Hybrid ovules from crosses between Populus simonii×P.pyramidalis,P.simonii×P.euphratica,P.simonii×P.lasiocarpa,P.simonii×P.wilsonii and P.×741 reciprocal combination containing immature hybrid embryos at various developmental stages are excised for culture.Plantlets are obtained successfully. The basal medium is 1/2MS.1.Effects of different concentrations of IAA and BA on adventitious shoot buds and leafy shoots formationare tested.The optimum differentiating medium is 1/2MS+IAA 0.01mg/1+BA 0.1mg/1.In the absence of IAA,1/2MS+BA0.1mg/1 is also efficient.2.Effects of different concentrations of NAA and IBA on roots formation are tested.The optimum rooting medium is 1/2MS+NAA 0.01—0.02mg/1 or 1/2MS+IBA0.1—0.5mg/1.The leafy shoots may also root on 1/2MS without supplemented with NAA or IBA. The developmental stages of contained embryos at the time of inoculation is influence on the percentage of germination and the growth of the cultured ovules.The percentage is rather low,33%,for the early heart-shaped embryos and the seedlings are very weak and difficult for further growth.The percentages are rather high,50—100%,for the heart-shaped,torpedo-shaped and the cotyledonary elongation embryos and the seedlings are healthy and may lead to shoot buds initiation and leafy shoots formation.Rooting plantlets are transferred to soil and grow normally. Histological sections show that the adventitious shoot buds dediffe-rentitiate from the epidermal,cortex,endodermis and even pericycle cells of the radicle and the hypocotyle.

Pinus tabulaeformis is one of the important reserve forest resourcesin Liaoning Province. From 1973 to 1983,a remarkable result of the intermediate cuttings has been achieved by the fixed-position observation.The volume of standing,crops has been increased by 15—30%,the stand diameter has been expanded by 25%,the matured timer rate has been boosted by 20%,the mature period has been shortened to 10—15% years,and the economic income has been raised by 20—25%. This research also puts forward a mode of quantitatively intermediate cuttings and its theory of "Three-Factor Control" in the intermetiate cuttings procedure of comprehensive reaction;the precision of the ready-made Managing Chart is over 98% (Over 95% for that of inspection).

In this paper some statistical models have been established of propagation of light through forest canopies and some equtions have also been induced,based on the above models,for calculating the ability of canopies to transmit,absorb and reflect light.All of the models and equations were quite well accordance with the data obtained from practical measurements and it was found that the young stands of Pinus massoniana fixed the models better than stands of other species.The statistical models were generalized for the stands on slope sites,both deep and gently. The models and equations were examined with simulant theory of Monte Carlo and it was demonstrated that the theory was effective.

According to "-3/2 self-thinning rule" and the model of biomass growth of plant population,the authors offer a mathematical model of forest population density change during population undergoing selfthinning:where r,β,k are positive constant,N represents forest density.

The authors'experiments proved that ectomycorrhizae may improve the early growth of Pinus tabulaeformis.It obviously stimulates the biomass production of pine seedlings.The approximate percentage of increase is 40%. Among the mycorrhizal fungi used in our experiments,five were selected as good ones which are capable of forming ectomycorrhizae and stimulating growth of P.tabulaeformis seedlings,i.e,Boletus sp.,suillus grevillei,Pisolithus tinctorius,and strains obtained from the ectomycorrhizal association of loblolly pine and scotch pine trees. Biological analysis in greenhouse studies shows that all species mentioned above,whether collected from mycorrhizae association or from mature fruitbodies of fungi,can easily from ectomycorrhizae with P.tabulaeformis. The results of experiments show that by inoculum of solid pure culture,mycorrhizal fungi on roots have a great capacity to establish ectomycorrhizae of coral type.The stimulation of seedling growth (including measurements of height,thickness and biomass)is proportional to the development of mycorrhizae on it. The fact that acid soil conditions are needed for the formation of ectomycorrhizae is well documented throughout the world.Usually ectomycorrhizae develops either weakly or not at all basic soil.But in the authors' experiments mycorrhizae are formed both in nursery soil (pH8.6) and in greenhouse soil (with alkalinity of up to 8.9),and can improve the growth of seedlings well.It has been proved by these authors that even under harsh soil conditions suitable strains can survive and grow significantly.This fact enlarges the area of potential research into the ability of fungi to survive in adverse soil conditions. The ingredients of the nutrient medium are as follows:1) pine needle extract,2)acidic malt agar.

The EAG responses of male Cossus mongolicus Ersch.to Z-5-C₍₁₂₎AC,E-5-C₍₁₂₎AC and Z-3-C₍₁₀₎AC are strong,but only Z-5-C₍₁₂₎AC showed an obvious attraction in the trapping tests.On an average,12.67 moths were caught by a trap baited with 0.5mg of Z-5-C₍₁₂₎AC per night.It was 5.3 and 2 times as many as the moths caught by a trap baited with one virgin female and a black light trap (400W),respectively.The type and setting up height of the traps and the carrier materials of the lure showed a significan influence on the attractive effects.The sample was specific to the Cossus mongolicus Ersch.

By a field inoculation and laboratory experiment,the ecological factors effected the quantity of parasitic nymph of M.matsumarae are studied.The results indicate that high temperature in the summer is the key factor.The colony quantity of perasitic nymp vary in different generations obviously.Temperature in the spring suits for its propagation and existence,for its death rate over 90% at high temperature in the summer.The nymph's ability to endure high temperature isn't as strong as it against low temperature.Two linear equations are developed to show the Close relationships respectivly between the intensity of light and nymph's death rate and between the surface temperature and the death rate.

The tortrix Choristoneura metasequoracalci Liu is a common pest of the Metasequoia glyptostroboides.It has one generation per year in Lichuan,Hubei province.After the larvae's being hatched,their diapause appears under the bark and the larvae spend winter there.The diapauselasts 9 or 10 months.The larvae begin to be active again in early April next year.There are five larval instars.Being mature,the larvae pupate in the tied-up leaves of their host.Now it has been found that a few larvae pupate in the rolled-up grass on the ground with the help of spin.Pupation period varies 9.5 to 15 days.Female moths oviposit on the first or second day after its emergence.Usually masses of the laid eggs are on the back of leaves.Male moths may live for 3.5—7 days,and the female moths 5—12.5 days.Each female moth lays 27—109 eggs.It will take the eggs 7.5—12 days to become hatched. It is proved to be quite effective that insecticides,such as Fenitrothion,dimethoate,Decamethrin Fevalerate and Fenthion,are sprayed to kill the larvae inside the laboratory.

Attempts were made to find a quantitative method for determining the rheological parameters of wood in order to have a better understanding of the rheological behaviour of wood chips in compression perpendicular to grain.The deformation of wood in compression perpendicular to grain over the rheological range is quite complicated.In the rheological range,the instantaneous deformation consists mainly of elastic deformation and plastic deformation.In most cases,the creep is an overlap of viscoelastic function and time-dependent plastic deformation.However,the overlaped rheological parameters can be separated by a simple method.Five kinds of creep-recovery curves were found in the wide range of constant stresses due to the overlap of various rheological parameters and functions.

The purpose of this paper is to give a general introduction of the development of Forest Harvesting at home and abroad.During last 30 years,forest harvesting has been progressed from stem-only utilization to whole-tree utilization.Both treelength system and whole-tree system are increasingly used in many countries.The whole-tree chipping system,which increases the biomass yield and shortens the rotation period,is being given priority consideration and is becoming promising.The general incerase in the physical standard of living in industrialized countries has led to a considerable increase in labour cost and consequently the technical evolution from manual and motor-manual to fullymechanized operations occured.Microprocessors make it possible to realize the automation of work-sequences and the remote control of tree harvesing machines,which increase significantly the productivity and safety of forest operations.In planning forest harvesting the methods of determining optimum forest road spacing and the appropriate level of mechanization are developed.In conclusion,the author draw lessons from other countries,which can be used in China,and give prediction of the development in this field.

This article is based on the testing of seed germinate rate,germinating energy,vigour index etc of Cunninghamia lanceolata,Cryptomeria fortunei,Pinus massoniana,Pseudolarix amabilis.With their moisture content of 10.13%,8.66%7.72%,and 12.93% respectively by sun drying,the seeds were put in glass bottles of different relative humidity of 75%,64%,55%,33% under 25℃ for three months. Results show that the most suitable moisture content to preserve the germinate rate and vitality of the seeds in storage under 25℃ is 7—8% for Cunninghamia lanceolata,about 10% for Cryptomeria fertunei,7—9% for Pinus massoniana and 6—7% for Pseudolarix amabilis.

Spatial distribution patterns for egg-masses,larvae and pupae of the pine caterpillar were measured by means of several indexes of aggregation.Frequency distribution of egg-masses fits to poisson distribution,and that of the larve and pupae obeys aggregation distribution,but the aggregation indexes are the highest in small larve and lowest in pupae. Lwao's method of regression of mean crowding(x) on mean density(x)is a good method for detecting the aggregation patterns.In the pine caterpillar,larve and pupae,all x-x relation in a series of distribution is fitted to a single linear regression for a>0,β>1.Lwao's equations for data transformation were applied and tested for its fitness,the transformed data all obey normal distribution and the tests of homogeneity variance indicate that the results of transformation are well fitted.From this method the optimal sampling size is determined,the sequential analysis is also applied.

Based on the ISO 817"Determine the temperature of released combusting gas with a small amount of powdering material"and the Chinese standard of"The method on determining heat value of biological fuels"the igniting temperatures and the heat values of eight species of genus Paulownia and the other six Chinese hardwoods had been determined. The igniting temperatures of Paulownias were 256—268℃ and higher than those Gossampinus malabaricus (DC.)Merr.and Populus tomentose Carr.It might be explained that the ignition of Paulownias is more difficult than the other hardwoods under the same conditions (including sp.gr.).It would be wrong that the igniting temperature of P.tomentose(Thunb.)Steud.was high up to 425℃ reported by some writers before. The heat values of eight Paulownias were 4196—4486 Cal/g.Not so much differences were occurred among the species.

This paper describes the test results about the water resisance on the rafts passing through ship lock.It also provides the data which may be used for design and operation of the ship lock,and for the selection of favorable mean velocity for the rafts passing through the ship lock. The capacity of traction equipment,as well as the reasonable sectional dimensions and width allowance of the lock chamber are also discussed.