The characteristics and mechanism of 9 Platycladus orientalis provenances were studied With respect to their hydro-eeophysiologieal specifics，water parameters，photosynthesis，transpiration and water utilization efficiency based upon the quantitative model of comprehensive appraisal of drought tolerance for tree species．The results show that under normal water condition the cell elastic modulus of southern provenances (Queshan，Mianyang，Liping) are higher than that of other provenances，thus can maintain larger turgor pressure to facilitate better growth．Both their photo-synthetic rates and water consumption through transpiration are higher and their water utilization ef-ficiency are low．While under water stress condition their leaf water potential，cell elasticity，drought tolerance productivity and water utilization efficiency are worsened greatly revealing their weak adaptability to water stress．Only the cell elasticity of middle-north provenance (Fu county) has been increased under water stress．and the declining degree of its leaf water potential，drought tolerance productivity and water utilization efficiency is minimal，therefore it has the greatest ability to tolerate drought than other provenances．The response indications of leaf water potential．cell e-lastieity，drought tolerance productivity and water utilization efficiency for Northeast (Changzhi，Zanhunag and Yidu) and Middle (Chunhua and Changzhi) provenances reveal their medium ability of drought tolerance．

In this paper，the solar energy utilization efficiency (SUE) of Agroforestry System was stud-ied in Raoyang County，Hebei Province．The initial resultS showed：(1)The SUE of Agroforestry System in 1992 was 62.3％ much higher than in 1984 (Con-sidered that 1984 and 1992 were the representive year before and after which the Agroforestry Sys-tern had constructed respectively)．(2)The value of SUE in model of pear intercroping with crops protected by sheltemets was 10.3％ higher than that of common shelternets．(3)The value of SUE of Agroforestry System was 25.0％higher than that of the unprotec-ed field (CK) and the SUE of wheat in Agroforestry System were 10.4％higher than that in theunprotected field．(4) Agroforstry System could raise solar energy utilization efficiency (SUE) comparing with the single Agricultral System，which based on making full utilization of multiple layered and spacialstructure，and mainly resulted from that water utilization efficiency and resistence to natural adversi-ty (such as freeze injure，dry-hot wind(weather) and wind erosion) could be raised in Agrofostry System．

Using Beta-biodiversity index to analyse the environmental heterogenousity in Badagong Moun-tain in Hunan province，the study showed that there were very significant differences between the values in different sites(Shamujie，Tianping Mountain，Doupeng Mountain)．The mean number in each sample per gradient of species and new increasing species gradually declined with the increase of the elevation．The species in each sample distributed randomly．All 66 samples could be divided into 14 types by using systematic duster method to analyse the relationship between the species and the abundance．This was accorded with the actural situation．10 sample pairs were extremely alike．And 20 sample pairs were alike．

The surface soil layer humus and fertility in Chinese fir，Pinus massoniana and evergreen broad leaved forests before and after controlled burning were studied．After controlled burning，the soil or-ganic matter and total N of surface soil layer decreased．the activities of soil biochemistry strength-ened,the amount of available nutrient supply enhanced．Soil humus，the ratio of HA/FA，humic acid and E₄ value decreased， E₄/E₆ elevated，loosely and tightly combined humus contents and its ratio deseended，the activation of soil humus decreased．It was unfavov able to maintain ventilation penetration and forest soil fertility．

Generated through 13 years study，a Ulmus pumila superior clon e#65212 has been chosen．It is not only resistant to Pyrrhalta aenescens lalva but also growing fast with fine trunk form．Feeding P．aenescens lalva with the leaves of #65212 in the laboratory,the dead ratio of lalva is 86.44％—93.41％，which is 269.14％—479.50％ higher than that of control (8052)．The number of pupae in 8—9 years old trees is lower 93.9％—97.7％ than that of control in average and the harmful in-dex of leaf area is 90.67％ lower than that of control．The trunk height，volume，form parameter at breast height ate 3.91％—38.65％,17.47％—80.80％，12.72％—43．69％higher than those of 8052，8015 respectively．Its characteristics of rapid growth and resistance to pest can be passed to their hybrid descendents．

Through the experiment by split block design，and variance analysis as well as offsetting analysis from the normal distribution，the paper enclosed the systematical studies on the status of settlement and competition of three arbor mangrove species-Bruguiera sexangula (Lour) poir，B．gymnorrhiza (L) Lamk and Rhizophora stytosa Griff after they were introduced artificially into a degraded dense Aegiceras corniculatum+Ceriops tagal Community，and revealed the influences of the serial of thinning bush measures before introducing upon their settlement．Variance analysis shows that thinning the bush in plot way is obviously good for increasing the survival rate of R．stylosa and for promoting the growth of B．sexangula．Offsetting analysis from normal distribution shows as follows：B．sexangula in competition with the bush results in left offsetting seriously (off-setting ratio equaling 5.69)after two years and seven months，which means that the bush has a great unfavorable influence upon its growth，it is necessary to adopt the measures again for controlling the recovery of the bush．B．gymnorrhiza and R．stylosa develop into left offset slightly(offsetting ratio equaling 2.54 and 1.85 respectively which basically belong to normal distribution，this means that the bush has a very small unfavorable influence upon their growth，so that the improvement of A． corniculatum+C．tagal community will have more certainty of success．Based on analysis of the morphology and development in combination with offsetting analysis from normal distribution，it is concluded that B．gymnorrhiza and R．stylosa are more shade-tolerant tree specties，B．sexangula is light-demanding tree speies．

In order to realize quantity management of Masson pine plantation，a growth and Yield model system was studied with data from various experiment stands，permanent and temporary sample plots，and stem analysis，which were accumulated for a long time．The component and structure of whole model system，and the relation among models were briefed．Based on site classification and evaluation，a series of forecast models of stand self-thinning，diameter and basal area growth under natural state，diameter distributions and tree height curve，mean height and mean diameter at breast height of thinning tree and mean diameter at breast height growth of post thinning stand were established．The forecast models of taper equation，volume ratio and economic biomass Were also established．The problems of density control，prediction of stand structure and growth yield，thin-ning efficiency analysis， nongrowth increment caused by thinning， were resolved， each model in the model system was tested and the model system might be applied in other relative Study areas．

The effects of planing density on the growth and economic benefit of Chinese fir were analysed by data of 15-year-old planting density trial stand，the results showed that planting density had the effect on the mean height of trees，but the difference was not significant．Diameter at breast height，single-tree volume，crown diameter alI decreased with the increase of density，the differ-ence among treatments was significance after 4 years．Both growing stock and height/diameter ratio increased with the increase of density，the difference in growing stock was significant from 7 to 12 years-old，but height/diameter ratio was not significant．Trees percentage of small logs increased with the increase of density，but trees and merchantable volume of large timber rapidly decreased．The peak of curve of trees distribution skewed to left．the peak move a diameter groups to left with　increasing a density class．By a synthetic analysis of growth increment，merchantable volume and e-conomic evaluation，the initial planting density was 1667 tree/hm²，which was considered as opti-mum．for cultivating large or middle diameter timber on a 18—20 site index．the density of 2500 tree/hm2 is also beneficial next to former one．

According to different sites，Fraxinus mandshurica and Agnus japonica,F．mandshurica and Larix olgensis mixed forest were planted either 5，8 lines belt-mixing or 10×10 trees plot-mixing for studying mixing effects．The results indicated that：survival rate and growth increment of tree species in mixed forest were increased significantly．The mixing effect of 5 lines belt-mixing had the most significant effect among the several mixing types．in which the productivity of forest land was increased effectively．The next better one is 8 line belt-mixing，10×10 trees plot-mixing was not so effective．

In this paper，according to the law of density effect of plantation．a new basal growth model was estab-lished based on improving the basal area growth model proposed by senior research fellow Tang shouzheng．Using the data collected from the sample plots of Chinese fir kernel growing area of Fuiian，the parameters of the new model were fitted．The precision test result of the model showed that the improved basal area model has higher precision than the former．It also inuvduced an approach to analyse tranrang effect by using the improved basal growth model．

The protective effect range of windbreake networks for cotton production area，which was exposed to violent wind storm, was divided into the damaged zone and protective by fuzzy dustering stepwise discriminant method．The protective zone is for O.42H-23.00H to northern forest belt in the direction of South-North,and0.36H-0.23H to east forast belt in the direction of East-West．The protective area of simplex windbreak networks accounted for44.44％of the total area．The protective areas of complex windbreak networks increased by 18.76% comparing with the former．The unginned cotton，ginning outturn，and ginned cotton in protected area had increased 45.01%，5.30％，and 52.69% comparing with the damaged area respeetivety．The protection magnitude of the unginned cotton and ginned cotton had increased by 260.50kg/hm² and 107．3Skg/hm² in the complex winworks networks with the protective per-centage of 21.05% and 24.65% respectively．

The effects of the Dothiorella gregaria canker caused by natural and artificial inoculation on the growth and volume loss rate of young poplar trees were studied．The results showed that the num-bers of spots on stem were positively related to the disease index and volume loss rate．The height and breast height diameter of trees were effected by the number of the spots on stem (over 25)．When the spots spread around the stem．the loss rates of breast height diameter and volume became prominent．The cankers mainly occurred on little vesicles (about 0.8 cm in diameter)of young trees stem．As，trees grew older the disease resistence became stronger and the disease incidence and vol-ume loss rate dropped．The control methods should be taken at the developmental stage of young poplar trees，so as to reduce the disease incidence and loss of growth and volume．

The diversity of insect community of the horsetail pine，Pinus massoniana L．，forests in dif-ferent stand conditions were studied at the same period from April to May in 1995．The sampling in-vestigations were carried out in Xiangfan of Hubei，Xinshao of Hunan．Deqing of Guangdong，which are at three different latitudes．The results indicate that the insect communities in the horsetail pine forests at different latitude are different in the composition of groups，species，and individual quanti-ties，as well as the degree of diversity．In general，the compositions and the diversity degrees of in-sect community in three areas don’t have the tendency of decreasing with the increasing of latitude according to both the horizontal and the vertical distribution，and their values are influenced by the air temperature and the stand conditions of the horsetail pine forests，such as the vegetal cover and the forest canopy，ect．According to the stand conditions and the compositions of the insect commu-nities，the Xinshao insect communities and the Xiangfan insect communities could be divided into two types and the Deqine insect communities could be divided into three types．

This paper aims to study on the improving effect of Chinese pine caterpillar’S frass on the soil fertility in the light of the frass that can compensate the tree growth in lagging time．The results show that during feeding of the Chinese pine caterpillar the fragmentation is important in material transformation；that the frass can ameliorate the physical and chemical characters；and that the frass applying can boost the number of soil microbe，especially the fungi which is three times as that of the check soil．The total microbiomass shows obvious increasing．The tannic acid and phenol in frass can promote the activity of nitrogenase by 3 times and every 100 gram dry frass soil can fix 22 milligram nitrogen by biological nitrogen fixation．

With the help of advanced modern spectroscopy analytic techniques，such as IR，ESCA and ESR，the function group composition of Korean pine wood and alkyd resin varnish was determined，also the adhesion mechanism at the interface between the wood and the varnish was mainly investi-gated．The results showed that there was no remarkable chemical reaction of function group，alkyd resin varnish between korean pine wood and alkyd resin varnish，but there was noticeable chemical reaction of free radicals，so that a certain amount of chemical bond was formed．The results support powerfully“the theory of the chemical bond at the interface between the paint molecule and painted body surface”．

Emerging of genetic transformation provided a new way for oriented breeding in forest．Appli-cation and developing of transformation in trees，especially with Agrobacterium-mediated transfor-mation were recommended．The main problem and devolopment of tree genetic transformation in future were discussed．

In order to measure stand volume with angle gauge，according to the form point of standing tree，we propose and define a new concept-stand trunk，invent and make the three-dimensional an-gle gauge dendrometer．It is used directly tO measure the height of stand in the form point，obtain stand volme from deducing the stand trunk．The procedure is the method of stand form point．The method avoids visual difficulty in the forest that results from overlapping of the tree crown．Compare with the method of corresponding height sum，it is simple and convenient.easy to use．The simula-tion result with computer shows：applying the method to measure stand volume，the sampling preci-sion is about 95％ and systematic error is in the range of±5％．

The results showed that 5％ carbendazol and 75％ thiophanate methyl were able to inhibit the growth of Trichoderma viride at the concentration of 0.5mg/L．Moreover,50％ carbendazol showed less effect on the growth of Xianggu mushroom (inhibitory rate was 7.69％) at the same concentration．The water decoction of Phellodendron amurense was able tO inhibit the growth of T．viride significantly．Compared with using 50％ carbendazol．75％ thiophanate methyl and ger-micide of P．amurense alone，the compound of P．amurense，carbendazol and thiophanate methyl was more effective to inhibit T．viride．

Sesia singensis Hsu is a serious pest boring in poplar trunk．The control measures were carried out using sex-attractant in this study．The quantity and the emergence period of the adult were mea-sured and the control effects were investigated．Possible factors that affect the quantity of forest pest trapping were studied．

This paper dealt with the biological rhythm of sex pheromone of the females and the responsive-ness of the males of Illiberis pruni．The methods of electroantennogram and wind tunnel assay were used．The results showed that seX pheromone production occured in the newly emerged and 1 to 7-day-old female moths，but the maximum level occured in 3-day-old female moths，while the 3-day-old male moths had the maximum responsiveness tO seX pheromone，There were two peaks of both the sex pheromone production of the females and the responsiveness of the males in a day；the male response peaks lasted longer．This indicated the sexual sensitivity of the males and the harmonious synchronization of the sexual behaviour between the females and the males．