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Constructing atomic interfaces in catalysts is an effective strategy to improve catalytic performance.

Graphical abstract, Highlights • A growth‒defense tradeoff following root pruning. • Root growth lagged behind root physiology after root pruning. • The growth–defense tradeoff was induced by indole-3-acetic acid. • Proteomic analysis supported a growth–defense tradeoff. • Root pruning altered the expression of genes at the protein and mRNA levels., Introduction Root pruning is commonly used to facilitate seedling transplantation for the restoration of degraded or damaged ecosystems. However, little is known about how root growth coordinates morphology, physiology and defense functions following root pruning. Objectives We aim to elucidate whether and how root growth trades off with defense functioning after pruning. Methods Seedlings of Platycladus orientalis, a tree species widely used in forest restoration, were subjected to root pruning treatment. A suite of root growth, morphological and physiological traits were measured after pruning in combination with proteomic analysis. Results Root growth was insensitive to pruning until at 504 h with a significant increase of 16.8%, whereas root physiology was activated rapidly after pruning. Key root morphological traits, such as root diameter, specific root length and root tissue density, showed no response to the pruning treatment. Plant defense syndromes such as reactive oxygen species-scavenging enzymes and defensive phytohormones such as jasmonic acid and abscisic acid, were recruited at six hours after pruning and recovered to the unpruned levels at 504 h. Compared with the controls, 271, 360 and 106 proteins were differentially expressed at 6, 72 and 504 h after root pruning, respectively. These proteins, associated with defense function, showed temporal patterns similar to the above defense syndromes. Conclusion Our results suggest a root growth-defense tradeoff following root pruning in P. orientalis. This tradeoff was potentially due to the significant increase of indole-3-acetic acid, the phytohormone stimulating root branching, which occurred soon after pruning. Together, these results provide a holistic understanding of how root growth is coordinated with root morphology, physiology, and defense in response to root pruning.

Olfaction plays a major role in the host-finding behaviors of insects. However, the irregularity of insect responses to odor interactions has hindered our efforts to draw broad conclusions about how a host-finding insect uses the complex mixture of various odor plumes in natural environments. Particularly, it is still unclear so far why the use of non-host odors to control insect pests in practices have met with mixed results. To further understand the host-finding of a specific insect, we highlight the role of the real-time odor environment (ROE) that the host-finding insect is passing through. The ROE may contain various odors with different ranks and changes during the insect’s host finding. A host-finding insect may always prone to switch to the higher rank odor plumes in each ROE regardless of the distance is “short” or “long” from the odor source. For a specific herbivorous insect, only mixing degree of the given host and non-host plant odors reaches some certain level (threshold value), can the non-host odors significantly affect its ability to locate host plants. When the odor mixing degree is low, masking effects may not occur or the non-host plant odors’ “attractive” effects at long distances and “repellent” effects at short distances can even increase the pest loads. In forests, the mixing degree of different plant odors is determined by turbulence intensity which is mainly affected by plant structures. These may further advance our understanding of herbivorous insects’ host finding and have important implications for the development of pest management strategies.

Tree diversity has long been considered a key driver of insect herbivory in forest ecosystems. However, studies have given contradictory results: increased tree diversity can have positive, negative or neutral effects on insect herbivory. Since many issues can complicate the tree-herbivore interactions, the descriptor ‘tree diversity’ per se actually has only limited explanatory power for insect herbivory. Particularly, in addition to the direct bottom-up effects on insect herbivores, tree diversity may have stronger indirect top-down effects via natural enemies of insect herbivores. However, most research has addressed only direct bottom-up impacts. In fact, insect herbivory is the result of complex interactions (food webs) among all the species in a community. Although it is hard to integrate all functionally important species and dynamic information into food webs, the effects of tree diversity on insect herbivory are highly dependent on the dominant species at different trophic levels. It is important and practical to simultaneously consider the characteristics of main trees, herbivores, and natural enemies when attempting to predict the overall effects of forest tree diversity on insect herbivory. In order to ensure comparability between studies, it is necessary to classify them according to the descriptors of insect herbivory and tree diversity, and to compare results within each category. These measures might enhance our understanding of the mechanisms by which tree diversity drives insect herbivory and, in turn, help to develop sustainable pest management strategies for forests.

To reveal the effects of different land-use types on soil enzyme activities, soil samples were collected from 0–10, 10–20 and 20–30 cm soil layers to compare and analyze soil β-glucosidase (BG), urease (URE), protease (PROT) and catalase (CAT) activities in farmland (FL), abandoned land (AL) and three plantation forests: Platycladus orientalis (L.) Franco (PO), Robinia pseudoacacia L. (RP) and Quercus variabilis Bl. (QV) in the rocky mountainous region of North China. The results showed that the soil enzyme activities varied significantly under different land-use types, and the interannual mean values of FL and PO were remarkably higher than those of other land uses in the 0–30 cm soil layer, in which the soil BG and URE activities of FL were 22% and 12% higher than those of AL, and 428% and 179% higher than those of QV, respectively; the soil PROT and CAT activities of PO were 66% and 23% higher than those of AL, and 479% and 113% higher than those of QV, respectively. Soil BG, URE and PROT activities were all higher in June and lower in December, while soil CAT activity was slightly lower in June. The soil enzymatic activities all showed a notable decrease with the depth of the soil layer. Soil BG, URE, PROT and CAT activities were remarkably (p < 0.01) or significantly (p < 0.05) positively correlated with available nitrogen, available phosphorus, available potassium, dissolved organic carbon (DOC), NO3−-N, soil organic carbon, water content, clay and silt volume fraction, and significantly negatively correlated with sand volume fraction. Soil DOC and pH were important factors influencing soil enzymatic activity, implying that changes in soil enzymatic activity under different land-use types may be the result of a combination of temperature, moisture and plant type. In conclusion, PO plantations are conducive to improving the physicochemical and biological properties of soil and enhance soil fertility, which is a reasonable land-use method to achieve sustainable development in the rocky mountainous region of North China.

Background Insect herbivory has profound impacts on ecosystem processes and services. Although many efforts have been made to recognize the main drivers of insect herbivory at different scales, the results are inconsistent. One likely reason is that studies have insufficiently captured the spatially heterogeneous factors such as soil type and forest stratum within the stand that may significantly affect insect herbivory. In particular, there is a lack of studies that address the detailed spatial patterns of insect herbivory which are influenced by these factors. Methods We measured the detailed spatial patterns of insect herbivory on cork oak (Quercus variabilis Bl.) in response to soil type (gravel soil and loam) and forest stratum (the upper, lower, and sapling stratum), and correlated these patterns with a set of influencing factors (litter coverage, coverage of shrubs and herbs, soil nutrients, soil moisture, and leaf traits) in a forest landscape. Results Generally, insect herbivory was spatially heterogeneous within stands. Herbivory was significantly lower in gravel soil areas than in loam soil areas and the highest herbivory occurred in the lower stratum. However, there were also 41 individual plots in which the highest herbivory occurred in the upper stratum and 29 plots in which the highest herbivory occurred in the sapling stratum. There were significant differences in soil nutrient and water status between soil types, but no significant differences in leaf traits. The effects of forest stratum on leaf traits were also inconsistent with those on insect herbivory. Conclusions Leaf traits may not be the main factors influencing insect herbivory in the field. Soil type may have major effects on herbivory patterns by influencing litter coverage while higher coverage of shrubs and herbs may reduce herbivory in the sapling stratum. These findings may advance our understanding of tree-herbivore interactions in real-world situations and have important implications for the sustainable management of forest ecosystems.

Shrub encroachment is very common in the semiarid regions of China. However, surprisingly little research has been conducted to evaluate the effects of shrubs on soil properties in these regions co...

Climate change has major effects on background insect herbivory, but only a few studies have involved long-term investigation, and the effects of wind on bigger insect herbivores such as moths have...

Phosphorus (P) fertilizers are added to improve the soil P fertility, but the rate of P release can greatly influence its availability. Organic acids are effective in the release of inorganic P (Pi), but the contribution of each Pi fraction is not well understood. This study reported the transformation rate of P and solubility of Pi fractions induced by organic acids. Path analysis was utilized to explore the direct and indirect effects of Pi fractions on the amount of total Pi (TPi) solubilized. Results showed that the P release was initially rapid, followed by a slower release that lasted up to 2160 h, and the Elovich equation was the best-fitted kinetic equation to estimate the transformation rate of available P. The amount of TPi-solubilized by oxalic and citric acids tended to increase with increasing organic acid concentrations. Oxalic acid exhibited a lower TPi-solubility capability than citric acid when the organic acid concentration was ≤1 mmol L−1, whereas citric acid was higher at ≥1.5 mmol L−1. The Al-P-solubilized had the highest content of studied fractions, and path analysis revealed that the Al-P-solubilized exhibited a significant direct effect on TPi-solubilized. Thus, Al-P is a potential P source in black soil.

Leaf chlorophyll content is an important indicator of the growth and photosynthesis of maize under water stress. The promotion of maize physiological growth by (AMF) has been studied. However, studies of the effects of AMF on the leaf chlorophyll content of maize under water stress as observed through spectral information are rare. In this study, a pot experiment was carried out to spectrally estimate the leaf chlorophyll content of maize subjected to different durations (20, 35, and 55 days); degrees of water stress (75%, 55% and 35% water supply) and two inoculation treatments (inoculation with Funneliformis mosseae and no inoculation). Three machine learning algorithms, including the back propagation (BP) method, least square support vector machine (LSSVM) and random forest (RF) method, were used to estimate the leaf chlorophyll content of maize. The results showed that AMF increased the leaf chlorophyll content, net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), and water use efficiency (WUE) of maize but decreased the intercellular carbon dioxide concentration (Ci) of maize and atmospheric vapor pressure deficit (VPD) regardless of the water stress duration and degree. The first-order differential spectral data can better reflect the correlation between leaf chlorophyll content and spectrum of inoculated maize when compared with original spectral data. The BP model performed bestin modeling the maize leaf chlorophyll content, yielding the largest R2-values and smallest root mean square error (RMSE) values, regardless of stress duration. These results provide a reliable basis for the effective monitoring of the leaf chlorophyll content of maize under water stress.

INTRODUCTION Salvia miltiorrhiza is a frequently used herb in traditional Chinese medicine, and tanshinone IIA (Tan IIA) and salvianolic acid B (Sal Acid B) are two major extracts obtained from its dried root. The quality of herbal ingredients can be affected by environmental factors. OBJECTIVE To evaluate the quality of wild S. miltiorrhiza and investigate the influence of soil constituents and parameters as well as climatic conditions and factors on the content of Tan IIA and Sal Acid B. METHODOLOGY We collected samples in 12 natural locations in the Dao Di area in China, the area in which S. miltiorrhiza grows, that results in a distinctive higher quality of medicinal materials from the harvested plant. The concentrations of Tan IIA and Sal Acid B were measured by high-performance liquid chromatography (HPLC). Soil total carbon, total nitrogen, available nitrogen, available phosphorus, available potassium, and particle size distribution were determined. We also collected climate data using ArcGIS from the WorldClim database, and correlation tests, redundancy, and regression analyses were conducted to analyse the relationship and cluster the samples according to their chemical profile. RESULTS The content of Tan IIA and Sal Acid B in most of the samples was significantly different (P < 0.05). Soil available phosphorus was considered as a key factor that influenced the quality of wild S. miltiorrhiza, and we found a significant negative association between the concentration of Tan IIA in roots and soil available phosphorus. Moreover, the accumulation of Tan IIA in S. miltiorrhiza was also significantly associated with precipitation in April, May, and October, maximum temperature in January, and standard deviation of temperature seasonality. There was no significant correlation between the content of Sal Acid B and ecological factors. In addition, samples collected from Mengshan, Hexian, and Lushi locations were rich in Tan IIA and tended to cluster together, whereas samples collected from Longquan and Huoshan locations tended to cluster and were poor in Tan IIA. CONCLUSION The Tan IIA content in samples collected from southern Anhui was significantly lower than that in other Dao Di locations. The content of Tan IIA was related more to the soil than the temperature. Compared with Tan IIA, Sal Acid B was less influenced by soil and climate factors. The findings of this study may provide helpful references for quality control of medicinal plants that exert pharmacological effects in humans.

Greenhouse gases (GHGs) carbon dioxide (CO

Air-root pruning (AP) has been identified as an effective technique for enhancing root growth and development. However, little information is available regarding the temporal changes in the root system of Platycladus orientalis (L.) Franco under AP. We performed integrated morphological, physiological, and anatomical analyses of the roots in P. orientalis seedlings that had been air-root pruned for 120, 150, and 190 days. Our results found that the whole root length, number of root tips, and root surface area of AP seedlings at 120, 150, and 190 days were higher than those of the non–root-pruned (NP) seedlings (P < 0.05), but the average root diameter did not differ significantly between the treatments. Compared with NP treatment, AP increased the root length, surface area, number of tips, and specific root length of the ≤0.5 mm diameter roots in P. orientalis during the experimental periods (P < 0.05), but those of 0.5- to 1-mm-diameter roots were only increased on day 190 (P < 0.05). The AP plants also exhibited higher root vitality and proportion of live fine roots than the NP plants (P < 0.05). Our anatomical evaluation of the ≤0.5 mm roots and taproots revealed features that could account for the morphological differences found between the AP and NP plants. In conclusion, our results indicate that air-root pruning induced changes in the roots that promote the root system development in P. orientalis compared with the NP treatment during the experimental period. These results thus provide experimental evidence to support the use of AP in P. orientalis seedlings.

Geological events have been shown to be the main factors affecting the distributions and population genetic structure of species. However, the impact of the Yellow River, the second longest river in China, on the distribution and genetic structure of the endemic flora remains largely unknown. Here, we used microsatellites to evaluate the genetic structure of Tamarix austromongolica and Tamarix chinensis (343 individuals in total), two endemic tree species widely distributed along the Yellow River, as well as the role of river drainages in shaping the structure. We found that frequent gene flow resulted in low genetic differentiation among populations within species (T. austromongolica: Fst = 0.144, Nm = 1.486; T. chinensis: Fst = 0.103, Nm = 2.177); and low levels of genetic differentiation were detected between populations within species on the north and south banks. Also, high gene flow was found between populations in the upper reaches and those in the middle reaches, and middle reaches and lower reaches of the Yellow River (T. austromongolica: Fst = 0.023, Nm = 10.619; T. chinensis: Fst = 0.045, Nm = 5.306). Additionally, discriminant analysis of principal components (DAPC) and Bayesian analysis revealed a weak population structure in T. austromongolica and T. chinensis. Therefore, the Yellow River does not act as a barrier to dispersal and gene flow for Tamarix. Our findings provide support for the role of the river in shaping the spatial distribution and the genetic structure of species.

The present study was designed to assess the potential effects of low-molecular-weight organic acids on the activation of inorganic phosphorus, obtain exact information on the acidity effect of proton and complex effect of organic anion in P availability, and determine the components among phosphorus fractions that contributed the most to inorganic phosphorus activation in black soil. Both oxalic and citric acids treated with different concentrations and pH values were carefully selected. The activating amounts of total inorganic phosphorus and individual phosphorus fractions were estimated. Path analysis was used to analyze the direct and indirect effects on inorganic phosphorus activation. The amount of total activating-Pi increased as the concentrations of oxalic and citric acids increased. When the concentrations were ≤ 1.0 mmol L−1, oxalic acid exhibited a lower capability than citric acid in total activating-Pi, but when the concentrations were ≥ 1.5 mmol L−1, oxalic acid exhibited a higher capability. The amount of total activating-Pi decreased as pH of LMWOAs increased. LMWOAs-induced Pi activation might be attributed to combine acidity and complex effects. Correlation analysis showed that the activation of total Pi was significantly correlated with the activation of H2O-Pi, NaHCO3-Pi, NaOH-Pi, and HCl-Pi (p

The geological events and climatic fluctuations during the Pleistocene played important roles in shaping patterns of species distribution. However, few studies have evaluated the patterns of species distribution that were influenced by the Yellow River. The present work analyzed the demography of two endemic tree species that are widely distributed along the Yellow River, Tamarix austromongolica and Tamarix chinensis, to understand the role of the Yellow River and Pleistocene climate in shaping their distribution patterns. The most common chlorotype, chlorotype 1, was found in all populations, and its divergence time could be dated back to 0.19 million years ago (Ma). This dating coincides well with the formation of the modern Yellow River and the timing of Marine Isotope Stages 5e-6 (MIS 5e-6). Bayesian reconstructions along with models of paleodistribution revealed that these two species experienced a demographic expansion in population size during the Quaternary period. Approximate Bayesian computation analyses supported a scenario of expansion approximately from the upper to lower reaches of the Yellow River. Our results provide support for the roles of the Yellow River and the Pleistocene climate in driving demographic expansion of the populations of T. austromongolica and T. chinensis. These findings are useful for understanding the effects of geological events and past climatic fluctuations on species distribution patterns.

As one of the trait‐based approaches, leaf economics spectrum (LES) has led to significant advances in plant ecology; however, hypothetical root economics spectrum (RES) which is even more important than the LES aboveground is still less well understood. By analogy with the LES, hypothetical RES may emerge from the coordinated functional traits of fine roots. However, lots of previous studies revealed inconsistent evidence of an RES across the woody species which dominate the terrestrial ecosystem. By discussing the sampling problems in previous studies, we realize that the main reason of failing to search the RES across woody species might be the lack of a standardized sampling protocol. Using inconsistent and inaccurate basic samples of absorptive roots in previous studies impeded the search for an RES. Mycorrhizal interactions and soil matrix constraints do have influences on fine‐root traits; however, there is no adequate evidence to support that these factors can offset or impede selection for an RES. In order to make sure the comparability across species and between studies, we come up with a concept absorptive unit of fibrous roots. The absorptive unit, which integrates all the absorptive fibrous root orders interconnected in a distal nonwoody cluster as a whole, is a parallel to a leaf. Excluding all the pioneer roots and treating absorptive unit as a basic sample can make sure the comparability across species and between studies. We believe it will offer a promising way to find consistent evidence that support the RES.

Soil carbon (C), nitrogen (N), and phosphorus (P) are three important elements. The study of stoichiometric relationships of soil C, N, and P in tropical forests on Hainan Island, China could improve our understanding of nutrient cycling and provide valuable information for forest management. Soil samples were collected at five different depths from 0 to 100 cm at 100 sites among four different forest types on Hainan Island, and total C, N, and P concentrations were measured. Soil C and N concentrations and soil C:P and N:P ratios declined from the surface soil layer to the deeper soil layers and soil P and C:N ratio had relatively small variations among different depths, due to that soil C and N were mostly controlled by biological processes such as photosynthesis and N2-fixation, while P was more influenced by bedrock. Large spatial variations were found for soil C, N, P concentrations and their ratios. Soil C and N concentrations were significantly influenced by longitude and vegetation cover, while soil P concentration and C:P and N:P ratios were significantly controlled by latitude. This study produced a comprehensive data set of soil C, N, and P stoichiometry, and their variation patterns and controls in the tropical forests. The information generated here could help improve ecosystem models for better understanding of forest element stoichiometry, ecosystem productivity, and plant-environment relationships.

In this study, we investigated the 2D contours and horizontal distributions of fine and coarse roots and tested their relationships with soil properties. Fine (≤2 mm) and coarse roots (≥5 mm) play important roles in water and nutrient cycling in forested ecosystems and are the major organs that trees use to absorb water and nutrients. However, few studies have investigated the distributions of these root types in rocky mountain regions. An understanding of the distribution of root systems would facilitate the study of how available resources are used belowground in rocky mountain regions. We measured the distribution of the root biomass (RB), specific root length (SRL), and root length density (RLD) for both fine and coarse roots of two tree species: Platycladus orientalis and Prunus davidiana. The results showed that the fine-root RB and RLD of P. orientalis were higher than those of P. davidiana, but that the fine-root SRL of P. orientalis was lower than that of P. davidiana. In contrast, the coarse-root RB, SRL, and RLD of P. orientalis were lower than those of P. davidiana. From the 2D contour distribution, we found that most fine and coarse roots of P. orientalis and P. davidiana were concentrated near tree stems. The horizontal distribution of P. davidiana root showed less horizontal extension ability than that of P. orientalis root. The RB, SRL, and RLD of both fine and coarse roots of P. orientalis declined with increasing soil depth, and the roots of P. davidiana exhibited different distribution patterns. We found that P. orientalis has a more dominant and explorative fine-root system, whereas P. davidiana has an explorative coarse-root system. The fine- and coarse-root traits of P. orientalis were susceptible to soil nutrients, but these nutrients had only a slight effect on the coarse-root traits of P. davidiana.

Wastewater contaminated with heavy metals is a world-wide concern. One biological treatment strategy includes filamentous fungi capable of extracellular adsorption and intracellular bioaccumulation. Here we report that an acclimated strain of filamentous fungus Pleurotus ostreatus HAU-2 can withstand Pb up to 1500 mg L(-1) Pb, conditions in which the wildtype strain cannot grow. The acclimated strain grew in liquid culture under 500 mg L(-1) Pb without significant abnormity in biomass and morphology, and was able to remove significant amounts of heavy metals with rate of 99.1% at 200 mg L(-1) and 63.3% at 1500 mg L(-1). Intracellular bioaccumulation as well as extracellular adsorption both contributed the Pb reduction. Pb induced levels of H2O2, and its concentration reached 72.9-100.9 μmol g(-1) under 200-1000 mg L(-1) Pb. A relatively higher malonaldehyde (MDA) concentration (8.06-7.59 nmol g(-1)) was also observed at 500-1500 mg L(-1) Pb, indicating that Pb exposure resulted in oxidative damage. The fungal cells also defended against the attack of reactive oxygen species by producing antioxidants. Of the three antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), CAT was the most responsive and the maximal enzyme activity was 15.8 U mg(-1) protein. Additionally, glutathione (GSH) might also play a role (3.16-3.21 mg g(-1) protein) in detoxification under relatively low Pb concentration (100-200 mg L(-1)). Our findings suggested that filamentous fungus could be selected for increased tolerance to heavy metals and that CAT and GSH might be important components of this tolerance.

Greenhouse gases (GHGs) carbon dioxide (CO2) and nitrous oxide (N2O), contribute significantly to global warming, and they have increased substantially over the years. Reforestation is considered as an important forestry application for carbon sequestration and GHGs emission reduction, however, it remains unknown whether reforestation may instead produce too much CO2 and N2O contibuting to GHGs pollution. This study was performed to characterize and examine the CO2 and N2O emissions and their controlling factors in different species and types of pure and mixture forest used for reforestation. Five soil layers from pure forest Platycladus orientalis (PO), Robinia pseudoacacia (RP), and their mixed forest P-R in the Taihang mountains of central China were sampled and incubated aerobically for 11 days. The P-R soil showed lower CO2 and N2O production potentials than those of the PO soils (P

This investigation evaluates the contrasting metabolic characteristics of anthracene and pyrene by wood rot fungus Pycnoporus sanguineus H1. Under in vivo conditions, P. sanguineus H1 degraded 67.5% of the anthracene and showed maximal laccase activity of 1568.2 U L−1. When piperonyl butoxide (PB) was added to the liquid cultures, the anthracene degradation rate increased to 73.1% and maximal laccase activity increased to 2034.3 U L−1. For pyrene, the degradation rate was 31.1%; however, after PB addition, the value decreased to 5.3% while maximal laccase activity increased to 1625.3 U L−1 from 1469.1 U L−1. Under in vitro conditions, the extracellular liquid culture (10 kDa membrane, ultra-filtered) transformed 59.9% of the anthracene, while addition of 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) enhanced the anthracene transformation rate up to 92.0%. The extracellular liquid did not convert the pyrene, however, suggesting that anthracene is modified extracellularly, (likely via laccase) while pyrene is not. Whole mycelium, as well as homogenized mycelium and microsomal proteins, transformed both anthracene and pyrene; conversion was inhibited to some extent by the PB, implying that cytochrome P450 participates in intracellular PAHs transformation. Additional evidence that ABTS enhances anthracene transformation by homogenized mycelium suggests that mycelium-associated laccase cooperates in the intracellular degradation of anthracene. These results altogether elucidate the metabolism of PAHs by P. sanguineus via extracellular laccase, intracellular cytochrome P450, and mycelium-associated laccase.

Background Indole-3-butyric acid (IBA) is applied to the cuttings of various plant species to induce formation of adventitious roots (ARs) in commercial settings. Tetraploid black locust is an attractive ornamental tree that is drought resistant, sand tolerant, can prevent sand erosion and has various commercial uses. To further elucidate the mechanisms of AR formation, we used Illumina sequencing to analyze transcriptome dynamics and differential gene expression at four developmental stages in control (CK) and IBA-treated groups. Results The short reads were assembled into 127,038 unitranscripts and 101,209 unigenes, with average lengths of 986 and 852 bp. In total, 10,181 and 14,924 differentially expressed genes (DEGs) were detected in the CK and IBA-treated groups, respectively. Comparison of the four consecutive developmental stages showed that 282 and 260 DEGs were shared between IBA-treated and CK, suggesting that IBA treatment increased the number of DEGs. We observed 1,721 up-regulated and 849 down-regulated genes in CI vs. II, 849 up-regulated and 836 down-regulated genes in CC vs. IC, 881 up-regulated and 631 down-regulated genes in CRP vs. IRP, and 5,626 up-regulated and 4,932 down-regulated genes in CAR vs. IAR, of which 25 up-regulated DEGs were common to four pairs, and these DEGs were significantly up-regulated at AR. These results suggest that substantial changes in gene expression are associated with adventitious rooting. GO functional category analysis indicated that IBA significantly up- or down-regulated processes associated with regulation of transcription, transcription of DNA dependent, integral to membrane and ATP binding during the development process. KEGG pathway enrichment indicated that glycolysis/gluconeogenesis, cysteine and methionine metabolism, photosynthesis, nucleotide sugar metabolism, and lysosome were the pathways most highly regulated by IBA. We identified a number of differentially regulated unigenes, including 12 methionine-related genes and 12 ethylene-related genes, associated with the KEGG pathway cysteine and methionine metabolism. The GO enrichment, pathway mapping, and gene expression profile analyses revealed molecular traits for root induction and initiation. Conclusion Our study presents a global view of the transcriptomic profiles of tetraploid black locust cuttings in response to IBA treatment and provides new insights into the fundamental mechanisms associated with auxin-induced adventitious rooting. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3554-4) contains supplementary material, which is available to authorized users.

List of the genes and primers selected for q-PCR validation. (DOCX 15 kb)

Gene Ontology classification of the differentially expressed genes of IBA treated from stage II to stage IAR. (DOCX 2985 kb)

Venn diagrams of unigenes showing differential expression in pairwise comparisons of developmental stages in the IBA treatment. (DOCX 93 kb)

Summary of the blastx results for the tetraploid black locust transcriptome against five databases. (DOCX 13 kb)

Gene Ontology classifications of the differentially expressed genes in CK and IBA from all four stages. (DOCX 4032 kb)

Genes differentially expressed between IBA-treated and CK cuttings at each developmental stage. (DOCX 201 kb)

RNA-seq-based transcriptome dynamics of CK cuttings during AR development. (DOCX 561 kb)

Polychlorinated diphenyl ether (PCDE) has attracted great attention recently as an important type of environmental pollutant. The influence of iron and copper oxides on formation of PCDEs was investigated using laboratory-scale flow reactors under air and under nitrogen at 350 °C, a temperature corresponding to the post-combustion zone of a municipal solid waste incinerator. The results show that the 2,2',3,4,4',5,5',6-otachlorodiphenyl ether (OCDE) formed from the condensation of pentachlorophenol (PCP) and 1,2,4,5-tetrachlorobenzene (Cl4Bz) is the predominant congener formed on the SiO2/Fe2O3 surface with and without oxygen. This indicated that HCl elimination between PCP and 1,2,4,5-Cl4Bz molecules formed 2,2',3,4,4',5,5',6-OCDE in the presence of Fe2O3. On the other hand, decachlorodiphenyl ether, nonachlorodiphenyl ether, and OCDE were the dominant products on the SiO2/CuO surface without oxygen, although the 2,2',3,4,4',5,5',6-OCDE was the dominant product on the SiO2/CuO surface with oxygen. Therefore, the presence of Fe2O3 and CuO influences the formation and homologue distribution of PCDEs, which shifted towards the lower chlorinated species. Fe2O3 can promote both the condensation and dechlorination reaction without oxygen. On the contrary, with oxygen, Fe2O3 suppresses the condensation of chlorobenzene and chlorophenol to form PCDEs and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). CuO can increase the formation of lower chlorinated PCDEs and PCDDs without oxygen. In conclusion, the different fly ash components have a major influence on PCDE emissions.

Natural regeneration is the natural process by which plants replace themselves. It is a cost-effective way to re-establish vegetation, and it helps to preserve genetic identity and diversity. In this study, we investigated the natural regeneration of trees in three types of afforested stands in the Taihang Mountains, China, which were dominated by Robinia pseudoacacia (black locust), Quercus variabilis (Chinese cork oak) and Platycladus orientalis (Chinese arborvitae) respectively. A consistent pattern was found among the three types of stands, being that the density of seedlings was positively correlated with the overstory canopy cover and negatively correlated with the covers of shrub, herb and litter layers. While a positive correlation between the density of seedlings and stand age was found for the conifer stands, negative correlations were found for the two types of broadleaf stands. Correlations between the density of saplings and the stand attributes were not consistent among the three types of stands. The two types of broadleaf stands had higher densities of seedlings and saplings than the conifer stands. While the broadleaf stands had adequate recruits for regeneration, the conifer stands did not have enough recruits. Our findings suggest that the overstory canopy should be prevented from being disturbed, any reduction of the canopy cover will decrease the recruits and affect the regeneration.

長野県御岳山において, 地震荒廃地における森林の成立過程を明らかにするため, 地震発生後12年目の荒廃地における木本植物の発達状態を検討した。その結果, 地震発生後12年を経過した現在, 木本群落の発達段階を三つに分けることができた。(1) 階層構造未発達段階: 木本植物の侵入・消失の繰り返しが激しく, 樹高生長が遅かった.この段階がみられる地点は, 岩塊におおわれているところがほとんどであり, これは地表が乾燥しやすいことに基因していると考えられる。(2) 階層構造をもつ段階: 堆積地点および地表が浅く削りとられた地点では, 先駆樹種の樹高生長が速く, 階層構造が形成された。上層はやせ地や乾燥地に耐え育つ先駆樹種のヤマハンノキおよびミヤマヤシャブシに占められ, 下層は, ヤナギ類が優勢樹種であったが, 耐陰性樹種の侵入も多くみられる。(3) 先駆樹種の侵入が抑制される段階: 樹冠閉鎖度が60%近くになり, 先駆樹種の下層への侵入が抑制され, 先駆樹種以外の樹種 (カツラ, ミツデカエデ, ヒノキなど) の侵入が多くなり, 徐々に優勢となった。

Using GIS and relation data, soil erosion change on the Fu-niu Mountains of Huaihe River Valley was made in 1986, 2000 and 2002. From the space this aspect, Soil erosion is mainly distributed in the north and west and south, the east is better than the west, the central region is better than the south and the north. From the time aspect, Soil erosion is a slight decrease, Erosion area rate is 24.74% in 1987, and it reduce to 24.12% in 2000, and it reduce to 22.33% in 2007. The results of the study show, the soil erosion in general presents alleviate trend.

According to the disadvantages of the assessment methods, considering complexity and limitation of assessment indexes, a comprehensive model for forest ecosystem health evaluation is established. By establishing forest ecosystem health evaluation index system, combining variation coefficient method with fuzzy mathematics theory, and making use of variation coefficient to obtain the weight of every index, the fuzzy mathematics method is used to make a comprehensive evaluation of forest ecosystem health. Meanwhile, the model is used to analyze the health condition of Quercus acutissima and Pinus massoniana forest in the south-mountainous area of Henan province. Results indicate that the model makes forest ecosystem health evaluation more comprehensive, more scientific and more coincident than practical situation, which provides scientific basis for project decision-making.

This paper measured the numbers and biomass of soil microbes as well as the soil respiration rate under mixed coniferous--broadleaved forest, mixed coniferous forest, pure coniferous forest, pure deciduous broadleaved forest, shrubs, and bare land in Taihang Mountain area, aimed to evaluate the soil microbial characters under different vegetation communities in this area. The results showed that shrub land had the greatest numbers and biomass of soil microbes, followed by deciduous broadleaved forestland, mixed coniferous--broadleaved forestland, pure coniferous forestland, and bare land. Soil respiration rate had the similar trend. When restoring the vegetations on degraded mountain land, more attention should be paid to the natural restoration capability of forest ecosystems.