Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar...Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar is an inherent catalyst for pyrolysis.In this study,in order to investigate the influence of functionalities and pore structures of biochar on its capability for catalyzing the conversion of homologous volatiles in bio-oil,three char catalysts(600C,800C,and 800AC)produced via pyrolysis of poplar wood at 600 or 800℃or activated at 800℃,were used for catalyzing pyrolysis of homologous poplar wood at 600℃,respectively.The results indicated that the 600C catalyst was more active than 800C and 800AC for catalyzing cracking of volatiles to form more gas(yield increase by 40.2%)and aromatization of volatiles to form more light or heavy phenolics,due to its abundant oxygen-containing functionalities acting as active sites.The developed pores of the 800AC showed no such catalytic effect but could trap some volatiles and allow their further conversion via sufficient aromatization.Nevertheless,the interaction with the volatiles consumed oxygen on 600C(decrease by 50%),enhancing the aromatic degree and increasing thermal stability.The dominance of deposition of carbonaceous material of a very aromatic nature over 800C and 800AC resulted in net weight gain and blocked micropores but formed additional macropores.The in situ diffuse reflectance infrared Fourier transform spectroscopy characterization of the catalytic pyrolysis indicated superior activity of 600C for removal of -OH,while conversion of the intermediates bearing C=O was enhanced over all the char catalysts.展开更多
This paper introduces the identification characteristics,occurrence regularity and control methods of several leaf diseases of poplar,including poplar angular leaf spot,poplar large spot,poplar leaf blight and poplar ...This paper introduces the identification characteristics,occurrence regularity and control methods of several leaf diseases of poplar,including poplar angular leaf spot,poplar large spot,poplar leaf blight and poplar rust,in order to provide the basis for the healthy growth of poplar and the technical support for the sustainable development of forestry industry.展开更多
Wet wood is an abnormal phenomenon in growing trees,which adversely affects growth,subsequent wood processing and economic values of wood products.In this study,the influences of factors such as clones,afforestation m...Wet wood is an abnormal phenomenon in growing trees,which adversely affects growth,subsequent wood processing and economic values of wood products.In this study,the influences of factors such as clones,afforestation methods,site conditions and climate conditions on the characteristics of poplar wetwood were studied through field investigations in 27 clones from 48 sample plots in 28 counties.Results showed that the incidences of wetwood were almost 100%in all plots.Ratios of wetwood area among the48 plots differed from 15.1 to 90.2%.Wetwood area ratios,moisture contents and pH differed significantly between the 27 clones.Wetwood area ratios of the clones ranged from18.7 to 62.3%.Ratios of wetwood areas were positively correlated with wet wood moisture content and pH,tree age,and negatively correlated with pH of sap wood.The repeatability of wet wood area ratios was 0.52,moderately controlled by genetics.Wetwood moisture content and pH were highly controlled by genetics,indicated by the repeatability of 0.91 and 0.89,respectively.There were significant differences in wetwood area ratios,moisture content and pH between different site conditions,afforestation methods,and geographical regions.Sloping land had the lowest wetwood area ratios and moisture content among four types of sites.Afforestation by direct seeding and rooted cuttings had the lowest wetwood area ratios and moisture content,respectively.In the three geographical regions,the Yellow River Basin had the lowest wetwood values of all three factors.展开更多
Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood ...Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.展开更多
The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woo...The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woody plants.As a model material of woody plants,poplar not only has very significant value of research,but also possesses economic and ecological properties.This study reports the Populus trichocarpa DJ-1C(PtrDJ1C)factor,encoded by a nuclear gene,and a member of the DJ-1 superfamily.PtrDJ1C knock-out with the CRISPR/Cas9 system resulted in different albino phenotypes.Chlorophyll fluorescence and immunoblot analyses showed that the levels of photosynthetic complex proteins decreased significantly.Moreover,the transcript level of plastid-encoded RNA polymerase-dependent genes and the splicing efficiency of several introns were affected in the mutant line.Furthermore,rRNA accumulation was abnormal,leading to developmental defects in chloroplasts and affecting lignin accumulation.We concluded that the PtrDJ1C protein is essential for early chloroplast development and lignin deposition in poplar.展开更多
Poplar wood,which was used as the absorption material for the solar-driven interfacial evaporation,was treated for 3 days,6 days and 9 days with the pectinase,and then was simulated for photothermal evaporation test a...Poplar wood,which was used as the absorption material for the solar-driven interfacial evaporation,was treated for 3 days,6 days and 9 days with the pectinase,and then was simulated for photothermal evaporation test at one standard solar radiation intensity(1 kW⋅m^(−2)).The effects of pectinase treatment on cell passage and water migration capacity of poplars were analyzed by the mercury intrusion porosimetry,the scanning electron microscope and fractal theory.It was found that the pit membrane and the ray parenchyma cells of poplar wood were degraded and destroyed after pectinase treatment.Compared with the untreated poplar wood,the evaporation rate of three sections of the specimen was changed.Especially the evaporation rate of radial and tangential direction was significantly increased.At the same time,based on the experimental data and fractal dimension deduction,fractal characteristics could be found in that the structure of poplars treated with pectinase.The porosity decreased with the increase of the fractal dimension in a certain range.It was shown that it is feasible to evaluate solar-driven water migration capacity by using fractal theory.展开更多
Drought seriously affects the growth and development of plants.MiR159 is a highly conserved and abundant microRNA family that plays a crucial role in plant growth and stress responses.However,studies of its function i...Drought seriously affects the growth and development of plants.MiR159 is a highly conserved and abundant microRNA family that plays a crucial role in plant growth and stress responses.However,studies of its function in woody plants are still lacking.Here,the expression of miR159a was significantly upregulated after drought treatment in poplar,and the overexpression of miR159a(OX159a)significantly reduced the open area of the stomata and improved water-use efficiency in poplar.After drought treatment,OX159a lines had better scavenging ability of reactive oxygen species and damage of the membrane system was less than that in wild-type lines.MYB was the target gene of miR159a,as verified by psRNATarget prediction,RT-qPCR,degradome sequencing,and 5′rapid amplification of cDNA ends(5′RACE).Additionally,miR159a-short tandem target mimic suppression(STTM)poplar lines showed increased sensitivity to drought stress.Transcriptomic analysis comparing OX159a lines with wild-type lines revealed upregulation of a series of genes related to response to water deprivation and metabolite synthesis.Moreover,drought-responsive miR172d and miR398 were significantly upregulated and downregulated respectively in OX159a lines.This investigation demonstrated that miR159a played a key role in the tolerance of poplar to drought by reducing stomata open area,increasing the number and total area of xylem vessels,and enhancing water-use efficiency,and provided new insights into the role of plant miR159a and crucial candidate genes for the molecular breeding of trees with tolerance to drought stress.展开更多
Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,...Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,and mode-II interlaminar fracture of poplar LVL.We investigated stress mechanisms,failure modes,and fracture toughness values of the different fracture types.The experimental results revealed that the crack in the mode-I along-grain interlaminar fracture specimen propagated along the prefabricated crack direction,and the crack tip broke.The mode-I cross-grain interlaminar fracture specimen had cracks in the vertical direction near the prefabricated crack.In the mode-II interlaminar fracture specimen,cracks appeared along the initial prefabricated crack direction.The load–displacement curves of these three specimens were linear in the early stage of loading.With the increase in the load,a nonlinear segment appeared before crack propagation and a descending segment appeared after crack propagation.The nonlinear segments of the mode-I along-grain interlaminar fracture and mode-II interlaminar fracture were very short,and cracks expanded quickly after their initiation,resulting in brit-tle fracture.The nonlinear segment of the mode-I cross-grain interlaminar fracture was long,resulting in plastic failure.The average toughness values of the mode-I along-grain interlaminar fracture,mode-I cross-grain inter-laminar fracture,and mode-II interlaminar fracture were 15.43,270.15,and 39.72 MPa·mm^(1/2),respectively.展开更多
We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard (CBPB) containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland...We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard (CBPB) containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM (Response Surface Methodology). The mathematical model equations (second-order response functions) were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values (R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively). RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength > 12.5 MPa and internal bond strength > 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 (2003) for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.展开更多
To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,...To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).展开更多
We developed a system for the regeneration of Lombardy poplar (Populus nigra L. var. italica) shoots from internodal stem explants. Using this system, shoots regenerated from 87% of the stem explants placed on Murashi...We developed a system for the regeneration of Lombardy poplar (Populus nigra L. var. italica) shoots from internodal stem explants. Using this system, shoots regenerated from 87% of the stem explants placed on Murashige and Skoog (MS) medium supplemented with 0.1 mg/L indole-3-acetic acid and 0.5 mg/L benzylaminopurine without undergoing callus formation. About 80% of the in vitro regenerated shoots developed roots on MS medium supplemented with 0.5 mg/L indole-3-butyric acid and 0.02 mg/L 1-naphthylacetic acid. Well-rooted seven-to eight-week-old regenerated plants could be transferred to soil for further growth and the survival rate of such plants after three weeks was 88%. The protocol presented here is simple and economical because it does not rely on pre-incubation in callus induction medium or repeated subculture in shoot induction medium containing trans-zeatin, an expensive substance. The in vitro regeneration system presented here could be used for evaluation of radiation sensitivity for Lombardy poplar tissues.展开更多
Growth characteristics have complex inheritance patterns and genotype(G) by environment(E) interaction make predicting tree response to environmental changes difficult.In this study,the growth of seven poplar clones a...Growth characteristics have complex inheritance patterns and genotype(G) by environment(E) interaction make predicting tree response to environmental changes difficult.In this study,the growth of seven poplar clones at three different sites was taken as the research focus,and heights and basal diameters were investigated in the second growing season.An ANOVA showed that all main effects,site,clone number and their interactions were highly significant in the overall F-tests.The coefficients of variation and repeatability of different traits ranged from 15.5 to 43.9%and from 0.549 to 0.912,respectively.AMMI(Additive Main Effects and Multiplicative Interaction) analysis results showed that genotype,environment and G × E interaction were significantly highly correlated.The stability analysis indicated that different clones showed different growth traits on different sites,which suggests that elite clones should be selected separately for different sites.Based on the growth traits,under a 10% selection rate,three clones were selected for different sites and the genetic gains of growth traits ranged from 4.7 to 11.2%.The three selected clones could be used to establish plantations in the future in different sites.展开更多
The above-ground biomass and nutrient accumulation by poplar plantations were evaluated for pulpwood production ]n China, Experimental treatments applied in a split-plot design included four planting densities (1111, ...The above-ground biomass and nutrient accumulation by poplar plantations were evaluated for pulpwood production ]n China, Experimental treatments applied in a split-plot design included four planting densities (1111, 833, 625 and 500 stems hm-2), three rotation lengths (4a, 5a and 6a) and three poplar clones (1-69.NL-80351 and 1-72). The highest biomass was achieved in the highest stocked stand (1111 stem hm-2’) at 6 of rotation age for both clone 1-69 and clone 1-72, which is about two times that in the stands of 500 stems hm-2 at 4 ofrotation age. However, the highest occurred in the stand of 833 stems-hm-2 at 6-year rotation for NL-80351. Ranking of the plantation biomass production by component was stem > branches > foliage> stem--bark and the production of the Support components of the plantation was 10-fold that of the productive component, i.e., foliage. Thepattern of accumulation of nutrients by the plantations was similar to the biomass. Nutrient accumulation in theplantations was in the order of Ca>N>K>Mg>P, but some differences existed in annual nutrient accumulationrates for four planting densities and three poplar clones, The mean annual accumulation of N and P in the plantations was 13.2 and 2.8 kg hm-2 in stem, 12.1 and 1 .9 kg hm 2 in branch, and 98.5 and 9.5 kghm’ in foliage. Themean Ca, K and Mg accumulations were 28.2, 1 8.5 and 2.9 kg’hm-2 a-1, 26,9. 11,0 and 2.3 kg-hm-2-a-1 in branch.and 116.5, 81 .3 and 16, 1 kg hm-2 a-1 in foliage, respectively. Biomass utilization standards markedly affected theexport of nutrients from the site, Whole tree utilization yields the most biomass and removes the most nutrients,Removal of stem with 2 10-cm diameter exports about half of the biomass, but N and nutrients removals are only23% and 28% of the total, respectively, Removal of the entire stem provides about tWo--thirds of the total biomassand removes 31,1% total N and 37.5 % total nutrients respectively. Including the branches in the removal increases biomass yield to 92% of the total, and nutrient removal is about 68% of the total,展开更多
With economic incentives and interests in fastgrowing poplar trees for short-rotation production of fiber and veneer,many new poplar hybrids have been bred and planted in China,but how to match the new poplar clones t...With economic incentives and interests in fastgrowing poplar trees for short-rotation production of fiber and veneer,many new poplar hybrids have been bred and planted in China,but how to match the new poplar clones to suitable sites and maintain their higher growth rates is still not very clear.In this study,the photosynthetic response of poplar leaves at various developmental stages during two seasons(summer and autumn) was explored and mechanistic models for the photosynthesis of poplar leaves at different developmental phases in response photosynthetic active radiation(PAR),temperature,and relatively humidity were established using the optimization software package 1 st Opt.Mature poplar leaves in autumn had significantly higher photosynthetic capacity than leaves at other stages and seasons.Based on the models established for poplar leaves at different phases,the main limiting factors for photosynthesis at the research site were high PAR and temperature in the summer and low PAR in the autumn.Our results highlight the importance of selecting suitable sites,pruning and stand density control during the plantation development to maintain higher photosynthetic rates of poplar trees and to establish optimum cultivation patterns for various utilization of poplar plantations.展开更多
The main disease species on poplar are introduced in this paper. The main content of the integrated control technique on poplar diseases is summarized:(1) Forecast technique based on the initial disease and provention...The main disease species on poplar are introduced in this paper. The main content of the integrated control technique on poplar diseases is summarized:(1) Forecast technique based on the initial disease and provention factors. (2) Control index is established, based on the relationship among the disease index, height of tree, diameter grade and the loss rate of volume. (3) Five fine varieties are selected according to three integrated indexes of host, such as resistance, volume growth and form ratio; They are 613 (Poulus alba ×P. berolinensis), A15 (P. xiaohei × P. euramericana CV. Polska-15A), A98 (P.xiaohei×(P. simonii×P. nigra) CV. A98), A102 (P. xiaohei) × (P. simonee × P. nigra) CV. A102), L2 (P. simonii × P nigra var. italica) in northeast Chnia. (4) Sivicultural control is known as the main protection measures, combined with chemical control and biocontrol,based on the disease forecast and control index by tracing the whole process of forest production.展开更多
Dendroremediation,a novel strategy for cleaning up contaminants from the environment by using special woody plant species and microbes,is a popular phytoremediation approach.It is a cost-effective and environmentally ...Dendroremediation,a novel strategy for cleaning up contaminants from the environment by using special woody plant species and microbes,is a popular phytoremediation approach.It is a cost-effective and environmentally friendly method that is being increasingly adopted.Poplar species(Populus L.)have been suggested for use in remediation because of their characteristics of high biomass production,fast growth,and potential for removing pollutants.Our environment is often contaminated by toxic substances produced by human activities,and remediation of contamination is therefore a global issue.Atrazine is one of the most widely used herbicides in China.In the present study,‘I-69/55’poplar(P.deltoides cv.‘I-69/55’)and hybrid poplar(Populus deltoides×nigra,DN34)grown in pots were assayed for their ability to remediate atrazine-contaminated soils.The degradation dynamics of atrazine were assessed with a high-performance liquid chromatography system using materials from a greenhouse with different rhizosphere environments.We studied the dynamic variation in microbes and microbial biomass carbon to elucidate the rhizosphere effects and mechanism of remediation of atrazine-contaminated soil by poplar.Our four treatments included a control with uncontaminated soil without a tree,atrazine pollution without a tree,atrazine pollution with‘I-69/55’poplar,and atrazine pollution with hybrid poplar.Hybrid poplar showed potential for remediation of atrazine-contaminated soil,and the degradation of atrazine in the rhizosphere was faster than that in non-rhizosphere soil.Atrazine significantly inhibited bacteria growth in nonrhizosphere soil.The high concentration of bacteria in the hybrid poplar rhizosphere might be key to atrazine degradation.Trends of change among fungi and actinomyces did not correspond to trends in atrazine degradation throughout the trial period.Further research is needed to predict the effects of atrazine on cultivable microorganisms in various soils.Atrazine had significant inhibitory effects on microbial biomass carbon in non-rhizosphere soil,and the rhizosphere environment of poplars enhanced the recovery of microbial biomass carbon.The potential for hybrid poplar as a dendroremediation material needs further study.展开更多
First, a theoretical model of density of cuttage seedlings on poplar was evaluated by using mathematical tools based on anatomy and morphology of photosynthesis organ, then,according to this, an afforestation density ...First, a theoretical model of density of cuttage seedlings on poplar was evaluated by using mathematical tools based on anatomy and morphology of photosynthesis organ, then,according to this, an afforestation density of the trces was put forward, finally, the importance,scope and method of the theoretic application wcre described through a concretc calculation. The result showed that these density models had not only rigorous theory base, including biology and mathematics, but also wide applying prospect. And at the same timc, the model parameters could be gotten easily in forestry practice.展开更多
To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic s...To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.展开更多
The priming effect(PE)induced by biochar provides a basis for evaluating its carbon(C)sequestration potential in soils.A 60 days’laboratory incubation was conducted,which involved the amendment of biochar(1%of soil m...The priming effect(PE)induced by biochar provides a basis for evaluating its carbon(C)sequestration potential in soils.A 60 days’laboratory incubation was conducted,which involved the amendment of biochar(1%of soil mass)produced from rice straw at 300℃(B300)and 500℃(B500)to young(Y)and old(O)poplar plantation soils,with the aim of studying the responses of biochar-induced PEs to poplar plantation ages.This incubation included six treatments:Y+CK(control),Y+B300,Y+B500,O+CK,O+B300,and O+B500.Carbon dioxide(CO_(2))emissions were significantly increased(p<0.05)in the B300 amended soils,while it was decreased in the B500 amended soils compared to the CK.The primed CO_(2) emissions were 2.35 times higher in the Y+B300 than the O+B300 treatments,which was measured to be 18.6 and 5.56 mg C·kg^(-1) with relative PEs of 12.4%and 3.35%,respectively.However,there was little difference between the primed CO_(2) emissions in Y+B500 and O+B500 treatments,which were measured to be-24.9 and-29.6 mg·C·kg^(-1) with relative PEs of-16.6%and-17.8%,respectively.Dissolved organic carbon(DOC)was significantly lower in the young poplar plantation soil than that in the old poplar plantation soil regardless of biochar amendment throughout the incubation,indicating greater C-limit of soil microorganisms in the young poplar plantation soil.Using ^(13)C isotope tracing,neither B300 nor B500 decreased native soil-derived DOC,which indicated that the negative B500-induced PEs were not due to a reduction in the availability of native soil-derived C.In conclusion,the response of biochar-induced PEs to poplar plantation age depends on biochar types while soil available C indirectly affects biochar-induced PEs.Further studies should focus on how the interactive effects between soil C availability and microbial community impacts biochar-induced PEs.展开更多
基金supported by the National Natural Science Foundation of China(51876080)the Program for Taishan Scholars of the Shandong Province Government。
文摘Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar is an inherent catalyst for pyrolysis.In this study,in order to investigate the influence of functionalities and pore structures of biochar on its capability for catalyzing the conversion of homologous volatiles in bio-oil,three char catalysts(600C,800C,and 800AC)produced via pyrolysis of poplar wood at 600 or 800℃or activated at 800℃,were used for catalyzing pyrolysis of homologous poplar wood at 600℃,respectively.The results indicated that the 600C catalyst was more active than 800C and 800AC for catalyzing cracking of volatiles to form more gas(yield increase by 40.2%)and aromatization of volatiles to form more light or heavy phenolics,due to its abundant oxygen-containing functionalities acting as active sites.The developed pores of the 800AC showed no such catalytic effect but could trap some volatiles and allow their further conversion via sufficient aromatization.Nevertheless,the interaction with the volatiles consumed oxygen on 600C(decrease by 50%),enhancing the aromatic degree and increasing thermal stability.The dominance of deposition of carbonaceous material of a very aromatic nature over 800C and 800AC resulted in net weight gain and blocked micropores but formed additional macropores.The in situ diffuse reflectance infrared Fourier transform spectroscopy characterization of the catalytic pyrolysis indicated superior activity of 600C for removal of -OH,while conversion of the intermediates bearing C=O was enhanced over all the char catalysts.
基金Supported by General Program of Natural Science Foundation of Henan Province(222300420508)Scientific and Technological Research Program of Science and Technology Department of Henan Province(202102310478)+1 种基金Highlevel Talents Start-up Fund of Pingdingshan University(PXY-BSQD-2012009)Training Program for Young Key Teachers in Colleges and Universities of Henan Province(2021GGJS147)。
文摘This paper introduces the identification characteristics,occurrence regularity and control methods of several leaf diseases of poplar,including poplar angular leaf spot,poplar large spot,poplar leaf blight and poplar rust,in order to provide the basis for the healthy growth of poplar and the technical support for the sustainable development of forestry industry.
基金funded by the Hubei Provincial Natural Science Foundation of China (2021CFB446)the National Natural Science Foundation of China (31570665)+1 种基金the National Key Research and Development Program of China (2021YFD2201202)the Fundamental Research Funds for the Central Universities (2662020YLPY017)。
文摘Wet wood is an abnormal phenomenon in growing trees,which adversely affects growth,subsequent wood processing and economic values of wood products.In this study,the influences of factors such as clones,afforestation methods,site conditions and climate conditions on the characteristics of poplar wetwood were studied through field investigations in 27 clones from 48 sample plots in 28 counties.Results showed that the incidences of wetwood were almost 100%in all plots.Ratios of wetwood area among the48 plots differed from 15.1 to 90.2%.Wetwood area ratios,moisture contents and pH differed significantly between the 27 clones.Wetwood area ratios of the clones ranged from18.7 to 62.3%.Ratios of wetwood areas were positively correlated with wet wood moisture content and pH,tree age,and negatively correlated with pH of sap wood.The repeatability of wet wood area ratios was 0.52,moderately controlled by genetics.Wetwood moisture content and pH were highly controlled by genetics,indicated by the repeatability of 0.91 and 0.89,respectively.There were significant differences in wetwood area ratios,moisture content and pH between different site conditions,afforestation methods,and geographical regions.Sloping land had the lowest wetwood area ratios and moisture content among four types of sites.Afforestation by direct seeding and rooted cuttings had the lowest wetwood area ratios and moisture content,respectively.In the three geographical regions,the Yellow River Basin had the lowest wetwood values of all three factors.
基金This work was financially supported by National Natural Science Foundation of China(32201485)Natural Science Foundation of Hunan Province,China(2022JJ40863)+1 种基金Scientific Research Project of Hunan Provincial Education Department,China(21B0238)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.
基金supported by the National Natural Science Foundation of China(Grant Nos.32201516,91954202)the Youth Top-notch Talent Program of Hebei Education Department(BJK2022028)+1 种基金National Training Program of Innovation and Entrepreneurship for Undergraduates(Grant Nos.S202110022037,G202010022075)the funding of Hebei North University(XJ2021013)。
文摘The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woody plants.As a model material of woody plants,poplar not only has very significant value of research,but also possesses economic and ecological properties.This study reports the Populus trichocarpa DJ-1C(PtrDJ1C)factor,encoded by a nuclear gene,and a member of the DJ-1 superfamily.PtrDJ1C knock-out with the CRISPR/Cas9 system resulted in different albino phenotypes.Chlorophyll fluorescence and immunoblot analyses showed that the levels of photosynthetic complex proteins decreased significantly.Moreover,the transcript level of plastid-encoded RNA polymerase-dependent genes and the splicing efficiency of several introns were affected in the mutant line.Furthermore,rRNA accumulation was abnormal,leading to developmental defects in chloroplasts and affecting lignin accumulation.We concluded that the PtrDJ1C protein is essential for early chloroplast development and lignin deposition in poplar.
基金The authors’funding is supported by the Fundamental Research Funds Jiangsu Vocational College of Agriculture and Forestry(2021KJ20).
文摘Poplar wood,which was used as the absorption material for the solar-driven interfacial evaporation,was treated for 3 days,6 days and 9 days with the pectinase,and then was simulated for photothermal evaporation test at one standard solar radiation intensity(1 kW⋅m^(−2)).The effects of pectinase treatment on cell passage and water migration capacity of poplars were analyzed by the mercury intrusion porosimetry,the scanning electron microscope and fractal theory.It was found that the pit membrane and the ray parenchyma cells of poplar wood were degraded and destroyed after pectinase treatment.Compared with the untreated poplar wood,the evaporation rate of three sections of the specimen was changed.Especially the evaporation rate of radial and tangential direction was significantly increased.At the same time,based on the experimental data and fractal dimension deduction,fractal characteristics could be found in that the structure of poplars treated with pectinase.The porosity decreased with the increase of the fractal dimension in a certain range.It was shown that it is feasible to evaluate solar-driven water migration capacity by using fractal theory.
基金This work was supported by the National Natural Science Foundation of China(32371577)the Beijing Natural Science Foundation(6232030)the Major Project of Agricultural Biological Breeding(2022ZD0401503).
文摘Drought seriously affects the growth and development of plants.MiR159 is a highly conserved and abundant microRNA family that plays a crucial role in plant growth and stress responses.However,studies of its function in woody plants are still lacking.Here,the expression of miR159a was significantly upregulated after drought treatment in poplar,and the overexpression of miR159a(OX159a)significantly reduced the open area of the stomata and improved water-use efficiency in poplar.After drought treatment,OX159a lines had better scavenging ability of reactive oxygen species and damage of the membrane system was less than that in wild-type lines.MYB was the target gene of miR159a,as verified by psRNATarget prediction,RT-qPCR,degradome sequencing,and 5′rapid amplification of cDNA ends(5′RACE).Additionally,miR159a-short tandem target mimic suppression(STTM)poplar lines showed increased sensitivity to drought stress.Transcriptomic analysis comparing OX159a lines with wild-type lines revealed upregulation of a series of genes related to response to water deprivation and metabolite synthesis.Moreover,drought-responsive miR172d and miR398 were significantly upregulated and downregulated respectively in OX159a lines.This investigation demonstrated that miR159a played a key role in the tolerance of poplar to drought by reducing stomata open area,increasing the number and total area of xylem vessels,and enhancing water-use efficiency,and provided new insights into the role of plant miR159a and crucial candidate genes for the molecular breeding of trees with tolerance to drought stress.
基金the National Natural Science Foundation of China(Grant No.51878590)the Jiangsu Provincial Department of Housing and Construction(Grant Nos.2019ZD092,2020ZD40,2020ZD42)the Sixth Phase of“333 Project”Training Objects in Jiangsu Province and Jiangsu Province High-Level Talent Selection Training(Grant No.JNHB-127)for their financial support.
文摘Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,and mode-II interlaminar fracture of poplar LVL.We investigated stress mechanisms,failure modes,and fracture toughness values of the different fracture types.The experimental results revealed that the crack in the mode-I along-grain interlaminar fracture specimen propagated along the prefabricated crack direction,and the crack tip broke.The mode-I cross-grain interlaminar fracture specimen had cracks in the vertical direction near the prefabricated crack.In the mode-II interlaminar fracture specimen,cracks appeared along the initial prefabricated crack direction.The load–displacement curves of these three specimens were linear in the early stage of loading.With the increase in the load,a nonlinear segment appeared before crack propagation and a descending segment appeared after crack propagation.The nonlinear segments of the mode-I along-grain interlaminar fracture and mode-II interlaminar fracture were very short,and cracks expanded quickly after their initiation,resulting in brit-tle fracture.The nonlinear segment of the mode-I cross-grain interlaminar fracture was long,resulting in plastic failure.The average toughness values of the mode-I along-grain interlaminar fracture,mode-I cross-grain inter-laminar fracture,and mode-II interlaminar fracture were 15.43,270.15,and 39.72 MPa·mm^(1/2),respectively.
基金supported by Department of Wood and Paper Science and Technology,University of Zabol
文摘We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard (CBPB) containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM (Response Surface Methodology). The mathematical model equations (second-order response functions) were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values (R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively). RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength > 12.5 MPa and internal bond strength > 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 (2003) for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFD0600404)the Fundamental Research Funds for the Central Universities(2572017DA02)
文摘To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).
文摘We developed a system for the regeneration of Lombardy poplar (Populus nigra L. var. italica) shoots from internodal stem explants. Using this system, shoots regenerated from 87% of the stem explants placed on Murashige and Skoog (MS) medium supplemented with 0.1 mg/L indole-3-acetic acid and 0.5 mg/L benzylaminopurine without undergoing callus formation. About 80% of the in vitro regenerated shoots developed roots on MS medium supplemented with 0.5 mg/L indole-3-butyric acid and 0.02 mg/L 1-naphthylacetic acid. Well-rooted seven-to eight-week-old regenerated plants could be transferred to soil for further growth and the survival rate of such plants after three weeks was 88%. The protocol presented here is simple and economical because it does not rely on pre-incubation in callus induction medium or repeated subculture in shoot induction medium containing trans-zeatin, an expensive substance. The in vitro regeneration system presented here could be used for evaluation of radiation sensitivity for Lombardy poplar tissues.
基金supported by the National Key Research and Development Program of China (Grant No.2016YFD0600404)the Fundamental Research Funds for the Central Universities (Grant No.2572017DA02)。
文摘Growth characteristics have complex inheritance patterns and genotype(G) by environment(E) interaction make predicting tree response to environmental changes difficult.In this study,the growth of seven poplar clones at three different sites was taken as the research focus,and heights and basal diameters were investigated in the second growing season.An ANOVA showed that all main effects,site,clone number and their interactions were highly significant in the overall F-tests.The coefficients of variation and repeatability of different traits ranged from 15.5 to 43.9%and from 0.549 to 0.912,respectively.AMMI(Additive Main Effects and Multiplicative Interaction) analysis results showed that genotype,environment and G × E interaction were significantly highly correlated.The stability analysis indicated that different clones showed different growth traits on different sites,which suggests that elite clones should be selected separately for different sites.Based on the growth traits,under a 10% selection rate,three clones were selected for different sites and the genetic gains of growth traits ranged from 4.7 to 11.2%.The three selected clones could be used to establish plantations in the future in different sites.
文摘The above-ground biomass and nutrient accumulation by poplar plantations were evaluated for pulpwood production ]n China, Experimental treatments applied in a split-plot design included four planting densities (1111, 833, 625 and 500 stems hm-2), three rotation lengths (4a, 5a and 6a) and three poplar clones (1-69.NL-80351 and 1-72). The highest biomass was achieved in the highest stocked stand (1111 stem hm-2’) at 6 of rotation age for both clone 1-69 and clone 1-72, which is about two times that in the stands of 500 stems hm-2 at 4 ofrotation age. However, the highest occurred in the stand of 833 stems-hm-2 at 6-year rotation for NL-80351. Ranking of the plantation biomass production by component was stem > branches > foliage> stem--bark and the production of the Support components of the plantation was 10-fold that of the productive component, i.e., foliage. Thepattern of accumulation of nutrients by the plantations was similar to the biomass. Nutrient accumulation in theplantations was in the order of Ca>N>K>Mg>P, but some differences existed in annual nutrient accumulationrates for four planting densities and three poplar clones, The mean annual accumulation of N and P in the plantations was 13.2 and 2.8 kg hm-2 in stem, 12.1 and 1 .9 kg hm 2 in branch, and 98.5 and 9.5 kghm’ in foliage. Themean Ca, K and Mg accumulations were 28.2, 1 8.5 and 2.9 kg’hm-2 a-1, 26,9. 11,0 and 2.3 kg-hm-2-a-1 in branch.and 116.5, 81 .3 and 16, 1 kg hm-2 a-1 in foliage, respectively. Biomass utilization standards markedly affected theexport of nutrients from the site, Whole tree utilization yields the most biomass and removes the most nutrients,Removal of stem with 2 10-cm diameter exports about half of the biomass, but N and nutrients removals are only23% and 28% of the total, respectively, Removal of the entire stem provides about tWo--thirds of the total biomassand removes 31,1% total N and 37.5 % total nutrients respectively. Including the branches in the removal increases biomass yield to 92% of the total, and nutrient removal is about 68% of the total,
基金financially supported by the National Key Technology R&D Program(2015BAD09B0203)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘With economic incentives and interests in fastgrowing poplar trees for short-rotation production of fiber and veneer,many new poplar hybrids have been bred and planted in China,but how to match the new poplar clones to suitable sites and maintain their higher growth rates is still not very clear.In this study,the photosynthetic response of poplar leaves at various developmental stages during two seasons(summer and autumn) was explored and mechanistic models for the photosynthesis of poplar leaves at different developmental phases in response photosynthetic active radiation(PAR),temperature,and relatively humidity were established using the optimization software package 1 st Opt.Mature poplar leaves in autumn had significantly higher photosynthetic capacity than leaves at other stages and seasons.Based on the models established for poplar leaves at different phases,the main limiting factors for photosynthesis at the research site were high PAR and temperature in the summer and low PAR in the autumn.Our results highlight the importance of selecting suitable sites,pruning and stand density control during the plantation development to maintain higher photosynthetic rates of poplar trees and to establish optimum cultivation patterns for various utilization of poplar plantations.
文摘The main disease species on poplar are introduced in this paper. The main content of the integrated control technique on poplar diseases is summarized:(1) Forecast technique based on the initial disease and provention factors. (2) Control index is established, based on the relationship among the disease index, height of tree, diameter grade and the loss rate of volume. (3) Five fine varieties are selected according to three integrated indexes of host, such as resistance, volume growth and form ratio; They are 613 (Poulus alba ×P. berolinensis), A15 (P. xiaohei × P. euramericana CV. Polska-15A), A98 (P.xiaohei×(P. simonii×P. nigra) CV. A98), A102 (P. xiaohei) × (P. simonee × P. nigra) CV. A102), L2 (P. simonii × P nigra var. italica) in northeast Chnia. (4) Sivicultural control is known as the main protection measures, combined with chemical control and biocontrol,based on the disease forecast and control index by tracing the whole process of forest production.
基金supported by the Central Non-profit Research Institution of Chinese Academy of Forestry(CAFYBB2017MA027,CAFYBB2014QB046)the Overseas Outstanding Scholars Lecture Program+2 种基金the Fundamental Research Funds for the Central Non-profit Research Institution of CAF(CAFYBB2017ZF005)the National Natural Science Foundation of China(Nos.30700637,31460133)‘‘948’’ Project(No.2013-4-80)
文摘Dendroremediation,a novel strategy for cleaning up contaminants from the environment by using special woody plant species and microbes,is a popular phytoremediation approach.It is a cost-effective and environmentally friendly method that is being increasingly adopted.Poplar species(Populus L.)have been suggested for use in remediation because of their characteristics of high biomass production,fast growth,and potential for removing pollutants.Our environment is often contaminated by toxic substances produced by human activities,and remediation of contamination is therefore a global issue.Atrazine is one of the most widely used herbicides in China.In the present study,‘I-69/55’poplar(P.deltoides cv.‘I-69/55’)and hybrid poplar(Populus deltoides×nigra,DN34)grown in pots were assayed for their ability to remediate atrazine-contaminated soils.The degradation dynamics of atrazine were assessed with a high-performance liquid chromatography system using materials from a greenhouse with different rhizosphere environments.We studied the dynamic variation in microbes and microbial biomass carbon to elucidate the rhizosphere effects and mechanism of remediation of atrazine-contaminated soil by poplar.Our four treatments included a control with uncontaminated soil without a tree,atrazine pollution without a tree,atrazine pollution with‘I-69/55’poplar,and atrazine pollution with hybrid poplar.Hybrid poplar showed potential for remediation of atrazine-contaminated soil,and the degradation of atrazine in the rhizosphere was faster than that in non-rhizosphere soil.Atrazine significantly inhibited bacteria growth in nonrhizosphere soil.The high concentration of bacteria in the hybrid poplar rhizosphere might be key to atrazine degradation.Trends of change among fungi and actinomyces did not correspond to trends in atrazine degradation throughout the trial period.Further research is needed to predict the effects of atrazine on cultivable microorganisms in various soils.Atrazine had significant inhibitory effects on microbial biomass carbon in non-rhizosphere soil,and the rhizosphere environment of poplars enhanced the recovery of microbial biomass carbon.The potential for hybrid poplar as a dendroremediation material needs further study.
文摘First, a theoretical model of density of cuttage seedlings on poplar was evaluated by using mathematical tools based on anatomy and morphology of photosynthesis organ, then,according to this, an afforestation density of the trces was put forward, finally, the importance,scope and method of the theoretic application wcre described through a concretc calculation. The result showed that these density models had not only rigorous theory base, including biology and mathematics, but also wide applying prospect. And at the same timc, the model parameters could be gotten easily in forestry practice.
基金the Scientific Research Project of Hunan Provincial Education Department,China(21B0238)Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology,China(2019RS2040)+1 种基金National Natural Science Foundation of China(32171708)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.
基金This work was supported by National Priority Research and Development Program of China(2016YFD0600204)National Natural Science Foundation of China(41701264)+2 种基金Natural Science Foundation of Jiangsu Province,China(BK20170931)Natural Science Research Program(16KJB210005)Overseas Training Program and Priority Academic Program Development Funds(PAPD)of Jiangsu Higher Education Institutions.
文摘The priming effect(PE)induced by biochar provides a basis for evaluating its carbon(C)sequestration potential in soils.A 60 days’laboratory incubation was conducted,which involved the amendment of biochar(1%of soil mass)produced from rice straw at 300℃(B300)and 500℃(B500)to young(Y)and old(O)poplar plantation soils,with the aim of studying the responses of biochar-induced PEs to poplar plantation ages.This incubation included six treatments:Y+CK(control),Y+B300,Y+B500,O+CK,O+B300,and O+B500.Carbon dioxide(CO_(2))emissions were significantly increased(p<0.05)in the B300 amended soils,while it was decreased in the B500 amended soils compared to the CK.The primed CO_(2) emissions were 2.35 times higher in the Y+B300 than the O+B300 treatments,which was measured to be 18.6 and 5.56 mg C·kg^(-1) with relative PEs of 12.4%and 3.35%,respectively.However,there was little difference between the primed CO_(2) emissions in Y+B500 and O+B500 treatments,which were measured to be-24.9 and-29.6 mg·C·kg^(-1) with relative PEs of-16.6%and-17.8%,respectively.Dissolved organic carbon(DOC)was significantly lower in the young poplar plantation soil than that in the old poplar plantation soil regardless of biochar amendment throughout the incubation,indicating greater C-limit of soil microorganisms in the young poplar plantation soil.Using ^(13)C isotope tracing,neither B300 nor B500 decreased native soil-derived DOC,which indicated that the negative B500-induced PEs were not due to a reduction in the availability of native soil-derived C.In conclusion,the response of biochar-induced PEs to poplar plantation age depends on biochar types while soil available C indirectly affects biochar-induced PEs.Further studies should focus on how the interactive effects between soil C availability and microbial community impacts biochar-induced PEs.
