sites. All the 184 and 204 trees of the selected eight half-sib genetic families on sites 1 and 2 respectively were tested using TOF acoustic tool, and two 5 mm core samples taken at breast height level (1.3 m) used to for the anatomical and physical properties analysis. The results indicated a significant positive linear relationship between dynamic MOEs (DMOE_G and DMOE_B) versus tree diameter, slenderness, and fiber length while dynamic MOEs negatively but nonsignificant correlated with MFA. While there was no significant difference in DMOE_B between sites; velocity² for site 1 was significantly higher than site 2 but DMOE_G was higher for site 2 than site 1. Again, the mean DMOE_G and DMOE_B reported in the present study presents a snapshot of the expected static MOE for green and 12% moisture conditions respectively for loblolly pine. Furthermore, there were significant differences between families for most of the traits measured and this suggests that forest managers have the opportunity to select families that exhibit the desired fiber morphology for final product performance. Lastly, since the dynamic MOE based on green density (DMOE_G), basic density (DMOE_B) and velocity² present difference conclusions, practitioners of this type of acoustic technique should take care when extrapolating results across the sites.

Since the generation of full-sib artificial triploid families, rapid clone establishment and genetic improvements have been needed. Here, we report an in vitro method of direct shoot regeneration of a triploid hybrid poplar [(Populus simonii × P. nigra ‘Italica’) × (P. × ‘popularis’)]. Using different randomized block designs, we selected one triploid to evaluate the explant type, optimal concentrations of plant growth regulators and agar, and culture time under light or dark conditions over 60 days. The highest rate of shoot induction, 80.0%, was obtained using Murashige and Skoog (MS) medium supplemented with 0.2 mg/L benzyladenine, 0.04 mg/L naphthaleneacetic acid (NAA), and 5.5 g/L agar for the first 30 days in the dark, then 3 g/L agar for the next 30 days in light. This last medium yielded the best rate of shoot induction (6.32 shoots/explant). These three media were also used to evaluate the influence of the genotypes of the parents and hybrid triploids on regeneration. Two parents and three of the four full-sib triploids were regenerated successfully; different genotypes and explant types significantly affected the rate of shoot induction and average number of shoots. Leaves but not petioles were a suitable explant. One genotype produced the highest rate of shoot induction of 96.67%. Half-strength MS medium supplemented with 0.2 mg/L indole butyric acid and 0.04 mg/L NAA was the most effective for rooting; rooting rate was 96.67%, survival rate of transplants was 73.33%, and rooting frequency surpassed 85% for each genotype. Overall, this in vitro regeneration system will be useful for the propagation and genetic modification of triploid poplars.

Physiological responses and changes in growth of Indocalamus decorus Q.H.Dai under different ecological conditions are essential for further understanding growth regulation and adaptive mechanisms and establishing an evidence-based management system for optimal growth. In this study, the endogenous hormone content in tillering stem bases, germination of lateral buds, and biomass allocation of this bamboo species in different growth environments were investigated. Among the endogenous hormones in the basal stems of tillers, indole-3-pyruvic acid and zeatin riboside were highly correlated with lateral buds that germinated to form shoots, while gibberellic acid was highly correlated with lateral buds that germinated to form rhizomes. The best lateral bud germination characteristics were achieved with full sun, a density of six plantlets per pot, and watering every 6 days. I. decorus plantlets used different resource allocation strategies depending on treatment. Different ecological factors influenced endogenous hormones in the bamboo stem base, which affected lateral bud germination and biomass allocation.

‘Zhongqiusucui’ jujube secondary shoots were treated with 3-indolebutyric acid (IBA) at three concentrations, 500, 1000 and 1500 mg/L. Results show that IBA could significantly enhance rooting and root characteristics of cuttings and were best with IBA at 1500 mg/L. In the rooting process, the formation of adventitious roots was related to the consumption and accumulation of nutrients (soluble sugars and proteins) and the changes in endogenous hormones in phloem, leaf tips and leaf bases. The rooting of cuttings had a positive correlation with the consumption of soluble sugars during the period of callus formation and with the accumulation of soluble sugars during adventitious root formation and growth. Rooting was positively related to the breakdown of soluble proteins in the phloem when the callus formed, and had a positive correlation with its accumulation during adventitious root formation and growth. Leaf tips and leaf bases showed a reverse trend in changes of soluble protein. However, together with the phloem, leaf tips and leaf bases regulated and controlled the formation and development of adventitious roots. The main activities of soluble proteins exist in the leaf tips as this was the main source of soluble proteins. The relation between rooting and IAA (indole-3-acetic acid) content in phloem was positive and thus a high concentration of IAA could benefit the induction and formation of adventitious roots. However, rooting was negatively related with ABA (abscisic acid) and GA (gibberellic acid) and a high concentration of both could inhibit the induction and formation of adventitious roots. Rooting had a positive correlation with phloem IAA/ABA ratios, and higher ratios could improve rooting. Low concentrations of ZR (zeatin riboside) triggered the induction of adventitious roots, while higher concentrations promoted root growth. Endogenous hormones in leaf tips and bases had an impact on rooting. The activities of endogenous hormones mainly existed in leaf tips because they play a major role in the production and consumption of IAA and its ABA content increased during rooting. The ZR in leaf tips influenced the rooting of cuttings, especially in the callus formation and rooting stage. Leaf tips were the main source of GA.

This study in the dry tropical woodlands of SE Angola in Cuando-Cubango Province assessed the diversity and composition of woody species in fallows compared to those in mature woodlands. We assessed the population structure of the most harvested woody species by calculating size class distribution and evaluated their regeneration potential based on the density of saplings. The vegetation was surveyed in 20 plots of 20 × 50 m (1000 m²). In each plot, we measured the diameter at breast height (DBH) of all woody species with DBH ≥ 5 cm. The saplings were counted, identified and recorded; 718 individuals, corresponding to 34 species in 32 genera and 15 families were recorded. The size class distribution of target woody species showed three different patterns in fallows and mature woodlands. In general, most of the smaller diameter classes had more individuals than the larger ones did, showing that the regeneration may take place. However, in some diameter classes, the absence of larger stems indicated selective logging of larger trees. Few saplings were recorded in the fallows or mature woodlands; fire frequency and intensity is probably the main obstacle for seed germination and seedling survival rates in the studied area.

With embryogenic callus of Larix olgensisis, we investigated the effects of inositol, glutamine, casein hydrolysate, carbohydrate, abscisic acid and silver nitrate concentration on the maturation of the somatic embryo. Three dominant factors emerged, and we developed a response surface model based on the Box–Behnken design. We defined the optimal conditions for the maturation of somatic embryos. The contents of abscisic acid, silver nitrate, sucrose and casein hydrolysis significantly affected the amount of maturing embryos, but inositol, maltose and glutamine had no effect. By establishing a response surface model with multiple factors, we predicted that the optimal number of L. olgensis somatic embryos was 204 ± 4 g⁻¹ on basal medium, containing 18.28 mg L⁻¹ abscisic acid, 5.46 mg L⁻¹ silver nitrate and 82.67 g L⁻¹ sucrose. In the verification experiments, the addition of 20 mg L⁻¹ abscisic acid, 5 mg L⁻¹ silver nitrate and 80 g L⁻¹ sucrose to BM yielded an average of 202.06 somatic embryos per gram. These results should guide large-scale breeding of L. olgensis.

This paper discusses the early silviculture of silver fir (Abies alba Mill.), a major softwood in Romania covering more than 294,000 ha. Three research plots (DRP1, DRP2 and DRP3) were established in a 25-year-old silver fir-dominated stand in May 2012. In DRP1 and DRP2, heavy cleaning-respacing were carried out while DRP3 was kept as a control. After the treatments in 2012, the plots had stocking between 1470 trees ha⁻¹ (DRP2) and 10,030 trees ha⁻¹ (DRP3), basal areas between 11.8 m² ha⁻¹ (DRP2) and 31.6 m² ha⁻¹ (DRP3). The average diameters were between 5.7 cm (DRP3) and 9.6 cm (DRP2). Measurements in September 2016 confirmed the rapid response of silver fir to cleaning-respacing. The best results in average diameter increments and basal area between 2012 and 2016 were in DRP2: 3.7 cm (36.4%) and 7.7 m² ha⁻¹ (85.0%) respectively. The largest diameter trees in 2012 were the best growers, and a strong linear correlation between the initial diameter of the remaining trees and their increment was established. Natural dieback of trees occurred only in DRP3 (8.6%). The selection of crop trees based on the vigour, quality, and spacing criteria during cleaning-respacing was possible as individuals stood out in terms of vigour and early diameter growth. An issue encountered in DRP1 and DRP2 was the occurrence of epicormic shoots, especially on less vigorous individuals with small crowns. However, four years after cleaning-respacing, these branches are small and do not significantly affect the wood quality.

The spatial pattern and abundance of herbaceous vegetation in semi-arid savannas are dictated by a complex and dynamic interaction between trees and grasses. Scattered trees alter the composition and spatial distribution of herbaceous vegetation under their canopies. Therefore, we studied the effect of Vachellia tortilis on herbaceous vegetation composition, biomass and basal area, and soil nutrients on sites with varying grazing intensities in the central rift valley of Ethiopia. Data were collected on species composition, cover and biomass of herbs and grasses, and soil moisture and nutrient contents under light, medium, and heavy grazing pressures, both under the inside and outside of V. tortilis canopies. Species richness was similar in both locations but decreased with increased grazing. Only the overall biomass and herb cover were significantly greater under the canopy than outside, and overall biomass showed significant unchanging decline with increased grazing. However, vegetation cover was significantly greater on moderately grazed sites compared to low and heavily grazed sites. All soil variables were significantly higher under V. tortilis canopies than outside. Our findings suggest that V. tortilis has more effect on composition and diversity of herbaceous vegetation than on species richness, and that V. tortilis promotes the herbaceous layer biomass by reducing soil moisture loss and increasing soil fertility under the inside than outside the canopies. Therefore, we suggest that management practices should be directed on reducing pressure on V. tortilis by regulating grazing. Low to moderate grazing levels (i.e., a stocking rate less than 39.6 TLU ha⁻¹ yr⁻¹) seems to be tolerable to ensure sustainable conservation of the species in the study area in particular and in semi-arid savannas in general.

In future decades, initiatives on biomass-based energy development in Europe should reduce fossil fuel dependence and help to combat climate change as required by the conference of the parties 21. In this context, forest biomass can play a key role within the bioenergy sector due to its high growth potential. The use of forest biomass for energy has positive and negative effects on other ecosystem services, on stand characteristics, and on forest management practices. The aim of this study is to analyse the effects of forest bioenergy production on six ecosystem services (biodiversity, recreation, landscape aesthetics, carbon sequestration, soil erosion protection, water quality). These effects have been assessed by 80 experts in two countries (Italy and Turkey), considering two different forest management practices (clear-cutting of coppices and woody residue removal after felling in high forests). The results show that coppice clear-cutting has negative effects on almost all ecosystem services according to the experts’ opinions. The highest negative effects are on landscape aesthetics and soil protection. The effects of woody residue removal on biodiversity, carbon sequestration, soil erosion protection, and water quality are considered negative by the experts, while the effects on recreation activities and landscape aesthetics are considered positive. The highest negative effects of this forest management scenario are on soil protection and biodiversity. The experts’ opinions about the effects of forest management practices on ecosystem services can provide information to understand the environmental sustainability of bioenergy development in future years.

Terrestrial ecosystems represent a major sink for atmospheric carbon (C) and temperate forests play an important role in global C cycling, contributing to lower atmospheric carbon dioxide (CO₂) concentration through photosynthesis. The Intergovernmental Panel of Climate Change highlights that the forestry sector has great potential to decrease atmospheric CO₂ concentration compared to other sectoral mitigation activities. The aim of this study was to evaluate CO₂ sequestration (CO₂S) capability of Fagus sylvatica (beech) growing in the Orfento Valley within Majella National Park (Abruzzo, Italy). We compared F. sylvatica areas subjected to thinning (one high-forest and one coppice) and no-management areas (two high-forests and two coppices). The results show a mean CO₂S of 44.3 ± 2.6 Mg CO₂ ha⁻¹ a⁻¹, corresponding to 12.1 ± 0.7 Mg C ha⁻¹ a⁻¹ the no-managed areas having a 28% higher value than the managed areas. The results highlight that thinning that allows seed regeneration can support traditional management practices such as civic use in some areas while no management should be carried out in the reserve in order to give priority to the objective of conservation and naturalistic improvement of the forest heritage.

For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors (elevation, aspect, slope, CaCO₃, K, P, C, N, C/N, bulk density, soil porosity, saturation moisture content, EC, pH, sand, silt and clay) was investigated in the Khonj forests, Fars Province, Iran. Characteristic land units, each 200 m², were chosen for sampling to analyze species composition, soil characteristics and topographic factors. The floristic data were classified using a two-way indicator species analysis (TWINSPAN). Means were then compared using an ANOVA and Duncan multiple range test to detect any variations between groups. Also, the Kaiser–Meyer–Olkin index and Bartlett test were used to measure sampling adequacy. The four vegetation groups identified comprised the species Achillea wilhelmsii, Tanacetum parthenium, Convolvulus spinosus, Capparis spinosa. A detrended canonical correspondence analysis (DCCA) ordination diagram clearly illustrated the relationship between vegetation and environmental factors. According to the results, group 1 with A. wilhelmsii as the indicator species has a positive relation with slope and elevation. T. parthenium was the indicator species of group 2, that appears in areas with high silt and low bulk density and sand. The results showed that group 3 with Convolvulus spinosus as the indicator species was distributed in soils with high bulk density, low silt and pH as well. Group 4 with C. spinosa as the indicator species occurs in sandy soils and low slopes. Using DCCA, we determined the relationship between species and environmental factors more accurately. Results of this study can be used to restore vegetation or maintain species composition in ecological sensitive areas.

Trees on sand dunes are more sensitive to environmental changes because sandy soils have extremely low water holding capacity and nutrient availability. We investigated the dynamics of soil respiration (R _s) for secondary natural Litsea forest and plantations of casuarina, pine, acacia and eucalyptus. Results show that significant diurnal variations of R _s occurred in autumn for the eucalyptus species and in summer for the pine species, with higher mean soil respiration at night. However, significant seasonal variations of R _s were found in all five forest stands. R _s changed exponentially with soil temperatures at the 10-cm depth; the models explain 43.3–77.0% of R _s variations. Positive relationships between seasonal R _s and soil moisture varied with stands. The correlations were significant only in the secondary forest, and the eucalyptus and pine plantations. The temperature sensitivity parameter (Q ₁₀ value) of R _s ranged from 1.64 in casuarina plantation to 2.32 the in secondary forest; annual R _s was highest in the secondary forest and lowest in the pine plantation. The results indicate that soil temperatures and moisture are the primary environmental controls of soil respiration and mainly act through a direct influence on roots and microbial activity. Differences in root biomass, quality of litter, and soil properties (pH, total N, available P, and exchangeable Mg) were also significant factors.

Soil chemistry influences plant health and carbon storage in forest ecosystems. Increasing nitrogen (N) deposition has potential effect on soil chemistry. We studied N deposition effects on soil chemistry in subtropical Pleioblastus amarus bamboo forest ecosystems. An experiment with four N treatment levels (0, 50, 150, and 300 kg N ha⁻¹ a⁻¹, applied monthly, expressed as CK, LN, MN, HN, respectively) in three replicates. After 6 years of N additions, soil base cations, acid-forming cations, exchangeable acidity (EA), organic carbon fractions and nitrogen components were measured in all four seasons. The mean soil pH values in CK, LN, MN and HN were 4.71, 4.62, 4.71, and 4.40, respectively, with a significant difference between CK and HN. Nitrogen additions significantly increased soil exchangeable Al³⁺, EA, and Al/Ca, and exchangeable Al³⁺ in HN increased by 70% compared to CK. Soil base cations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) did not respond to N additions. Nitrogen treatments significantly increased soil NO₃ ⁻–N but had little effect on soil total nitrogen, particulate organic nitrogen, or NH₄ ⁺–N. Nitrogen additions did not affect soil total organic carbon, extractable dissolved organic carbon, incorporated organic carbon, or particulate organic carbon. This study suggests that increasing N deposition could increase soil NO₃ ⁻–N, reduce soil pH, and increase mobilization of Al³⁺. These changes induced by N deposition can impede root grow and function, further may influence soil carbon storage and nutrient cycles in the future.

Although carbon (C), nitrogen (N), and phosphorous (P) stoichiometric ratios are considered good indicators of nutrient excess/limitation and thus of ecosystem health, few reports have discussed the trends and the reciprocal effects of C:N:P stoichiometry in plant–litter–soil systems. The present study analyzed C:N:P ratios in four age groups of Chinese pine, Pinus tabulaeformis Carr., forests in Shanxi Province, China: plantation young forests (AY, < 20 year-old); plantation middle-aged forests (AM, 21–30 year-old); natural young forests (NY, < 30 year-old); and natural middle-aged forests (NM, 31–50 year-old). The average C:N:P ratios calculated for tree, shrub, and herbaceous leaves, litter, and soil (0–100 cm) were generally higher in NY followed by NM, AM, and AY. C:N and C:P ratios were higher in litter than in leaves and soils, and reached higher values in the litter and leaves of young forests than in middle-aged forests; however, C:N and C:P ratios were higher in soils of middle-aged forests than in young forests. N:P ratios were higher in leaves than in litter and soils regardless of stand age; the consistent N:P < 14 values found in all forests indicated N limitations. With plant leaves, C:P ratios were highest in trees, followed by herbs and shrubs, indicating a higher efficiency in tree leaf formation. C:N ratios decreased with increasing soil depth, whereas there was no trend for C:P and N:P ratios. C:N:P stoichiometry of forest foliage did not exhibit a consistent variation according to stand age. Research on the relationships between N:P, and P, N nutrient limits and the characteristics of vegetation nutrient adaptation need to be continued.

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region, south India. We sampled woody trees (≥ 1 cm dbh) from 21 forest patches in the upper Nilgiri hills (> 2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs (≥ 1 to < 10 cm dbh) increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees (≥ 10 to < 30, ≥ 30 to < 60 and ≥ 60 cm dbh, respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance. Our findings suggest that with increasing forest patch area, tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns. Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area.

Poplar is useful in different climates for bioenergy production and carbon sequestration when planted as a single species or in agroforestry. Europe has large areas potentially suitable for poplar forestry and a bioenergy policy that would encourage poplar forestry. In this study I estimated biomass production and carbon sequestration in poplar monoculture plantation and poplar-wheat agroforestry, in the Mediterranean region of France. A single-tree harvesting method was used to estimate biomass and an empirical conversion factor was adopted to calculate sequestered carbon. Total biomass was higher in agroforestry trees (1223 kg tree⁻¹) than in monoculture plantation trees (1102 kg tree⁻¹). Aboveground and belowground biomass distributions were similar in both cases (89 and 88% aboveground, and 11 and 12% belowground, respectively in agroforestry and monoculture). The partitioning of total biomass in an agroforestry tree in leaves, branch, and trunk (aboveground), and fine roots, medium roots, coarse roots and underground stem (belowground) was 1, 22, and 77, and 6, 9, 44 and 40%, respectively. Except for branch and trunk, all other compartments were similarly distributed in a monoculture tree. Storage of C was higher in agroforestry trees (612 kg tree⁻¹) than in monoculture trees (512 kg tree⁻¹). In contrast, C storage on a per hectare basis was lower in agroforestry (85 Mg ha⁻¹) than in monoculture (105 Mg ha⁻¹) due to the lower density of trees per hectare in agroforestry (139 trees in agroforestry vs 204 trees in monoculture). On a per hectare basis, soil C stocks pattern were similar to per tree stocking: They were higher in agroforestry at 330 Mg ha⁻¹ than in monoculture 304 Mg ha⁻¹. Higher C accumulation by agroforestry has a direct management implication in the sense that expanding agroforestry into agriculture production areas with short rotation and fast growing trees like poplar would encourage quicker and greater C sequestration. This could simultaneously fulfil the requirement of bioenergy plantation in Europe.

This study developed allometric models to estimate aboveground biomass and carbon of Prosopis africana and Faidherbia albida. The destructive method was used with a sample of 20 trees per species for the two parkland sites. Linear regression with log transformation was used to model aboveground biomass according to dendrometric parameters. Error analysis, including mean absolute percentage of error (MAPE) and root mean square of error (RMSE), was used to select and validate the models for both species. Model 1 (biomass according to tree diameter) for P. africana and F. albida were considered more representative. The statistical parameters of these models were R ² = 0.99, MAPE 0.98% and RMSE 1.75% for P. africana, and R ² = 0.99, MAPE 1.19%, RMSE 2.37% for F. albida. The average rate of carbon sequestered was significantly different for the two species (P ≤ 0.05). The total amount sequestered per tree averaged 0.17 × 10⁻³ Mg for P. africana and 0.25 × 10⁻³ Mg for F. albida. These results could be used to develop policies that would lead to the sustainable management of these resources in the dry parklands of Niger.

We quantified the diversity of vascular plant species and described soil properties and topographical and climatic conditions of the Çitdere and Kavakli Nature Reserves in the Yenice Forest of Turkey. We used the Shannon–Weiner and Simpson’s indices of diversity, Margalef’s index of species richness and Pielou’s evenness index to quantify the structure of vascular plant assemblages. We measured soil parameters (NO₃ ⁻, NH₄ ⁺, available P, Mg⁺⁺, K⁺, Na⁺, Ca⁺⁺, organic matter, pH, soil moisture), elevation, slope gradient and aspect and their correlations with plant community parameters. In total, we recorded and identified 207 species and subspecies in the study area. Species cover, richness and diversity indices varied significantly by vegetation type (P < 0.01). Available NO₃ ⁻ and Ca⁺⁺ in the soil were important factors for the area and species representation in the species-environment correlations estimated for the Kavaklı area. Available NO₃ ⁻, pH, organic matter, Ca⁺⁺ and K⁺ in the soil were important factors for the area and species representation in the species-environment correlations analysed for the Çitdere area.

There has been growing attention to intraspecific variation in trait-based plant ecology. However, studies on these changes across ontogenetic stages and the potential trade-offs with interspecific traits along environmental gradients are rare. In this study, we measured six wood and bark traits of 1030 trees of six species (Castanopsis nigrescens; C. carlesii; Lithocarpus polystachyus; L. synbalanos; Ormosia glaberrima; O. pachycarpa) from a 10-ha plot in a subtropical forest. Mean intraspecific variation in bark thickness and bark percentage to DBH was more than twice that for wood density and bark density. Bark thickness and bark percentage showed a consistent trend with increasing tree size. Small-tree traits were more variable than the same traits in larger trees. Altitude, convexity and soil nutrients explained the majority of the variations in the six traits, while sibling species had similar relationships between traits and environmental variables. Trees with dense wood and thin bark were usually found on steep slopes at lower altitudes. Our findings show intraspecific trait variability has different spatial patterns compared with interspecific variabilities along an environmental gradient.

We tested the hypothesis that the biometrical characters of wood elements in ash trees (Fraxinus excelsior L.) become modified in response to the progression of disease caused by Chalara fraxinea. Anatomical analyses were performed on wood samples collected at breast height from the trunks of groups of ash trees which contained healthy, weakened and dead trees. We measured (1) tree-ring width, (2) earlywood vessel diameter, (3) earlywood vessel element length, (4) fibre length, (5) fibre diameter, (6) fibre lumen diameter, and (7) fibre wall thickness. We showed that tree-ring width diminished in all analysed groups during disease progression. However, the greatest suppression of growth was observed in dead trees. In both weakened and dead ash trees, the reduction in tree-ring width was accompanied by diminished vessel diameter in the earlywood of the outermost annual rings. The annual rings of dead trees had shorter fibres having greater lumen diameter and thinner cell walls. Consequently, water conduction in the sapwood of dead ash trees was less efficient owing to reduced vessel diameter, and this seems to be one of the greatest disease-induced morphological modifications. All the anatomical modifications might be due to leaf loss and crown dieback triggered by Chalara fraxinea.

A new species, Spiraea cudidaghense (sect. Spiraeoideae, Rosaceae), is described and illustrated with diagnostic characters and taxonomic comments. Its characteristics are compared with those of the type species from which it differs mainly in compound corymbs inflorescence, ovate-obovate leaves, white petals, glabrous branches and densely pilose corymbs. In addition, a map of the geographic distribution of the new species, an IUCN ranking and notes on taxonomic affinities are also provided.

Due to severe anthropogenic impacts on lowland and submontane zones of the Hyrcanian forests of northern Iran, wild grapevine (Vitis vinifera subsp. sylvestris), a sporadically distributed woody liana, is currently considered an endangered species. Using data from the literature and 34 studied populations, herbarium assessments and nine palynological sites, we provide an overview of its taxonomy, distribution and ecology in the first part of the investigation. The separation of the two subspecies, namely V. sylvestris subsp. anebophylla and V. sylvestris subsp. trichophylla (sensu Flora Iranica), based on their leaf indumentums, could not be confirmed by our examination of herbarium materials and field observations. Indumentum of the leaves is a result of leaf polymorphism in different Vitis specimens and can be strongly influenced by environmental conditions. Vitis vinifera subsp. sylvestris grows in a wide range of habitats including wetlands, seasonal stream sides in closed forests, alluvial beds of large rivers, sand dune shrublands and forested wetlands (alder forests). Parrotia persica and Carpinus betulus were the most frequent host species in the studied populations. In the Hyrcanian region, no pollen record of Vitis older than the Mid-or Late-Holocene has yet been established. Despite the intrinsic problem in pollen identification by normal (i.e., light) microscopy of wild from cultivated grapevines, the significant values and persistent occurrence of Vitis pollen since the Mid-Holocene (before the Bronze Age) in the Hyrcanian pollen records may imply the onset of viticulture in low- to mid-elevation sites in the region. This represents an argument to consider the Hyrcanian region as a possible domestication center for V. vinifera. However, the question of wild versus cultivated origin of grapevines in the Hyrcanian pollen records and the possible date of its domestication and/or cultivation will remain open until further palynological studies are undertaken.

In January 2017, symptoms of a leaf-spot disease were observed on Viscum coloratum plants in Yichun, China. The infected leaves were chlorotic, while sunken lesions formed on diseased branches, which were initially light brown and later turned dark brown. Moreover, diseased branches and leaves formed semi-buried, small, and spherical pycnidia. In total, 20 leaves and 19 branches diseased samples from Yichun, China were collected and examined. The fungus was isolated and identified using Koch’s postulates, morphological characteristics and DNA sequence data. The data presented herein confirmed that the pathogen responsible for the disease was Sphaeropsis visci. To the best of our knowledge, this is the first report of it in China.

Mongolian pine is an important afforestation species widely used for ecological management in northeast China. The environment in this region is very unstable and the flora are regularly subjected to drought stress. This paper reports on the influence of inoculation with the Suillus luteus on seedlings under different water conditions. Both inoculated and non-inoculated ectomycorrhizal fungi (ECMF)-S. luteus seedlings were maintained under well-watered or water-stress conditions for 3 months. The S. luteus colonization rate under water stress was higher than that in well-watered conditions. Under water stress, inoculated seedlings had greater growth than non-inoculated seedlings. In addition, under water stress, S. luteus-inoculated seedlings had greater superoxide dismutase and peroxidase activity, higher soluble protein content, lower proline content, and lower malondialdehyde content than non-inoculated seedlings. S. luteus colonization increased the rhizosphere soil-enzyme activity and the rhizosphere soil nutrition content under both well-watered and water-stress conditions. Given the positive impact on seedling growth and physiology, S. luteus shows potential for use in the arid and semi-arid regions of northeast China for afforestation.

Detection of wood plate surface defects using image processing is a complicated problem in the forest industry as the image of the wood surface contains different kinds of defects. In order to obtain complete defect images, we used convex optimization (CO) with different weights as a pretreatment method for smoothing and the Otsu segmentation method to obtain the target defect area images. Structural similarity (SSIM) results between original image and defect image were calculated to evaluate the performance of segmentation with different convex optimization weights. The geometric and intensity features of defects were extracted before constructing a classification and regression tree (CART) classifier. The average accuracy of the classifier is 94.1% with four types of defects on Xylosma congestum wood plate surface: pinhole, crack, live knot and dead knot. Experimental results showed that CO can save the edge of target defects maximally, SSIM can select the appropriate weight for CO, and the CART classifier appears to have the advantages of good adaptability and high classification accuracy.

Wood has no inherent natural resistance against agents of biodegradation. We evaluated the effects of metal bath heat treatment (MBHT) on decay resistance and dimensional stability of Chinese parasol (Firmiana simplex) and Chinese fir (Cunninghamia lanceolata) wood. A low melting point alloy was used as heating medium in the treatment of the wood samples at 150, 180, and 210 °C for 2, 4, and 8 h. Heat-treated and control samples were exposed to brown rot fungus (Poria placenta) and white rot fungus (Coriolus versicolor) for decay resistance testing and anti-swelling efficiency (ASE). The improved decay resistance with increase temperatures with low mass losses of 7.3 and 7.3% for F. simplex, and 3.9 and 3.6% for C. lanceolata at 210 °C for 8 h against Coriolus versicolor and Poria placenta, respectively. ASE indicated that MBHT contributed to improved dimensional stability of both wood species after treatment. Scanning electron micrograph results indicate that metal bath-treated samples showed strong decay resistance. Therefore, our approach to thermally modify wood should be explored to overcome the energy utilization by using low melting point alloy for the heat treatment of wood.

Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h, respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time. Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.

In order to investigate the temperature characteristics of wood during microwave (MW) treatments, optical fiber sensors were used to measure wood (Pinus sylvestris L. var. mongolica Litv.) temperatures. The results show that the development of internal temperatures in wood basically includes two patterns during the process of MW treatment. The first may be divided into three phases: warming, constant temperature, and a sharply rising phase. The second pattern may be divided into two phases: warming, and constant temperature. The maximum temperature (MT) and rate of temperature increase (RTI) rose as the microwave power increased. The initial wood moisture content decreased while the period of constant temperature fell. Temperatures varied in different positions in the wood. The order of MT and RTI levels were the upper surface, center, bottom surface and the end point. Along the direction of wood thickness, the closer the monitoring point was to the generator, the faster the temperature increased. The MT and RTI of the end point was a minimum value because of the rapid removal of steam.