Search

Background China has been increasingly subject to significant acid rain, which has negative impacts on forest ecosystems. Recently, the concentrations of NO3− in acid rain have increased in conjunction with the rapid rise of nitrogen deposition, which makes it difficult to precisely quantify the impacts of acid rain on forest ecosystems. Methods For this study, mesocosm experiments employed a random block design, comprised of ten treatments involving 120 discrete plots (0.6 m × 2.0 m). The decomposition of fine roots and dynamics of nutrient loss were evaluated under the stress of three acid rain analogues (e.g., sulfuric (SO42−/NO3− 5:1), nitric (1:5), and mixed (1:1)). Furthermore, the influences of soil properties (e.g., soil pH, soil total carbon, nitrogen, C/N ratio, available phosphorus, available potassium, and enzyme activity) on the decomposition of fine roots were analyzed. Results The soil pH and decomposition rate of fine root litter decreased when exposed to simulated acid rain with lower pH levels and higher NO3− concentrations. The activities of soil enzymes were significantly reduced when subjected to acid rain with higher acidity. The activities of soil urease were more sensitive to the effects of the SO42−/NO3− (S/N) ratio of acid rain than other soil enzyme activities over four decomposition time periods. Furthermore, the acid rain pH significantly influenced the total carbon (TC) of fine roots during decomposition. However, the S/N ratio of acid rain had significant impacts on the total nitrogen (TN). In addition, the pH and S/N ratio of the acid rain had greater impacts on the metal elements (K, Ca, and Al) of fine roots than did TC, TN, and total phosphorus. Structural equation modeling results revealed that the acid rain pH had a stronger indirect impact (0.757) on the decomposition rate of fine roots (via altered soil pH and enzyme activities) than direct effects. However, the indirect effects of the acid rain S/N ratio (0.265) on the fine root decomposition rate through changes in soil urease activities and the content of litter elements were lower than the pH of acid rain. Conclusions Our results suggested that the acid rain S/N ratio exacerbates the inhibitory effects of acid rain pH on the decomposition of fine root litter.

The biological pretreatment for the enzymatic hydrolysis of lignocellulosic biomasses depends exclusively on the effective pretreatment process. Herein, we report a significant enhancement of enzymatic saccharification obtained with corn stover using a bacterial strain Bacillus sp. P3. The hemicellulose removal from corn stover by the strain Bacillus sp. P3 was evaluated for enhancing subsequent enzymatic hydrolysis. Therefore, our study revealed that an alkaline-resistant xylanase as well as other enzymes produced by Bacillus sp. P3 in fermentation broth led to a substantially enhanced hemicellulose removal rate from corn stover within pH 9.36–9.68. However, after a 20-day pretreatment of corn stover by the strain P3, the glucan content was increased by 51% and the xylan content was decreased by 35%. After 72 h of saccharification using 20 U/g of commercial cellulase, the yield of reducing sugar released from 20-day pretreated corn stover was increased by 56% in comparison to the untreated corn stover. Therefore, the use of the strain P3 could be a promising approach to pretreat corn stover for enhancing the enzymatic hydrolysis process of industrial bioenergy productions.

The biological pretreatment for the enzymatic hydrolysis of lignocellulosic biomasses largely depends on an effective pretreatment process. A significant enhancement of enzymatic saccharification was obtained with corn stover using Bacillus sp. P3. The hemicellulose removal from corn stover by the strain Bacillus sp. P3 was evaluated for enhancing subsequent enzymatic hydrolysis. Therefore, our study revealed that an alkaline resistant xylanase produced by Bacillus sp. P3 in fermentation broth led to a substantially enhanced hemicellulose removal rate from corn stover within pH 9.36–9.68. However, after 20 d pretreatment of corn stover by the strain P3, the glucan content was increased by 51% and the xylan content was decreased by 35%. After 72 h of saccharification using 20 U g− 1 of commercial cellulase, the yield of reducing sugar released from 20 d pretreated corn stover was increased by 56% in comparison to the untreated corn stover. Therefore, the use of the strain P3 could be a promising approach to pretreat corn stover for enhancing the enzymatic hydrolysis process of industrial bioenergy productions.

Enzymatic saccharification of corn stover can be enhanced by partially replacing commercial enzymes with bacterial crude enzyme extracts. Three bacteria, Bacillus sp. A0, Bacillus sp. CH20S1, and Exiguobacterium sp. AS2B, were cultured in a media with corn stover as the substrate. The cultural conditions were monitored and optimized to maximize CMCase and xylanase activity in the crude enzyme extracts. After 72 h of hydrolysis of corn stover with diluted crude enzymes (DCE) from the three strains, reducing sugars were released from non-pretreated and pretreated corn stovers. Values of the released sugars ranged from 48.23–71.69 mg g− 1, which were lower than those released by commercial cellulase (100–400 mg g− 1). The synergistic effects were observed when 12 FPU g− 1 and 4 FPU g− 1 of commercial cellulase were added to the DCE of the CH20S1 strain producing 315.90 mg g− 1 and 320.65 mg g− 1 reducing sugars, respectively. It was shown that an effective combination of bacterial DCE with commercial enzymes could achieve more cost-efficient saccharification of lignocellulosic biomass compared to either of the two enzymes used alone.

There are a large number of abandoned mining areas in China, where external-soil spray seeding is a common technique used to assist with the restoration of these areas. However, the soil component of external-soil spray seeding is deficient, and they are prone to collapse, which complicates ecological restoration. In this study, we added a mineral-solubilizing microbial strain to an external-soil spray seeding substrate in Robinia pseudoacacia and Lespedeza bicolor pots, which were monitored from December 2018 to November 2019. We investigated their root growth and root tensile properties, as well as root-reinforced soil shear strength. The results revealed that the addition of the microbial strain in the substrate improved root growth of Robinia pseudoacacia. The root-reinforced soil shear strength, tensile force and strength were also strengthened by the added microbial strain. Although the growth rate of Robinia pseudoacacia was faster than that of Lespedeza bicolor, the shear strength of the root-reinforced Robinia pseudoacacia soil was lower than that of the Lespedeza bicolor root-reinforced soil of the same diameter. Finally, compared with the cohesion, the change in the friction angle is relatively small, and differences in cohesion resulted in shear strength changes under the same treatment. Our results suggested that the addition of a mineral-solubilizing microbial strain to the external-soil spray seeding substrate could help plants strengthen the soil and positively enhance its effects. These results might also enrich the existing data on the effects of mineral-solubilizing microbial strains on plant roots, while guiding further studies toward improving the efficacy of external-soil spray seeding technologies.

The brassinosteroids (BRs) constitute a recently defined class of plant hormone that can enhance the resistance of plants to multiple stresses. However, the effects of BRs on salt-stressed woody plants, notably on photosynthesis and chloroplast ultrastructure, have received little attention. Black locust (Robinia pseudoacacia L.) seeds and seedlings were pretreated with 1.04 µmol L− 1 24-epibrassinolide (24-epiBL) by soaking and root dipping, respectively, and grown under non-saline or saline conditions (0, 100, 200 mmol L− 1 NaCl). Salinity stress decreased photosynthesis, chlorophyll concentration, transpiration, and stomatal conductance but also decreased the water-use efficiency, while chlorophyll fluorescence indicated a decrease in photochemical quenching and in maximum potential quantum efficiency. Indicators of oxidative stress (for example, H2O2 and antioxidant enzymes), membrane leakage, and amounts of Na+ ions in leaves and chloroplasts were increased and, at the highest stress, chloroplast ultrastructure was severely disrupted. Exogenous 24-epiBL improved membrane stability and reduced foliar Na+ levels, while substantially alleviating stress-induced changes in photosynthetic gas exchange. Improvements in chlorophyll content and indicators of oxidative stress were not as large but were still highly significant. Thylakoid membrane structure was protected. Both methods of applying 24-epiBL were effective, but root-dipped seedlings performed marginally better. The results suggest that treatment of black locust seedlings with 24-epiBL prior to planting may improve performance and aid establishment on salt-affected soils.

Drought is one of the most critical limiting environmental factors for plant survival and restoration in areas of rocky desertification in southwestern China. Here, we aimed to understand how arbuscular mycorrhizal fungi (AMF) affect the growth and drought tolerance of tree species used for afforestation, with the ultimate aim of using them to restore degraded karst ecosystems. A pot experiment was conducted in which Zenia insignis seedlings were inoculated separately with three AMF (Funneliformis mosseae, Rhizoglomus intraradices, and Diversispora versiformis) and a mixture of all three species under two water regimes (drought stress and normal water) in a greenhouse. The results showed that AMF have a positive effect on plant biomass, osmolytes, and antioxidant enzyme activity under drought conditions. Shoot/root biomass increased by 12.5–33.8% and plant height increased by 13.6–32.1% after inoculation with AMF under drought conditions. The phosphorus content of the shoots significantly increased in mycorrhized plants, whereas nitrogen content was minimally affected. Superoxide dismutase and catalase activity was higher under drought stress in mycorrhized plants than in non-mycorrhized plants. The same pattern was found for soluble sugar and proline content in mycorrhized seedings under water deficit conditions. Mixed AMF inoculation had a more beneficial effect on plant growth than single AMF inoculation. In conclusion, our results indicate that AMF inoculation could help restore degraded ecosystems in desertified karst regions.

To find a multifunctional lignocellulolytic enzyme-producing strain, ten bacterial isolates from paper mill wastewater were tested for their carboxymethyl cellulose (CMC) hydrolytic ability. Bacillus sp. TPF-1, which exhibits the highest hydrolytic ability, was selected to produce lignocellulolytic enzymes using various biomass types as carbon sources. The highest CMCase (9.12 U/mL) and xylanase (102.55 U/mL) activities were obtained by green algae, and the maximum laccase activity (7037.28 U/L) was induced by Sargassum fusiforme. CMCase and xylanase showed the highest activities at 55 and 50 °C, respectively, with the same optimum pH of 5.4. The laccase exhibited optimum temperature of 40 °C and retained 60% more activity at 80 °C in extreme acid conditions (pH 2.2). To explore the multiple applications of these enzymes, crude enzymes induced by green algae were used to saccharify untreated algae. The reducing sugar produced by crude enzymes and commercial cellulase was 23 and 14% higher than that of the control, respectively, and it was 48% higher using crude enzymes with commercial cellulase (72 h). Additionally, the laccase induced by S. fusiforme was tested to decolorize two chemical dyes under an acidic condition (pH 2.2). The highest decolorization rates were 56.13 and 62.14% for Coomassie brilliant blue R-250 and Congo Red, respectively, in the presence of hydroxybenzotriazole monohydrate.

The influence of acid rain on forest trees includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in fine-root growth. In addition, the concentration of NO3- in acid rain increases with the rapidly growing of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO42-/NO3- (S/N) ratios, which were 5:1 (S), 1:1 (SN) and 1:5 (N), on fine-root growth from March 2015 to February 2016. Results showed that fine roots were more sensitive to the effects of acid rain than soils in the short-term. Both soil pH and fine root biomass (FRB) significantly decreased as acid rain pH decreased, and also decreased with the percentage of NO3- increased in acid rain. Acid rain pH significantly influenced soil total carbon and available potassium in summer. Higher acidity level (pH=2.5), especially of the N treatments, had the strongest inhibitory impact on soil microbial activity after summer. The structural equation modelling results showed that acid rain S/N ratio and pH had stronger direct effects on FRB than indirect effects via changed soil and fine root properties. Fine-root element contents and antioxidant enzymes activities were significantly affected by acid rain S/N ratio and pH during most seasons. Fine-root Al ion content, Ca/Al, Mg/Al ratios and catalase activity were used as better indicators than soil parameters for evaluating the effects of different acid rain S/N ratios and pH on forests. Our results suggest that the ratio of SO42- to NO3- in acid rain is an important factor which could affect fine-root growth in subtropical forests of China.

Labile fractions of soil carbon pools are sensitive to environmental changes, which would influence the stabilization of soil carbon. However, it is unclear whether the dynamics of labile organic carbon (LOC) and soil organic carbon (SOC) are coupled and how they influence each other in coastal wetland. The present work investigated the trends of soil carbon fractions among mangrove and Spartina alterniflora communities with different stand ages (1, 5, 10, and 15 years), at Quanzhou Bay Estuary Wetland Nature Reserve, China. We found that SOC in a mangrove ecosystem increased over time, while there was no significant trend in S. alterniflora dominated ecosystems. The highest LOC of mangrove appeared in 5-year-old communities, and then decreased with stand age. In S. alterniflora communities, content of labile fractions increased with the stand age. These trends indicated different soil carbon dynamics when comparing mangrove and S. alterniflora ecosystems. The development of mangroves promoted accumulation of recalcitrant carbon, while S. alterniflora ecosystems contributed to an increase of labile carbon. This phenomenon is probably caused by the characteristics of vegetation and the hydrological conditions. Mangroves contribute more refractory organic carbon to the soil carbon pool, while accumulation of LOC in S. alterniflora communities may inhibit the stabilization of SOC. Our study on the relationship of LOC and SOC implies that complex interactions occur among soil carbon pools and environmental conditions in coastal wetlands, suggesting soil carbon models should take into account decoupled dynamics of LOC and SOC.

A new honeycomb-like 2D Metal-organic polyhedral framework, {Cu3.75(BrCPEIP)2.5·(H2O)2.75·DMF}n (NJFU-5, H3BrCPEIP ​= ​5-((3-bromo-5-carboxyphenyl)ethynyl)isophthalic acid) was solvothermally synthesized and structurally characterized, which shows a BET surface area of 473 ​m2 ​g−1. Meanwhile, NJFU exhibits a comparably higher CO2 adsorption capacity of 37.0 ​cm3 ​g-1 (4.6 ​wt%) at 1 ​bar and 298 ​K in 2D MOF family, and a high CO2 selective adsorption toward N2 and CH4 as well.

Acid rain is mainly caused by dissolution of sulfur dioxide and nitrogen oxides in the atmosphere, and has a significant negative effect on ecosystems. The relative composition of acid rain is changing gradually from sulfuric acid rain (SAR) to nitric acid rain (NAR) with the rapidly growing amount of nitrogen deposition. In this study, we investigated the impact of simulated SAR and NAR on litter decomposition and the soil microbial community over four seasons since March 2015. Results first showed that the effects of acid rain on litter decomposition and soil microbial were positive in the early period of the experiment, except for SAR on soil microbes. Second, soil pH with NAR decreased more rapidly with the amount of acid rain increased in summer than with SAR treatments. Only strongly acid rain (both SAR and NAR) was capable of depressing litter decomposition and its inhibitory effect was stronger on leaf than on fine root litter. Meanwhile, NAR had a higher inhibitory effect on litter decomposition than SAR. Third, in summer, autumn and winter, PLFAs were negatively impacted by the increased acidity level resulting from both SAR and NAR. However, higher acidity level of NAR (pH = 2.5) had the strongest inhibitory impact on soil microbial activity, especially in summer. In addition, Gram-negative bacteria (cy19:0) and fungi (18:1ω9) were more sensitive to both SAR and NAR, and actinomycetes was more sensitive to SAR intensity. Finally, soil total carbon, total nitrogen and pH were the most important soil property factors affecting soil microbial activity, and high microbial indices (fungi/bacteria) with high soil pH. Our results suggest that the ratio of SO 4 2 − to NO 3 − in acid rain is an important factor which could affect litter decomposition and soil microbial in subtropical forest of China.

In this study, we investigated the effect of forest types changes (from coniferous and broadleaf mixed forest (CBMF) to plantation forests of bamboo (Phyllostachys pubescens forest, MBF) and hickory (Carya cathayensis forest, CHF)) combined with intensive management on soil organic carbon (SOC) and microbial community structure, using the 13C-nuclear magnetic resonance (NMR) and phospholipid fatty acid (PLFA). The results indicated that soil organic carbon significantly decreased by 30.7 and 28.5% in MBF and CHF, respectively. The aromatic C and aromaticity also significantly decreased in MBF and CHF (P 0.05). Significant changes of the soil microbial community were found after the forest type changed from CBMF to MBF and CHF. Total soil microbial PLFAs, soil bacteria PLFAs, fungus PLFAs, actinobacteria PLFAs, arbuscular mycorrhizal fungi PLFAs and protozoan PLFAs ranked as follows: CBMF > CHF > MBF (P CHF (0.66) > CBMF (0.49) (P CHF > MBF, P

The soil and water loss in rock mining areas is an extremely serious problem, while microbes play significant roles in soil remediation of those areas. In this study, a fungal strain Gongronella sp. NF-15 was isolated from the abandoned dolostone mines, and its mechanism of promoting dolostone dissolution was explored by analyzing the changes of pH value, Ca 2+ concentration, Mg 2+ concentration, organic acid concentration, micromorphology of rock surface, and rock particle diameter under controlled experimental conditions. After incubation of strain NF-15 with dolostone, the pH value continuously decreased significantly within 15 d, while the concentrations of Ca 2+ and Mg 2+ rose rapidly (1.8–2.7 times higher than that of control group). High performance liquid chromatography (HPLC) analysis showed that organic acids (succinic acid, citric acid, oxalic acid, malic acid, and lactic acid) were secreted by the strain NF-15 in the process of dolostone dissolution, and succinic acid was found more effective than other organic acids in lowering the pH and accelerating dissolution of rocks by Pearson correlation and Structural Equation Model (SEM) path analysis. In addition, the ultrastructure observation of the rock exhibited the significant erosion by fungal hyphae. Thus, strain NF-15 was suggested to combine with environmental remediation technologies to solve the problems of thin soil layer and mineral deficiency in destroyed dolostone mines. These results not only enrich the available microbial resources but also provide a new strategy for rehabilitating abandoned land in rock mining areas.

Carbonate minerals are extensively distributed across China, and their special rock structures make them vulnerable to land damage through mining, leading to rocky desertification. Soil microorganisms play an important role in mineral weathering. However, little is known about the utilization of the mineral-weathering microorganisms to alleviate the problem of rocky desertification in mines. In the present study, the mineral-solubilizing bacterium NL-11 was isolated from soil around weathered dolostones and identified as Bacillus thuringiensis (B. thuringiensis) based on the Biolog identification system and 16S rDNA sequence analysis. The mineral dissolution experiments revealed that inoculation with the live bacterium significantly increased the mineral sample dissolution via significantly enhancing Ca and Mg release, with increase values of 303.27 and 50.55 mg·L-1, respectively, compared to that with the inactivated bacterium. Moreover, the acetic acid secreted by strain NL-11 markedly decreased the size of particle diameter (quantified with a laser diffraction particle size analyser) through reducing pH value. The eroded traces were observed by scanning electron microscopy (SEM) analysis, and the results further verified the erosional effects of this strain. In addition, this bacterium contributed to the establishment and proliferation of plants by providing nutrient elements, such as phosphorus (P) and potassium (K). Our study not only provided an efficient bacterial strain NL-11, but also enriched the technologies to mitigate problems associated with ecological restorations of carbonate mines.

The distribution of species and communities in relation to environmental heterogeneity is a central focus in ecology. Co‐occurrence of species with similar functional traits is an indication that communities are determined in part by environmental filters. However, few studies have been designed to test how functional traits are selectively filtered by environmental conditions at local scales. Exploring the relationship between soil characteristics and plant traits is a step toward understanding the filtering hypothesis in determining plant distribution at local scale. Toward this end, we mapped all individual trees (diameter >1 cm) in a one‐ha subtropical forest of China in 2007 and 2015. We measured topographic and detailed soil properties within the field site, as well as plant leaf functional traits and demographic rates of the seven most common tree species. A second one‐ha study plot was established in 2015, to test and validate the general patterns that were drawn from first plot. We found that variation in species distribution at local scale can be explained by soil heterogeneity and plant functional traits. (From first plot). (1) Species dominant in habitats with high soil ammonium nitrogen and total phosphorus tended to have high specific leaf area (SLA) and relative growth rate (RGR). (2) Species dominant in low‐fertility habitats tended to have high leaf dry matter content (LDMC), ratio of chlorophyll a and b (ratioab), and leaf thickness (LT). The hypothesis that functional traits are selected in part by environmental filters and determine plant distribution at local scale was confirmed by the data of the first plot and a second regional site showed similar species distribution patterns.

Based on a new V-shaped tetracarboxylic ligand with a methoxyl group, a new mfj-type microporous metal–organic framework [Cu6(MBDPB)3(H2O)6]·12DMF·10H2O (NJFU-3, NJFU for Nanjing Forestry University; H4MBDPB for 5-methoxyl-1,3-bis(3,5-dicarboxylphenyl)-benzene) was successfully synthesized and structurally characterized. With moderately high porosity, appropriate pore aperture and unsaturated metal sites, the activated NJFU-3a exhibits high H2 (2.56 wt% at 77 K and 1 bar) and CO2 uptakes (15.8 wt% at 298 K and 1 bar), and a moderately high CH4 storage capacity of 155 cm3 cm−3 at 35 bar and 298 K. Meanwhile, it shows a comparably high delivery amount of 135 cm3 cm−3 when taking 5 bar as a specific lower pressure limit and 65 bar as the upper limit.

Dendrobium officinale is a kind of crop and precious herbal that is widely distributed in China. We applied transcriptomics to investigate the flavonoids and their biosynthesis-related genes from different tissues. Total flavonoid was determined in three different tissues. In this study, nine cDNA libraries were generated from Dendrobium officinale. A total of 530 million (70.73%) of the high-quality reads were successfully mapped to the reference genome of Dendrobium officinale and nine libraries were combined and assembled into 24,927 non-redundant genes. We mapped all of these genes to reference pathways in the KEGG database to identify polysaccharide and secondary metabolites pathways in which the genes may be involved. We outlined the biosynthetic pathway of flavonoids and identified putative genes, which provide understanding of the biosynthesis and regulation of Dendrobium officinale flavonoids at the molecular level. We identified five CHS genes from Dendrobium officinale and characterized the CHS gene family. The flavonoid-related key enzyme genes were identified, and their expression patterns in different tissues were further analyzed using quantitative real-time PCR. These data on flavonoid genes obtained in this work will be useful in understanding the molecular mechanisms of different tissues in Dendrobium officinale.

The Chinese honey locust tree Gleditsia sinensis Lam. (Fabaceae) is a precious ecological and economic tree species that has wide-ranging usage. However, knowledge regarding seedling cultivation (especially the use of arbuscular mycorrhizal fungi (AMF)) is scarce, which limits the developent of Gleditsia plantations. A pot experiment was carried out under greenhouse conditions to estimate the effects of three AMF strains (Funneliformis mosseae 1, Funneliformis mosseae 2, and Diversispora tortuosa) on the growth, photosynthetic rate, and nutrient content of G. sinensis seedlings. Results showed that the growth parameters (seedling height, basal diameter, dry biomass) of the seedlings were significantly increased by each of the three AMF strains, associated with high root colonization rates (greater than 75%). Chlorophyll concentrations and photosynthetic rates were also increased by AMF, and phosphorus (P), and potassium (K) content in the three organs (leaf, stem, and root), and nitrogen (N) content in the leaf and stem of arbuscular mycorrhizal (AM) seedlings were significantly higher than in non-AM seedlings. Mycorrhizal dependency of the AM seedlings was greater than 350%, and significantly correlated with the increased P and K content in all three organs and increased N content in the leaf and stem. Positive effects of F. mosseae on growth and the nutrient content of seedlings were higher than those of D. tortuosa, but no significant different effects on G. sinensis seedlings were observed between the two strains of F. mosseae. Hence, growth of G. sinensis seedlings was effectively enhanced by AMF, with F. mosseae being more suitable for the inoculation of G. sinensis seedlings. These results indicate that arbuscular mycorrhization is beneficial for the growth of young G. sinensis plants. Further research is needed to determine whether the effects can be reproduced in a forest situation.

Dendrobium, an important medicinal plant, is a source of widely used herbal medicine to nourish the stomach and treat throat inflammation. The present study is aimed at distinguishing and evaluating three major Dendrobium species by comparing physiochemical characteristics and understanding differences between different growth years in the Ta-pieh Mountains. Polysaccharides and total alkaloids of Dendrobium were determined, and the amino acids and trace elements were determined by UPLC (Ultra High-Performance Liquid Chromatography) and ICP-MS (Inductively coupled plasma mass spectrometry). It can be seen from the results that the polysaccharide content of these three kinds of Dendrobium in different growth years ranges from 249.31 mg·g-1 to 547.66 mg·g-1, and the highest content is in the 3-year-old Dendrobium huoshanense. The total alkaloid content ranges from 0.21 mg·g-1 to 0.54 mg·g-1, and the highest content is also the 3-year-old Dendrobium huoshanense. We determined the amino acid content of these three Dendrobium in different growth years, and we can see that each of the three kinds of Dendrobium contain seven kinds of amino acids required by the human body. We conducted a safety evaluation of the essential trace elements of Dendrobium, and the results showed that the dosage of 12g·d-1 Dendrobium prescribed in China Pharmacopoeia is in accordance with the recommended daily intake of trace elements recommended by the Food and Drug Administration of the United States, and will not cause trace element poisoning. Linear discriminant analysis was carried out on the basis of amino acids and trace elements and confirmed the applicability of multi-elemental analysis for identifying different Dendrobium species.

The harm of acid rain (AR) to plants foliage is mainly manifested by changing their physiological and biochemical processes, such as chlorosis, nutrient loss, enzyme activity changes, etc., which in turn impacts plant growth. Since the types of AR in China is changing, the response of plants to different types of AR has become a research hotspot. In this research, we investigated the responses of Q. acutissima foliage to simulated AR with different SO42−/NO3−(S/N) ratios and pH through chlorophyll contents, chlorophyll fluorescence characteristics, malondialdehyde content and antioxidant enzyme activities. The results showed that the maximal photochemical efficiency of PSⅡ (Fv/Fm) and superoxide dismutase (SOD) activity of Q. acutissima gradually decreased as the increase of NO3− concentration. With the decrease of AR pH, the inhibitory effect of simulated AR on growth rate and photochemical quenching coefficient (qP) gradually increased, and it also induced the increase of SOD and catalase (CAT) activities. Besides, pure NAR with low acidity (pH = 4.5) significantly increased basal diameter growth rate (DGR), chlorophyll content, peroxidase (POD) activity and qP, while decreased Chla/Chlb, fluorescence efficiency, non-photochemical quenching coefficient (NPQ), malondialdehyde (MDA) content and SOD activity. Correlation analysis indicated that the growth rate, chlorophyll content and fluorescence characteristics of Q. acutissima were highly correlated with foliar antioxidant enzyme activities under simulated AR stress. Our results indicated that different types of simulated AR had discrepant influences on the foliage physiological characteristics and above-ground growth of Q. acutissima, but not always negative, which made the protection of Q. acutissima plantation more complicated.

There has been a rapid increase in abandoned mines across China, Consequently, external-soil spray seeding technologies have emerged as a common method for their remediation. However, slope soils are typically unstable and easily collapsed and the nutrients absorbed by plants are insufficient, which complicate ecological restoration. For this study, we added mineral-solubilizing microbes and a water retaining agent to an external-soil spray seeding substrate in Lespedeza bicolor pots. We investigated the soil nutrients, soil enzyme activities, root growth parameters, root tensile properties, and root-reinforced soil shear strengths. The results revealed that the addition of microbes enhanced soil nutrients, soil enzyme activities, and the content of lignin and hemicellulose, which promoted root growth. Further, the addition of a water retaining agent promoted Lespedeza bicolor root growth but decreased the root tensile strength and force. Shear stress under the microbe treatment was more robust than without it. Finally, root growth was correlated with soil nutrients and enzyme activities, whereas the root tensile force and strength were correlated with lignin and cellulose. Our results suggested that the addition of mineral-solubilizing microbes had the capacity to enhance the quality of soils to facilitate the growth of plants. These results provide a new and viable strategy for the ecological restoration of abandon mine sites.

A new methyl-functionalized metal-organic framework, {Cu3(CMPEIP)2*2H2O}n (m-NB13, H3CMPEIP = 5-((4-carboxy-2-methylphenyl)ethynyl)isophthalic acid) was solvothermally synthesized and structurally characterized. {Cu3(CMPEIP)2*2H2O}n exhibits a high BET surface area of 3215.4 m2 g1, large H2 uptake (1.92 wt% at 1 bar and 77 K), and excellent CO2 storage capacity(9.24 wt% at 1 bar and 298 K).

Background The distribution and use of camphor (Cinnamomum camphora L.) trees are constrained by increasing soil salinity in south-eastern China along the Yangtze River. However, the response mechanism of this species to salinity, especially in team of photosynthesis, are unknown. Methods Here, we analysed themorphological, physiological, ultrastructural, and proteomic traits of camphor seedlings under NaCl (103.45 mM) treatment in pot experiments for 80 days. Results The growth was limited because of photosynthetic inhibition, with the most significant disturbance occurring within 50 days. Salinity caused severe reductions in the leaf photosynthetic rate (An), stomatal conductance (gs), maximal chlorophyll fluorescence (Fm), maximum quantum yield of PSII (Fv/Fm), non-photochemical quenching (NPQ), relative quantum efficiency of PSII photochemistry (ΦPSII), photochemical quenching coefficient (qP) and photo-pigment contents (chlorophyll a (Cha), chlorophyll b (Chb), total chlorophyll (Chl)); weakened the antioxidant effects, including those of malondialdehyde (MDA), superoxide dismutase (SOD) and peroxidase (POD); and injured chloroplasts. The physiologicalresults indicated that the main reason for photo-inhibition was oxidative factors induced by NaCl. The proteomic results based on isobaric tags for relative and absolute quantitation (iTRAQ) further confirmedthat photosynthesis was the most significant disrupted process by salinity (P C. camphor.

Acid rain (AR) is a serious issue in China, particularly in the Yangtze River Delta region where the economy has undergone rapid development. Over the last few years, the composition of acid rain in the Yangtze River Delta region has gradually changed from sulfuric acid rain (SAR) to nitric acid rain (NAR) due to controls on SO2 emissions, but increased NOx emissions. These changes have made ecosystems more complex. For this study, we halted AR treatments in Quercus acutissima forest plots that had received simulated AR for one year and monitored them from the following February to November. We investigated their soil resident enzyme and microbial metabolic activities, as well as community functional diversity. The results revealed that AR treatments negatively affected both the soil microbial activity and soil microbial community functional diversity; however, both managed to recover over time, once the AR treatments were stopped. During the AR treatment and recovery periods, four main categories (carbohydrates, carboxylic acids, amino acids, and polymers) were dominantly utilized. The utilization of pyruvic acid, which was affected by the AR treatments, as well as d-mannitol and tween 80, accounted for changes in the peak values of the C substrate groups during the AR treatment recovery period. Finally, changes in the activities of soil enzymes recorded following AR recovery, were closely related to the utilization of six C substrate groups. Our results suggested that the recovery of soils following the cessation of NAR stress was more rapid than from SAR. Further, that short-term NAR could be easily treated during the transformation from SAR to NAR in the Yangtze River Delta region. These results might also enrich the basic data relating to post-AR treatments on the soil environment, while having significance toward guiding further studies on the recovery of ecosystems from AR.

Dendrobium officinale is an important traditional Chinese medicinal plant and crop, which contains many kinds of medicinal components. The quality of medicinal plants is closely related to the ecological factors in a growing environment. The main components of D. officinale determined in this study were polysaccharides, total alkaloids and total flavonoids. In addition, this study dealt with the correlation of these components to 16 ecological factors under three different cultivation modes (Greenhouse, Bionic, Wild, Lu&rsquo, an, Anhui Province, China). The relationship between ecological factors and quality factors was analyzed step by step using correlation analysis, principal component analysis and stepwise multiple linear regression. Eight ecological factors: maximum relative humidity, minimum relative humidity, maximum temperature, sunshine duration, soil pH, soil total nitrogen, soil total phosphorus and soil available phosphorus were considered as key factors that influenced the main medicinal qualities of cultivated D. officinale. This study provides an insight for exploring the complex relationship between ecological factors and D. officinale medicinal value in artificial cultivation.

As a brassinosteroid (BR), 24-epibrassinolide (24-epiBL) has been widely used to enhance the resistance of plants to multiple stresses, including salinity. Black locust (Robinia pseudoacacia L.) is a common species in degraded soils. In the current study, plants were pretreated with three levels of 24-epiBL (0.21, 0.62, or 1.04 &micro, M) by either soaking seeds during the germination phase (Sew), foliar spraying (Spw), or root dipping (Diw) at the age of 6 months. The plants were exposed to salt stress (100 and 200 mM NaCl) via automatic drip-feeding (water content ~40%) for 45 days after each treatment. Increased salinity resulted in a decrease in net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular:ambient CO2 concentration ratio (Ci/Ca), water-use efficiency (WUEi), and maximum quantum yield of photosystem II (PSII) (Fv/Fm). Non-photochemical quenching (NPQ) and thermal dissipation (Hd) were elevated under stress, which accompanied the reduction in the membrane steady index (MSI), water content (RWC), and pigment concentration (Chl a, Chl b, and Chl). Indicators of oxidative stress (i.e., malondialdehyde (MDA) and antioxidant enzymes (peroxidase (POD) and superoxide dismutase (SOD)) in leaves and Na+ content in chloroplasts increased accompanied by a reduction in chloroplastid K+ and Ca2+. At 200 mM NaCl, the chloroplast and thylakoid ultrastructures were severely disrupted. Exogenous 24-epiBL improved MSI, RWC, K+, and Ca2+ content, reduced Na+ levels, maintained chloroplast and thylakoid membrane structures, and enhanced the antioxidant ability in leaves. 24-epiBL also substantially alleviated stress-induced limitations of photosynthetic ability, reflected by elevated chlorophyll fluorescence, pigment levels, and Pn. The positive effects of alleviating salt stress in R. pseudoacacia seedlings in terms of treatment application was Diw &gt, Sew &gt, Spw, and the most positive impacts were seen with 1.04 &micro, M 24-epiBL. These results provide diverse choice for 24-epiBL usage to defend against NaCl stress of a plant.

The influence of acid rain on plant growth includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in root growth. In addition, the concentration of NO3- in acid rain increases along with the rapid growth of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO42-/NO3- (S/N) ratios, which were 1:0, 5:1, 1:1, 1:5 and 0:1, on Chinese fir sapling growth from March 2015 to April 2016. Results showed that Chinese fir sapling height growth rate (HGR) and basal diameter growth rate (DGR) decreased as acid rain pH decreased, and also decreased as the percentage of NO3- increased in acid rain. Acid rain pH significantly decreased the Chlorophyll a (Chla) and Chlorophyll b (Chlb) content, and Chla and Chlb contents with acid rain S/N 1:5 were significantly lower than those with S/N 1:0 at pH 2.5. The chlorophyll fluorescence parameters, maximal efficiency of Photosystem II photochemistry (Fv/Fm) and non-photochemical quenching coefficient (NPQ), with most acid rain treatments were significantly lower than those with CK treatments. Root activities first increased and then decreased as acid rain pH decreased, when acid rain S/N ratios were 1:1, 1:5 and 0:1. Redundancy discriminant analysis (RDA) showed that the Chinese fir DGR and HGR had positive correlations with Chla, Chlb, Fv/Fm ratio, root activity, catalase and superoxide dismutase activities in roots under the stress of acid rain with different pH and S/N ratios. The structural equation modelling (SEM) results showed that acid rain NO3- concentration and pH had stronger direct effects on Chinese fir sapling HGR and DGR, and the direct effects of acid rain NO3- concentration and pH on HGR were lower than those on DGR. Our results suggest that the ratio of SO42- to NO3- in acid rain is an important factor which could affect the sustainable development of monoculture Chinese fir plantations in southern China.

Immobilized chitosan-Ag nanoparticles (CTS-Ag NPs) with special surface state have been synthesized successfully through immobilizing Ag NPs on the amino-enriched surface of CTS by reducing Ag (I) in situ. The antimicrobial efficiency and potency of CTS-Ag NPs against Escherichia coli and Staphylococcus aureus were studied. Our results reveal that surface-immobilized CTS-Ag NPs show better antimicrobial efficacy than several other reported monodisperse colloidal Ag NPs, because the unique surface state of our CTS-Ag NPs leads to both "contact killing" and "ion mediated killing" functions. Due to the synergetic effect of CTS and Ag NPs, the immobilized CTS-Ag NPs present a broader antimicrobial spectrum and a more effective antifungal activity against Monilia albican. In addition, CTS as an environment friendly dispersant can help to reduce the cytotoxicity of Ag NPs on higher organisms. The immobilized CTS-Ag NPs are stable and can maintain good disinfection potential after 6 months' shelf-time.

Highly stable dispersions of nanosized copper (Cu) particles with an average size of (2.6 ± 0.5) nm were synthesized by in situ reduction of Cu(II) to immobilize Cu nanoparticles on the amino-enriched surface of chitosan (CTS). The synthetic process and stability of the l -ascorbic acid-stabilized Cu-CTS nanocomposites were investigated by X-ray photoelectron spectroscopy and Fourier transform Infrared spectroscopy. The antimicrobial efficiency and potency of the Cu-CTS nanocomposites were studied. The Cu-CTS nanocomposites were found to exhibit a broad antimicrobial spectrum and high antimicrobial activity against Gram-positive bacterial pathogen Staphylococcus aureus and fungal pathogen Monilia albican. The minimum inhibitory concentration of the Cu-CTS nanocomposites toward S. aureus was found to be 6.4 µg mL−1, much lower than those reported in the literature. Furthermore, the Cu-CTS nanocomposites were stable and maintained good disinfection potential even after 90-day shelf-time under ambient conditions.

Cyclobalanopsis glauca is an important afforestation tree species that is widely used for revegetating the karst region of southwest China. Vegetation in this region is regularly commonly subjected to drought stress because of the geology and water shortages. Here, we investigated the influence of two arbuscular mycorrhizal fungi (AMF) Glomus mosseae and Glomus intraradices on the drought tolerance of C. glauca seedlings under greenhouse conditions. AMF-treated and non-AMF-treated C. glauca seedlings were maintained under two different water regimes (well watered: 80 % field capacity; drought stress: 40 % field capacity) for 90 days. The AMF colonization rate was higher under well-watered conditions compared to drought stress conditions. The growth and physiological performance of C. glauca seedlings were significantly affected by drought stress. Under drought stress conditions, mycorrhizal seedlings had greater height, base diameter, leaf area, and biomass compared to non-mycorrhizal seedlings. In addition, under drought conditions, AMF-inoculated seedlings had greater superoxide dismutase and peroxidase activity, higher soluble sugar content, and lower proline content compared to non-inoculated seedlings. Furthermore, AMF colonization increased the phosphorus and potassium content of seedling shoots under both well-watered and drought stress conditions. Therefore, AMF colonization enhanced the drought tolerance of C. glauca seedlings by improving growth performance, nutrient content, the quantity of osmotic adjustment compounds, and antioxidant enzyme activity. The results indicate that AMF are of potential use for the restoration of vegetation in the karst region of southwest China.

To reveal the biological characteristics of urban forest soil and the effects of soil enzyme on soil fertility as well as the correlation between physicochemical properties and enzyme activities, 44 urban forest soil profiles in Nanjing were investigated. Basic soil physicochemical properties and enzyme activities were analyzed in the laboratory. Hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase were determined by potassium permanganate titration, TTC (C19H15N4·Cl) colorimetry, phenyl phosphate dinatrium colorimetry, and anthrone colorimetry, respectively. The result showed that soil pH, organic carbon (C), and total nitrogen (N) had great effects on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 0–20 cm thick soil. However, pH only had great effect on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 20–40 cm thick soil. Hydrogen peroxidase, dehydrogenase, and alkaline phosphatase were important biological indicators for the fertility of urban forest soil. Both in 0–20 cmand 20–40 cmsoil, soil enzyme system (hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase) had a close relationship with a combination of physicochemical indicators (pH, organic C, total N, available K, available P, cation exchange capacity (CEC), and microbial biomass carbon (Cmic)). The more soil enzyme activities there were, the higher the fertility of urban forest soil.

Chinese hickory (Carya cathayensis), a popular nut food tree species, is mainly distributed in southeastern China. A field study was carried out to investigate the effect of long-term intensive management on fertility of soils under aC.cathayensisforest. Results showed that after 26 years’ intensive management, the soil organic carbon (SOC) content of the A and B horizons reduced by 19% and 14%, respectively. The reduced components of SOC are mainly the alkyl C and O-alkyl C, whereas the aromatic C and carbonyl C remain unchanged. The reduction of active organic matter could result in degradation of soil fertility. The pH value of soil in the A horizon had dropped by 0.7 units on average. The concentrations of the major nutrients also showed a decreasing trend. On average the concentrations of total nitrogen (N), phosphorus (P), and potassium (K) of tested soils dropped by 21.8%, 7.6%, and 13.6%, respectively, in the A horizon. To sustain the soil fertility andC.cathayensisproduction, it is recommended that more organic fertilizers (manures) should be used together with chemical fertilizers. Lime should also be applied to reduce soil acidity.