Due to increasing timber demands, large areas of secondary forests have been converted to larch plantations (LPs) in Northeast China because the secondary forests could not produce timber as much as LPs. However, there are a series of ecological problems such as lower soil fertility, reduced water-holding capacity and acidification of surface runoff water occurring in LPs because of the single-species composition of LPs. Therefore, a guidance on how to transform LPs into larch-broadleaf mixed forests (LBMFs) at a large spatial scale is needed for local foresters. First, Landsat time series data set and SPOT-5 images were combined to map the spatial–temporal distribution of LPs in Northeast China. Then, the topographical characteristics of LPs in 2010s were determined. Furthermore, three sub-regions of LPs were divided closely linking to their ecosystem services and forest management aims. Finally, detailed information on how to transform the LPs into LBMFs was given according to the three sub-regions. The results showed that the area of LPs increased during 1980s and 2010s, and reached 2.61 million ha in 2010s. Of which, 0.72 million ha (27.6%) and 1.89 million ha (72.4%) LPs distributed in slopes less than 5° and greater than 5°, respectively. Of the LPs (72.4%) in slopes greater than 5°, 48.7 and 23.7% located in downslope (LPs locating at the down slope of adjacent secondary forests in the same aspect) and upslope (LPs locating at the up slope of adjacent secondary forests in the same aspect), respectively; 0.10 million ha (3.8%) located in slopes greater than 25°. The LPs were divided into Sub-Regions-I, II, III according to slopes. For Sub-region-I (top role is to produce timber), self-fertilizing shrub species can be introduced after clean cutting for young-aged LPs, and release thinning can be applied for middle-aged LPs, fast growth thinning for near-matured LPs, and clear cutting for matured LPs. For Sub-Region-II (the priority is to provide water conservation combined with timber production), the LPs should be induced into LBMFs. The LPs located the downslope positions in Sub-Region-II can be transformed to LBMFs by natural regeneration of broadleaved tree species after thinning because of enough seed sources of broadleaved tree species from the secondary forests locating the upslope positions. The LPs located the upslope positions or the region where seed sources of broadleaved tree species are unavailable in Sub-Region-II must be induced to LBMFs by artificial regeneration. For Sub-Region-III (the preference is only for water conservation because the slope is greater than 25°), the LPs should be particularly protected from intensive disturbances, and induced into LBMFs by natural regeneration.

Nutrient resorption before abscission is an important nutrient conservation mechanism regulated by climatic conditions and soil nutrients. However, our current understanding of leaf nutrient resorption is primarily derived from site-specific studies or from the use of green-leaf nutrient concentrations to represent those in soils. It remains unknown how nutrient resorption responds to natural soil-nutrient concentrations at a global scale. The effects of plant functional groups, climatic conditions, and soil nutrients and their interactions on leaf nutrient resorption are also unknown. In this study, we established a global database derived from 85 published papers, including 547 reports of nitrogen and phosphorus resorption efficiency (NRE and PRE), climatic factors (LAT, latitude; MAT, mean annual temperature; MAP, mean annual precipitation) and soil-nutrient data (STN, soil total nitrogen; STP, soil total phosphorus) across 111 research sites. The results demonstrated that mean NRE and PRE were 48.4 and 53.3%, respectively. NRE of trees was lower than those of shrubs. NRE and PRE of coniferous species were both higher than those of broad-leaved species. Evergreen species had higher PRE than did deciduous species. NRE was negatively related to STN, but PRE and STP were not related. Both NRE and PRE decreased with increasing MAT and MAP but increased with increasing LAT. Plant functional groups, climate and soil nutrients jointly explained 22 and 32% of the variations in NRE and PRE, respectively. It is important to note that climate (especially MAT) explained 12 and 29% of the variations in NRE and PRE, respectively, implying that continuing global warming will exert an increasingly profound influence on plant nutrient cycles.

Understanding the impact of plant litters on soil nitrogen (N) dynamics could facilitate development of management strategies that promote plantation ecosystem function. Our objective was to evaluate the effects of different litter types on N mineralization and availability, microbial biomass, and activities of l-asparaginase and o-diphenol oxidase (o-DPO) in soils of a poplar (Populus deltoides) plantation through 24 weeks of incubation experiments. The tested litters included foliage (F), branch (B), or root (R) of poplar trees, and understory vegetation (U) or a mixture of F, B, and U (M). Litter amendments led to rapid N immobilization during the first 4 weeks of incubation, while net N mineralization was detected in all tested soils from 6 to 24 weeks of incubation, with zero-order reaction rate constants (k) ranging from 7.7 to 9.6 mg N released kg⁻¹ soil wk⁻¹. Moreover, litter addition led to increased microbial biomass carbon (C) 49–128% and increased MBC:MBN ratio by 5–92%, strengthened activities of l-asparaginase and o-DPO by 14–74%; Up to about 37 kg N ha⁻¹ net increase in mineralized N in litter added soils during 24 weeks of incubation suggests that adequate poplar and understory litter management could lead to reduced inputs while facilitate sustainable and economic viable plantation production.

Previous studies showed that Chaetomium globosum ND35 fungus fertilizer can improve the microbial community structure and enzyme activities of replanted soil. However, it remains unclear whether can improve the physiological and ecological characteristics of plants under successive rotation. In this study, we investigated the photosynthetic, physiological, and biochemical indexes including photosynthetic parameters, chlorophyll fluorescence, and chlorophyll content of 1-year-old poplar seedlings under seven different doses (range from 0 to 1.67 g kg⁻¹) of C. globosum ND35 fungus fertilizer to study the effects of fungus fertilizer on photosynthesis of Poplar. Our results showed that: (1) With increasing application of fungus fertilizer in replanted soil, chlorophyll content of poplar leaves (Chl) increased, while physiological indexes such as electron transport rate (ETR), net photosynthetic rate (P _n), quantum efficiency (Φ), nitrate reductase (NR) activity and root vigor initially increased and then declined. Meanwhile, heat dissipation that depended on the xanthophyll cycle declined and non-photochemical quenching (NPQ) initially increased and then decreased. When the dose of C. globosum ND35 fungus fertilizer was 0.67 g kg⁻¹ (T3) and 1.00 g kg⁻¹ (T4), excess light energy of photosynthetic apparatus was reduced, and photosynthetic apparatus distributed more light energy to the direction of photochemical reactions, which improved the efficiency of energy use. Plant height and biomass of leaves, stems, and roots were maximum at T3. We conclude that applying appropriate amounts of C. globosum ND35 fungus fertilizer can improve root physiological activity and capacity for use of light by poplar leaves. This can improve the operating states of the photosynthetic apparatus and lead to increased photosynthetic efficiency of poplar leaves and accumulation of dry matter. This suggests a strategy to alleviate the successive rotation obstacle of soil nutrient depletion.

In forest ecosystems, gap formation changes the allocation of abiotic resources and thus affects the survival and growth of understory plants. However, how tree seedling survival and growth respond to low-temperature events and the influencing mechanisms remain unclear. To clarify how low-temperature event limits the survival and growth of tree seedlings in the montane regions of eastern Liaoning Province, northeast China, we investigated temperature and light intensity within secondary forest gaps, and the survival and growth of Juglans mandshurica seedlings after a low-temperature event in the spring of 2014. Damage to seedlings due to low temperature significantly varied in different aspects. Seedlings in gaps on southeast-facing slopes were the most seriously damaged, followed by those in gaps on northeast-facing slopes. In contrast, seedlings in west-facing gaps and in control plots without slope aspect were not damaged. The freezing injury index for seedlings was negatively correlated with minimum temperature (r = − 0.608, P < 0.01), but it was positively correlated with light intensity (r = 0.818, P < 0.01). In addition, height and root collar diameter of damaged seedlings were significantly lower than those of the undamaged seedlings (P < 0.01) during the early growing season (April–July), but no significant difference were observed during the late growing season (July–October) (P > 0.05). The extent of seedling damage was directly related to slope aspect. Low temperature and high light intensity were found to be the dominant factors affecting extent of damage to seedlings on southeast- and northeast-facing slopes.

Nitrogen (N) and phosphorus (P) additions can affect soil microbial carbon (C) accumulation. However, the mechanisms that drive the changes in residual microbial C that occur after N and P additions have not been well-defined for Chinese fir plantations in subtropical China. We set up six different treatments, viz. a control (CK), two N treatments (N₁: 50 kg ha⁻¹ a⁻¹; N₂: 100 kg ha⁻¹ a⁻¹), one P treatment (P: 50 kg ha⁻¹ a⁻¹), and two combined N and P treatments (N₁P: 50 kg ha⁻¹ a⁻¹ of N + 50 kg ha⁻¹ a⁻¹ of P; N₂P: 100 kg ha⁻¹ a⁻¹ of N + 50 kg ha⁻¹ a⁻¹ of P). We then investigated the influences of N and P additions on residual microbial C. The results showed that soil pH and microbial biomass decreased after N additions, while microbial biomass increased after P additions. Soil organic carbon (SOC) and residual microbial C contents increased in the N and P treatments but not in the control. Residual microbial C accumulation varied according to treatment and declined in the order: N₂P > N₁P > N₂ > N₁ > P > CK. Residual microbial C contents were positively correlated with available N, P, and SOC contents, but were negatively correlated with soil pH. The ratio of residual fungal C to residual bacterial C increased under P additions, but declined under combined N + P additions. The ratio of residual microbial C to SOC increased from 11 to 14% under the N₁P and N₂P treatments, respectively. Our results suggest that the concentrations of residual microbial C and the stability of SOC would increase under combined applications of N and P fertilizers in subtropical Chinese fir plantation soils.

To improve the productivity of poplar plantations, a field experiment of split-plot design with four tree spacings and three poplar clones was established, and four soil enzyme activities and microbial biomass were monitored in the trial. Soil enzyme activities, in most cases, were significantly higher in topsoil (0–10 cm) than in lower horizons (10–20 cm). Soil cellulase, catalase and protease activities during the growing season were higher than during the non-growing season, while invertase activity followed the opposite trend. Soil invertase, cellulase and catalase activities varied by poplar clone but soil protease activity did not. Cellulase and protease activities in the plantation at 5 × 5 m spacing were significantly higher than in the other spacings. The highest catalase activity was recorded at 6 × 6 m spacing. At the same planting density, invertase activity was greater in square spacings than in rectangular spacings. Soil microbial biomass was also significantly affected by seedling spacing and poplar clone. The mean soil MBC was significantly lower in topsoil than in the lower horizon, while MBN showed the opposite pattern. Significantly positive correlations were observed among soil cellulase, protease and catalase activities (p < 0.01), whereas soil invertase activity was negatively and significantly correlated with cellulase, protease and catalase activities (p < 0.01). Soil microbial biomass and enzyme activities were not correlated except for a significantly negative correlation between soil MBC and catalase activities. Variations in soil enzyme activity and microbial biomass in different poplar plantations suggest that genotype and planting spacing should be considered when modeling soil nutrient dynamics and managing for long-term site productivity.

Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses (i.e. poplar-crop integrated system, poplar plantation, and cropland), from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes (5, 1 and 0. 01 mm, respectively) to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef’s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags under the same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna (3.31%). The percentage of remaining litter mass was inversely related to the density of the soil fauna (P < 0.05) in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.

The uniparental inheritance and conserved structure of the chloroplast genome among many angiosperms makes it suitable for constructing gene lineages and inferring population histories based on these relationships. However, the analysis of a single chloroplast region to solve population issues has not yielded the desired amount of variability due to the low mutation rate. Therefore, it is necessary to screen and carefully analyze chloroplast intergenic or intronic regions to select the most appropriate for studying the genetic variability in the chloroplast genome of a particular taxon. In this context, the aim of this work was to characterize 8 regions in Calophyllum brasiliense using 11 selected primer pairs and to evaluate their usefulness for phylogeographic analysis. Intergenic spacers petA-psbJ, petG-trnP and rpl32-trnL and the trnL intron demonstrated potentially informative sites. The combination of these 4 regions will allow the analysis of genetic population structure and the integration of historical aspects to inform strategies for conserving C. brasiliense, especially for highly impacted populations and those at risk of local extinction.

Information on population genetic structure and crop genetic diversity is important for genetically improving crop species and conserving threatened species. The PAL gene sequence is part of a multigene family that can be utilized to design DNA marker systems for genetic diversity and population structure investigation. In the current study, genetic diversity and population structure of 100 accessions of wild Pistacia species were investigated with 78 PAL markers. A protocol for using PAL sequences as DNA markers was developed. A total of 313 PAL loci were recognized, showing 100% polymorphism for PAL markers. The PAL markers produced relatively more observed and effective alleles in Pistacia falcata and Pistacia atlantica, with a higher Shannon’s information index and expected heterozygosity in P. atlantica, Pistacia vera and Pistacia mutica. Pairwise assessment of Nei’s genetic distance and genetic identity between populations revealed a close association between geographically isolated populations of Pistacia khinjuk and Pistacia chinensis. The accessions of wild Pistacia species had more genetic relationship among studied groups of species. Analysis of molecular variance indicated 19% among-population variation and 81% within-population variation for the PAL gene based DNA marker. Population structure analysis based on PAL revealed four groups with high genetic admixture among populations. The results establish PAL markers as a functional DNA marker system and provide important genetic information about accessions from wild populations of Pistacia species.

By screening sequence reads from the Salix suchowensis chloroplast (cp) genome that were generated by next-generation sequencing platforms, we assembled a complete circular pseudomolecule for the cp genome. This pseudomolecule is 155,508 bp long and has a typical quadripartite structure that contains two single copy regions, a large single copy region (LSC, 84,385 bp), and a small single copy region (SSC, 16,209 bp) separated by inverted repeat regions (IRs, 27,457 bp). Gene annotation revealed that the S. suchowensis cp genome encoded 119 unique genes, including four ribosome RNA genes, 30 transfer RNA genes, 82 protein-coding genes, and three pseudogenes. Analysis of the repetitive sequences revealed 31 tandem repeats, 16 forward repeats, and five palindromic repeats. In addition, a total of 148 perfect microsatellites, which were characterized as A/T dominant in nucleotide composition, were detected. Significant shifting of the IR/SSC boundaries was revealed by comparing this cp genome with those of other rosid plants. We also constructed phylogenetic trees to demonstrate the phylogenetic position of S. suchowensis in Rosidae based on 66 orthologous protein-coding genes present in the cp genomes of 32 species. Sequencing 30 amplicons based on the pseudomolecule for experimental verification revealed 99.88% accuracy for the S. suchowensis cp genome assembly. Therefore, we assembled a high-quality pseudomolecule of the S. suchowensis cp genome, which is a useful resource for facilitating development of this shrub willow into a more productive bioenergy crop.

RAPD (randomly amplified polymorphic DNA) markers were employed to characterize polymorphisms among 5 provenances of Acacia leucophloea and to detect genetic relatedness of the species with 6 other acacias (A. holosericea, A. auriculiformis, A. mangium, A. dealbata, A. ferruginea, and A. nilotica) widely grown in India. Of 194 markers scored for the provenances, 29.38% exhibited polymorphism. Also, 326 markers were generated among 7 species of Acacia, accounting for 55.82% of the polymorphisms. The fifteen 10-mer primers employed were capable of producing 1–8 polymorphic bands for the provenances, and 6–17 for all seven species of Acacia. The genetic similarity coefficient based on Jaccard’s coefficient revealed that provenances Thirumangalam and Dharmapuri were closely related. The dendrogram based on a sequential agglomerative hierarchical non-overlapping (SAHN) clustering analysis grouped 4 provenances of A. leucophloea (Dharapuram, Thirumangalam, Pudukottai and Dharmapuri) into one cluster and the other provenance, Sendurai, into a separate cluster. The genetic similarity matrix for 7 Acacia species showed that A. nilotica and A. dealbata were distantly related, while A. holosericea and A. ferruginea were very closely related. Cluster analysis grouped the species of Acacias into 3 major groups of which A. dealbata alone formed a separate group. The RAPD markers generated 36 provenance-specific markers and 162 species-specific markers that could have strong applications for species identification and tree breeding programs for A. leucophloea and for other Acacia species included in this study.

To improve wood quality for pulpwood industries, it is important to examine not only wood density but also its components, especially tracheid characteristics. We studied genetic variations in the following tracheid traits by earlywood (EW) and latewood (LW): tracheid length (TL), double wall thickness (WT), radial lumen diameter (R_D1), tangential lumen diameter (T_D1), radial central diameter (R_D2), and tangential central diameter (T_D2). We also studied the relationship with the following growth traits: diameter at breast height (DBH), height (H), crown breadth south-north axis (NSC), crown breadth east–west axis (EWC), ring width (RW), latewood percentage (LWP), and wood density (WD). All sample materials were collected from a 33-year old clonal seed orchard of Pinus tabuliformis Carr. Genetic variation among clones was moderate for all tracheid traits, 9.49–26.03%. Clones significantly affected WT, R_D1, R_D2, T_D1, T_D2, and the two ratios WT/R_D1 and TL/T_D2 in EW but had no effects in LW. Clones significantly affected TL in LW but had no effects in EW. $ H\frac{2}{C} $ was higher in LW (0.50) than in EW (0.20) for TL, while $ H\frac{2}{C} $ was higher in EW (0.27–0.46) for other tracheid traits and the two ratios (TL/T_D2 and WT/R_D1) than in EW (0.06–0.22). WD and TL were significantly positively correlated, but WT and TL were negatively correlated both at individual and clone levels; all tracheid diameters and the four ratio values (EW_WT/R_D1, LW_WT/R_D1, EW_TL/T_D2 and LW_TL/T_D2), were strongly positively correlated with DBH, H, NSC, WEC and RW, and strongly negatively correlated with WD both at individual and clone levels. The most important variables for predicting WD were LW_TL, EW_WT and R_D1 in both EW and LW (r² = 0.22). Selecting the top 10% of the clones by DBH would improve DBH growth by 12.19% (wood density was reduced by 0.14%) and produced similar responses between EW and LW for all tracheid traits: a reduction of 0.94 and 3.69% in tracheid length and increases in tracheid diameters (from 0.36 to 5.24%) and double wall thickness (0.07 and 0.87%). The two ratios WT/R_D1 and TL/T_D2 across tissues (EW and LW) declined 0.59 and 4.56%, respectively. The decreased tracheid length and the ratio between tracheid length and diameter is disadvantageous for pulp production. The unfavorable relationship of tracheid traits with wood density indicate that multiple trait selection using optimal economic weights and optimal breeding strategies are recommended for the current long-term breeding program for P. tabuliformis.

Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection. To evaluate the early selected time for Larix kaempferi, tree height and diameter at breast height of 57 L. kaempferi clones were measured over many different growth years. The results indicated that, except for age × clone interaction for diameter at breast height (P = 0.741), there were significant differences among all variation sources (P < 0.01). The coefficient of phenotypic variation ranged from 14.89 to 35.65% for height and from 19.17 to 23.86% for diameter at breast height in different growth years. The repeatability of height and of diameter at breast height among clones was high, ranging from 0.6181 to 0.8531 (height) and from 0.8443 to 0.8497 (diameter at breast height), in different growth years. There were significant positive correlations between all pairs of growth traits except between height in the 2nd growth year and height in the 30th growth year; and between height in the 2nd growth year × diameter at breast height in the 30th growth year. With a comprehensive evaluation method and a selection ratio of 10%, L65, L1, L62, L9, L15, and L78 were selected as excellent clones in the 30th growth year. Their average values of height and diameter at breast height were 9.81 and 16.57% higher than the overall average, representing genetic gains of 6.46 and 13.99%, respectively. This study provides a theoretical foundation for the genetic improvement of L. kaempferi.

The aqueous extract of Phellodendron amurense Rupr. (Amur Cork Tree) provides a rich source of antioxidants and chemical compounds, and can be used for food and wood preservative materials. In this study, we characterized the chemical composition of this extract by GC and GC/MS. The antioxidant capacity was evaluated using a variety of antioxidant assays (superoxide radical, hydroxyl radical, nitric oxide radical, and DPPH radical scavenging activity). Additionally, total polyphenolic content was determined. Phenolic acids and acetone derivatives were major compounds of the extract capable of scavenging the DPPH free radical and reducing ferric ions. DPPH and ferric ion reduction results were strongly correlated with total phenolic content of the extract which also exhibited strong nitric oxide, hydroxyl radical scavenging and superoxide anion radical scavenging activities.

We applied under pot-culture conditions and the double-casing pot method to study the characteristics of photosynthetic gas exchange and chlorophyll fluorescence in the leaves of Physocarpus amurensis Maxim (PA) and Physocarpus opulifolius under flooding stress. Our results indicate a significantly higher flooding tolerance of P. opulifolius compared to P. amurensis. Especially in P. amurensis, the limitation of non-stomatal factors played a major role in the advanced stages of flooding stress, observed as a rapid increase of the intercellular CO₂ concentration (C _i) and a decrease of the stomatal limitation value (L _s). The maximal PSII photochemical efficiencies (F _v/F _m) and actual photochemical efficiency (Ф _PSII) in the leaves of P. opulifolius were significantly higher, and the extent of decrease during the flooding process was smaller than in P. amurensis. In addition, the non-chemical quenching (NPQ) in the leaves of P. opulifolius significantly increased from the 10th day under flooding stress, while the variation of NPQ in the leaves of P. amurensis was much smaller. This indicates that the leaves of P. opulifolius had not only higher PSII photochemical activity, but also improved tolerance to flooding stress, which may be caused by its ability to dissipate excess excitation energy by starting NPQ. At the 16th day under flooding stress, the P _IABS significantly decreased with greater extent of decrease than F _v/F _m in the leaves of both Physocarpus, but the decreasing extent of P _IABS in P. opulifolius was significantly smaller than in P. amurensis. In the 16th day under flooding stress, the fluorescence at J and I point (V _J and V _I) in P. amurensis were significantly higher, and the extent of increase in V _J was greater than V _I. However, the variations of V _J and V _I in the leaves of P. opulifolius were smaller, suggesting that the damage sites of flooding stress to PSII in the leaves of P. amurensis were mainly located in the electron transport process from Q_A at the PSII receptor side to Q_B. Flooding stress reduced the proportion (φE _o) of luminous energy absorbed by the PSII reaction center for the electron transport following Q_A ⁻, while the maximum quantum yield (φD _o) of non-photochemical quenching increased. However, the TR_o/RC and ET_o/RC in the leaves of P. amurensis decreased accompanied by a dramatic increase of energy (DI_o/RC) from the dissipation in the reaction center. This further indicated that the function of the PSII reaction center in the leaves of P. amurensis was significantly lower than in P. opulifolius.

We assessed different rootstocks and grafting techniques to clonally propagate mastic tree (Pistacia lentiscus var. chia). Mastic tree is a dioecious tree but the quantity and quality of the resin secreted by female trees are very low; therefore, male trees that are clonally propagated are used to establish commercial plantations for mastic production. Conventional long branch cuttings for clonal production requires too much materials and has a very low rooting rate. Rooting with tissue culture and green cuttings has also failed outdoors. Grafting of mastic on other Pistacia species has not been tried so far; therefore, this study was aimed at developing grafting methods for the clonal propagation of mastic. P. atlantica and P. lentiscus rootstocks were grafted from 15 February to 15 October every 15 days using three grafting methods and a two-factor randomized block trial design. Early spring (15 February–15 March) proved to be the best time for grafting using either of the rootstocks. The highest grafting success was attained using the scions grafted on P. atlantica from 15 February to 15 March. The best bud-burst percentage was obtained using P. atlantica and P. lentiscus rootstocks.

Season and concentration of sterilizing agents play a significant role for establishment of aseptic in vitro shoot cultures and sprouting of nodal explants from field growing culms of bamboo species. In the present investigation the nodal segment explants of Bambusa tulda Roxb collected in different seasons and treated with various concentrations of HgCl₂ showed significant variation in aseptic culture establishment and bud break. The rainy season (July–August) recorded with highest of 78% aseptic culture establishment whereas autumn recorded with lowest 46%. Summer and winter seasons emerged to be the best period, registering > 60% in vitro bud break. On the other hand, the autumn season had the lowest value for bud break, i.e. 42%. Among different doses of sterilizing agent tried, HgCl₂ 0.1% found to be suitable for maximum aseptic culture establishment (66%) as well as bud break (59%). However, among the interactions, summer season and the dose of 0.1% HgCl₂ exhibited maximum of 73% response for both aseptic culture establishment and bud break. MS medium (liquid) enriched with 5.0 µM BA + 5.0 µM Kn [Kinetin (N6-Furfuryladenine)] with additional supplementation of 100 µM glutamine + 0.1 µM IAA supported a maximum in vitro shoot multiplication of 4.75 fold. The proliferated shoots were successfully rooted on MS medium (liquid) supplemented 40 µM coumarin. The plantlets transferred to the polythene bags showed 98% survival.

For developing nature-based silvicultural practices in a beech forest to promote, abundance, height, vitality, and preferred growth form, regenerated trees growing in gaps were compared with those under closed canopies. A systematic 50 × 50 m grid was plotted in a beech stand in the Kheyrud Experimental Forest for selecting trees to measure variables in gaps and under closed canopies. Abundance and mean height of regenerated beech trees were significantly higher in closed canopies than in canopy gaps. Beech seedlings with excurrent growth were significantly taller within regeneration patches under closed canopy. Moreover, regenerated trees with high vitality were more abundant in closed canopy areas than in gaps. Thus, beech regeneration should improve under closed canopies; hence, gaps in a near natural forest should be created only after adequate regeneration and appropriate growth under the parent tree in a closed canopy area is ensured. The results of this research have profound implications for the sustainable management of the forest and for ensuring sustainable beech regeneration. The presence of a closed canopy cover likely will reduce potential stresses on oriental beech regeneration.

To explore fertilization methods for wine bamboo cultivation in southwestern semi-arid areas of China, this study analyzed annual changes in sap yield and nutrient composition from May 2013 to March 2015 by using bamboo charcoal-based bio-fertilizer (ZT) and organic fertilizer treatments (CK). The study also provided basic data for functional beverage preparation and for application of ZT. The results of the two experimental cycles revealed that under the ZT treatment, sap was available for collection from May, the beginning of the rainy season, to November, the beginning of the dry season. The period of abundance was July to October with the highest yield of sap of 3.18 L stalk⁻¹ in September, 2014, still lower than the moso bamboo sap, which was likely due to the scale of sap production of monopodial bamboos being different from that of sympodial bamboos. In January, trace amounts of sap were still detected, suggesting that the effect of the treatment was significant. Moreover, in the dry season, soil water content and soil temperatures at 10–15 cm depths indicated that the fertilizer had the ability to maintain soil temperatures and moisture. In both fertilizer treatments, the correlation between the collected sap and environmental parameters was significant. In the ZT treatment for the entire 2 years, the effectual environmental factors were soil water at 10–15 cm, air temperatures, and wind speeds. The same determining factors were observed for the rainy season. In the CK treatments, the effectual environmental factors for the entire year and the rainy season were soil water at 0–5 cm and air moisture. The bamboo charcoal-based bio-fertilizer elevated the potassium, calcium, iron, manganese, copper, and total phosphorus content, simultaneously increasing the sap yield, protein and reducing sugar contents, and with a relative increase in sap pH. The wine bamboo sap contained 18 amino acids. Glutamic acid, alanine and proline were the most abundant. Compared to the controls, the treatment showed higher levels of all amino acids. Thus, the ZT treatment could be more beneficial to the development of root systems because the function of heat preservation and moisture retention prolong the sap collection period, increase sap yields, and elevate mineral element, conventional nutrients, and amino acid contents with evident fertilization effects and broader application prospects.

Bruguiera sexangula (Lour) Poir., a threatened mangrove tree, was inoculated with beneficial microbes in a nursery to assess any improvements in growth and biomass. From soil samples from the rhizosphere of B. sexangula in a mangrove forest in Panangadu of Kerala India, nitrogen-fixing bacteria Azotobacter chroococcum and Azospirillum brasilense were isolated. The phosphate-solubilising bacterium Bacillus megaterium and potassium-mobilizing bacteria Frateruria aurantia were also isolated and cultured on suitable media. Later, ripe propagules of B. sexangula were collected from matured trees and raised in sterilized soil bags (13 × 25 cm) containing sterilized soil and sand (2:1 ratio). The cultured beneficial microbes were propagated and used to inoculate the ripe propagules of B. sexangula and maintained in the nursery for 6 months. After 6 months, growth and biomass of the inoculated propagules were greater than for the uninoculated control propagules. Shoot length, number of leaves, stem girth and root length were also significantly greater than in the controls. This study showed that the mangrove-specific beneficial microbes influenced the growth of B. sexangula in the nursery and will help in the establishment of B. sexangula in degraded mangrove forests.

Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings (Tilia cordata Mill.) were planted with a 1 × 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings (2475 cherries and 825 limes) were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots (10 × 10 m) were randomly established in group and row planting stand, respectively. The survival rate, stability (height to diameter ratio), diameter, and height growth were significantly higher in group planting. In the group plantings, 40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting. This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture.

Teak plantations date back to 1871 in Bangladesh. This study was designed to assess how teak monoculture has impacted the soil properties in Bangladesh. Multiple linear regression and correlation matrices were estimated to evaluate these impacts. The means of soil physicochemical properties were compared across various attributes of the plantations. Older plantations accumulated more organic carbon in the soils than the younger plantations. Excessive removal of litter from the forest floor resulted in reduced levels of N, P, K, and other nutrients in the soils. Since bulk density was continuously decreasing deeper into the soil, the penetration of mineral nutrients into the soil was low. Furthermore, moisture content in the topsoil was significantly lower than that in the bottom layers due to the exposed and dry condition of the forest floor under teak plantations. For improving depleted teak plantation soils, teak could be planted with other tree species rather than just in monocultures. In addition, the forest floor could be enriched with leguminous herbs and shrubs to improve soil health in these plantations.

It remains unclear whether the elevational diversity gradients observed in seed plants across different taxonomic levels (family, genus, and species) are driven by the same macro-environmental variables. In this study, seed plant elevational distribution data from the Lancang River Nature Reserve (Yunnan, China) were used to investigate spatial patterns in diversity and their environmental correlates, comparing across taxonomic levels. Environmental variables included energy availability, climate seasonality and environmental heterogeneity. All taxonomic levels (family, genus, and species) were found to have strong elevational richness gradients, with the strength of the gradient weakening at higher taxonomic levels. Spatial patterns in richness were explained by a combination of contemporary environmental variables and the mid-domain effect at all taxonomic levels. The independent effects of temperature- and precipitation-related variables were similar in explaining geographical patterns of family, genus and species richness. Energy, seasonality and heterogeneity variables influenced seed plant spatial richness at different taxonomic levels in similar ways.

The phenology of figs (Ficus spp. Moraceae) is being monitored in the dry forests of Mudumalai, southern India and individuals belonging to the genus are marked with unique tag numbers and their vegetative and reproductive phenologies have been monitored since August 2000 on a monthly basis. The influence of abiotic factors on fig phenology and the differences between fig and non-fig phenologies are being examined. The seasonality of different phenophases of fig phenology is also being examined. The maximum intensity of leaf flush occurred in drier months. Fig and non-fig species showed significant differences with expansion and senescence phenophases of leafing. Flowering also occurred in drier months. There were significant differences between fig and non-fig species with reproductive phenophases. As with non-fig species, leafing was influenced by maximum temperatures. Both vegetative and reproductive phenophases were significantly seasonal.

Accurate estimates of forest biomass are increasingly important in relation to sequestration of carbon by forest trees. Satellite remote sensing is a useful tool for biomass estimation and monitoring of forest ecological processes. Microwave synthetic aperture radar (SAR) can increase the accuracy of estimations of forest biomass in comparison to optical remote sensing, due to the unique capacities of SAR, including high penetrability, volumetric scattering, interaction with surface roughness, and dielectric property. We studied the potential of multi-polarized C-band Radarsat-2, a SAR technology, with HH, HV and VV polarization for estimating biomass of moist tropical Indian forest. Backscatter values are correlated with field-based biomass values and are regressed to generate models for estimating biomass. HH polarization provided maximum information regarding tree biomass. A coefficient of determination of 0.49 was calculated for HH polarized C-band image with in situ measurements. An exponential model was proved to be best suited for estimating forest biomass. Correlation of 0.62 and RMSE of 24.6 t ha⁻¹ were calculated for the relationship between estimated and predicted biomass values for the best fit model. The average absolute accuracy of the model was 61%, while Willmott’s index of agreement was 0.87. Results suggest that most of the biomass of the area ranged within 70 t ha⁻¹ a probably due to the saturation of C-band around 60–70 t ha⁻¹ for tropical forests.

Prediction of potential geographic distributions is important for species protection and habitat restoration. Ulmus lamellosa is an endangered and endemic species in China for which conservation efforts are required. The maximum entropy (MaxEnt) model was used to predict the current and future geographic distribution (from 2030 to 2070) of U. lamellosa in China and discuss the reasons for changes in climatic suitability. The MaxEnt model provided a good fit to our data as confirmed by an AUC value of 0.948. The suitable areas for U. lamellosa were primarily projected in the northern part of China from 2030 to 2070, especially in Liaoning province. The variables “temperature seasonality”, “precipitation of wettest month” and “precipitation of warmest quarter” were the most influential climatic variables in limiting the distribution of U. lamellosa. Our results clearly predict the future impacts of climate change on the geographic distribution of U. lamellosa and this can help prioritize design of localized conservation strategies in China.

Plantations of tropical species are becoming an increasingly important source of wood. However, it is important that research trials focus not only on tree growth performance, but also on wood quality. The aims of this study were to assess the growth performance of six commercially and ecologically important tree species from separate plantation trials in Indonesia and to determine the relationships between tree growth and wood quality in terms of the dynamic modulus of elasticity (MOE) and wood density. Forty-eight 7-year Maesopsis eminii Engl. and thirty-five 9-year specimens (7 each of 5 Shorea spp.) were selected from two trials. The MOE, based on acoustic velocity, was indirectly measured to evaluate wood stiffness. Tree-growth performance was evaluated, and correlations between growth traits and acoustic velocity as well as density and wood stiffness properties were estimated. The growth performance of M. eminii in terms of tree volume was significantly different in three different categories of growth (i.e. fast, medium, slow). Of the five Shorea spp. studied, Shorea leprosula Miq. had the highest growth rate, as expected since it is known to be a fast-growing Shorea species. Indirect measurement of wood quality by means of non-destructive ultrasonic methods showed a weak negative correlation between tree volume and acoustic velocity and dynamic MOE. Although each fast-growing tree could reach a merchantable size faster than other varieties or species, wood traits of various species tested were not significantly different based on tree growth rate performance. The findings from this study could be used to improve selection criteria in future breeding trials; indirect measurements of the dynamic modulus of elasticity can be used in mass pre-selection of genetic materials, to choose the most-promising material for in-depth evaluation.