Cloning of sft-4 and its influence on vitality and virulence of pine wood nematode,Bursaphelenchus xylophilus

In our previous screening of the transcriptome of the causal agent of the devastating pine wilt disease,pine wood nematode(PWN,Bursaphelenchus xylophilus),after treatment with the nematicide fomepizole,Surfeit locus gene sft-4,which encodes a regulatory factor,was found to be downregulated.In situ hybridization results showed that the sft-4 was continuously expressed from egg to adult and was especially high in the reproductive system.Here in a study of the effect of RNA interference(RNAi)of sft-4 and recombinant SFT-4 on PWN activity,treatment with sft-4 dsRNA inhibited feeding,reproduction,oviposition and egg hatching of PWN with the greatest inhibition on reproduction and oviposition,whereas recombinant SFT-4 had the opposite effect.In addition,RNAi of sft-4 changed the female–male ratio and lifespan of PWN.In bioassays of PWNs,with RNAi of sft-4 on seedlings and 2-year-old Pinus thunbergii trees,none of the treated plants developed symp-toms during the monitoring period,indicating that virulence of PWNs was either significantly weakened.These results indicate that the influence of sft-4 on PWN pathogenicity may be mainly through regulating reproductive function of PWN and its lifespan.

Modeling the effect of stand and site characteristics on the probability of mistletoe infestation in Scots pine stands using remote sensing data

Over the past decade,the presence of mistletoe(Viscum album ssp.austriacum)in Scots pine stands has increased in many European countries.Understanding the factors that influence the occurrence of mistletoe in stands is key to making appropriate forest management decisions to limit damage and prevent the spread of mistletoe in the future.Therefore,the main objective of this study was to determine the probability of mistletoe occurrence in Scots pine stands in relation to stand-related endogenous factors such as age,top height,and stand density,as well as topographic and edaphic factors.We used unmanned aerial vehicle(UAV)imagery from 2,247 stands to detect mistletoe in Scots pine stands,while majority stand and site characteristics were calculated from airborne laser scanning(ALS)data.Information on stand age and site type from the State Forest database were also used.We found that mistletoe infestation in Scots pine stands is influenced by stand and site characteristics.We documented that the densest,tallest,and oldest stands were more susceptible to mistletoe infestation.Site type and specific microsite conditions associated with topography were also important factors driving mistletoe occurrence.In addition,climatic water balance was a significant factor in increasing the probability of mistletoe occurrence,which is important in the context of predicted temperature increases associated with climate change.Our results are important for better understanding patterns of mistletoe infestation and ecosystem functioning under climate change.In an era of climate change and technological development,the use of remote sensing methods to determine the risk of mistletoe infestation can be a very useful tool for managing forest ecosystems to maintain forest sustainability and prevent forest disturbance.

Aging Mongolian pine plantations face high risks of drought-induced growth decline:evidence from both individual tree and forest stand measurements

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.

Long-term changes in radial growth of seven tree species in the mixed broadleaf-Korean pine forest in Northeast China:Are deciduous trees favored by climate change?

The role of the temperate mixed broadleaf-Korean pine forest(BKF)in global biogeochemical cycles will depend on how the tree species community responds to climate;however,species-specific responses and vulner-abilities of common trees in BKF to extreme climates are poorly understood.Here we used dendrochronological meth-ods to assess radial growth of seven main tree species(Pinus koraiensis,Picea jezoensis,Abies nephrolepis,Fraxinus mandshurica,Phellodendron amurense,Quercus mongolica,and Ulmus davidiana)in an old-growth BKF in response to climate changes in the Xiaoxing’an Mountains and to improve predictions of changes in the tree species compo-sition.Temperature in most months and winter precipita-tion significantly negatively affected growth of P.jezoensis and A.nephrolepis,but positively impacted growth of P.koraiensis and the broadleaf species,especially F.mandshu-rica and U.davidiana.Precipitation and relative humidity in June significantly positively impacted the growth of most tree species.The positive effect of the temperature during the previous non-growing season(PNG)on growth of F.mandshurica and Q.mongolica strengthened significantly with rapid warming around 1981,while the impact of PNG temperature on the growth of P.jezoensis and A.nephrolepis changed from significantly negative to weakly negative or positive at this time.The negative response of radial growth of P.jezoensis and A.nephrolepis to precipitation during the growing season gradually weakened,and the negative response to PNG precipitation was enhanced.Among the studied species,P.koraiensis was the most resistant to drought,and U.davidiana recovered the best after extreme drought.Ulmus davidiana,P.jezoensis and A.nephrolepis were more resistant to extreme cold than the other species.Climate warming generally exacerbated the opposite growth patterns of conifer(decline)and broadleaf(increase)spe-cies.Deciduous broadleaf tree species in the old-growth BKF probably will gradually become dominant as warming continues.Species-specific growth-climate relationships should be considered in future models of biogeochemical cycles and in forestry management practices.

The variation in basal channels and basal melt rates of Pine Island Ice Shelf

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.

Changes in the growth of Scots pine(Pinus sylvestris L.)stands in an urban environment in European Russia since 1862

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.

Response of soil bacterial community to biochar application in a boreal pine forest

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.

Pteropine Orthoreovirus(PRV7S)does not Establish Persistent Infection in NP460 Cells but with Inflammatory Response Triggered

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].

Effect of acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust in subcritical water

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.

Dynamics of mediterranean pine forests reforested after fires

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.

The morphological changes of basal channels based on multisource remote sensing data at the Pine Island Ice Shelf

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.

Microwave Drying of Scots Pine Lumber:Structure Changes,Its Effect on Liquid Permeability

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.

In Situ Generation of Copper Nanoparticles in Heat-Treated Copper-Containing Masson’s Pine as a Preservative Process for Sawn Timber

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.

Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers

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.

Analysis of Influencing Factors of Pine Wood Nematode Disease in Lu an City Based on GIS

[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.

Patterns of biomass,carbon,and nitrogen storage distribution dynamics after the invasion of pine forests by Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) in the three Gorges Reservoir Region

Masson pine stands infected by Pine wilt disease(PWD) in the Three Gorges Reservoir Region of central China were surveyed to quantify the immediate responses and subsequent trajectories of biomass,carbon(C),and nitrogen(N) in stand-level major ecosystem compartments.The biomasses of above-and belowground tree components,as well as of the understory,forest floor,and mineral soil(0–40 cm),were determined within each stand.C and N storage were also estimated for each ecosystem compartment.Overstory biomass decreased steadily with the extent of PWD infection.Understory biomass ranged from1.97 to 4.16 Mg ha,and the observed value for forest floor biomass was 12.89–22.59 Mg ha.The highest mean C and N concentrations were found in the stem bark and needles of Masson pine,respectively,while the lowest were found in the semi-to fully decomposed layer of the forest floor and stem wood of Masson pine,respectively.The C and N storage of aboveground trees,tree roots,and the aboveground ecosystem decreased with the extent ofPWD infection.However,the C and N contents of the understory,forest floor,and total mineral soil initially declined after PWD infection before recovering over the following several years.Those result concluded that the biomass,C,and N storage of different forest ecosystem compartments have experienced certain variations following the PWD epidemic.This is vital to understand the shifts in stand-level C and N allocation in PWD-damaged forest stands,as well as for predicting the responses of regional and global C and N cycling.

美国Spruce Pine与新疆阿尔泰地区高纯石英伟晶岩的对比研究

对美国北卡罗来纳州Spruce Pine地区白岗岩/伟晶岩和新疆阿尔泰白云母花岗岩/伟晶岩进行了对比研究。这两个地区的伟晶岩可能是过铝质花岗岩浆通过熔体-蒸汽分异作用的产物。美国产高纯石英的伟晶岩发育在片岩、片麻岩的背景之上,主要造岩矿物中富含斜长石,Na大于K,大离子亲石元素Sr和Ba含量高,高场强元素和稀土元素含量低,Eu正异常,石英中杂质元素含量低。这些特征可作为高纯石英伟晶岩的判别标志。我国阿尔泰地区的伟晶岩脉十分发育,所研究的样品中,有些样品已经具有这些特点,阿尔泰伟晶岩区具有产高纯石英的成矿前景。

Cloning of cDNA Fragment of Chitinase Gene from the Mycoparasite Trichoderma atroviride on Armandii Pine Blister Rust

[Objective] The aim of this study was to isolate chitinase gene from Trichoderma atroviride strain SS003. [Method] With the aeciospore wall of armandii pine blister rust as inducer, chitinase gene was induced to express in Trichoderma atroviride cells. The cDNA fragment of chitinase gene was cloned by RT-PCR approach. [Result] The activity of chitinase induced reached 40.17 μg/10 min; and the specific fragment amplified was 834 bp in length and proved to be the fragment of chitinase gene by sequencing and sequence analysis. [Conclusion] The result showed the feasibility of isolating the full length of chitinase gene and its transformation, and further producing chitinase.

Genetic variations of wood properties and growth characters of Ko-rean pines from different provenances

Totally 26 provenance stands of 17-year-old Korean pine were selected for investigating wood properties and growth characters in Mao抏rshan Experimental Forest Farm of Northeast Forestry University in 1999. The anatomical property indexes, including tracheid length, tracheid diameter and wall-indiameter ratio, and the physical property indexes, such as growth ring width, late wood percentage and growth ring density, were measured for wood properties. Growth character indexes, including tree height and diameter at breast height, were also measured. The analytical results showed that there exited obviously dif-ference in wood property indexes between different provenances, which is suggested that wood properties are controlled by their genetic differences. The growth character indexes of Korean pines presented significant difference and they might also be controlled by their genetic differences. Most parameters of wood properties mainly varied in the direction of longitude, but the parameters of growth characters varied in the direction of latitude.

Influence of canopy on precipitation and its nutrient elements in broadleaved/Korean pine forest on the northern slope of Changbai Mountain

The precipitation distribution quantity of canopy in broadleaved/Korean pine forest was measured during the growing season (Jun.–Sept.) in 2001 in the Changbai Mountain, Jilin Province, P. R. China. Results indicated that the amounts of stemflow, throughfall, and interception were 37.39, 322.12 and 109.69 mm, accounting for 7.97%, 68.65% and 23.38% of the total rainfall, respectively. The rate of stemflow was higher in Jul. and Aug. than other months. The rate of throughfall dropped off from Jun. to Sept., however, rate of interception changed contrarily from 19.43% to 31.02% during the growing season. According to our analysis, the concentration of nutrient elements were arranged as Ca>Mg>N>K>Fe>P>Cu>Mn for rainfall, K>N>Mg>Ca>P>Fe>Mn>Cu for throughfall, and Mn>P>K>Cu>Fe>N>Mg>Ca for being leached through canopy. Nutrients concentration in stewflow and throughfall changed significantly when rainfall passed canopy, and concentration of all elements increased except for Ca and Mg.