Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An im...Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.展开更多
In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly...In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly impact the stability of the PIIS.In this study,we used a variety of remote sensing data,including Landsat,REMA DEM,ICESat-1 and ICESat-2 satellite altimetry observations,and Ice Bridge airborne measurements,to study the spatiotemporal changes in the basal channels from 2003 to 2020 and basal melt rate from 2010 to 2017 of the PIIS under the Eulerian framework.We found that the basal channels are highly developed in the PIIS,with a total length exceeding 450 km.Most of the basal channels are ocean-sourced or groundingline-sourced basal channels,caused by the rapid melting under the ice shelf or near the groundingline.A raised seabed prevented warm water intrusion into the eastern branch of the PIIS,resulting in a lower basal melt rate in that area.In contrast,a deepsea trough facilitates warm seawater into the mainstream and the western branch of the PIIS,resulting in a higher basal melt rate in the main-stream,and the surface elevation changes above the basal channels of the mainstream and western branch are more significant.The El Ni?o event in 2015–2016 possibly slowed down the basal melting of the PIIS by modulating wind field,surface sea temperature and depth seawater temperature.Ocean and atmospheric changes were driven by El Ni?o,which can further explain and confirm the changes in the basal melting of the PIIS.展开更多
A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present day.In the twentieth century...A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present day.In the twentieth century,climate changes and,due to industrial development,forest areas were under air pollution.Based on observations from 157 sites,this study shows that the growth and density of Scots pine(Pinus sylvestris L.)have decreased by the end of the twentieth century.The environment has changed,and the growth and development of plantations has slowed.Pine yields(-34%stand volume)and their life expectancy(on average 50 years)have decreased.These changes are critical for forestry and for the management of forests in urban centers.Due to the decline in growth,ecosystem functions by urban forests has decreased.In order to increase the sustainability of urban forests and the provision of ecosystem services,it is preferable to create multi-species stands with a complex structure.展开更多
The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose th...The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose through cleavage of the glycosidic bonds,the dissociation energies of which were supplied by the impact of a ball on pine sawdust,during milling.The destruction of glycosidic and hydrogen bonds in pine sawdust resulted in a decrease of crystallinity and an increase of water solubility.The sulfuric acid could promote the hydrolysis of holocellulose and its hydrolysis products.It also destroyed the chemical linkages between holocellulose and lignin during ball milling.The cleavage of chemical linkages with holocellulose made lignin more difficult to hydrolyze in subcritical water,and higher activation energy was needed to hydrolyze pretreated pine sawdust at higher reaction temperatures.It also led to the formation of glucose char and aromatic-linked polymer char from the hydrolysis products of holocellulose.展开更多
Boreal forests commonly suff er from nitrogen defi ciency due to low rate of nitrogen mineralization.Biochar may promote soil organic matter decomposition and accelerate nitrogen mineralization.In this study,Illumina ...Boreal forests commonly suff er from nitrogen defi ciency due to low rate of nitrogen mineralization.Biochar may promote soil organic matter decomposition and accelerate nitrogen mineralization.In this study,Illumina NovaSeq sequencing combined with functional annotation of prokaryotic taxa(FAPROTAX)analysis was used to investigate the eff ect of biochar pyrolysis temperatures,the amount of applied biochar,and the period since the biochar application(2-and 3-year)on soil bacterial communities.The results show that biochar pyrolysis temperatures(500℃ and 650℃)and the amount of applied biochar(0.5 kg m^(−2)and 1.0 kg m^(−2))did not change soil properties.Nevertheless,the interaction of biochar pyrolysis temperature and the amount had signifi cant eff ects on bacterial species richness and evenness(P<0.05).The application of biochar produced at 500℃ had a lower abundance of Actinobacteria and Verrucomicrobia,while that produced at 650℃ had a higher abundance of Conexibacter and Phenylobacterium.When biochar produced at 650℃ was applied,applying 0.5 kg m^(−2)had a higher abundance of Cyanobacteria,Conexibacter,and Phenylobacterium than that of 1.0 kg m^(−2)(P<0.05).Functionally,the abundance of the aromatic compound degradation group increased with the extension of application time and increase of pyrolysis temperature.The time since application played an important role in the formation of soil bacterial communities and their functional structure.Long-term studies are necessary to understand the consequence of biochar on bacterial communities in boreal forests.展开更多
Pteropine orthoreovirus(PRV)is a nonenveloped double-stranded RNA(dsRNA)virus of the genus Orthoreovirus under the family Reoviridae.The PRV genome is composed of 10 dsRNA segments,including three large(L)segments,thr...Pteropine orthoreovirus(PRV)is a nonenveloped double-stranded RNA(dsRNA)virus of the genus Orthoreovirus under the family Reoviridae.The PRV genome is composed of 10 dsRNA segments,including three large(L)segments,three medium(M)segments,and four small(S)segments surrounded by an icosahedral capsid[1].展开更多
Forest fires are frequent under a Mediterranean climate and have shaped the landscape of the region but are currently altered by human action and climate change.Fires have historically conditioned the presence of pine...Forest fires are frequent under a Mediterranean climate and have shaped the landscape of the region but are currently altered by human action and climate change.Fires have historically conditioned the presence of pine forests,depending on severity and forest regeneration.Regeneration of Mediterranean pine forests is not always successful,and a transition to shrublands or stands of resprouting species can occur,even after reforestation.This study analyses vegetation changes in two Mediterranean pine forests after severe fires and both reforested.The pines had difficulty to regenerate,even despite post-fire reforestation.The problem is the difficulty of young seedlings to survive,possibly due to increased summer drought.Problems are greater in pine species at the limit of their ecological tolerance:Pinus pinea had a much better recovery success while P.sylvestris and P.nigra virtually disappeared.Pinus pinaster had intermediate results but recovery was generally poor.A transition has taken place in many burnt areas to scrubland or to thickets of the resprouting Quercus rotundifolia,although it is not possible to know whether they will evolve into forests or remain in a sub climatic state.Resprouting species may increase fire severity but facilitates post-fire colonisation.Post-fire recovery difficulties are closely linked to issues of natural regeneration.Fire could initiate the disappearance of pine forests,but even in the absence of fire they may disappear in the long-term due to the lack of regeneration.Action is needed to increase the resilience of these forests,ensuring natural regeneration,and incorporating resprouting species in the understorey.展开更多
The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object ...The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object of sea-ice interaction and plays a vital role in studying the relationship between the ice sheet/ice shelf and global warming.In this paper,high-resolution remote sensing image and ice penetration data were combined to extract the basal channel of the Pine Island Ice Shelf.The depth variation of Pine Island Ice Shelf in the recent 20 years was analyzed and discussed by using ICESat-1,ICESat-2,and IceBridge data.Combined with relevant marine meteorological elements(sea surface temperature,surface melting days,circumpolar deep water and wind)to analyze the basal channel changes,the redistribution of ocean heat is considered to be the most important factor affecting the evolution and development of the basal channel.展开更多
Microwave(MW)drying method was adopted to enhance the liquid permeability of Scots pine lumber.Structure changes were characterized by stereoscope microscope,scanned electron microscope(SEM)and transmission electron m...Microwave(MW)drying method was adopted to enhance the liquid permeability of Scots pine lumber.Structure changes were characterized by stereoscope microscope,scanned electron microscope(SEM)and transmission electron microscope(TEM)examination.Pore parameters before and after MW treatment were detected by mercury intrusion porosimetry(MIP)method,and the effect of structure changes on liquid permeability were analyzed.As stereoscope microscope,SEM and TEM examination results showed,macro and micro checks mainly developed at intercellcular of tracheids,intercellular of ray parenchyma and tracheid,while these checks extend main along the radial-longitudinal plane.Pit border destruction,aspirated pits’orus translocation and micro-checks in tracheid cell wall were also observed.MIP test shown that pore volume and pore area increased as macro and micro checks generated to form new cavities.Microstructure changes would increase the quantity of pores or enlarge the pore diameter.Liquid flow pathways increased as macro and micro checks generated,aspirated pits reopened to form new pathways;liquid flow efficiency improved as porosity,pore volume and pore diameter increased which facilitated the liquid flow.展开更多
Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lam...Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lamb.)was vacuum impregnated with a basic copper salt solution(copper hydroxide,diethanolamine,and polyethylene glycol 200)prior to heat-treatment at 220℃ for 3 h.Antifungal properties,surface chemistry,crystal structure and sugar contents were tested,compared with heat treatment alone.The results showed that the samples treated by heating without copper salt treatment showed poor suppression of fungal growth,the copperimpregnated heat-treated wood suppressed(100%)the growth of Botryodiplodia theobromae Pat.,Aspergillus niger V.Tiegh.,Penicillium citrinum Thom,and Trichoderma viride Pers.The combined results of X-ray photoelectron spectroscopy,X-ray diffraction and sugars analysis suggested that fungal inhibition by the heat-treated copper-bearing Masson’s pine was mainly due to the reduction of the metal salt by PEG200 at high temperature to generate copper nanoparticles.In addition,the reduced sugar content of the treated timber,and hence the nutrient substrate for spoilage microbes,reduced in the presence of the metal salts at high-temperature.This study has demonstrated an effective method of increasing low-grade wood’s utility and commercial value.展开更多
Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects o...Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.展开更多
[Objectives]The paper was to figure out the distribution of Monochamus alternatus in the stumps of pine wood nematode infected wood in Lu'an City and to provide a theoretical and practical basis for differentiated...[Objectives]The paper was to figure out the distribution of Monochamus alternatus in the stumps of pine wood nematode infected wood in Lu'an City and to provide a theoretical and practical basis for differentiated prevention and control of pine wood nematode disease in the future.[Methods]The factors influencing the number of epidemic small classes and infected plants in all counties and districts of Lu'an City were analyzed by GIS method,and the number of worms and wormholes of M.alternatus inside and outside the stumps of pine wood nematode infected wood in Lu'an City were investigated on the spot.[Results]There were 98,40,54,781,193,268 and 34 epidemic small classes of pine wood nematode disease,and 7241,6099,9532,39161,11079,49876 and 4853 infected plants in Yu'an District,Jin'an District,Yeji District,Shucheng County,Huoshan County,Jinzhai County and Huoqiu County,respectively.Pine wood nematode disease in Lu'an City mostly occurred in Huoshan County,Shucheng County and Jinzhai County,with relatively high altitude,paddy soil,the annual precipitation higher than 2062 mm,and the annual average temperature lower than 16.2℃.The number of diseased plants of pine wood nematode disease was positively correlated with altitude and annual precipitation,and was negatively correlated with annual average temperature.The number of worms and wormholes in pine wood nematode infected wood was very small at different altitudes,stump heights and stump diameters.[Conclusions]The pine wood nematode infected wood can be differentially processed after stump treatment,and stumps can be peeled.The results will provide a theoretical and practical basis for differentiated prevention and control of pine wood nematode disease in the future.展开更多
In order to found new carriers of pine wood nematode(PWN),Bursaphelenchus xylophilus,beetles were collected from pine wilt disease-affected areas in six provinces in China.A total of 8830 beetles of 29 species was col...In order to found new carriers of pine wood nematode(PWN),Bursaphelenchus xylophilus,beetles were collected from pine wilt disease-affected areas in six provinces in China.A total of 8830 beetles of 29 species was collected and examined to determine whether they were PWN carriers.Eight species were identified as carriers.Results included the first worldwide report of Monochamus uigromaculatus,Semanotus siuoauster,and Uraecha angusta being carriers of PWN,and the first report from China of A rhopalus rusticus carrying PWN.Monochamus alternatus was commonly collected in all six provinces and was the dominant species in four inland affected areas and A.rusticus was dominant in two coastal affected areas.The species varied between different neighboring regions in the same province.The distribution of the same species varied considerably over different regions.展开更多
Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however th...Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however the mechanism of that influence is not clear. In order to examine the reproductive strategies of PWN in response to the stress of the volatile material a-pinene, we investigated different aspects of population changes of B.xylophilus under two concentrations of a-pinene. The results show that a high concentration(214.5 mg ml-1)promoted population growth while a low concentration(56.33 mg ml-1) decreased the population. Population structure was analyzed and it was found that a high concentration of a-pinene decreased the percentage of adults but increased the percentages of larvae and eggs.Furthermore, from the results of an evaluation of sex ratios(female/male), it was determined that a high concentration could elevate sex ratios but a low concentration decreased ratios sharply. These results suggest that the PWN could regulate its population by changing sex ratios under stress of a-pinene. This study has provided a theoretical basis for the prevention and control of pine wilt disease caused by the pine wood nematode.展开更多
Korean pine population strueture in natural Korean pine forest was studied through massive field investigation and indoor analvsis. Small-diameter Korean pines origination, growth charaeter and their roles in stand we...Korean pine population strueture in natural Korean pine forest was studied through massive field investigation and indoor analvsis. Small-diameter Korean pines origination, growth charaeter and their roles in stand were discussed from the view of population origination and tree growth. The results show that small-diameter Korean pines origination and growth havc close relations to the overstory canopy structure dynamics and play an important role in the maintenance and development of Korean pine forest. The process from small-diameter trees to dominant canopy is a selfmaintenance phase, with diffieulty, in Korean pine population. To complete this phase, it not only demands some morphological characters and physiological conditions, but severe forest strueture conditions as well. The time for complating this phase needs separation from overstory Korean pines and converge with overstory broad-leaf trees. In vertical space, it needs to fell overstory canopy or reduce the layers of overstory canopy, and in horizontal space it should be separated from Korean pines but accompanied by broad-leaf trees.展开更多
Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of...Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m^3 ha^(-1) a^(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m^2 ha^(-1) and mean annual seed yield 141 kg ha^(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production.展开更多
Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The re...Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The relationships between fluxes (N2O and CH4) and some major environmental factors (temperature, soil water content and soil availabIe nitrogen) were studied. A significant positive correlation between Nzo emission and air/soil temperature was observed, but no significant correIation was found between N2O emission and soil water content (SWC). This result showed that temperature was an important controlling factor of N2O flux. There was a significant correlation between CH4 uptake and SWC, but no significant correlation was found between CH4 uptake and temperature. This suggested SWC was an important factor controlling CH4 uptake. The very significant negative correlation between logarithmic N2O flux and soil nitrate concentration, significant negative correlation between CH4 flux and soil ammonium content were also found.展开更多
Huashan pine (Finus armandii Franch) is a poential species for dendroclimatic study. Ring-width cores were sampled for four stands of two sites from the eastern extreme of the Qinling Mountains. The ring-width chronol...Huashan pine (Finus armandii Franch) is a poential species for dendroclimatic study. Ring-width cores were sampled for four stands of two sites from the eastern extreme of the Qinling Mountains. The ring-width chronologies developed in this study cover a maximum Period from A.D. 1359 t0 1992 and show high common chronology variance over the common period 1911-1960.All the chronologies are significantly correlated with all others, and the degree of correlation appears related to tree age. Response function analyses reveal that from 41 to 75 Percent of chronology variance can be accounted for by monthly mean air temperature and monthly total precipitation. A sufficiently strong correlation of ringwidth index with May and June rainfall and June temperature exists, implying soil moisture to be a limiting factor for Huashan pine growth. The association displayed by response diagrams between narrow rings, low precipitation, and high temperature during spring and early summer indicates a promising potential of ring widths for reconstruction of spring drought for the study area.展开更多
基金financially supported by the National Natural Science Foundation of China(31901093,32220103010,32192431,31722013)National Key R&D Program of China(2020YFA0608100,2022YFF1302505)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(ZDBS-LY-DQC019)。
文摘Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.
基金The National Natural Science Foundation of China under contract Nos 41941010 and 42006184the Fundamental Research Funds for the Central Universities under contract No.2042022kf1068。
文摘In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly impact the stability of the PIIS.In this study,we used a variety of remote sensing data,including Landsat,REMA DEM,ICESat-1 and ICESat-2 satellite altimetry observations,and Ice Bridge airborne measurements,to study the spatiotemporal changes in the basal channels from 2003 to 2020 and basal melt rate from 2010 to 2017 of the PIIS under the Eulerian framework.We found that the basal channels are highly developed in the PIIS,with a total length exceeding 450 km.Most of the basal channels are ocean-sourced or groundingline-sourced basal channels,caused by the rapid melting under the ice shelf or near the groundingline.A raised seabed prevented warm water intrusion into the eastern branch of the PIIS,resulting in a lower basal melt rate in that area.In contrast,a deepsea trough facilitates warm seawater into the mainstream and the western branch of the PIIS,resulting in a higher basal melt rate in the main-stream,and the surface elevation changes above the basal channels of the mainstream and western branch are more significant.The El Ni?o event in 2015–2016 possibly slowed down the basal melting of the PIIS by modulating wind field,surface sea temperature and depth seawater temperature.Ocean and atmospheric changes were driven by El Ni?o,which can further explain and confirm the changes in the basal melting of the PIIS.
基金supported by the Russian State Agrarian University–Moscow Timiryazev Agricultural Academy。
文摘A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present day.In the twentieth century,climate changes and,due to industrial development,forest areas were under air pollution.Based on observations from 157 sites,this study shows that the growth and density of Scots pine(Pinus sylvestris L.)have decreased by the end of the twentieth century.The environment has changed,and the growth and development of plantations has slowed.Pine yields(-34%stand volume)and their life expectancy(on average 50 years)have decreased.These changes are critical for forestry and for the management of forests in urban centers.Due to the decline in growth,ecosystem functions by urban forests has decreased.In order to increase the sustainability of urban forests and the provision of ecosystem services,it is preferable to create multi-species stands with a complex structure.
基金supported by the National Natural Science Foundation of China(22078225)the Natural Science Foundation of Zhejiang Province(LGF22E080025 and LHY22E080005)。
文摘The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose through cleavage of the glycosidic bonds,the dissociation energies of which were supplied by the impact of a ball on pine sawdust,during milling.The destruction of glycosidic and hydrogen bonds in pine sawdust resulted in a decrease of crystallinity and an increase of water solubility.The sulfuric acid could promote the hydrolysis of holocellulose and its hydrolysis products.It also destroyed the chemical linkages between holocellulose and lignin during ball milling.The cleavage of chemical linkages with holocellulose made lignin more difficult to hydrolyze in subcritical water,and higher activation energy was needed to hydrolyze pretreated pine sawdust at higher reaction temperatures.It also led to the formation of glucose char and aromatic-linked polymer char from the hydrolysis products of holocellulose.
基金funded by The Foundation for Research of Natural Resources in Finland(2016085)supported by the Academy of Finland(286685,294600,307222,277623)the FCoE of atmospheric sciences(Center of Excellence(1118615)).
文摘Boreal forests commonly suff er from nitrogen defi ciency due to low rate of nitrogen mineralization.Biochar may promote soil organic matter decomposition and accelerate nitrogen mineralization.In this study,Illumina NovaSeq sequencing combined with functional annotation of prokaryotic taxa(FAPROTAX)analysis was used to investigate the eff ect of biochar pyrolysis temperatures,the amount of applied biochar,and the period since the biochar application(2-and 3-year)on soil bacterial communities.The results show that biochar pyrolysis temperatures(500℃ and 650℃)and the amount of applied biochar(0.5 kg m^(−2)and 1.0 kg m^(−2))did not change soil properties.Nevertheless,the interaction of biochar pyrolysis temperature and the amount had signifi cant eff ects on bacterial species richness and evenness(P<0.05).The application of biochar produced at 500℃ had a lower abundance of Actinobacteria and Verrucomicrobia,while that produced at 650℃ had a higher abundance of Conexibacter and Phenylobacterium.When biochar produced at 650℃ was applied,applying 0.5 kg m^(−2)had a higher abundance of Cyanobacteria,Conexibacter,and Phenylobacterium than that of 1.0 kg m^(−2)(P<0.05).Functionally,the abundance of the aromatic compound degradation group increased with the extension of application time and increase of pyrolysis temperature.The time since application played an important role in the formation of soil bacterial communities and their functional structure.Long-term studies are necessary to understand the consequence of biochar on bacterial communities in boreal forests.
基金supported by the Fundamental Research Grant Scheme (FRGS)2019-1 (FRGS/1/2019/STG05/IMU/02/1)from the Ministry of Higher Education,Malaysia,International Medical University Research Grant (BP I-01-2018 (33))Pump priming Grant (F0013.54.04)University of Nottingham Malaysia。
文摘Pteropine orthoreovirus(PRV)is a nonenveloped double-stranded RNA(dsRNA)virus of the genus Orthoreovirus under the family Reoviridae.The PRV genome is composed of 10 dsRNA segments,including three large(L)segments,three medium(M)segments,and four small(S)segments surrounded by an icosahedral capsid[1].
文摘Forest fires are frequent under a Mediterranean climate and have shaped the landscape of the region but are currently altered by human action and climate change.Fires have historically conditioned the presence of pine forests,depending on severity and forest regeneration.Regeneration of Mediterranean pine forests is not always successful,and a transition to shrublands or stands of resprouting species can occur,even after reforestation.This study analyses vegetation changes in two Mediterranean pine forests after severe fires and both reforested.The pines had difficulty to regenerate,even despite post-fire reforestation.The problem is the difficulty of young seedlings to survive,possibly due to increased summer drought.Problems are greater in pine species at the limit of their ecological tolerance:Pinus pinea had a much better recovery success while P.sylvestris and P.nigra virtually disappeared.Pinus pinaster had intermediate results but recovery was generally poor.A transition has taken place in many burnt areas to scrubland or to thickets of the resprouting Quercus rotundifolia,although it is not possible to know whether they will evolve into forests or remain in a sub climatic state.Resprouting species may increase fire severity but facilitates post-fire colonisation.Post-fire recovery difficulties are closely linked to issues of natural regeneration.Fire could initiate the disappearance of pine forests,but even in the absence of fire they may disappear in the long-term due to the lack of regeneration.Action is needed to increase the resilience of these forests,ensuring natural regeneration,and incorporating resprouting species in the understorey.
基金The National Natural Science Foundation of China under contract Nos 41941010 and 42006184the Fundamental Research Funds for the Central Universities under contract No.2042022kf1068the Independent Scientific Research Project of the State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing.
文摘The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object of sea-ice interaction and plays a vital role in studying the relationship between the ice sheet/ice shelf and global warming.In this paper,high-resolution remote sensing image and ice penetration data were combined to extract the basal channel of the Pine Island Ice Shelf.The depth variation of Pine Island Ice Shelf in the recent 20 years was analyzed and discussed by using ICESat-1,ICESat-2,and IceBridge data.Combined with relevant marine meteorological elements(sea surface temperature,surface melting days,circumpolar deep water and wind)to analyze the basal channel changes,the redistribution of ocean heat is considered to be the most important factor affecting the evolution and development of the basal channel.
基金supported by Key Research&Development Program of Zhejiang Province(2021C02012)Chinese National Natural Science Foundation,Study on Pore Structure and Liquid Permeate Mechanism of Moso Bamboo(31700489).
文摘Microwave(MW)drying method was adopted to enhance the liquid permeability of Scots pine lumber.Structure changes were characterized by stereoscope microscope,scanned electron microscope(SEM)and transmission electron microscope(TEM)examination.Pore parameters before and after MW treatment were detected by mercury intrusion porosimetry(MIP)method,and the effect of structure changes on liquid permeability were analyzed.As stereoscope microscope,SEM and TEM examination results showed,macro and micro checks mainly developed at intercellcular of tracheids,intercellular of ray parenchyma and tracheid,while these checks extend main along the radial-longitudinal plane.Pit border destruction,aspirated pits’orus translocation and micro-checks in tracheid cell wall were also observed.MIP test shown that pore volume and pore area increased as macro and micro checks generated to form new cavities.Microstructure changes would increase the quantity of pores or enlarge the pore diameter.Liquid flow pathways increased as macro and micro checks generated,aspirated pits reopened to form new pathways;liquid flow efficiency improved as porosity,pore volume and pore diameter increased which facilitated the liquid flow.
基金This research was sponsored by the Guangdong Forestry Science and Technology Innovation Project“Research on the Thermal Modification of Eucalyptus and Spingbract Chinkapin Wood and the Key Technologies of Their Wood Flooring Preparation”(No.2018KJCX006).
文摘Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lamb.)was vacuum impregnated with a basic copper salt solution(copper hydroxide,diethanolamine,and polyethylene glycol 200)prior to heat-treatment at 220℃ for 3 h.Antifungal properties,surface chemistry,crystal structure and sugar contents were tested,compared with heat treatment alone.The results showed that the samples treated by heating without copper salt treatment showed poor suppression of fungal growth,the copperimpregnated heat-treated wood suppressed(100%)the growth of Botryodiplodia theobromae Pat.,Aspergillus niger V.Tiegh.,Penicillium citrinum Thom,and Trichoderma viride Pers.The combined results of X-ray photoelectron spectroscopy,X-ray diffraction and sugars analysis suggested that fungal inhibition by the heat-treated copper-bearing Masson’s pine was mainly due to the reduction of the metal salt by PEG200 at high temperature to generate copper nanoparticles.In addition,the reduced sugar content of the treated timber,and hence the nutrient substrate for spoilage microbes,reduced in the presence of the metal salts at high-temperature.This study has demonstrated an effective method of increasing low-grade wood’s utility and commercial value.
基金funded by the National Natural Science Foundation of China (32160348)Forestry Science and Technology Research Project of Guizhou Forestry Bureau (J[2022]21 and[2020]C14)+1 种基金Department Program of Guizhou Province ([2020]1Y128)the Cultivation Project of Guizhou University of China ([2019]37).
文摘Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.
基金Supported by Youth Project of Natural Science Foundation of Anhui Province(2008085QC135)Postdoctoral Workstation Project of West Anhui University(WXBSH2020003)+4 种基金Key Program of Natural Science Research Project for Anhui Universities(KJ2021A0954)Forestry Carbon Sequestration Self-funded Science and Technology Project of Anhui Province(LJH[2022]267)Key School-level Nature Research Project of West Anhui University(WXZR202020)Subject of Lu'an Forestry Bureau(0045021093)Provincial Quality Engineering Project of West Anhui University(2022jyxm1765).
文摘[Objectives]The paper was to figure out the distribution of Monochamus alternatus in the stumps of pine wood nematode infected wood in Lu'an City and to provide a theoretical and practical basis for differentiated prevention and control of pine wood nematode disease in the future.[Methods]The factors influencing the number of epidemic small classes and infected plants in all counties and districts of Lu'an City were analyzed by GIS method,and the number of worms and wormholes of M.alternatus inside and outside the stumps of pine wood nematode infected wood in Lu'an City were investigated on the spot.[Results]There were 98,40,54,781,193,268 and 34 epidemic small classes of pine wood nematode disease,and 7241,6099,9532,39161,11079,49876 and 4853 infected plants in Yu'an District,Jin'an District,Yeji District,Shucheng County,Huoshan County,Jinzhai County and Huoqiu County,respectively.Pine wood nematode disease in Lu'an City mostly occurred in Huoshan County,Shucheng County and Jinzhai County,with relatively high altitude,paddy soil,the annual precipitation higher than 2062 mm,and the annual average temperature lower than 16.2℃.The number of diseased plants of pine wood nematode disease was positively correlated with altitude and annual precipitation,and was negatively correlated with annual average temperature.The number of worms and wormholes in pine wood nematode infected wood was very small at different altitudes,stump heights and stump diameters.[Conclusions]The pine wood nematode infected wood can be differentially processed after stump treatment,and stumps can be peeled.The results will provide a theoretical and practical basis for differentiated prevention and control of pine wood nematode disease in the future.
基金supported by the National Key Research and Development Program of China(Grant Number:2017YFD0600104)the Shenyang Science and Technology Planning Project(Grant Number:18-400-3-03)。
文摘In order to found new carriers of pine wood nematode(PWN),Bursaphelenchus xylophilus,beetles were collected from pine wilt disease-affected areas in six provinces in China.A total of 8830 beetles of 29 species was collected and examined to determine whether they were PWN carriers.Eight species were identified as carriers.Results included the first worldwide report of Monochamus uigromaculatus,Semanotus siuoauster,and Uraecha angusta being carriers of PWN,and the first report from China of A rhopalus rusticus carrying PWN.Monochamus alternatus was commonly collected in all six provinces and was the dominant species in four inland affected areas and A.rusticus was dominant in two coastal affected areas.The species varied between different neighboring regions in the same province.The distribution of the same species varied considerably over different regions.
基金financially supported by Fundamental Research Funds of Research Institute of Forest New Technology,CAF(CAFYBB2018SY037)National Key Research and Development Program(2016YFC1200604)。
文摘Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however the mechanism of that influence is not clear. In order to examine the reproductive strategies of PWN in response to the stress of the volatile material a-pinene, we investigated different aspects of population changes of B.xylophilus under two concentrations of a-pinene. The results show that a high concentration(214.5 mg ml-1)promoted population growth while a low concentration(56.33 mg ml-1) decreased the population. Population structure was analyzed and it was found that a high concentration of a-pinene decreased the percentage of adults but increased the percentages of larvae and eggs.Furthermore, from the results of an evaluation of sex ratios(female/male), it was determined that a high concentration could elevate sex ratios but a low concentration decreased ratios sharply. These results suggest that the PWN could regulate its population by changing sex ratios under stress of a-pinene. This study has provided a theoretical basis for the prevention and control of pine wilt disease caused by the pine wood nematode.
文摘Korean pine population strueture in natural Korean pine forest was studied through massive field investigation and indoor analvsis. Small-diameter Korean pines origination, growth charaeter and their roles in stand were discussed from the view of population origination and tree growth. The results show that small-diameter Korean pines origination and growth havc close relations to the overstory canopy structure dynamics and play an important role in the maintenance and development of Korean pine forest. The process from small-diameter trees to dominant canopy is a selfmaintenance phase, with diffieulty, in Korean pine population. To complete this phase, it not only demands some morphological characters and physiological conditions, but severe forest strueture conditions as well. The time for complating this phase needs separation from overstory Korean pines and converge with overstory broad-leaf trees. In vertical space, it needs to fell overstory canopy or reduce the layers of overstory canopy, and in horizontal space it should be separated from Korean pines but accompanied by broad-leaf trees.
基金financially supported by the National Natural Science Foundation of China(31600511)the Fundamental Research Funds for the Central Universities of the People’s Republic of China(2572017CA04)
文摘Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m^3 ha^(-1) a^(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m^2 ha^(-1) and mean annual seed yield 141 kg ha^(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production.
文摘Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The relationships between fluxes (N2O and CH4) and some major environmental factors (temperature, soil water content and soil availabIe nitrogen) were studied. A significant positive correlation between Nzo emission and air/soil temperature was observed, but no significant correIation was found between N2O emission and soil water content (SWC). This result showed that temperature was an important controlling factor of N2O flux. There was a significant correlation between CH4 uptake and SWC, but no significant correlation was found between CH4 uptake and temperature. This suggested SWC was an important factor controlling CH4 uptake. The very significant negative correlation between logarithmic N2O flux and soil nitrate concentration, significant negative correlation between CH4 flux and soil ammonium content were also found.
文摘Huashan pine (Finus armandii Franch) is a poential species for dendroclimatic study. Ring-width cores were sampled for four stands of two sites from the eastern extreme of the Qinling Mountains. The ring-width chronologies developed in this study cover a maximum Period from A.D. 1359 t0 1992 and show high common chronology variance over the common period 1911-1960.All the chronologies are significantly correlated with all others, and the degree of correlation appears related to tree age. Response function analyses reveal that from 41 to 75 Percent of chronology variance can be accounted for by monthly mean air temperature and monthly total precipitation. A sufficiently strong correlation of ringwidth index with May and June rainfall and June temperature exists, implying soil moisture to be a limiting factor for Huashan pine growth. The association displayed by response diagrams between narrow rings, low precipitation, and high temperature during spring and early summer indicates a promising potential of ring widths for reconstruction of spring drought for the study area.
