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.

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 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.

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.

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.

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.

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.