The energy variation pattern in the fine roots turnover process of Pinus tabulaeformis and Quercus aliena var. acuteserrata natural forests in Qinling mountains were studied systematically. The results showed that the energy loss was followed by an attenuation index pattern in the process of fine root decomposition. The decomposition coefficient of Quercus aliena var. acuteserrata forest was 0.0031 and its turnover rate was 0.35 time·a^-1. The decomposition coefficient of Pinus tabulaeformis forest was 0.0024 and its turnover rate was 0.48 time·a^-1. The average annual storage energy in living fine roots of Pinus tabulaeformis forest was 119.43×10⁶ kJ·hm^-2 and the average annual energy loss in dead fine roots was 21.84×10⁶ kJ·hm^-2 which was 31.7% of litter energy loss. Similarly, the average annual storage energy in living fine roots of Quercus aliena var.Acuteserrata forest was 172.70×10⁶ kJ·hm^-2 and the average annual energy loss in dead fine roots was 58.31×10⁶ kJ·hm^-2 which was 62.8% of litter energy loss.

The urban forest structure of Hefei, the capital city of Anhui Province, was investigated using sample method in the paper. The results showed that in the study area of 23 km² in the city there are 350 thousand trees and totally 31741 t for biomass. Based on biomass or basal area, the trees were equivalent to 497 hm² forestland. Meanwhile the species composition, DBH classes, health condition, biomass and leaf area of the tree community for different land uses were analyzed. In the urban forest of Hefei city, 10 top species occupied almost 80% of tree individuals; almost 50 percent of trees were classified as small tree (DBH<10 cm); most of trees (84%) had good or medium health level. For this situation, the study area had about 21%～22% of forest land cover and needed to increase 16～20 hm² of forest land at least to get 30% of forest land cover. The tree community in the study area could remove CO₂ of 12483 t from atmosphere each year.

Based on the data collected by located observation, the biomass and productivity of the second generation of Chinese fir plantation at fast growing stage was studied. At the same time, a comparison of biomass and productivity between the first generation and the second of successive rotation was made. The results showed that biomass of tree and stands in the first and second rotation Chinese fir plantation were 37.54, 34.74kg and 85.6,71.45 t·hm^-2, decreased by 8.52% and 16.53% respectively. The total biomass of the ecosystem in the first and second rotation account for 87.93 and 76.02 t·hm^-2, of which trees occupied a large portion. The biomass of shrub, herb and litter in the second rotation was 2 times of that in the first rotation. The first rotation Chinese fir had a stronger competition for underground and higher biomass accumulation in stem, while the second had stronger competition for above ground and lower biomass in stem. Productivity of the second rotation Chinese fir plantation was 6.49 t·hm^-2a^-1, and lower than that of the first rotation (7.78 t·hm^-2a^-1). However, the leaves in the second rotation had higher photosynthesis productivity. This case confirmed that there was potential improvement in productivity in the second rotation Chinese fir plantation.

Studying the effects of land use change on soil organic carbon(SOC) by means of soil physical fractionation may help to understand the stability of SOC. According to 25 years historic data of land use in the Guyuan region of Ningxia, China, the land use type were classified into natural secondary forests dominated by Quercus liaotungensis or Populus davidiana, brushwood, 13,18,25-year-lod larch ( Larix principis-rupprechtii) plantation, rangeland and cropland. The SOC content and its fraction in soil physical fractionation (light-fraction organic matter(LF-OM) and particulate organic matter (POM)) and unprotected soil organic carbon pool in 0～110 cm depth of soil for these land uses were investigated. It was found that the proportion of SOC in LF-OM was lower in natural secondary forests than other land use ways, i.e., larch plantation, rangeland and cropland. The differences among plantations, rangeland and cropland were not significant. The SOC content in LF-OM in cropland and rangeland was 46% and 14% respectively lower than natural secondary forest, and those for plantations were over doubled and 27% higher respectively than cropland and rangeland. The proportion of SOC in POM was higher in plantations and cropland than the natural secondary forests, but these for rangeland is near the natural secondary forests. The SOC content in POM for cropland and rangeland were 38% and 25% respectively lower than natural secondary forests, and those for plantations were 79% and 47% respectively greater than cropland and rangeland. The proportion of SOC in unprotected SOC pool was lower for natural forests than cropland and plantations. The stability of SOC can been showed by analyzing SOC fraction in soil physical fractionation and unprotected soil organic carbon,while SOC content in this fractionation can indicate content of unstable SOC. The comparison of the SOC content and its fraction in soil physical fractionation and unprotected soil organic carbon pool infer that conversion of natural forests into cropland or afforestion in rangeland would cause the destabilization of SOC, while afforestion in cropland or conversion of natural forests into rangeland would have no obvious impacts on the stabilization of SOC.Land use change has obvious impacts on the SOC content and its fraction in soil physical fractionation of unprotected SOC pool in 0～50 cm soil depth.These SOC content and its fraction in soil physical fractionation of unprotected pool decreased with increased soil depth for different land uses and there is significant difference for them among different groups of soil layers of surface soil layer (0～10 cm), soil layers with rich roots, soil layers with few roots and bottom soil (below 90 cm),but there is no significant differences for them within in same soil layers.

The spatial distribution characteristics of apple tree fine roots in the apple-wheat intercropping were analyzed in order to provide the basic documents for constructing the model of water uptake by roots and analyzing the water ecological characteristics of the inter cropping in the hilly area of Taihang Mountain. The main results showed that : vertically, the fine roots concentrated at the 0～80 cm soil zone where the amount of the fine roots accounted for 94.33% of the total; horizontally, the amount of the fine root in the wheat zone and the tree land accounted for 60 29% and 39.71% of the total respectively;the regression function between the fine roots density(RD:cm·cm^-3) , the soil depth (Z:cm) and the distance from the tree row (X:cm)was the following: RD=- 6.617×10^-9Z⁴+1.8149×10^-6Z³-1.7526×10^-4Z²+4.9418×10^-3Z-5.83×10^-7X²+ -2.16×10^-5X+1.1299ZX+0.06359,r=0.8647.

Camptotheca acuminata was an important medicinal tree as its camptothecin with anti-tumor activity. The diurnal changes of net photosynthesis rate (Pn) in leaves of C. acuminata under natural condition were studied in this paper by CI-301 CO₂ analyzer. The results showed that the curve of diurnal variation of Pn was demonstrated two peaks in clear day, which appeared at 10:00 and 16:00 respectively. The first peak value was 7.9075 μmol CO₂·m^-2s^-1 and the second one was 3.7340 μmol CO₂·m^-2s^-1. There was a clear depression at noon, which was 2.4470 μmol CO₂·m^-2s^-1 appeared at 14:00. Only one peak had the curve of Pn in cloudy day, which occurred at 12:00 Daily average Pn in clear day was 4.3300 μmol CO₂·m^-2s^-1, and that of cloudy was 3.7500 μmol CO₂·m^-2s^-1 Photon flux density (PFD) and relative humidity played very important roles in Pn changes among the ecological factors. Depression of Pn was not caused by the decreasing of stomatal conductance that would decrease the CO₂ supply. Factly it was regulated by nostomatal factors.

Phenolic glycosides were main defense chemicals for Salicaceae. The variation of phenolic glycosides in leaves, height and diameter for all individuals of a whole Populus deltoides back cross population was studied. The result indicated that salicin, salicortin, deltoidin, height and diameter all followed normal distribution, so these traits displayed in quantitative fashion. The concentration of total phenolic glycosides showed negative correlation with height and the correlation coefficient was r=-0 304. Tremulacin was discovered for the first time in P.deltoides. The plant defenses were at the cost of growth only in some degree. The individuals with high phenolic glycosides concentration and higher height could be selected from the population. Mechanical wounding on the stem bark induced significant increases in concentrations of phenolic glycosides, especially for salicortin, and the increase was 78.9% within 48h. The increase of phenolic glycosides under wounding was the main mechanism for poplar resistance to animal, insects as well as pathogenic bacteria.

Eucalyptus urophylla MLA clone(MLA) was difficult-to-root clone. E.urophylla U₆ clone(U₆) and E. ABL No.12 W₅ clone(W₅) were relatively easy-to-root clones. After the cuttings of MLA, U₆ and W₅ were treated with indoleacetic acid(IAA), indolebutyric acid(IBA), and nathphylacetic acid(NAA), the activities of peroxidase (POD), polyphenol oxidase(PPO) and indoleacetic acid oxidase(IAAO) increased regularly. The differences of enzyme activities in different stages of rooting were very significant. It was indicated that the origin and development of adventitious roots in Eucalyptus were relative to POD,PPO, and IAAO. The differences of the promoting efficiency of IAA, IBA, and NAA to different clones and different oxidase activities were significant or very significant. The mechanism of promoting oxidase activities and promoting rooting of Eucalyptus cuttings by auxins was discussed.

This paper dealts with the appropriate trials and optimum age for early selection of clone in Chinese fir(Cunninghamia lanceolata Hook) .The estimated parameters of early selection were based on tree heightand diameters at brast height (D.B.H) of four clonal trials, which included 107 clones.The height of trees was measured at 2～6、8～9、13～15 a; D.B.H was measured at 4～6、8～9、13～15 a after planting. The last investigation was carried out in 1999, for trial 8401 and 8402 was 15 year old, but 8501 and 8502 was 14-year-old. The correlation matrix of age-age genetic and phenotype for height and D.B.H of clones was analyzed. It was calculated that genetic variance accounted for percent of total variance.The average heritabilities and coefficient of genetic variance for every clone were also calculated. The results showed that clonal selection or elimination of clone in Chinese fir might be carried out at early age.Comparing the results of selection at 2～3 a,5～6 a、8～9 a,13～14 a for four trial forests,it was euggested that the clonal selection should not be carried out at 2～3 a,the first selection should be at 4～6 a、the second selection at 8～9 a.If the selection age was earlier,the wrong and lack was more.For the selected clone at 8～9 a,the actual gain of hieght,D.B.H and volume was 17.87%,23.48% and 64.50%,respectively;the genetic gain of height,D.B.H and volume was 15.19%,20.41% and 55.47%,respectively.

Genetic diversity of 15 populations from whole natural range of L.chinense was analyzed by using RAPD markers.It was found that L.chinense had a relatively high genetic diversity,but genetic diversity of the eastern populations was obviously less than that of the western because the eastern population had a small population size.Population genetics revealed that the small population effect,for lack of gene flow and special endangering mechanism resulted in a high genetic differentiation within populations which amounted to 34.34% of the genetic variation.Genetic differentiation among populations varied with geographic regions.Neighboring populations at eastern region showed large genetic differentiation,comparing with the western populations.The whole natural distribution range of L.chinense might be divided obviously into the western and the eastern provenance zone,the former could be further subdivided into Southwest and Center China subzone by cluster analysis(UPGMA) based on Nei's unbiased genetic distance.

Based on the Liriodendron interspecies hybridization study by professor Ye Peizhong,according to the satisfying and exact mating system and field design,the reciprocal cross with extensive genetic background of Liriodendron tulipifera Linn., the backcross and F₁ crossing which had never been made, and the genetic analysis of heterosis of the hybrid tulip tree were carried out.The results are as follows:(1)One-year-old hybrid seedlings of plus crossing,minus crossing,BC₁ and F₂ universally showed notable positive growth heterosis.Growth characters of the seedlings had extremely significant difference among families and expressed great variation among individuals of family.Growth performance of BC₁ families was particularly excellent.Thus family selection,individual selection and utilization of BC₁ and F₂ hybrids had tremendous potential.(2)The paper preliminarily put forth the photosynthetic superiority hypothesis regarding as the theoretical explanation of heterotic mechanism of the hybrid tulip tree and other forest-tree hybrids.(3)Some important genetic parameters were calculated simply.

In this paper,the determination of flavone (Quercetin,Kaempferol and Isorhametin),lactone (Ginkgolides and Bilobalide) contents in leaves collected from two year old seedling of 28 open pollinated families grown in 7 origins and 30 individuals within three families which came from the whole native range of Ginkgo biloba was carried out.These results showed that the differences of all the flavone and lactone compounds exhibited both among origins (populations),among families within a origin(population),more over,the differences among genotypes within a families appeared more significant than those among families within location.Negative relationship between flavones content and lactones content was observed,which was not at significant level.The concents both Ginkgolides and Bilobalide in leaves collected from two year old trees was similar to 16-year-old trees.All information obtained in this study provided basis for genetic improvement strategy of Ginkgo biloba and intensive management of plantation for medicinal production.

With biological inoculation technology, experiment was conducted in pot cultures to study the effect of dual inoculation of Rhizobium and mycorrhizal fungi. The result showed the stimulation on the growth of the host plant of mycorrhizae or Rhizobium and the more obviously improved effects on the growth of Robinia pseudoacacia than the treatment inoculated singly by VAM or Ectomycorrhiza. It also showed the corelation of Rhizobium and mycorrhizae. The best treatment of better growth of plant was inoculating VAR+ Rhizobium (336)+ H.mesophaseum (870191).

Brown spot needle blight of pine was an important disease in South China, which was caused by Lecanosticta acicola. The pathogen could produce two kinds of toxin, LA-Ⅰand LA-Ⅱ. The toxin activities and basic properties of LA-Ⅰand LA-Ⅱ were studied in the way of bioassay. The results indicated that LA-Ⅰand LA-Ⅱ could not only injure the seedlings of host pine (Pinus elliottii,P.taeda) but also make the seedlings of other plants (P.yunnanensis,P.armandii and Eupatorium sp.) wilt. So both of the two toxins were non host specific toxins(NHST). LA-Ⅰand LA-Ⅱ could keep their toxic activities for 15 minutes after boiling. The minimal effective concentrations of LA-Ⅰand LA-Ⅱ were 100?μg·mL and 500 μg·mL respectively and their activities were not very strong.LA-Ⅰand LA-Ⅱ could not affect their activities each other when they were mixed.

Inoculations revealed that the Chinese isolates of Sphaeropsis sapinea were similar to American A isolates in pathogenicity which was much nore aggressive than B isolates.Type B isolates could also penetrate host without wounding,but with lower incidence than type A.During the periods of shoot elongation and needle development the fungus could directly enter the current year shoots and eventually kill them,then with shoot maturation,the role of wounding was gradually shown up,and inoculations of nonwounded shoots resulted in no symptoms or only some necrotic needles.The fungus could also enter needles through stomata.It could infect and kill twigs through wounds on the 2^nd or the 3^rd year node.Pinus tabulaeformis,P.densiflora and P.densiflora var.zhangwuensis were more disease resistant than Pinus sylvestris var.mongolica,and P.densiflora var.Zhangwuensis showing a sort of disease tolerance.Young trees of Pinus sylvestris var.mongolica were more disease resistant than old ones.After inoculation shoots weakened by girdling showed symptoms more rapidly and severely than non weakened ones.The durations of incubation and reproduction were related to host species,tree vigor,maturity of host tissue, and air temperature,etc.

Dendroctonus valens LeConte is a new recorded species in China. It is devastating and highly dangerous to the stands of Pinus tabulaeformis, and it can cause the ten year old trees to die in a short time. The pest overwinters mainly as adult or mature larvae (77.5%), others as 2 to 3 instar larvae (21.7%), and a few as pupa (0.8%). When the population density is low, the pest mainly harms the weak firedtrees, newfelled trees, and the new stumps. When the population density is high, the pest can quickly attack the healthy trees with breast height diameter over 10cm and over 20 years old. The damaging situation in low canopy density forests is higher than that in the high canopy density forests.

The activities of enzymes of protective system of the larvae and diapausing prepupa of sawfly Chinolyda flagellicornis were determined by the testing boxes of protective enzymes.The results showed that there was a positive correlation between the activities of protective enzyme SOD,CAT and the instars,while that there was a negative correlation between POD activities and the instars. Compared with the larva,the activities of the three protective enzymes reduced sharply in the diapausing prepupa. The activities of POD,SOD and CAT were closely correlated with the temperature. The activities of all three protective enzymes in male were obviously higher than that in the female prepupa, but there was no difference in the dynamics of them.

The development of Oligonychus ununguis feeding on the leaves of Castanea mollissima BL.,Quercus acutissima Carr., Quercus variabilis BL.and Quercus dentata Thunb. was observed through leaf disk rearing method and the content of some chemicals in these leaves were determined. Results showed that, compared with the spruce spider mites feeding on the leaves of Castanea mollissima, Quercus acutissima and Quercus variabilis, the mites feeding on the leaves of Quercus dentata had the longest developmental periods, the shortest life span of adult females and the least ovipositional quantity. There were no significant differences among the development of the mites feeding on the leaves of Castanea mollissima, Quercus acutissima and Quercus variabilis. But the period of larvae feeding on the leaves of Castanea mollissima was short. Of these four plant species, Quercus acutissima, Quercus variabilis, Castanea mollissima and Quercus dentata, the content of free amino-acids, total nitrogen, total soluble sugar in the leaves of Quercus dentata was the lowest, tannin content was the highest. In the leaves injured by Oligonychus ununguis, the content of total free amino-acids, total nitrogen decreased and the content of soluble sugar, crude fat and tannin increased.

Gas flows through the passages that consist of various pores inside wood. The structure of the pores is complex and changeful, and the connections between the pores are different in the longitudinal, radial and tangential directions. The existing models for gas permeability of softwoods only considered the connection of the pores in one direction of wood grain or two directions. In this paper, a three-dimensional flow-resistor network was constructed according to the connection of the pores in longitudinal, radial and tangential directions. The flow-resistor network could be used to describe the mechanism of gas flow in the longitudinal direction. The equivalent flow-resistor of the flow-resistor network was work out by means of the real space renormalization approach, and the evaluation of the gas permeability of softwood could be evaluated from the equivalent flow-resistor. The calculated values of the longitudinal gas permeability of Masson pine(Pinus massoniana) was compaered with the corresponding measured values. There is a close agreement between the calculation and the measurement. It shows the validity of the theory on three-dimensional flow-resistor network.

The characteristics of sub- and supercritical extraction of wood with ethanol or ethanol-water were studied in a semi-continuous experimental apparatus using the non-isothermal dynamic extraction technique,the effects of pressure and water on the sub- and supercritical extraction of wood with ethanol were mainly investigated.The results showed that the main extraction process of wood could be classified as two phases roughly,the temperature range in the first phase was from 200℃ to 280℃,and the extract formation rate had the maximum value at about 250℃.The temperature range in the second phase was from 280℃ to 380℃,and the extract formation rate had the maximum value at about 350℃,a great quantity of gas was generated in this phase simultaneously.Wood conversion and extract yield increased and gas yield decreased with the increasing of pressure and the molar fraction of water in ethanol-water mixture.The effect of pressure mainly reflected after 250℃,and the effect of water mainly reflected before 300℃.From an engineering standpoint,the sub- and supercritical extraction technology could be suited to the different conversion ways of wood resources through regulating and controlling process variables such as temperature,pressure and the molar fraction of water in ethanol-water mixture.

The trial stand of 2 m×2 m spacing for slash pine was founded on yellow-red soil in 1991.Eleven sorts of fertilization treatments were designed in forms of randomized blocks in this trial.Fertilizes of nitrogen (N),potassium (K) and phosphorous (P) were successively done in this stand in 1992 and 1994.Effects of fertilization on tree growth increments and wood physical mechanic properties of young slash pine were studied in March of 1998.Variance analyses showed that there were significant effects of fertilization on tree growth of slash pine and latewood percent,wood basic density and compression parallel to the grain of wood (CP),modulus of elasticity (MOE) and modulus of rupture (MOR) for slash pine.Nitrogen fertilize made trees in the stand grow slowly and had a distinct negative effects on tree growth of slash pine.Volume of trees fertilized with K was smaller than that of unfertilized trees.Fertilize of P,fertilizes of P combined with N or K and Combined fertilizes of N-P-K were very clearly helpful to increase tree growth of slash pine.Significant differences in shrinkage percent of tangential,radial,axial (AL),volume of wood at air dried condition and ratio (T/R) of tangential to radial shrinkage were not found among eleven treatments at 0 05 level.But the AL and T/R of wood from trees fertilized with P,N-P were smaller than those from unfertilized trees and AL of wood from trees treated with only nitrogenous or potash fertilizer were than that unfertilized trees.P fertilizer,N-P fertilizers,N-K fertilizer and combined fertilizers of N-P-K enhanced distinctly latewood percent,basic density,CP,MOR and MOE compared with the physical mechanical properties of wood from unfertilized trees in trail stand of slash pine.Increasing percents of wood properties above were positively correlated with the amount of P fertilizer treated per hm². Growth increments of tree height,diameter at breast height and tree volume in stands treated with fertilizers were positively related with latewood percent,wood basic density,CP,MOR and MOE,respectively.Latewood percent and wood basic density were separately correlated with CP,MOR and MOE in all treated trees.In trial stand of slash pine,wood physical mechanic properties from dominated trees were best compared with those from suppressed trees and intermediate trees.Wood properties from intermediate trees were better than those from suppressed trees in the stand.

By tracking test on the different density particleboard made of Populus ussuriensis and Larix gmelini,and the different thickness wood of Populus ussuriensis and Larix gmelini, this paper showed the thickness swelling equation of particleboard and wood are quite the same and coincide rather well with the theoretical deduction, that is TS(t)=a - be^-t/τ.It can be concluded that the equation of visco-elastic deformation and that of deformation from bonding breaking are the same mathematically. The equation of mechano-sorption creep will have uniform approximate expression by progression transforming. The paper also proved that describing dimensional stability of particleboard with thickness swelling equation would be more reasonable and practical, for it give the information such as the maximal TS and the velocity of thickness swelling.

Tree architecture has been recognized to be the consequence of interactions between a tree's blue print or genotype,its environment and its developmental history.In tropical trees and many temperate zone trees,tree architecture includes two contrasting branching types,sylleptic and proleptic branches.Sylleptic branches develop from lateral buds of the main stem without an intervening period of dormancy,whereas proleptic branches develop from lateral buds of the main stem with an intervening period of dormancy.Although these two branch types can occur in the same tree,they normally display marked discrepancies in morphogensis and the extent to which they phenotypically respond to environmental changes.It has been recognized that the phenotypic plasticity of sylleptic branching plays an important role in determining tree growth, architecture and adaptation for many temperate zone woody plants.In this article,we further examine control mechanisms for the phenotypic plasticity of sylleptic branches at the environmental,developmental and genetic levels.

The density effect of rare and endangered Tsuga longibracteata population was analyzed by the theoretical model describing the whole density change process of plant population, i.e.N=exp(aln²S+blnS+c), where N and S represent population density and mean basal area of T.longibracteata at breast height respectively, and a, b, c are parameters. Then, the authors proposed a density effect model considering the effect of different site and associated species on density regulation of T.longibracteata,which was described as N=exp(-0.42426H^0.55323ln²S-5.60238H^0.25191lnS-6.75209H^0.10815)+exp(0.20437ln²S'-0.095858lnS′-0.14548), where H and S′represented mean height of dominant trees and mean basal area of associated species at breast height. The simulated result showed that the model fitted well observed data from T. longibracteata population. Therefore it is very useful in practice, which will provide a scientific basis for density management of T. longibracteata population.

Human disturbance is one of the key concepts in ecological study. In this paper, human disturbances in the Songshan National Level Nature Reserve were distinguished into three types:the dot form, the line form and the patch form. The influences of different types of human disturbances on the deciduous broadleaved forests and Pinus tabulaeformis forest, which were the conservation objects in Songshan National Level Natural Reserve, were investigated. The dot form disturbance occured near the hostels,hotels and administrative buildings in the reserve. It was caused by strong trampling and characterized by strong intensity and small areas of damages. The vegetation had changed thoroughly into pioneer communities dominated by some androphiles. These places become the source of the androphiles to invade the other part of the reserve. The line form disturbance occured along the roads and trails. The construction of the roads had changed the vegetation into pioneer communities in a range of 3 m outside of the roads. The human disturbance near the trails for tourism had a range of effect up to 1～2 m. A negative effect on the regeneration of Pinus tabulaeformis forest at the roadside as well as the number of species and the coverage in the shrub layer had been demonstrated. But a positive effect occured in the herbaceous layer, which was probably due to the diversification of the habitat caused by boundary effect.The patch form disturbance was referred to the cut of the forests by the residents of a village inside of the reserve. The Quercus mongolica forest was damaged and changed into shrublands under this type of disturbance. Although the cutting activities had been forbidden, the existence of the village inside of the reserve had other negative effects to the management of the reserve. Strategies for decreasing the negative effects of human disturbance in Songshan National Natural Reserve, as well as those for a real ecotourism were also discussed.

The flower-meristem-identity gene LEAFY is a developmental switch,sufficient for flower initiation in diverse plants.Ginkgo biloba is a kind of gymnosperm,and a dioecious tree species.The nucleotide DNA sequence was cloned from the genomic DNA of the tender leaves collected from a male tree in Ginkgo biloba L.cv.Dafushou.The analysis of DNA sequence structure indicated that the gene was composed of 3450 bp,and inferred the sequence to LEAFY gene of the male Ginkgo.Comparing the gene with LEAFY gene of the female Ginkgo reported in the relative references,the rate of homology was 99%,only lacking 3 nucleotides.The research work laid a sound foundation for studing the regulation and controlling flowering mechanism in Ginkgo biloba L.at the molecuar level in the future.

Fire numbers, burned areas and return intervals in each large scale forest type with average patch area of 500 km² in Heilongjiang Province during the period of 1980 to 1999 were obtained by overlapping the ignition points and areas of 1482 forest fires with the Province's forest type maps in the same period by means of GIS software ARC/INFO. Analysis on the data indicated that the effects of the forest types on fire occurrence and burned areas in the Province were not significant, thus it was not necessary to take forest types into consideration when forest fire hazard was rated on a large scale. Years long human fire suppression activities increased fire return intervals in the region. Comparison was also made on the effects of forest types on fires at various scales.

Poplar lumber (Populus ussuriensis) is impregnated with low molecular weight PF resin, then it is heated and compressed so that the resin is fixed in wood. The wood is called surface compressive wood. This paper measured the index of physical mechanical properties. The result show that the average density of untreated wood is 415kg·m^-3, with the increase of compression set, the density went up clearly. From surface to inner the density is decrease gradually. With the increase of compression set , the compression strength of parallel to grain, bending strength, modulus of elasticity and surface hardness is raised obviously. The color of wood is slightly varied to yellow.