Haploid plants obtained by the in vitro anther culture were planted in the experimental plot.The anthers were collected from a hybrid between Populus simonii,P.nigra and P.berolinensis Dippel.After planting the number of chromosome of the haploid plant was examined under microscope for four times within 8 years.It was revealed that the plants had gradually changed their tissues into those dominated quantitatively by diploid cells from chimera dominated by haploid cells. The number of chromosome was doubled at the age of 7—8 years and the plants became completely diploid ones.

Laboratory tests were conducted to evaluate the toxicity of Diflube nzuron to pine caterpillars (Dendrolimus tabulaeformis) and (Dendrolimus spectabilis).Symptoms of poisoning and amount of food taking by the larvae were observed,also the effects on the natural enemies of the pine caterpillar were recorded.The acute oral LC₍₅₀₎ of Diflubenzuron to the 4th and 5th instar larvae is about 2—9ppm.The chief effect of the toxicant is the disruption of the molting process.Effected larvae are normal in food taking in the first 4 days,but the amount of food taken is greatly reduced after the 4th day.The effect of Diflubenzuron to two species of natural enemies of pine caterpillar-Corcelia rasella Boranoff (Tachinidae) and Casinaria nigripes Gravenhorst(Ichneumonidae) is slight.

Outbreaks of the pine caterpillar (Dendrolimus punctatus Walker) of Qinzhou County in Guangxi autonomous region are analysed by means of the double selection stepwise regression method. The density of pine caterpillars and the percentage of infected trees in two months are considered as dependent variables and eighteen factors,for example,the original insect density and the percentage of infected trees,various meteorological factors,seasonal month,control or not,interaction between control and R.H.and others are considered as independent variables.Four critical values are employed for selection,it is found that eliminated independent variables increase with the increase of F_x,thus the reserved independent variables are more important.The results show that the original status of pest population is the most important factor,while the man-made interference (i.e.control or not and interaction between control and R.H.)is another factor of importance.Among various meteorological factors,the sunshine-hour is considered as an important factor and the seasonal month factor should not be neglected. We realize that to forcast the average of pest population density in a larger area is inpossible of accuracy,its meaning is insignificant.It's more reasonable to forcast the infected areas and their respective pest density by our suggested method.

During September 1981,August 1982,and September 1983 to January 1984,a study was made concerning the beavers' architecture and their habit of inhabitation in Buergen River area Xinjiang Wei-wu-er Autonomus Region. The beavers' architecture which consists of burrows,lodges,burrowlodges,dams,canals,and stockpiles is just like those in Europe and North America. The beavers have three kinds of habit of inhabitation.They live in burrows,in lodges or in burrow-lodges.The burrows tend to be situated in high form of bank along the shores.The lodges are usually built at the shallow water zone or in low forest-land of bank along the shores.The burrow-lodges seem to be situated in middle form of bank along the shores.The most of them live in burrows.Only a few in lodges.The others in burrows-lodges. It is the adapting main manner for beavers to build dams for keeping the suitatble water environment.We do find that the beavers can build dams and lodges for inhabitation It's important to protect beavers' water environment of forest and their burrows,lodges,burrow-lodges,dams and canals,so that we can get good effect of preservation of the precious beavers.

According to the principle that equivalent amount of acetic acid is released when the bound acids in wood reacted with aqueous sodium acetate,the content of soluable acids and that of bound acids was determined separately from various parts of 8 species of wood.The effect of different drying conditions on wood acid content was tested,as well as the effect of different acid content on the gelating time of Urea-Formaldehyde resin.The conclusion are as follows:1.The content of bound acids is higher than that of soluable acids.2.Considerable differences exist between the acid content from sapwoods and that from heartwoods.3. The acid content of oven-dried wood is higher than that of air-dried wood,the gelating time of oven-dried Wood-Urea-Formaldehyde resin is lower than that of air-dried wood.4.There is a very close correlation between the bound acid content and the gelating time of Urea-Formaldehyde resin.

The variation of wood structure in normal growth rings and false rings as well as the structure outwards from the pith to bark are investigated with four trees of Cunninghamia lanceolata at different age stages. The width of growth rings become gradually narrow with the increase of the tree-age after about ten years. False rings mainly appear in the wide growth rings near the pith,the number of which may be 1—3.It might be due to changes of temperature and moisture in the growing season.False ring always locates in the transition region from early to late wood within the growth ring.The sizes of wood elements in false ring are in the range of non-false rings. In normal growth rings,the average length of tracheids in late wood is 21% longer than that in early wood,the thickness of tangential cell wall of tracheids is 55% thicker,and the radial diameter of tracheid is 50% smaller than those in early wood. The size of wood elements in growth rings of the first 10th-15th outwards from the pith increases with the tree-age and undulates in rings there after. There are much warties on the inner surface of tracheid walls and bordered pit.

This paper gives a method for calculating the width of cross cutting desk based on the technological requirement for cross cutting with portable electric chain saws in the Northeast Forest District,and a calculation is made on the basis of random sampling results of the"field accounts of tree-length transportation" taken from 22 forest bureaus including Cuiluan,Dafeng,Fangzheng,Dongjingcheng,Baihe and Wangou. According to the author,the appropriate width of the cross cutting desk is 10—11 meters for CA-10B Jiefang trucks and EQ-140 Dongfeng trucks;for T-138 Tatra trucks,T-148 Tatra trucks,LT-110 Scania trucks and T112H Scania trucks,the appropriate width is 14—15 meters.

P.'popularis' is the hybrids,Selected from P.simoii fertilized by the pollen mixture of P.nigra var.italica and Salix matsudana (1:8).In order to know if the second male has function in the process,The author has analysied the genetic mechanism of P.popularis with immunochemical technique. The double immunodiffusion was made between serum of anti-Salix total proteins with proteins from 9 'popularis' clones,and controlled samples,with 5 clones of the hybrid of P.opera (P.simonii×P.nigra var.italica).The comparison of the resulted immunoprecipitation lines showed: (1) The number of immunoprecipitation lines of'Popularis' is more than that of the hybrid of P.opera (2) Beyond the other clones.'Popularis' 39 and 40 presented an extra peculiar immunoprecipitation line, (3) The precipitation line of 'Popularis' is stronger than that of hybrid of P.opera It is likely,therefore,that DNA fragments of salix were assimilated and integrated into the zygote of P.simonii×P.opera. According to this experiment and many other evidences we believe that the fertilizing with double males is feasible method for breeder who want to get a hybrid which integrated the second male's DNA fragments,and maybe it is more suitable for the.plants which can be cloned easily.

The composition and distribution of the soil microflora,the intensity of soil respiration,and the activity of soil enzymes under three different forest types on the Northern slope of the Changbai Shan Mountain Natural Reserve in three diffrent seasons (Spring,Summer and Autumn) in 1982 were studied.The results indicated that under diffrent types of forest,the ecological distribution of soil microorganisms,the intensity of soil respiration and the activity of soil enzymes in three seasons were diffrent.But the tendency of variation was higher in Spring,lower in Summer and increased in Autumn.The number of soil microorganisms,especially the number of soil bacteria,and the intensity of soil respiration under broad-leaved and coniferous mixed forest was greater than that under the coniferous forest.

The following problems are studied in this paper: a) The seasonal variation of soil moisture and nutrients under Polownia-crop interplanting is affected by climate condition.The data analyses indicate that the content variations of soil moisture,Nitrogen,Calcium carbonate,Soluble calcium,and Magnesium occur mainly in May or August every year,the statistcal significale F being as high as 0.01. b) The content variations of the above mentioned materials are closely related with the distance from the tree plant and affected by biological elements.The variations are most significant within the scape of 2m—10m from the tree plant and within the depth of 80—100cm(F=0.05). These variations are intimately connected with both litter and rootsystem of Polownia forest.

This paper presents a new method of estimating the amount of forest trees using aerial photography data. It is an important property that can quantitatively process the images of remote sensing directly,and recognize and extract the hidden signals of ths images.Its basic principle is that the system model which is set up to meet the requirement of utility must preserve equality between the input-output change of modelling and that of true system. Some testing experiments have been done in the forest regions in the northeast of China using this method.(1)Digital processing technique was used on the airphoto data of No.25 sample ground at Daxinggou in Jilin Province.(2)ISODAT 1 utility program was made on the basic of the ball model.(3) Iterative calculation was run by TRS-80 I microcomputer.The experiment result has proved itself to approach to the true data,and its error is not more than 10 percent. The paper analyzes the basic theory of the method and presents the course of the experiment,the utility program and the initial result.

In China pine wilt disease occurred in many places.Several kinds of nematodes were found in the wilt tree wood from 11 provinces.Four prominent species were identified.They are Bursaphelenchus mucronatus,B.xylophilus,Cryptaphelenchoides propora sp.n.,and Cylintrotylenchus pini gen.n.,sp.n.,Cryptaphelenchoides propora sp.n.differs with C.macrobulbosus by not having stylet basal knobs,excretory pore anterior to hemizonid,vagina not at right angles to the body,spicules end curves.Cylindrotylenchus gen.n.resembles Anguillonema but differs in similar six lips,oesophagus very long,oesophagointestinal cells absent,excretory pore near posterior of isthmus,excretory duct distinct.The type species of Cylindrotylenchus gen.n.is C.pini sp.n..Body cylindrical,head not offset.Oesophagus very long,b=3.1—4.0(for female) and 4.5—7.4 (for male);isthmus narrow;terminal bulb long and clubshaped.Post-vulval sac present.Female tail cylindrical to a rounded end;anus indistinct.Male tail with large enveloping bursa;spicules and gubernaculum tylenchoid

Resistance of 28 clones of poplars to Anoplophora glabripennis(Motsch.) was investigated.These clones of poplars were divided into 3 groups with cluster method.Among them extremely significante difference was showed by variance analysis (p<0.01).P.×euramericana(Dode)CV"Robusta",P.×euramericana (Dode) CV"Sacrau-79" etc.are more resistant to insects,by contrast,P.pyramidalis,P.nigra,and P.×euramericana,CV.I-214,P.×simopyraidalis are less or intermedium resistant respectively. It is suggested that for establishment of poplars plantion,insect resistance clones of poplars should be selected.If poplars with medium resistance are to be planted,attention must be paid to watering and fertilizing to raise their insect resistance.It is also suggested that suitable small amount of insect susceptive clones of poplars be planted in the edge of plantation as luring trees attracking the insects in order to eliminate the pest in large quantities when it occurs.

The horntail Sirex rufi-abdomins Xiao et Wu is a new insect pest seriously damage to Pinus massoniana Lamb found recently at Chu Xian county,Anhui province.It has one generation per year and overwinters as larva in the sapwood.In the late March next year,the larvae eat sapwood.Pupation takes place in August and September,and the adults emerge in Septmber and October.The eggs are laid in the sapwood.The pine trees injured are gradually dead.The larval stage lasts more than ten months,and pupal stage 17 to 20 days and egg stage 21 to 24 days,and adult stage 5 to 15 days. The most effective control method is keeping the stand in a sanitary condition and cutting the dead trees before summer and handling them as quickly as possible.

This test was installed in 1980—1981 at Qingdao and Heinan island China to elucidate the natural resistance of fimber against marine borers attack.It comprised 41 species of Chinese woods.From the results obtained the following classification of the natural resistance is proposed:Ⅰ.Sound (unattacked);Ⅱ.Slightly attacked;Ⅲ.Attacked;Ⅳ.Badly attacked;Ⅴ.Destroyed. The results from the test are given in table.