A spatio-temporal multi-scale fusion algorithm for pine wood nematode disease tree detection

Pine wood nematode infection is a devastating disease.Unmanned aerial vehicle(UAV)remote sensing enables timely and precise monitoring.However,UAV aerial images are challenged by small target size and complex sur-face backgrounds which hinder their effectiveness in moni-toring.To address these challenges,based on the analysis and optimization of UAV remote sensing images,this study developed a spatio-temporal multi-scale fusion algorithm for disease detection.The multi-head,self-attention mechanism is incorporated to address the issue of excessive features generated by complex surface backgrounds in UAV images.This enables adaptive feature control to suppress redundant information and boost the model’s feature extraction capa-bilities.The SPD-Conv module was introduced to address the problem of loss of small target feature information dur-ing feature extraction,enhancing the preservation of key features.Additionally,the gather-and-distribute mechanism was implemented to augment the model’s multi-scale feature fusion capacity,preventing the loss of local details during fusion and enriching small target feature information.This study established a dataset of pine wood nematode disease in the Huangshan area using DJI(DJ-Innovations)UAVs.The results show that the accuracy of the proposed model with spatio-temporal multi-scale fusion reached 78.5%,6.6%higher than that of the benchmark model.Building upon the timeliness and flexibility of UAV remote sensing,the pro-posed model effectively addressed the challenges of detect-ing small and medium-size targets in complex backgrounds,thereby enhancing the detection efficiency for pine wood nematode disease.This facilitates early preemptive preser-vation of diseased trees,augments the overall monitoring proficiency of pine wood nematode diseases,and supplies technical aid for proficient monitoring.

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.

Investigation of beetle species that carry the pine wood nematode,Bursaphelenchus xylophilus(Steiner and Buhrer)Nickle,in China

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.

Emamectin benzoate 9.7%SL as a new formulation for a trunkinjections against pine wood nematode,Bursaphelenchus xylophilus

In this study,we investigated the preventive effects of emamectin benzoate 9.7%SL,which was newly developed to reduce the injection volume and number of injection holes required to protect against pine wood nematode.None of the Pinus thunbergii trees injected with emamectin benzoate 9.7%SL at 0.3 mL/cm diameter at breast height(DBH)died within 2 years of inoculation with pine wood nematodes.Emamectin benzoate 9.7%SL injected at 0.6 mL/cm DBH resulted in no tree mortality for 3 years.Mean residue of emamectin benzoate 9.7%SL in pine twigs injected with 0.3 mL/cm DBH was 0.490μg/g at 1 year after injection and 0.303μg/g after 2 years.These residues values are greater than 0.031μg/g,previously determined IC95 value for emamectin benzoate against the pine wood nematode.Our field experiment and residue analysis showed that emamectin benzoate 9.7%SL could be a substitute agent for emamectin benzoate 2.15%EC,which is widely used to prevent pine wood nematode in the field and that injection volume and number of injection holes can be greatly educed using this new formulation,which will reduce injury to the cambium,interruption of water movement,and infection of inoculation wounds by wood-decay or blue stain fungi.

Adaptation of pine wood nematode,Bursaphelenchus xylophilus,early in its interaction with two Pinus species that differ in resistance

Pine wilt disease(PWD)is one of the most devastating diseases of Pinu s spp.and is caused by the pine wood nematode(PWN),Bursaphelenchus xylophilus(Steiner&Buhrer)Nickle.To study adaptation of PWN to survive in hosts that differ in resistance,we examined the self-regulatory characteristics of PWN at the biological and molecular levels early in the interaction.Two-year-old susceptible Pinus thunbergii and resistant Pinus taeda were selected for this experiment,and changes in PWNs after inoculation were assessed.q RT-PCR was used to detect changes in genes related to PWN pathogenicity and detoxification.The results showed that the migration and reproductive abilities of PWNs in P.thunbergii were stronger than those of PWNs in P.taeda.After 7 d,the number of nematodes in P.thunbergii was approximately 3.2-fold higher than in P.taeda.After 15 d,the number of nematodes in P.thunbergii was approximately twofold higher than that in P.taeda.Because PWN can adjust its sex ratio after infection,we compared the sex ratio of uninoculated PWNs,to that in the two pine species.In P.thunbergii,the female to male ratio first decreased and then stabilized over time;in P.taeda first decreased and then increased.Relative fat accumulation in PWNs increased significantly after the PWNs entered the tree body;the accumulation rate in P.thunbergii was higher than in P.taeda at 7 d,but lower after 15 d.Scanning electron microscopy(SEM)showed significantly more bacteria on the surface of PWNs in P.taeda compared with PWNs in susceptible P.thunbergii.At 12 h after inoculation,the expression of genes related to cell-wall degradation(Bx Beta1-4 and Bxpel1),effectors(Bx CDP1,Bx Sap B1),and active oxygen metabolism(Bxy-ctl-1 and Bx GST3)was 2–6×higher in the resistant pine than in the susceptible one.In contrast,in PWNs,the expression of autophagy-related genes Bx ATG1 and Bx ATG16 was 1.5–2 times higher in P.thunbergii than in P.taeda.These results indicate that the interaction between PWNs and pine trees with different resistance levels elicits a series of physiological and molecular adaptations that affect nematode reproduction and virulence.This study will help elucidate the adaptive mechanisms of PWN in different pine trees.

COMPARATIVE STUDY OF WOOD PROPERTIES BETWEENWHITE WOOD OF DAHURIAN LARCH AND MONGOLIANSCOTCH PINE

The comparative result shows that the physical and mechanical properties of wood between white wood of Dahurian larch (Larix gmelini (Rupr.) Rupr.) and Mangolian scotch pine (Pinus cylvesthe var. mongolica) are different Some differences are very conspicuous,(e. g. compressivc strength parallel to grain, modulus of elasticity in static bending, toughness and bending strength etc. ),and others are slightly conSPicuous or not conspicuous,(e.g. shrinkage, differential shrinkage and shearing strength parallel to grain etc.). The properties of white wood of Dahurian larch are suitable weight and soft texture, median strength,median shrinkage and good in worability, while which of Mongolian scotch pine are light and soft nearly very soft,weak strength, median shrinkage are good in workability. However, the white wood of Dahuran larch is superior to the Mongolian scotch pine in Strength-to-weight ratio.It is a valuable timber tree.

Influence of Ammoniacal Copper Quaternary treatments on mechanical properties of blue-stained Lodgepole Pine wood

Three concentrations （2.8%, 2.0%, 1.2%） of Ammoniacal Copper Quaternary （ACQ） was selected to treat Lodgepole pine wood for evaluating ACQ treatment on mechanical properties of blue-stained wood. The bending modules of elasticity （MOE）, modules of rupture （MOR）, toughness and shearing strength parallel to grain on tangential surface, are tested according to the criteria GB1927-1943-91. Non-treated sample were also tested according to the same procedure. The results showed that the three groups specimen impregnated by different concentrations of ACQ solution met the AWPA standard 2003 of America （UC4A 6.4g/cm^3）. There were significant difference of toughness between treated wood and non-treated wood （p=0.01）, but there were no statistically significant differences among three concentrations in terms of toughness, and toughness of treated wood was approximately 20% lower than non-treated. MOR, MOE as well as sheafing strength parallel to grain were found to be not significantly different between treated wood and non-treated one, and there were no statistically significant difference among three concentrations of ACQ too. Toughness, MOR, MOE and sheafing strength parallel to grain increased with decrease of concentration of ACQ, but they were hardly affected by ACQ preservatives.

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.

松材线虫胁迫对5种松树的代谢组共性表达

为研究松树在松材线虫胁迫下的分子防御机制,分别选取15~20年生的辽宁抚顺的油松(LY)、辽宁抚顺的红松(LH)、山东威海的赤松(SC)、山东威海的黑松(SH)、湖南长沙的马尾松(HM)5种代表性松树作为研究对象,运用液相色谱-质谱联用技术的非靶向代谢组学,将以上5种松树分为健康组和感病组,分别对5组松树样本的差异代谢物分布情况、差异代谢物的共性特征、共有差异代谢物的表达显著性、代谢通路富集分布情况、差异性代谢通路的共性特征等进行研究。结果表明:5种松树感染松材线虫后的代谢产物在苯和取代衍生物、羧酸及其衍生物、脂肪酰基、酚类、孕烯醇酮脂类、类固醇及其衍生物、其他类等7类化合物中分布较为集中;HM、LH、LY和SC,HM、LY、SC和SH这两种组合,只有1种共有的显著性差异代谢物,分别是百里酚和6-姜酮酚,5种松树以及剩下的其他4种松树的组合都没有共有的显著性差异代谢物;HM、LY、SC和SH感染松材线虫后,6-姜酮酚表达量显著升高,LH感染松材线虫后,6-姜酮酚表达量无显著性差异;HM、SC、LY和LH感染松材线虫后,百里酚表达量显著升高,SC感染松材线虫后,百里酚表达量无显著性差异;HM、LH、LY、SC、SH分别富集到51、55、46、71、43条差异显著的信号通路,5种松树共有的差异显著的信号通路共有19条,主要反映在植物的抗逆相关信号通路上,包括花生四烯酸代谢、亚油酸代谢、苯丙烷生物合成、多种氨基酸代谢等。

基于高光谱与遥感影像技术的松材线虫病害监测

随着经济的发展,松材线虫病是当前威胁松树生长的主要病害,如何进行有效的监测和管控是目前松材线虫病治理的主要问题。针对当前松材线虫病识别效果不佳、识别精度不够等问题,提出了一种使用高光谱和遥感技术相结合的松材线虫病监测技术。新技术使用聚类方法和均值滤波提升高光谱数据效果,同时加入特征提取分析遥感影像敏感性提升了影像数据监测和分析能力。结果表明:在光谱波长为400~700 nm和1000~1300 nm之间松树出现较大的滤波系数变化。高光谱聚类均值方法的维度降低效果更好,相较于主成分分析法,其识别精度提升了2.35个百分点。使用混合模型进行数据分析,其Kappa系数识别精度得到提升。

Decomposition dynamics of coarse woody debris of three important central European tree species

Background： Coarse woody debris （CWD） is an important element of forest structure that needs to be considered when managing forests for biodiversity, carbon storage or bioenergy. To manage it effectively dynamics of CWD decomposition should be known. Methods： Using a chronosequence approach, we assessed the decomposition rates of downed CWD of Fagus sylvatica, Picea obies and Pinus sylvestfis, which was sampled from three different years of tree fall and three different initial diameter classes （〉10 - ≤20 cm, 〉20 - ≤40 cm, 〉40 cm）. Samples originating from wind throws in 1999 were collected along a temperature and precipitation gradient. Based on the decay class and associated wood densities, log volumes were converted into CWD mass and C content. Log fragmentation was assessed over one year for log segments of intermediate diameters （〉20 - 40 cm） after 8 and 18 years of decomposition. Results： Significantly higher decomposition constants （k） were found in logs of F. sylvotica （0.054 year^-1） than in P. abies （0.033 year^-1） and P. sylvestris （0.032 year^-1）. However, mass loss of P. sylvestris occurred mainly in sapwood and hence k for the whole wood may be overestimated. Decomposition rates generally decreased with increasing log diameter class except for smaller dimensions in P. obies. About 74 % of the variation in mass remaining could be explained by decomposition time （27 %）, tree species （11%）, diameter （17 %）, the interactive effects between tree species and diameter （4 %） as well as between decomposition time and tree species （3 %） and a random factor （site and tree; 9.5 %）, whereas temperature explained only 2 %. Wood fragmentation may play a more important role than previously thought. Here, between 14 % and 30 % of the decomposition rates （for the first 18 years） were attributable to this process. Carbon （C） density （mgC· cm ^-3）, which was initially highest for F. sylvatico, followed by P. sylvestris and P. obies, decreased with increasing decay stage to similar values for all species. Conclusions： The apparent lack of climate effects on decomposition of logs in the field indicates that regional decomposition models for CWD may be developed on the basis of information on decomposition time, tree species and dimension only. These can then be used to predict C dynamics in CWD as input for C accounting models and for habitat management.

First record of Bursaphelenchus rainulfi on pine trees from eastern China and its phylogenetic relationship with intro-genus species

Bursaphelenchus rainulfi isolated from dead pine trees in Zbejiang, China, is described and illustrated. It also provided some molecular characters of the Chinese population, including the PCR-RFLP and sequences of ITS region and D2-D3 expansion region of the large subunit （LSU） rRNA gene. Both the morphological characters and ITS-RFLP patterns match with the original description. The phylogenetic trees based on the 13 sequences of D2-D3 expansion region of the LSU rRNA gene and ITS region of Bursaphelenchus species were constructed, respectively, with the results showing the similar clades. The phylogenetic relationship based on the molecular data is similar to that with morphological characters. This is the first report of the species on pine wood in eastern China.

Microwave vacuum drying characteristics of Pinus massoniana wood

Microwave-vacuum （MV） drying characteristics of plantation Masson pine （Pinus massoniana） were studied experimentally for various levels of microwave radiation time, initial moisture content 0VIC）, vacuum level and wood thickness. The results show that the process of MV drying for wood can be significantly divided into a short accelerating rate drying period, a long constant rate drying period and falling rate drying period, and the second drying period can extend to levels of mean MC below the fiber saturation point. With the increase of initial MC and microwave radiation time, the drying rate of wood increases significantly. The vacuum level affects the drying rate in a slightly positive way. Within the range of 2 to 6 cm, the effects of sample thickness on the drying rate can be negligible.

Theory and Practice of Controlling and Extinguishing Pine Wilt Disease

[Objective] This study was aimed to review the controlling experience of pine wilt disease in the past 25 years, explore the theories and methods of controlling pine wilt disease, and improve the scientific level of controlling techniques and the protection capacity of healthy pine trees. [Method] Eleven items of effects were used to refine the theory of clearing dead pine trees affected by pine wilt disease, namely, ＂1 priority＂, ＂2 objections＂, ＂3 principles＂, ＂4 measures＂, and ＂5 manage- ments＂. On the basis of comprehensive control and complete removal of the infect- ed pine trees, a variety of comprehensive and efficient controlling methods were developed to carry out targeted chemical ecology trapping, bionic pesticide killing and releasing natural enemies of Sclerodermus guani, Dastarcus helophoroides. High ef- ficient emamectin benzoate immune injection was developed to inject the healthy pine trees for prevention, so as to extinguish the pine wilt disease. [Result] The pine wilt disease dropped from the peak of 3.5 million dead trees with an infecting area of 28 273 hectares in 1999 to 0.068 million with an area of 4 333 hectares in 2012 gradually, reducing by 98.06% in number and 84.84% in area, respectively. On the basis of removal, Dastarcus helophoroides was also released, which could make the number of dead pines decrease more significantly than the control, and af- ter releasing for 5 consecutive years, the dead pine trees dropped to 0.511 plant/hm2 in 2012, with a mortality rate of 0.022 7%, which achieved the control effect, reaching extremely significant level. ＂Forest land removal＋infected trees isolation＋natural enemy release＂ could extinguish the pine wilt disease. The test of isolating 24 heaps of infected pine trees showed that there were 9 heaps of pine trees extinguished the pine wilt disease, which controlled the occurrence of pine wilt disease for 100%, accounting for 37.5% of the total, in which the number of those isolated using iron netting and nylon net were 4 for each, accounting for 88.9%, and there was one heap using polypropylene net, accounting for 11.1%. The invention of em- amectin benzoate immune injection laid the foundation for extinguishing pine wilt disease. The follow checking of the effects of emamectin benzoate immune injection on pine wilt disease found that the number of dead trees caused by pine wilt dis- ease decreased significantly after injecting, and became very small in October of the next year, and the disease was completely extinguished in the third year. [Conclusionl Pine wilt disease could be controlled and extinguished with positive control by using ＂comprehensive cleaning＋industrialized removal＂, ＂comprehensive cleaning＋ natural enemy release＂, ＂comprehensive cleaning＋infected trees isolation＋natural ene- my release＂ and ＂comprehensive cleaning＋emamectin benzoate immune＂.

Resistance genes mediate differential resistance to pine defensive substances α-Pinene and H_(2)O_(2) in Bursaphelenchus xylophilus with different levels of virulence

The pine wood nematode(PWN),Bursaphelenchus xylophilus(Steiner & Buhrer) Nickle,is the pathogen of pine wilt disease(PWD) which can devastate forests.PWN can be of hi gh or low severity and the mechanisms underlying the differences in virulence are unclear.Therefore,it is necessary to study the relationship between differentiation of PWN severity and its resistance to the main defensive substances of pine species(i.e.,α-pinene and H_(2)O_(2)).The feeding rate and fecundity of PWN was examined at different levels of virulence under conditions of a-pinene and H_(2)O_(2) stress.Moreover,the expression patterns of the main resistance genes of PWN with different virulence were determined under conditions of α-pinene and H_(2)O_(2) stress.The feeding rate and fecundity of the high virulence strain AMA3 were higher than those of the low virulence strain YW4.The expression levels of the autophagy gene BxATG5,cytochrome P450 gene BxCYP33 D3,and glutathione S-transferase genes BxGST1 and BxGST3 in AMA3 increased significantly upon exposure to α-pinene for 2 h,while these genes showed smaller degrees of upregulation in YW4.Under conditions of H_(2)O_(2) stress,the expression levels of BxATG5,catalase genes Bxy-ctl-1 and Bxy-ctl-2,and the 2-cysteine peroxiredoxin gene BxPrx in AMA3 were higher than those in YW4.These findings suggest that high virulence PWN has greater resistance to pine defensive substances α-pinene and H_(2)O_(2) than low virulence PWN,and resistance genes mediate the differential resistance of PWN strains.This study will contribute to the clarification of the mechanism underlying virulence differentiation of PWN and will advance understanding of the pathogenic mechanism of PWD.

The population structure and sex ratios of Bursaphelenchus xylophilus under a-pinene stress

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.

Relations Between Permeability and Structure of Wood

The permeability and the structure of heartwood and sapwood of the solvent-exchange dried and the air-dried greenwood of Chinese-fir (Cunninghamia lanceolata (Lamb.) Hook.) and masson pine (Pinus massoniana Lamb.) were measured in order to study the relations between the permeability and the structure. The results showed that the permeability of sapwood of both the air-dried and the solvent-exchange dried wood was higher than that of heartwood, and the permeability of the solvent-exchanged dried heartwood and sapwood was higher than that of the air-dried. A higher permeability of wood was attributed to, on the one hand, a bigger number of flow path per unit area of the wood perpendicular to the flow direction resulted from a bigger number of unaspirated pits per unit area and a bigger number of effective pit openings per membrane, and on the other hand, a smaller number of tracheid in series connection per unit length parallel to flow direction resulted from a longer tracheid length and an effective tracheid length for permeability.

An integrated assessment approach to optimal forest bioenergy production for young Scots pine stands

Background: Bioenergy is re-shaping opportunities and imperatives of forest management. This study demonstrates,through a case study in Scots pine(Pinus sylvestris L.), how forest bioenergy policies affect stand management strategies.Methods: Optimization studies were examined for 15 Scots pine stands of different initial stand densities, site types, and temperature sum regions in Finland. Stand development was model ed using the Pipe Qual stand simulator coupled with the simulation-optimization tool Opti For Bioenergy to assess three forest bioenergy policies on energy wood harvest from early thinnings.Results: The optimal solutions maximizing bare land value indicate that conventional forest management regimes remain optimal for sparse stands. Energy harvests occurred only when profitable, led to lower financial returns. A forest bioenergy policy which included compulsory energy wood harvesting was optimal for denser stands. At a higher interest rate(4 %), increasing energy wood price postponed energy wood harvesting. In addition, our results show that early thinning somewhat reduced wood quality for stands in fertile sites. For less fertile sites, the changes were insignificant.Conclusions: A constraint of profitable energy wood harvest is not rational. It is optimal to carry out the first thinning with a flexible forest bioenergy policy depending on stand density.

Design and Experimental Analysis of NLT Trussed Rafter in Yellow Pine

The roof system of social housing in Brazil generally consists of components made out of native forest lumber of high market value. Taking into account the increasing number of planted forests and the need to develop new products and to add value to this timber, this work deals with the development and structural analysis of a roof system using yellow pine plantation wood （Pinus spp）, a sustainable material which however presents many defects. The NLT （laminated nailed timber） technology was chosen as it allows the use of shorter length and smaller cross section pieces, eliminating major defects. Seven samples of structural trussed rafters in NLT were tested; six made out of graded timber and one ungraded in order to verify the impact of the wood grading in the structural performance of the model. The results showed that the trussed rafter system in NLT meets the necessary structural performance requiring poor conditions of infrastructure for manufacture process, and that the graded wood samples showed better performance than the ungraded one.

Study on Weathering Behavior of Jack Pine Heat-Treated under Different Conditions

It is of considerable importance to investigate the influence of weathering on the degradation processes of heat-treated wood. Kiln-dried （untreated）jack pine （Pinus banksiana） and jack pine heat-treated at three different temperatures （190 ℃, 200 ℃, and 210 ℃） were exposed to artificial weathering for different periods in order to understand the degradation processes due to weathering. Before and after exposure, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using SEM （scanning electron spectroscopy）, FTIR （Fourier transforms infrared spectroscopy）, and XPS （X-ray photoelectron spectroscopy）. The results revealed that the photo-degradation of lignin and the presence of extractives play important roles in color change and wetting behavior of heat-treated wood surfaces during weathering. The structural changes also influence the wettability. The effects of weathering for woods heat-treated under different conditions were similar, but different from those for untreated wood.