From the view of disturbance ecology,this paper studied the species group age structure of Larix gmelini population in the north Daxinganling Mountains and its relation to natural disturbance factors, such as forest fire, windfall etc. Following results were obtained: The species group age structure of Larix gmelini population consists of one or more discrete age waves and can be derided into three groups: One-generation, two-generation and multi-generation, moreover eleven types according to the structure state. Natural disturbances have an important effect on the age structure. Forest fire almost affacts all age waves, and windfall and windbreakage are also proved to be important to the late generations. Generally, the weak fire with high frequency favors to form two or multi-generation, the strong fire with low frequency favors one-generation. The major reason for the coexistence of many types of age structure is ascribed to the differences in natural disturbance regime in each region. Age waves, being basic unit of age structure, evidently show β distribution feature with the shapes of right deviation, left deviation, progressive decrease and increase distribution. The shape of age waves is related to the environment of species group, which reflects the regeneration processes comprehansively.

The optimum fertilizer requirements of N, P, K were studied quantitatively for common jujube trees (Zizypus jujuba) by using the method of threefactor regressive opcimum design. An effector model between the amount of N, P, K fertilizer and the yield of jujube trees has been established, by which the optimum fertilization scheme, the main effector and intereffector of various fertilizers, and margining yield effector have been approached. Meanwhile, the diagnosis of nitrogen nutrition was studied; and inquired into the influence of nitrogen nutrient status on jujube trees growth, fruitage, and fruit quality, in which the ranges of the critical value for nitrogen nutrition diagnosis has been determined.

The roots of individual seabuckthorn plant grown in loess remaining plateau and gully region plantation have been studied systematically in this paper. The results show. (1) The age of the main root is the critical factor for the fuzzy cluster among individual plants. The roots at juvanile ages are clustered easily, and it is more difficult to cluster with the increase in the age of main root because of the differences in the roots of the same age individual plants. (2) Changes in root biomass and length of individual seabuckthorn plant have been described and forecasted by the grey Verhaulst model. The roots stop growing when the main roots are about at the age of 17. (3) The vertical distribution laws of root biomass and length in soil are in binary curve function, the goodness of fit between real data and calculated values is perfect. (4) The dense layers of seabackthorn roots increase in deepth with the main root ages and become stable at about 0-50cm finally. The large diameter roots are mostly in this layer. The linear regression equation between root biomass and leaf biomass of seabuckthorn has been established in this paper.

Expert system is a recently emerging techology that promises to reduce expense associated with human expertise for some restricted problem domains. The paper describes a pine caterpillar control expert system and talks about its establishment and its structure. Then it discusses its advantages and disadvantages. It also tells how to use the expert system and gave some examples to explain the case. Finaly it outlines TOES expert system tool with which the system is generated.

Casuarina tree, a main tree species in Fujian Province in sandwind break, is infested by Zeuzera multistrigata Moore. The results showed that Steinernema feltiae, an entomopathogenic nematode, was an effective parasite to suppress the population of Zeuzera pest. The comparison of infectivity of 9 steinernematid strains indicated that Steinernema feltiae Beijing is the best one. The Zeuzera larvae, young and mature, and pupae were all infected by Beijing strain of Steinernema feltiae. The temperature had effect on the mortality and killing speed of Zeuzera larvae infected by nematodes. The temperature range for nematodes infection is from 15-30℃. The quickest killing speed was gained at 25℃ with the mortality of 100% within 48 hours. The nematode was able to spread to the distance of 8cm to parasitize Zeuzera larvae in an infested tunnel. Application dosage of the nematode influenced the mortality of Zeuzera larvae. 61.5% and 100% larvae died under the dosage of 50 500 nematode juveniles per ml respectively. No difference in mortality happened when the dosage of nematode was above 500 juveniles per ml.Four methods of nematode application were tested. The best method is to stuff a small spiece of foam mixed with nematodes about 1000 juveniles. This application method was used in 25.3 hectares for control of Zeuzera larvae in Fujian Province.

According to four theories of catenary, parabola, suspension and pertuibation method five cableway design proqrams were compiled by the BASIC, which consisted of the design system of forestry cableways. It can be used for the skyline design of the single span or multispan cableways, drawing the verical section profile, fixing logging systems and logging ways.

The experiment indicated the analogy of water transport with temperature gradient in wood chips. The proportional coefficient related to the physical quantities was calculated by the least square method. The relational expression of water flux between the mass flow and the temperature qradient was established, and showed that the temperature gradient was the main driving force for water transport. The mechanism of water transport is natural convection in gaseous by wet air and evaporation-condensation of water vapour in the pores of wood particles. The relational expression of water flux established may simplify the existing models, and provide a new theoretic proposition for analyzing the transport processes of water in wood particles under non-isothermal condition The facilitating theoretic model would be convenient in application.

The vibration of band-saw caused by Lever-weight strain system was studied Results tested by 2034 type frequency analyzer showed, That the vibration spectrum of band-saw is a complex periodic signal discrete frequency spectrum, which consists of the repeated addition by a series of sinple harmonic vibration. At the same time, The investigation indicated that the lever-weight strain system of band-saw is different from "Weighing balancer" and can not reach "static balance" while produce a periodic forced vibration under the parametric excitation force of wheels. The interactions between the parametric excitation of the band-saw wheels and the displacement excitation of the leverweight system are critical causes for periodic vibrating and changing tensile force of band-saw.

The ontogeny of the mixed bud and floral organogensis were studied for Liriodendron chinense (Hemsl.) Sarg. By using optical microscopy and scanning electron microscopy. It was found that the mixed bud would take three years from its occurrence to anthesis. The transformation from vegetative initiation to flower initiation took place in June of the next year. The pattern of floral organogenesis was similar to that of helical phyllotaxis in the orders of floral envelope, stamens and pistils accompanied with the periodical apex growth. Occurrence of floral organs in one plant was unsynchronous, lasting for 1 to 3 months. The meristem of flower initiation was divided into five zones, which were perianth, central-mother cell, transition, rib meristem, and peripheral zone. The mixed bud initiation differed with vegetative initiation in the precocity of axillary and differentiation structure. The ratio of mixed bud to vegetative bud in the upper, middle and lower of a crown were 9.5/1,0.5/1 and 0.25/1 respectively. The significance of the mixed bud morphogensis on morphglogy, and the relation of morphological characteristics and the percentage of seed setting have been discussed in this paper.

Variations in internode diameter and length, fibre morphology and specific gravity of four rattans, i.e. Daemonorops margaritae, Calamus simplicifolius, C. tetradactylus and C. dioicus were analysed. In axial direction, the variation in internode diameter was very small. The fluctuation in internode length was relatively gentle. The fibre length has no definite variation pattern. The specific gravites of both bark and core show a decreasing trend from bottom to top. It seems that fibre length in the bark is longer than that in the core, but only that of C. dioicus reaches the statistical signlficance(p<0.05). Specific gravity of the bark is markedly larger than that of the core. In axial and radial dirction, both the width and the lumen diameter of fibre show an increasing trend from the periphery to the centre and from bottom to top while the wall thickness rate (2 × wall thickness ×100/width) exhibits a contrary trend. The qualities of the four rattans were also evaluated in this paper preliminarily.

ABA, ethylene and other abscisic accelerator were permeated into the stalks attaching with fruits and leaves by a hypobaric method. Although the leaf abscission was promoted, the fruit abscission could not be fulfilled. The results observed by microphotography and slanning electron microscopy indicated that the treatments promoted inducing the formation of absciss layer for leaf stalks, but not for fruit stalks, suggesting that seabuckthorn fruits belong to non-abscission type on anatomy, which similar to the needle structure of non-abscission type. In addition, during the full ripening of seabuckthorn fruits, there were very high levels of endogenous plant hormones (IAA, GA₃, iPA and Zeatin) retarding senescence and resisting abscission in fruit stalks, and much higher contants of total acid, Vitamine C, V_E, which related to resisting senescence. After winter, the levels of zeatin, GA₃ in fruit stalks markedly increased. The non-abscission of seabuckthorn fruits may be associated with them

After forest fire in the Daxinganling Mountains, the burnt-woods were seriously attacked by many kinds of borers Meanwhile the populations of the natural enemies increased rapidly with the outbreaks of the tree borers. The natural enemies were studied and classified in 1988-1989. 51 species of natural enemies were found, belonging to Insecta, Arachnoidea, Ares and Hyphomycetes.

Mole percent of G + C in DNA of Bacillus thuringiensis seven subspcies were determinated by means of thermal denaturation method of nucleic acid. The result showed that:B, t. Subsp, thuringiensis(H₁)" G+C% =32.5t B.t.subsp. finitimus (H₂) G+C%=31.0; B.t. Subsp, alesti(H_3a) G+C%=30.0; B.t. Subsp, Kurstaki(H_3a3b) G + C% = 30.03 B.t. Subsp, kenyae (H_4a4c) G + C% = 29.5; B.t. Subsp, galleriae(H_5a5b) G+C%=32.0; B.t. Subsp, wenquanensis G+C%=31.5.

The equations of the two-dimension temperature field were deduced by using the Weighted Residual Integral Galerkin's Method of finite Element Method (FEM) in this paper. The computer program was compiled by FORTRAN and the temperature distribution in wood was calculated according to the heating case. The experimental specie was Larix dahurica. At first longitudinal and transverse thermal conductivities as well as heat transfer coefficient of the specie were measured by DRM-1. Then the heat source was put on the experimental samples and the temperatures at some points in the samples were measured. The calculated temperatures were compared with the measured temperatures, and it was found that the errors between them could be satisfied the requirement of engineering calculation Therefore, we concluded that the temperature distribution in wood could be calculated by FEM.