The old-growth hardwood-korean pine (Pinus kocaiensis) forests in the Lesser Xing'an Mts.hold a vital base in timber production in the whole country.These forests have been exploited more than thirty years and have made significant contribution to the national economy.Up to now,their forested area and volume have been greatly decreased.The objective of the present study is to examine how to accelerate the process of stand rehabilitation on the cutovers.First of all,the early growth characteristics of korean pine and its regeneration on the logged area with various typessof site are studied,then some measures to regenerate and to grow it well have been explored in the light of the tendency of successional development. Main content involves the improvement cuttings of selective cutover stands and how to convert the birch-aspen stand naturally grown on the clear cuts to the stratified mixture with korean pine and the problems of korean-pine plantation from seedling to timber stage to make it grow fast and become high-quality timber.In short,this paper essentially emphasizes the fact that the artificial regeneration not only should be put into action,but the great potential of natural korean pine reproduction should be also developed,together worked with intermediate treatment and sound silviculture system.It is expected that all courses of development towards the hardwood-korean pine forest to be restored would be accelerated n the region.

In order to seek main factors that affect the survival percentage of air-seeding,multiple factors were studied in two kinds of main dune types in Yulin air-seeding area.12 factors were investigated in the first dune type,where sand dune is concentrated,space is very narrow between sand dunes and water table is very deep;16 factors were done in the second dune type,where the natural condition is opposite to the first one.The two groups of data were calculated with BASIC program by microcomputer,the result shows a homogenous regularity.It indicates that the main factors which affect the survival percentage of air-seedling are:the slope area of wind ward side,the area of plant community,the seedling density,whether the sand dunes be chain,the slope pattern,plant height,crown diameter ect.The achivement of the study provides a scientific basis for selecing sites in air-seeding area and improving the survival percentage of air-seeding.

Three hypotheses in the cause of winter injury in Korean pine(Pinus koraiensis Sieb.et Zucc.) seedlings—winter desiccation,late frost and winter solar radiation were tested.The results indicate that the injury is not related to winter desiccation or late frost but to wintet solar radiation.It enhances photosynthesis inhibition,resulting in irreversible photooxidation injury of the needles.'Negative' photosynthesis is also reported and discussed in relation to the injury.

There is significant difference in nitrate reductase (NR) activity between clones of Chinese fir with different growth rate.Generally,high NR activity was found in the fast growing clone.Trees with new shoot mean growth of 59 and 76 cm had NR activity values of 0.08 and 0.236 μ mol NO₂- per g fresh weight per hour respectively.The level of NR activity varied with the growing period.The maximum activity was observed when the tree is quick growing (Aug.).The NR activity in the leaves on 1 year old branch was higher than that in the leaves on two years old branch.The NR activity in mature leaves on current lateral branches from stem of current year growth higher than that from stem of last year growth and the year before last,which in mature leaves from the middle of the branch of current growth significantly higher than that in young leaves from the top and that in cutinized leaves from the base of the same branch.If the branch with the leaves on were induced with potassium nitrate solution and light,NR activity in leaves increased apparently.Higher NR activity was obtained when treated with 50 m mol/L KNO₃ and illumination of 2000 lux for 12 hours.According to the results obtained in these exprements,it is suggested that NR activity could be used as a biochemical indicator of growth rate of Chinese fir.

In 20 counties,11 provinces and autonomous regions,China,23878 galls were collected,which 3999 parasites(amounting to 30 species) were reared from.They belong to 11 famities (Hym.):Torymidae,Eurytomidae, Ormyridae,Eupelmidae,Eulophidae,Elasmidae,Pteromalidae;Encyrtidae,Scelionidae,Braconidae,Ichneummonidae.Among them,Torymus sinensis Kamijo,Torymus geranii (Walker),Eurytoma rosae Nees,Decaioma concinna(Boh),Decatoma variegata (Curtis),Ormyrus Punctiger var,rulifanus Mayr,Eupelmus urozonus Dalman,Tetrastichus sp.,which distribute extensively were studied further more.The relationship between parasites and parasites and chestnut gall wasp was assured.Through dissecting of galls and identification of parasite's larvae,it is certain that the natural enemies have a great influence on the dynamics of populations of chestnut gall wasp.

This paper deals with results of our investigation on the factors affecting the propagation of the nuclear polyhedrosis virus (NPV) of the polar looper,Apocheima cinerarius Erschff. The concentration had a conspicuous effect on the propagation of the nuclear polyhedrosis virus.Among the concentration tested,the 1.1×10⁶-1.1×10⁷ PIB/ml was found to be the best on early four instars average 2.42-2.64×10⁹ PIBs/larvae.When the larvae of poplar looper were fed with the poplar leaves contaminated with polyhedral inclusion bodies (PIB) of the virus,the mortality rate of the infected larvae was depended on concentration of the virus suspension and laral instar. The amount of propagated NPV was found to be proportional to the concentration of the inoculum suspension.The lag of the death of larvae inoculated with NPV was influences by the temperature and suspensioncon centration of the polyhedral virus.The propagation of the virus was inhibited at 35℃ and the optimal temperature was 22—27℃.The NPV would propagaten better in early four-instar larvae than in other instars on an average of 2.42×10⁹ PIBs/larvae. The propagation of field indicated that optimum suspension contration was 2.5×10⁶ PIBs/mu to second-instars and third-instars.Dry proparation of PIB of nuclear polyhedrosis virus of Apocheima cinerarius by precipitation with acetone from lactose suspensions indicated that the LC₍₅₀₎ values of 2.84×10~3 PIBs/ml for early third-instar larvae and 95% fiducial limit was 1.70×10³-4.96×10³ PIBs/ml.

A high differentiation ratio occurs once above 6 years of the 3rd generation of the Masson's pine caterpillar,Dendrolimus Punctatus,in the infested areas.It causes on early Autumn outbreak of caterpillar populations and killed large area of pine stands.Meteorological factors correlated significantly to high ratios are mean temperatures of August,the initial day stably over 10℃,and hours of sunshine above 10℃ through the year.Key factor to break the diapause of the caterpillar is the stimulus to the 4th instar of the long sunshine of mid to late August,which makes the differentiation increase substantially.Based on the computation of the data of the investigations for 22 years in Jinshishan Forest Farm and 7 meteorological factors,a mathematic model for prediction of the ratios of the 3rd generation was worked out as the following:Y_i=∑^M_j-1∑ⁱ_k-1cjkδ_i（jk） By time series method,the differentiation ratios for 1986 and 1987 are close to that investigated on site.

Based on the analysis for a soil-tree transplanter system,a empiric eduation relating the spading resistance of a tree transplanter with state of soil,type of spade and spading distance has been developed by the model spade which scale factor is equal to 0.5.Predicted spading resistance generally is accurate to within 8.95% of actual prototype spade in the range of the test value by the predicting equation.

This paper discussed the construction,the function and the application of a small mobile m ultipurpose spar yarder and loader.It ite sted that it can be used to yard uphill as a mobile spar yarder and downhill as a mobile skyline without spar,to load as a mobile hydraulic loader along the forest road for the logging truck in the cutting area.In this condition,it is unnecessary to set up any static skyline for loading,to construct the static landing.In the wood yard,it can deck up and load for the trains or the trucks and prepare logs for loading.In water transportation,it can dump the logs into the water,take down the stack in the water,pick up the logs from the holding area and finish some operation of the river engineering.When collecting the scattered logs,it can also transport the logs with the tailer.Having compared with the domstic and oversea similar equipments,we found that it had following advantages:multiple function;simple transfer system;compact construction;simplifed the productive technology;shortened the skidding distance;higher productivity;lower cost of construction and operation;remarkable social and economic benefit.

Among the methods involved in estimating the height of each age gradation by stem analysis,the height in a certain year between two disks is considered as the height of the upper disk by using the traditional method of"height curve line",which produces a plus systematic error.Although a"Modification Method" by Mr.Cheng Zichun makes the error become plus and minus ones,the absolute error is not contracted.Without considering the change of tree growth and replacing the actual stem height by a certain height,in fact,it is the same as the former,its result from calculation can not be used to analyze the tree growing process exactly.A lot of materials in pratice shows that the height can be estimated by using the method of vertical section chart,which possesses a scientific grand,moreover,it is convenient,accurate and direct in use,especially suitable for some fast-growing species such as Chinese fir,Masson's pine ect.

1.The best terms for storage of the Pinus tabulaeformis seed accelerated germination by sack conditioned air with silica gel transom are as follows:a.The normal atmospheric temperature (18—20℃);b.The rate of water absorbtion about 13%;c.The oxygen content 5—7% in room air and carbon dioxide content 6—8%.Under the conditions mentioned above,the split Pinus tabulaeformis seed by accelerating germination is stored after 15 days,its germination percentage also had more than 85 percent. 2.The accelerated germination seed emerged earlied 5—20 days in comparison with the not accelerated germination seed sown in control area in broadcast seedling afforestation test.It's rate of germination raised 21.4 to 49.7 percent,the date of emergence shortened 13 to 20 days,and also the emergence demended rainfall less.Owing to the long growing time the xylary tissues of the seedling increased the same year. Its survival rate over wintering and afforestation raised 16.03 and 14.13 percent in average respectively.

The study aims at selecting the plus stand as the seed stand.Based on investigation of main natural distribution regions of Pinus tabulaeformis in Hebei province,and taking some variable factors,such as volume,age,density,bearing ability,soil depth and slop direction,site class,mean temperature ect.,into consideration,the selection standard for the plus stand of Pinus tabulaeformis in the province is proposed by using Theory of Quantification Ⅰ.The result shows:It is feasible to determin the standard by using Theory of Quantification Ⅰ;if a plus stand possess these conditions——age<50 years old,density approches 30% of the age regression density,bearing grade>1.83,site class Ⅲ,slop degree<30°,which can be consider as a seed stand;the affect of the method is also discussed.

The regeneration effect of korean pine was studied in 5 kinds of secondary hardwood stands.Height growth and diamater growth were analyzed.A big difference in growth exists between stands,sunshine acts as a limited factor to juvenile Korean pine in thick hardwood stand,therefore,thinning is important to which.A high quality timber wood stand can be formed by rational mixture.In addition,a proper thinning method and time to improve growing condition are suggested.

The purification and characteristics of DNAs isolated from the broad-leaf species,Populus simonii,P.bolleana P.suaveolens,P.nigra var.italica,Ailanthus altissima,Paulownia fortunei,and Robinia pseudoacacia are reported in this paper.Analysis results of DNAs indicated that DNAs conform to the requirement as exogenous DNAs for genetic transformation of the molecular breeding of poplar.Purified DNAs show a typically ultraviolet absorption spectrum,the A₍₂₆₀₎/A₍₂₈₀₎ and A₍₂₆₀₎/A₍₂₃₀₎ ratio are 1.69—2.16 and 1.17-2.00 respectively.The melting temperature of DNAs are 68—78℃,therfore,those content of (G+C)% are 34.4-58.8% and thermal hyperchromic effect are 32-38%.DNAs were analysed by Sepharose 4B column chromatography.DNAs stain by EtBr in agrose gel present continul bands and major component molecular weight is about 40-1.0×10⁶ dal (67.6-1.5 kb).While the restruction endonucleases Xho Ⅰ and EcoR Ⅰ digested DNAs,the visible division bands can't be found.But the polymeric DNAs in the starting caves disappeared.

This paper reports that Syneta adamsi Baly is a pest to Larix and new to North China.A detailed morphological description of the species is given.The questionable systematic position of the genus Syneta Dejean has discussed too.

Phloeosinus sinensis is regarded as a key pest attacking China fir(Cunninghamia lanceolata).It has one generation a year in Xinyang district,Henan province,and overwinters as adult in the tunnel of phloem near the base of the trunk.The egg stage is from late April to early July,and larval stage is from early May to late June or to late September contiually.The overwintering stage is from early October to March of the following year. There are two important parasite species belonged to Eurytomidae and Lchueumonidae respectively with 18.3% percentage of natural parasitization. Appropriate time of control was when hibernated adults began to feed supplementary food or before newly emerged adults hibernate.More economic and effective methods of control are beating the tunnels,injecting mixed insecticides of 80% DDVP and 25 chlorclimeform (1:1) diluted with 200 times of water,and putting baits made of wood for attacking.

This paper studies on the aspect of attack,including hypha penetrating into cell wall and its distribution,and ultrastructure changes of Populus deltoides cv"Lux" by Coriolus versicolar with the aid of scanning electron microscope.The results show that white rot fungus (Coriolus versicolor) is capable of metabolixing all of the major components of wood both the carbohydrate and lignin.With this in mind,it would produce an uniform thinning or progressive removal of the wood cell wall,even in the advanced stage of white rot,little or no wood shrinkage or collapse of cells occurs and the original shape and outward appearance of the wood are maintained.These studies are of pratical significance to understand the decay mechanism of poplar,to put forward the measure of preservation and modification,and to extend the utilization of fast growing species of poplar.