Microenvironmental effects on growth response of Pinus massoniana to climate at its northern boundary in the Tongbai Mountains,Central China

The Tongbai Mountains is an ecologically sensi-tive region and the northern boundary of Pinus massoniana Lamb.To analyze the effect of different microenvironments on tree growth response to climate factors,we developed standard chronologies for earlywood width(EWW),late-wood width(LWW),and total ring width(TRW)of P.massoniana at two sampling sites on slopes with different orientations,then analyzed characteristics of the chronolo-gies and their correlations with climate variables from five stations in the region and with a regional normalized differ-ence vegetation index(NDVI).Statistical results showed that the TRW/EWW/LWW chronology consistency and charac-teristics(mean sensitivity,signal to noise ratio,expressed population signal)for trees growing on the southeastern slope were much higher than for trees on the northeastern slope.Correlations indicated that temperature in current March and August has a significant positive effect on TRW/EWW/LWW formation,and the effect on the northeastern slope was weaker than on the southeastern slope.Compared to temperature,precipitation has more complicated effects on tree growth,but the effect on the northeastern slope was also generally weaker than on the southeastern slope.Step-wise linear regression analyses showed that temperature in August was the main limiting factor at the two sampling sites.Similarly,the response of tree growth on the southeast-ern slope as determined by the NDVI is better than on the northeastern slope,and the TRW/EWW/LWW chronologies for the southeastern slope explained over 50%of the total NDVI variances in June.Overall,the results indicate that the difference in the climate response of P.massoniana at two sampling sites is clearly caused by differences in the microenvironment,and such differences should be properly considered in future studies of forest dynamics and climate reconstructions.

Differential aluminum tolerance and absorption characteristics in Pinus massoniana seedlings colonized with ectomycorrhizal fungi of Lactarius deliciosus and Pisolithus tinctorius

Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al tolerance,Pinus massoniana seedlings were inoculated with either Lactarius deliciosus(L.:Fr.)Gray isolate 2 or Pisolithus tinctorius(Pers.)Coker et Couch isolate 715 and cultivated in an acid yellow soil with or without 1.0 mM Al^(3+)irrigation for 10 weeks.Biomass production,Al bioaccumulation and transport in seedlings colonized by the two ECM fungi were compared,and the three absorption kinetics(pseudo-first order,pseudo-second order and intraparticle diffusion)models used to evaluate variances in root Al^(3+)absorption capacity.Results show that both fungi increased aboveground biomass and Al tolerance of P.massoniana seedlings,but L.deliciosus 2 was more effective than P.tinctorius 715.Lower Al absorption capacity,fewer available active sites and decreased affinity and boundary layer thickness for Al^(3+),and higher Al accumulation and translocation contributed to the increased Al tolerance in the ECM-inoculated seedlings.These results advance our understanding of the mechanisms and strategies in plant Alto lerance conferred by ECM fungi and show that inoculation with L.deliciosus will better enhance Al tolerance in P.massoniana seedlings used for forest plantation and ecosystem restoration in acidic soils,particularly in Southwest China and similar soils worldwide.

Modeling compatible single-tree aboveground biomass equations for masson pine(Pinus massoniana) in southern China

Because of global climate change, it is necessary to add forest biomass estimation to national forest resource monitoring. The biomass equations developed for forest biomass estimation should be compatible with volume equations. Based on the tree volume and aboveground biomass data of Masson pine （Pinus massoniana Lamb.） in southern China, we constructed one-, two- and three-variable aboveground biomass equations and biomass conversion functions compatible with tree volume equations by using error-in-variable simultaneous equations. The prediction precision of aboveground biomass estimates from one variable equa- tion exceeded 95%. The regressions of aboveground biomass equations were improved slightly when tree height and crown width were used together with diameter on breast height, although the contributions to regressions were statistically insignificant. For the biomass conversion function on one variable, the conversion factor decreased with increasing diameter, but for the conversion function on two variables, the conversion factor increased with increasing diameter but decreased with in- creasing tree height.

The essential oil components of Cinnamomum cassia: an analysis under different thinning models of plantation Pinus massoniana

Thinning is an important activity employed in forest management. To date, studies have mainly focused on the effects of thinning on the growth of trees during the same thinning period. In this study, plantation Pinus massoniana Lamb. near maturity were thinned at varying intensities and an economically important species, Cinnamomum cassia Presl., was planted beneath the thinned canopy. The aim of the study was to explore the effects of the extent of thinning on the essential oil content and its components of C. cassia in different parts of the plant, as well as the economic feasibility of the P. massoniana-C.cassia management model. Thinning significantly reduced the oil yield in the bark and branches of C. cassia, but hardly impacted the oil yield from C. cassia leaves compared with pure C. cassia forest（CK）. Among the different thinning treatments, both light（T.4） and extensive（T.1）thinning reduced the oil yield of C. cassia bark and new branches. The concentrations of the main aldehydes differed in different parts of the plant and were affected by the extent of thinning. The influence on cinnamaldehyde in the bark was minor, but was much greater in the branches and leaves. Both the oil yield and content of cinnamaldehyde showed that moderate（T.3） thinning was more favorable than other thinning models. These results not only provide a potentially promising model for the transformation of low-yield artificial pure forests of P. massoniana in the future, but also offer a reference for the management of artificial mixed stands.

Improving the assessment method of seed vigor in Cunninghamia lanceolata and Pinus massoniana based on oxygen sensing technology

Oxygen sensing technology was employed to study the rapid methods for seed vigor assessment of Chinese fir （Cunninghamia lanceolata） and Masson pine （Pinus massoniana）. Firstly, seeds of five lots were performed using accelerated aging （AA） into three vigor levels. Then, four oxygen sensing indices, including increased metabolism time （IMT）, oxygen metabolism rate （OMR）, critical oxygen pressure （COP）, relative germination time （RGT） and the control indiees such as labora- tory germination indices, dehydrogenase activity （DA）, and electrical conductivity （EC） were analyzed by the tests of 15 samples. The results of correlation analysis between these indices and field emergence per- formances based on two-year and two-spot data showed that RGT and OMR should be indicated as the optimal oxygen sensing indices to rap- idly and automatically evaluate seed vigor of Chinese fir and Masson pine, respectively. On the basis, one-variable linear regression equations were built to forecast their field emergence performances by the two oxygen sensing indices.

Selection of superior families of Pinus massoniana in southern China for large-diameter construction timber

This study addresses the increasing demand for large-diameter production timber,and considers the time and space variability of half-sib families of Pinus massoniana.Height,diameter at breast height(DBH)and timber volume of 440 open-pollinated half-sib progeny families were investigated in 14 progeny trials in different years and production regions.An evaluation of the genetic variation of all half-sib families was carried out during the sustainable rapid growth period and individual volumes were characterized as a major index.ANOVA analysis showed that there was considerable variance in the growth traits of most families in different years and on different sites.The variations caused by temporal and spatial changes of the mating system required three selection methods for analysis.The results show that there were differences among the heritabilities of different growth traits by different halfsib progenies.Average heritability values of height,DBH and volume were 0.33,0.34 and 0.36,respectively.Fortyfive superior families were selected in every progeny test,12 were selected in progeny trials by different years and five in different habitat progeny trials.Three superior families(Gui GC553A,Gui GC414A and Gui GC431A)were selected,although in different years and production regions.The genetic gains of timber volume of these selected r families ranged from 1.20 to 47.00%,which could provide a foundation for superior wood property selection and serve as material for seed improvement and extension in surrounding areas.

Acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China

Barks of Pinus massoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution. The conductivities of the inner barks differed significantly among the three sites, with higher values at the clean site. However, the significant differences were not observed among these sites. Furthermore, the pH values for the inner and outer barks were not correlated with the conductivity, which did not coincide with some other studies.

Spatial heterogeneity of fine root biomass of Pinus massoniana forests in the Three Gorges Reservoir Area, China

Environmental heterogeneity is a constant presence in the natural world that significantly affects plant behavior at a variety of levels of complexity. In order to estimate the spatial pattern of fine root biomass in the Three Gorges Reservoir Area, the spatial heterogeneity of fine root biomass in the upper layer of soils （0-10 cm） in three Mas- son pine （Pinus massoniana） stands in the Three Gorges Reservoir Area, China, was studied in 30 m x 30 m plots with geostatistical analysis. The results indicate that 1） both the live and dead fine root biomass of stand 2 were less than those of other stands, 2） the spatial variation of fine roots in the three stands was caused together by structural and ran- dom factors with moderate spatial dependence and 3） the magnitude of spatial heterogeneity of live fine roots ranked as： stand 3 〉 stand 1 〉 stand 2, while that of dead fine roots was similar in the three stands. These findings suggested that the range of spatial autocorrelation for fine root biomass varied considerably in the Three Gorges Reservoir Area, while soil properties, such as soil bulk density, organic matter and total nitrogen, may exhibit great effect on the spatial distribution of fine roots. Finally, we express our hope to be able to carry out further research on the quantitative relation- ship between the spatial heterogeneous patterns of plant and soil properties.

Impact of invasion of pine wood nematode on the growth of dominant shrub Pleioblastus amarus in Pinus massoniana communities

When pine trees are invaded by pine wilt diseases, the severely infected pine trees will die and fall down, or they will be removed when found to be damaged by the disease. It gives rise to the invasion of other species in these empty niches originally oc- cupied by pine trees, i.e., competing surrounding trees or understory shrubs will invade the empty niches during the following years. As a result, the spatial distribution and pattern of the main tree species in a pine forest will change, and a niche variety in the main population will occur. In the end, the direction of the succession and restoration of the pine forest ecosystem will be affected. In our study, a Pinus massoniana forest with the dominant shrub, Pleioblastus amarus, was invaded by pine wood nematode and was clear cut. Selecting this community as our research object, we studied the effect of the invasion of the pine wood nematode on the growth of the dominant shrub, P. amarus, in this Pinus massoniana forest. Our results show that, after the attacked pine trees were removed, the niche was occupied by Pleioblastus amarus and other shrubs, which benefited the growth ofP. amarus to its climax. Growth of P. amarus at the climax stage was greater compared with the unhealthy pine forest and the control group.

Effects of Steam Heat-Treatment on Properties of Pinus massoniana Wood and Its Bonding Performance

Pinus massoniana wood was modified by steam heat-treatment at 160℃,180℃,200℃ and 220℃ respectively and effects of the changes of density,pH,surface wettability and apparent morphology of Pinus massoniana heat-treated wood on its bonding performance were studied in this paper.The results showed that Pinus massoniana wood underwent a series of physical and chemical changes during heat-treatment as the the following:(1)The degradation of hemicellulose and cellulose with low degree of polymerization,degradation and migration of the extract resulting in the decline of density and pH of heat-treated Pinus massoniana wood.(2)Brittle fracture occured on the cell wall surface,and the pit collapse,shrink and deformation,resulting in the formation of roughness and porosity on the wood surface.(3)The surface energy decreased with the improvement of temperature,the surface wettability of Pinus massoniana wood treated at 160℃–180℃ was good,while that at 200℃–220℃ showed hydrophobicity.(4)Changes of density,pH,surface roughness and porosity,and wettability resulted in a reduction in the bonding strength and reliability of heat-treated Pinus massoniana wood with MUF resin adhesive.(5)When the temperature was at 160℃–180℃,the better wettability of heat-treated Pinus massoniana wood could guarantee the better bonding performance.

Cloning and characterization of geranylgeranyl diphosphate synthetase from Pinus massoniana and its correlation with resin productivity

Geranylgeranyl pyrophosphate synthetase(GGPPS) has gained increasing attention as a key enzyme in terpene analysis.We designed specific primers based on plant GGPPS homologs and used reverse transcription polymerase chain reaction(RT-PCR) to obtain and identify Pin GGPPS,a GGPPS gene sequence from Pinus massoniana,using bioinformatics tools.Quantitative PCR analysis of Pin GGPPS expression levels in roots,pine needles,immature stems,and semilignified stems from 6-month-old P.massoniana showed that expression levels of Pin GGPPS were highest in pine needles,followed by immature stems and semilignified stems,and lowest in roots.When we examined the correlation between Pin GGPPS gene expression levels and resin productivity in 20 adult plants for 28 successive days,Pin GGPPS expression levels presented a substantially linear distribution when plotted against their corresponding resin yields.In summary,we characterized the gene Pin GGPPS for the first time in P.massoniana,and established a correlation between Pin GGPPS gene expression levels and resin productivity,suggesting the importance of theory and production practice for P.massoniana.

Comparative study on the mRNA expression of Pinus massoniana infected by Bursaphelenchus xylophilus

Pine wilt disease(PWD)is a devastating disease affecting the growth of Pinus massoniana,often leading to withering and death.To reveal the changes involved during disease progression,we investigated the mRNA expression profile of P.massoniana infested by Bursaphelenchus xylophilus.The infestation resulted in the downregulation of genes involved in interactions with pathogenic pathways such as disease resistance gene,CC-NBS-LRR resistancelike protein,and the gene encoding a putative nematode resistance protein.Increased infestation pressure(number of nematodes inoculated)caused a continuous decline in the gene expression of stem samples.An infestation of P.massoniana also resulted in a pathway enrichment of genes involved in phenylpropanoid metabolism and flavonoid biosynthesis,which in turn reduced the levels of total phenols and total flavonoids.A downregulation of auxin responsive family protein was observed in infested samples,which resulted in a suppression of plant growth.Thus,upon B.xylophilus infestation,a downregulation of genes associated with the recognition of pathogens,PWD resistance,and growth regulation was observed in P.massoniana,together with a decrease in the levels of phytoalexinlike secondary substances,all of which resulted in withering and ultimately death of P.massoniana.

Changes in soil properties under Eucalyptus relative to Pinus massoniana and natural broadleaved forests in South China

The ecological effects of eucalypt plantations（EPs） have garnered increasing attention.To understand their effect on soil quality at a landscape scale,and to determine whether soil quality parameters differ due to different stand types,we evaluated soil characteristics in twenty-one groups of EPs,Pinus massoniana Lamb.plantations（PMPs） and natural broadleaved forests（NBFs）across Guangdong Province,China.Both the physical characteristics of soil hydrology and the properties of soil nutrients in A and B horizons were determined.Results showed that,compared to NBFs,EPs and PMPs produced a shallower litter layer,reduced canopy density,higher soil bulk density,significantly lower total porosity,non-capillary porosity,total water volume,and hygroscopic water in the A horizon（P〈0.05）.Moreover,total N,available K,and soil organic carbon（SOC） in EPs and PMPs were significantly lower than in NBFs.EPs and PMPs did not differ significantly in N,P or K content,but PMPs had significantly lower SOC and boron in the A horizon than EPs.Low p H and poor capacity to buffer acidification generally occurred in all cover types.Both EPs and PMPs showed a decline in soil properties relative to NBFs,but EPs and PMPs exhibited no significant difference.These results indicate that actions are needed to ameliorate the potential negative effects on soil quality in forestry plantations.

Tin-based metal bath heat treatment: an efficient and recyclable green approach for Pinus massoniana wood modification

Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.

Variability in the climate-radial growth correlation of Pinus massoniana of different diameter classes

The physiological characteristics of trees change with age,suggesting that growth-related climate signals vary over time.This study aimed to clarify the impacts of different diameter classes on the chronological characteristics of Pinus massoniana Lamb.and its response to climatic factors.Chronologies of P inus massoniana were established in small diameter(14.1 cm),middle diameter(27.3 cm),and large diameter(34.6 cm)trees according to dendrochronology.The results show that:(1)radial growth of different diameter classes had varied characteristics and climate sensitivities;(2)radial growth of small diameter trees was affected by climatic factors of the previous and the current year,while large diameter trees were mainly affected by climatic factors of the current year;and(3)precipitation and temperature were key factors that restricted the radial growth of small and large diameter trees,respectively.

The effect of high-pressure and high-temperature drying treatments on the deresination ratio of Pinus massoniana

This study investigated the possibility of using high-temperature and high-pressure schedules to treat Pinus massoniana wood in order to reduce its oil content. We discuss the effect of drying temperature, absolute pressure and the holding time on the deresination ratio in R massoniana wood and establish a model for the deresination ratio as a function of drying temperature, absolute pressure and holding time. The results show that the deresination ratio in- creased from 7.14% to 87.04% when the temperature increased from 150 to 200℃, the absolute pressure from 0.1 to 0.6 MPa and the holding time from 1 to 3 h. The optimal model for the deresination ratio （Y） with drying temperature （t）, absolute pressure （p） and holding time （r） is： Y = 0.284t ＋ 113.424p ＋ 3.518r - 42.486, with a coefficient of determina- tion （R2） of 0.930. Compared with drying temperature and holding time, absolute pressure plays the more significant role in the deresination process. This study could provide a theoretical basis to the practical production of R massoniana wood.

Correlative Analysis between Contents of Nutrients and Secondary Substances in Damaged Pinus massoniana Needles and Population Parameters of Dendrolimus kikuchii(Lepidoptera:Lasiocampidae)

In order to explore the effects of chemical substances changes in damaged masson pine （Pinus massoniana） needles on population dynamics of Dendroli- mus kikuchii, D. kikuchii larvae were reat~ with P. massoniana needles with different damage degrees （mild, moderate and severe）, and its population parame- ters and contents of nutrients and secondary substances in damaged P. massoniana needles were measured, and the integrated correlation coefficient was adopted for data analysis. The results showed that with the damage degree aggravating, flavones in needles increased accordingly, while contents of soluble sugars, polysaeeha- rides and proteins decreased. The average developmental duration and mortality of D. kikuchii larvae increased with the damage degree increasing. No significant correlation was found between the changes in contents of tannins or total phenols and the developmental duration or mortality of each instar larvae. There were signif- icant direct and integrated correlations between contents of nutrients and secondary substances of P. massoniana needles and the developmental duration or mortality of each instar larvae except the 6＇h instar larvae. With the damage degree increasing, all parameters of D. kikuchii population including body weight of the 7~ instar larvae, average feeding capacity of larvae, pupal weight, pupation rate, female ratio and fecundity decreased. No significant correlation was found between the changes in contents of tannins or total phenols and population parameters of D. kikuchii larvae. The results suggest that the contents of nutrients and secondary sub- stances in P. ,mssoniana needles dramatically influenced the population parameters of D. kikuchii, and the importance from high to low successively was soluble sugars 〉 proteins 〉 polysaccharides 〉 flavones. Contents of tannins and total phenols seemed to have little influence.

Mechanical characterization of Pinus massoniana cell walls infected by blue-stain fungi using in situ nanoindentation

Characterizing the mechanical properties of wood cell walls will lead to better understanding and optimization of modifications made to wood infected by the blue-stain fungi.In this study,in situ nanoindentation was used to characterize the mechanical properties of the cell walls of Pinus massoniana infected by blue-stain fungi at the cellular level.The results show that in situ nanoindentation is an effective method for this purpose and that blue-stain fungi penetrate wood structures and degrade wood cell walls,significantly reducing the mechanical properties of the cell walls.The method can also be used to evaluate and improve the properties of other wood species infected by blue-stain fungi.

Intratree Variation in Viscoelastic Properties of Cell Walls of Masson Pine (Pinus Massoniana Lamb)

In this study,Pinus massoniana Lamb at different heights,across the annual rings,and between earlywood and latewood was measured by X-ray diffraction and the chemical composition was analyzed by chemical treatment.Results indicated that the microfibril angle(MFA)decreased and the chemical composition changed little with the increase in height from 1 m to 9 m.In the radial direction,the MFA decreased and the chemical composition changed little with an increase in annual rings.The cellulose content of latewood was higher than that of early-wood.The viscoelastic changes of wood cell walls at different heights,across the annual rings by the method of quasi-static nanoindentation and dynamic modulus mapping techniques.Results indicated that the wood cell walls’elastic modulus increased,and the creep rate and creep compliance decreased with the increase in height;The elastic modulus and hardness increased with the annual rings.The cell walls’storage modulus increased and the loss modulus gradually decreased with an increase in height;the storage modulus gradually increased and the loss modulus decreased with the annual rings.

Metal pollution in relation to mass outbreaks of Dendrolimus punctatus Walker on Pinus massoniana Lamb.in China

Insects with their ecological superpower have enormous capacity to transform small pollution damage in forests to full scale calamities. Acid rain resulting from extensive coal burning is the chief pollutant in China. Acid rain activates from soil deposits toxic metals, which are transferred to trees and further to insects eating them. We studied the levels of the toxic Cd, its antagonists Zn and Cu, and acid rain indicators Fe and Mn in the forest pest moth Dendrolimus punctatus Walker (Lepidoptera:Lasiocampidae) in variously polluted Pinus massoniana Lamb forests in China.\; The highest density of D. punctatus , as well as the highest Cd levels developed in the moderately polluted forests. Possibly Cd had there broken down the pest resistance of the pines. The paradoxical coexistence of high Cd level and elevated population density of the pest seems to result from the high accumulation of Cd in its ichneumonid parasitoid. In the most heavily polluted forests the Cd level in needles was low, possibly because the strong acid rain had washed away most of the Cd deposit in the soil. It existed there no D.punctatus population. Absence of pest insects from the most heavily polluted areas is a common phenomenon.