In this paper, we investigated influences of plantation measures and forest ages on soil organic carbon (SOC) of Larix principis-rupprechtii plantations with different slope aspects in the Southern Liupan Mountains was studied. The results showed that the SOC content on all aspects presented the same trend of firstly decreasing after tree-planting and then recovering. The SOC sensibility to environment variation, such as plantation disturbance, decreased with increasing soil depth. The time required for restoring the SOC density in the soil layers of 0-45 cm to the level of pre-afforestation varied with site conditions. On the sunny and semi-sunny aspects, the SOC density (96.33 t·hm^-2) in 0-45 cm soil layers of a 10 years young plantation was still lower than that of the shrub land (122.12 t·hm^-2); however, the SOC density (189.27 t·hm^-2) of the 20 years middle-aged plantation after afforestation was higher than that of the shrub land, indicating that the SOC was restored before this forest age. On the shady and semi-shady aspects, the SOC density of the young and middle-aged plantations was 192.37 and 222.03 t·hm^-2, respectively, and both were lower than that of the naturally regenerated forests (256.64 t·hm^-2), indicating that the SOC was still not restored after 20 years afforestation. Based on the statistical analysis of the investigated SOC content in the soil layers of 0-45 cm, the SOC content of 0-45 cm soil layers would decrease to the lowest point after 8 years afforestation on the sunny/semi-sunny aspects, with the decrease of 3.72 g·kg^-1 compared to the control of shrub land (32.13 g·kg^-1) on sunny aspect, and the fully recovering of SOC to the pre-plantation level would require 16 years after plantation. On the shady/semi-shady aspects, the SOC content would decrease to the lowest point after 16 years plantation, with the decrease of 22.77 g·kg^-1 compared to the control of secondary forests (66.30 g·kg^-1), and the fully recovering of SOC to the pre-plantation level would require 32 years after plantation. The SOC on shady aspects after plantation had a bigger loss, longer decreasing period and slower recovering rate than those on the sunny aspect. However, the absolute values of the SOC pool on the shady aspects were always higher than that on the shady aspects at any forest age, suggesting that the capacity of carbon sequestration at shady aspects was higher than that of sunny aspects. Our study demonstrated that the planting disturbance was able to affect the change of SOC pool. The mean SOC content in the 0-45 cm soil layers on sunny/semi-sunny aspect was 31.05 g·kg^-1 after 10 years plantation if the trees were planted with sparse spacing, considerably higher than that (23.17 g·kg^-1) of forests planted with normal density, however still lower than that of the control of shrub land (35.55 g·kg^-1).

Seasonal dynamics in the soil seed bank under 4 different vegetation cover types (A: Rumex acetosa lakeshore, B: Shrub and grass lakeshore, C: Crop lakeshore, D: Natural reed lakeshore) were investigated with a germination method. The results showed that the seeds of 30 plant species were germinated from the soil seed bank. The species number of the germinated seeds was 21, 16 and 18, respectively in April, August and November 2010, and most of them belonged to therophyte and perennial plants. There were no significant differences in seed density in the soil seed bank among April, August and November, with an average 2 093±948.55 seed·m^-2, 1 173±897.01 seed·m^-2, 1 100±623.50 seed·m^-2, respectively. The largest density of type A, B and C was found in April, and was 1 040±526.91 seed·m^-2, 4 853±1 681.91 seed·m^-2, 1 360±586.55 seed·m^-2, respectively. Seasonal dynamics of lakeshore wetland seed bank density were ranked in an order: Spring (April)>Summer (August)>Autumn (November) in Lake Tai. This study indicates that wetland seed banks play an extremely important role in maintaining standing vegetation plant diversity, and provides a technical support for the protection and management of lakeshore wetland, Lake Tai.

Bamboo culm consists of vascular bundles and parenchyma, and vascular bundles determine mainly the strength of a bamboo culm. Vascular bundle is also an important connection of the microscopic properties and the macroscopic properties of bamboo culm. This paper accurately measured the area of a Moso bamboo (Phyllostachys edulis) vascular bundle by using the Confocal Laser Scanning Microscope(LCSM), and studied the area variation of inner and outer vascular bundles. The results showed that the area values were between 0.038 3 and 0.246 2 mm²; the vascular bundles could be divided into outer layers and inner layers according to morphology from outside to inside of bamboo wall; the area of the outer vascular bundle increased with the increasing size, while inner vascular bundle had no change.

A field experiment on vegetation restoration was carried out in the abandoned lead-zinc tailings for 3 years with 15 plant species to evaluate their potential adaptation to the tailings. Plant species expressed different tolerance to stress of the tailings. Most species appeared the heavy metal-induced etiolation, defoliation, or growing stopped. There were significant differences in the growth rate of height and base diameter, root growth, and biomass among the species. The mine tailings reduced the root distribution depth, and stimulated the max length of lateral roots, the fine root ratio, and increased to different extents the mass allocation proportion to roots in all species. Four nitrogen-fixed species, Alnus cremastogyne, Amorpha fruticosa, Lespedeza cuneata, and Medicago sativa, suffered from mild damage, and root nodules appeared in their roots. In addition, Rhus typhina and Nerium indicum had higher tolerance, which kept higher relative growth rate and biomass. The results showed that accumulation of lead (Pb), and zinc (Zn) differed dependent on plant species, their organs, and the heavy metals. Generally, most plant species had higher concentrations of Pb and Zn in roots than that in shoots, while some of tree species had higher Zn concentrations in shoots than that in roots. Among the 15 species, L. cuneata had the highest contents of Pb and Zn in shoots in per square meter of ground (65 and 199 mg·m^-2, respectively). A. fruticosa had the second high Pb and Zn contents, reaching to 43 and 127 mg·m^-2, respectively. Based on overall performance we selected eight species candidate: A. fruticosa, L. cuneata, R. typhina, N. indicum, A. cremastogyne, R. chinensis, M. sativa, and Cercis canadensis, which would be suitable for the vegetation restoration in lead and zinc mine tailings, especially the nitrogen-fixing species.

Ammopiptanthus mongolicus is one of the only two ever-green shrub species in the north-west China deserts, and is able to form nodules with rhizobia as an ancient legume. In this study, histology of root nodules of A. mongolicus was analyzed. Nitrogen-fixing nodules showed typical characteristics of indeterminate nodules, and from the distal (apical) part of a nodule to the proximal (basal) region, four central zones were able to be distinguished: the bacteria-free meristematic zone I; infection zone II, in which the cells began to differentiate; nitrogen-fixing zone III; and senescent zone IV. Exception for the apical meristem, the other three zones were surrounded by lateral nodular tissues such as the parenchyma (i.e ., the inner cortex), the vascular bundles, the endodermis and the cortex, successively. Intracellular infection was observed in A. mongolicus normal nodules, while intercellular infection characteristic was shown in abnormal nodules. Ultrastructural observation showed that the region between zone II and III contained diversified cell types, exhibiting diverse cell processes: 1) After bacteria were released, host cells initiated the assembling process of perbacteriod membrane, during which vesiculars were engaged in transporting membrane materials to bacteria vicinity from endomembrane reticulum. Intact perbacteriod membrane was formed and contained a single bacterium, afterwards adjacent membranes were fused and enlarged to form a large peripheral membrane which wrapped several bacteria. 2) Compared to other regions, interzone II-III contained much more starch granules. 3)Many plasmodesmata existed between contiguous infected cells. Electron microscopy cytochemistry studies showed that glycoprotein grains in a loose form were located at internal wall of parenchyma cells. After being infected by bacteria the glycoprotein was translocated into the intercellular spaces between infected cells or between infected and un-infected cells, where most glycoprotein grains were attached to the external wall with some dissociated.

A somatic embryogenesis system from immature zygotic embryos of Pinus thunbergii was established. The effects of basic medium, 2,4-D and 6-BA on embryogenic callus induction were studied, and the effects of ABA and PEG on somatic embryo maturation and plant regeneration were investigated. The results showed that cultured on DCR medium supplemented with 4 mg·L^-12,4-D and 2 mg·L^-16-BA, the embryogenic callus induction rate was 3.33%; and on DCR medium containing 30 mg·L^-1 ABA and 25 g·L^-1 PEG, the number of somatic embryo per gram embryogenic callus was up to 72, and the somatic embryo germination rate was 63.8% and plantlet conversion rate from the germinated somatic embryos was 43.5%. High quality somatic embryos could improve the germination rate and plantlet conversion rate. Up to 50% of the transplanted plantlets were successfully survived one month in soil. This study would provide a new way for rapid and large-scale propagation of wilt-resistant P. thunbergii.

Bretschneidera sinensis, an endemic plant species native to China, is in peril of extinction because of scarce natural genetic resources and human destruction of its natural habitat. In order to assess the genetic integrity of the ex situ conservation populations of this species, the genetic diversity of four natural and two planted populations from Nanling Mountains was investigated using inter-simple sequence repeat (ISSR) markers. A total of 86 discernible DNA fragments were detected with 7 primers, and the 62 fragments were polymorphic. The percentage of polymorphic loci (PPB) and Shannon's phenotypic diversity index(H_POP) in a population ranged from 36.05% to 53.49%, and from 0.204 0 to 0.307 9, respectively. The population genetic indexes of natural populations(PPB=70.93%,H_POP=0.388 2) were higher than those of planted populations (PPB=53.49%, H_POP=0.294 1). Analysis of molecular variance (AMOVA) revealed that there was significant genetic difference among and within populations, and the genetic differences (Φ_ST=0.340 7) among natural populations were obviously higher than those of planted populations (Φ_ST=0.224 8). This result indicated high level genetic diversity at both population and species level of B. sinensis. The planted populations for ex situ conservation could not effectively protect the genetic diversity of this species from Nanling region. The planting material collection strategies for ex situ conservation should include as many as possible different populations.

This study analyzed the effect of root restriction (potted cultivated) on carbohydrate metabolism in ‘Luoyanghong’ tree peony (Paeonia suffruticosa luoyanghong) leaves. The result showed that root restriction significantly reduced the net photosynthetic rate (P_n), sucrose phosphate synthase (SPS) activity and acid invertase (AI) activity of tree peony leaves. The declined SPS activity and AI activity in tree peony leaves showed that both source and sink strength were inhibited by root restriction. Before anthesis, sucrose and starch levels were significantly lower in root restriction tree peony leaves than that in control. However, from flowering-stage to late-flowering stage, sucrose and starch were accumulated in root restriction tree peony leaves mainly because of the low sink strength which limited the driving force to transport sucrose to sink organ and to hydrolyze starch. Hexose content in root restriction tree peony leaves were lower than the control overall and its change was smooth during anthesis period. The reduced P_n of root restriction tree peony was mainly because of the lower level of sink strength, and the reduction of leaf area and accumulation of carbohydrates in leaves can also explain it to a certain extent.

A Cerasus humilis population arisen from seeds was used to study hierarchical cluster and bivariant correlation analysis by measuring the polymorphism of vegetative growth traits and fruit mineral nutrient absorption. Our objective was to clarify the relationship between wild C. humilis population genetic variation and the mineral nutrient inheritance. The results indicated that wild C. humilis population had abundant genetic variation, especially in shape, size, colour, fresh and dry mass, water content, fruit mature period, and mineral nutrient elements contents of fruits and leaves, and showed significant difference in genetic characteristics and physiological characteristics. The clustering results were divided into two groups, one was small leaf and small fruit, the other was big leaf and big fruit. The two groups showed significant difference in water content of leaves and fruits, fresh and dry mass of fruits, fruit diameter, Ca and K contents of leaves and fruits. Correlation analysis indicated that there was a significant positive linear relationship between mineral nutrient elements of Ca,K,Mg,Zn,Mn except Fe in fruits and the vegetative growth traits indices of leaves and fruits. It was suggested that the vegetative growth traits indices of leaves and fruits of C. humilis, such as shape, size, fresh and dry mass and water content, could characterize the mineral nutrient absorption and metabolism of fruits.

To explore the feasibility of controlling Monochamus alternatus by using entomopathogenic nematodes Steinernema carpocapsae ALL and Heterorhabditis sp. WG, the natural state conditions of M. alternatus were simulated in laboratory, and control effect with the two entomopathogenic nematodes on the larvae of Japanese pine sawyer were determined. The TDM(time-dose-mortality) model of control function of the two nematodes against M. alternatus was established and tested. The results showed that under the doses of 30 000, 40 000, 50 000 and 60 000 mL^-1 for seven days, 41.11%, 51.11%, 53.33% and 82.22% individuals of M. alternatus at the 3rd instars were killed by S.carpocapsae ALL respectively; and 35.56%, 51.11%, 51.11% and 74.44% individuals were killed by H. sp. WG, respectively. The start time of killing M. alternatus at the 3rd instars by H. sp. WG was earlier than that by S.carpocapsae ALL. The peak of daily mean mortality of M. alternatus at the 3rd instars was between the 1st day to 3rd day. The LC₅₀ values of S.carpocapsae ALL between the 1st day and 7th day were calculated by the TDM model and they were 52 888 176, 147 128.61, 25 953.95, 17 915.36, 14 964.30, 12 968.78 and 11 663.99 mL^-1, respectively; and the LC₅₀ values of H. sp. WG of the 1st day to 7th day were 326 212.05, 29 566.51, 14 474.38, 13 934.78, 12 234.89, 10 531.74 and 9 543.33 mL^-1, respectively, and under the doses of 40 000, 50 000 and 60 000 mL^-1, the LT₅₀ of S.carpocapsae ALL was 6.70, 4.97, and 3.98 days, respectively; and under the doses of 50 000 and 60 000 mL^-1, the LT₅₀ of WG was 5.39 and 4.06 days, respectively. It is concluded that the two of nematodes species have a high control effect on the larvae of M. alternatus, which provides a basis for field control of M. alternatus.

To illustrate dynamics of secretion and the peptides patterns of Rana dybowskii, the crude skin secretions were collected at different time when their secretions were released with a mild electrical stimulation. The results showed that the restoring amount of skin secretions increased in a characteristic sigmoid curve during 0-21 days after an electrical stimulation. The HPLC showed that the skin secretions collected at different time had the identical components, however the components restored asynchronously. Two quickly-restored components peaks were tested for their antibacterial activity against Escherichia coli ATCC25922 and Staphylococcus aureus ATCC25923 and showed strong antibacterial activity. The two components were identified by ESI-MS/MS and their amino acid sequences were determined. The results indicated that the recovery rates of skin secretion components in R. dybowskii were asynchronous and the antimicrobial peptides had precedence over other peptides. The immune defense strategy would ensure the survival of frogs in a complex environment.

Volatile organic compounds(VOCs)emitted from building materials can influence indoor air quality. Based on small ventilated chamber, a method for measuring the VOCs emission characteristic parameters(including the mean initial concentration, the partition coefficient)of particle board and the convective mass transfer coefficient was presented. In this paper, parameters estimation of particle board P1 and P2 from Heilongjiang were calculated, and the relationships between the VOCs parameters of the board and temperature were discussed. The testing methods and measurements of the model can be used to guide the selection of building materials and for evaluating the emission characteristics of building materials, evaluating and forecasting indoor air quality.

Treatment of anaerobic effluent from Hengfan wastewater treatment plant in Lin'an with bamboo fiber biofilm carrier contact oxidation reactor was carried out. Effects of hydraulic retention time (HRT) and gas-water ratio on removal efficiencies in terms of chemical oxygen demand (COD_Cr), ammonium nitrogen (NH₄⁺-N), total nitrogen (TN) and total phosphorus (TP) were investigated. Results showed that the biofilm formation and startup of the reactor were finished in 12 days. When the HRT was between 8 h and 15 h, removal efficiency of COD_Cr increased with HRT. However, there were no significant variations in removal of NH₄⁺-N, TN and TP. Gas-water ratio did little effect on COD_Cr removal. The removal efficiencies of NH₄⁺-N and TN decreased from 91.46% and 46.12% to 69.21% and 36.43%, respectively, while that of TP increased from 29.18% to 36.40% with the increase of gas-water ratio. Comparison results of bamboo fiber biofilm carrier contact oxidation reactor and activated sludge aeration pond on COD_Cr removal indicated that the reactor was more efficient in removing COD_Cr and had better shock load tolerance. Thus, it is feasible to innovate the activated sludge aeration pond using the bamboo fiber biofilm contact oxidation reactor.

The mechanical properties of wood-based materials can be improved significantly by the modification of low molecular weight phenol-formaldehyde resin. In this paper, the samples of Chinese fir were treated by low molecular weight phenol-formaldehyde resin, then the cell wall mechanical properties of tracheids of PF treatment and untreated reference samples were tested by the technique of nanoindentation. Compared with untreated reference samples, the increases in the average modules of elasticity of 32.94% and in the average hardness of 32.93% were observed for PF treatment samples. The absorbance of PF treatment samples was higher than the untreated reference samples by the analysis of ultraviolet micro-spectrophotometer. This proves clearly that the low molecular weight phenol-formaldehyde resin was able to diffuse into the nanopores in the S₂ layer of tracheids cell wall of Chinese fir. Thus, the mechanical properties of cell wall could be improved.

Relying on the olfactory mechanism to recognize odors from the host and nonhost plants, the phytophagous insects can behaviorally orientate the host trees rapidly to mitigate the influence from detimental environmental impacts. Various nonhost volatiles may exert to different degrees repellent effects from nonhost habitat, species and unsuitable hosts. In this paper, we reviewed the category and functions of the nonhost volatiles, olfactory recognition by electrophysiological means as well as the behavioral responses of the conifer bark beetles to nonhost volatiles. Furthermore, the direction for research and potential use of nonhost volatiles in conifer bark beetle management in China were put forward.

On an oak forest and grassland in the Tongshan forest farm in Nanjing, 4 sets EM50 were installed to measure the soil volumetric water content with which the Daily Average Soil Volumetric Water Content (DASVWC) was calculated at depths of 5, 15, 30 cm, respectively. Simultaneously air humidity was measured at the height of 2 m. By analyzing the vertical-temporal variable quantity, variations of DASVWC and their correlation with meteorological factors were found to be affected by precipitation, air temperature and humidity and DASVWC. The variation pattern was different from that in the Yellow River watershed, where variability of DASVWC at the 0-5 cm layers was lower than that at the 15 cm and 30 cm soil layers, while variability of DASVWC at the 0-5 cm layers in this study sites was higher than that at the 15 cm and 30 cm soil layers regardless of types of land use. DASVWC at the 0-30 cm soil layers in the oak forest was lower compared with that in the grass land, indicating that DASVWC at the surface soil layer decreased with increase of plant coverage. During rain intervals in different seasons, DASVWC exponentially decreased with time very significantly. The daily decrease in DASVWC showed multifactor linear regression with DASVWC, air temperature, humidity in each period.

Based on the forest inventory data of Huanglong Mountain in 1986, 1997 and 2006, we analyzed the changes of landscape types and landscape structure. The landscape was changed greatly during the 20 years. The area of forested land continuously was increased, while the shrub land and wasteland were gradually decreased. The area of the cultivated land and immature forest land increased from 1986 to 1997, while decreased from 1997 to 2006. Changes in Cupressus forest land and nursery land, which accounted for only a small part of the entire landscape, were not significant. At the landscape level, the area of hard broad-leaved forests and coniferous forests was increased by 40% from 1986 to 2006. The area of Cupressus forest land remained unchanged at approximate 2 000 hm² during the two periods, while the area of soft broad-leaved forest land continuously decreased. Moreover, the age-class structure of the major species significantly varied. The hard broad-leaved forests and coniferous forests merged with a block which had the largest patch index and was much greater than that of the other landscape types in each period. The landscape diversity decreased, while the landscape heterogeneity, fragmentation and dominance increased. The patch types tended to distribute in reunion state.

Immature seeds during developmental period and dormant seeds during cold stratification were used to investigate the changes in germination ability and endogenous abscisic acid (ABA) content of Acer mono seeds. The results showed that the seeds of A. mono finished the nutrient accumulation and entered into rapid dehydration stage from 100 d after flowering. Germination ability and endogenous ABA content of A. mono seeds increased with the decrease of the seed moisture content. The seed germination percentage was just 32.7% at 120 d after flowering (fructify stage) but increased to 75.0% after 80 days of cold stratification. The ABA content of A. mono seeds decreased significantly with the prolongation of cold stratification. The present study suggested that the dormancy of A. mono seeds is strongly dependent on the ABA levels. The synthesis of ABA in A. mono seeds decreased and seed germination ability enhanced after cold stratification.

Guisang 12, a variety of mulberry (Morus alba), was used to study the effects of different levels of water hardening on physiological characteristics of the mulberry seedlings in the hydro-fluctuation belt of the Three Gorges Reservoir Area. The seedlings were subjected to different water regimes for 30 days. The results showed that: the chlorophyll content of mulberry seedlings was increased by 10.4% under the drought hardening (DH) condition than that of CK, while decreased by 3.2% under the waterlogging hardening (WH) condition than that of CK. With the soil moisture content reducing, the stomatal conductance (G_s) and transpiration rate (Tr) of mulberry seedlings both declined remarkably; The photosynthetic rate (P_n) of mulberry seedlings under the drought hardening and waterlogging hardening conditions was all higher than that of CK, and the intercellular CO₂ concentration (C_i) under the two conditions was lower than that of CK; The instantaneous water use efficiency of mulberry seedlings under the drought hardening and waterlogging hardening conditions was remarkably increased by 57% and 27% than that of CK, respectively, and the abscisic acid (ABA) content in the two conditions were remarkably increased by 79% and 29% than that of CK, respectively.

The results and characteristics of water potential measurements with four different methods, namely the Chardakov method, Pressure chamber, in situ hygrometry and leaf disc hygrometry were compared on several plants species. Experimental results showed that the former 3 methods produced similar results, but the leaf disc hygrometry yielded significant different results from the other 3 methods. Further investigation showed that the results with the leaf disc hygrometry varied considerably with the equilibrium time and was not able to show the actual water potentials of the plants. The Chardakov method was time-consuming, and its efficiency was very low. Pressure chamber was able to provide accurate and reliable measurements of plant water potentials if the sample water loss could be avoided and the repetitious samples were available. While the in situ hygrometry showed the merits such as more reliable results, non-destructive to plants, no harsh prerequisites for plants and could measure the same spot of a plant continuously.

An entomopathogenic fungal strain isolated from infected Melanotus cribricollis larvae was identified as Metarhizium pingshaense by both morphological and molecular methods. The 5' end of EF- 1 α of the isolate was sequenced, and submitted to GenBank with accession number JQ081264. Study on biological characteristics of the isolate showed that the optimum culture medium was PPDA. The range of optimum temperature for mycelium growth and conidia germination was from 25 ℃ to 30 ℃, respectively and the optimum temperature for conidia production was 25 ℃. The most suitable pH for conidia germination was 7.0. Conidia germination of this isolate could be obviously inhibited by ultraviolet radiation for less than 30 minutes.

With Pajek, a program for analysis and visualization of large networks, topologies of plant-insect pollinator interaction networks were constructed at the different taxa levels, and the change in patterns of interaction networks was studied. The results showed that patterns were different at the different taxa levels. The frequency distributions of species degree for insect pollinators and flowering plants were right-skewed at the species level. The insect pollinators and flowering plants with more than 1 links accounted for high proportion, with only a few species higher links, and the mean species degree for plants was higher than that of insect pollinator in plant-insect pollinator interaction networks in subalpine meadows. There was obvious lack of super generalized species indicating that phenological or morphologic mismatching between plant and insect pollinator forbad links between them. The frequency distributions of species degree for insect pollinators at the order level were different from that at the species level, however, generalized insect orders were also dominant. It is thus clear that studies on network patterns at the different levels would contribute to uncovering organization mechanism of pollination networks, and understanding that conservation on keystone insect pollinators or flowering plants with higher links is vital to maintain pollination system in subalpine meadows in Changbai Mountain.

Mongolian oak wood were thermally treated in atmospheric steam or 0.35 MPa pressurized steam. Chemical component changes of the treated samples were investigated by means of wet chemical analysis, elemental analysis and FTIR analysis. The results showed that, along with higher lignin and extractive contents, samples treated in pressurized steam exhibited lower holocellulose and moisture content compared with those treated in atmospheric steam. The analyses also suggested greater chemical structure changes in pressurized-steam-treated samples. Meanwhile, it could be determined that thermal degradation of both samples was modest at the treatment temperature of 185 ℃. These findings help explain the better dimensional stability and limited strength deterioration of wood treated in pressurized steam.

The physical and mechanical properties of wood were analyzed for 4 Larix species (Larix kaempferi, L. gmelinii, L. olgensis, and L. principis-rupprechtii) and 3 hybrids (L. kaempferi×L. gmelinii, L. kaempferi×L. principis-rupprechtii, and L. kaempferi×L. olgensis), and the differences were evaluated comprehensively using the membership function based on Fuzzy mathematics. The results showed that the timber of Larix spp. had significant heartwood ratio and great air-dried density as 0.634 g·cm^-3 in average. The dry shrinkage of the wood was relatively high with average radial and tangential shrinkage as 4.52% and 8.93%, respectively. However, the wettability of the wood was poor, showing the average contact angle in radial and tangential directions as 57.70° and 59.14°, respectively, which indicated the favorable natural decay resistance to water. The timber also showed fine mechanical properties with average modulus of elasticity (MOE), modulus of rapture (MOR), tensile strength parallel to grain, crushing strength, and cleavage strength as 15.36 GPa, 120.07 MPa, 134.25 MPa, 46.30 kJ·m^-2, and 9.93 N·mm^-1, respectively. Significant differences were found among species or hybrids in the properties of tree height, heartwood width, average ring width, wood radial contact angle, dry shrinkage, radial air-dried shrinkage, tangential-to-radial dry shrinkage ratio, MOE, and MOR. Generally, the 3 hybrids showed great improvement in growth and timber properties when compared with the male parents. As a result, the comprehensive evaluation based on the properties above indicated that the female parent of L. kaempferi and the 3 hybrids were more suitable to be selected as structural or non-structural timber tree species than the 3 native male parents.

The poplar variety ‘purui’ was naturally selected from a fast-growing and high-yield plantation of Populus×euramericana cv. ‘74/76’. In addition to ordinary 107 variety's growth habit, the variety still has the characteristics of resistance to sulfur dioxide toxic gases. It is suitable for growing in north China, the south of Yangtze River, an acid rain region, and the sulfur dioxide pollution areas.