Depend on the data obtained from a lot of field experiments, the paper deals with the circulation of matter ials and energy in a farmland shelterbelt network ecosystem for Populus tomontosa Carr. The results show that the biomass of the system was 42.0334t/ha, productivity was 24.3950 t/ha, annual litterfall was 0.5545t/ha. Return rate was 35.72% and average circulation rate of 6 nutrient elements (N. P. K, Ca. Mg. Mn) was 15.28%, which was 9.53% more than that in crop system.The results also show that the energy transformer efficiency of PHAR in the system was 2.14%,which was 3.19% more than that in crop community.

The endogenous hormone levels of cytokinin, gibberellin, auxin and abscisic acid in pistillate floral and vegetative buds,collected from early and late-fruiting types of 3-year-old walnut seedlings respectively,were measured using GLC-ECD or FTD at the stage of pistillate flower differentiation. Expressed sequentially as their relative amounts, the changes of these hormonal levels in both buds can be described simply and directly as follows, pistillate floral bud, (+,-,-,-); vegetative bud (-, +, +.+).This pattern suggests that (1) pistillate flower differentiation is the result of a specific balance of the four hormones acting in bud meristem tissues, and (2) the ratio of cytokinins to gibberellins appears to be positively correlated with the theoretical and practical ability of these tissues to form pistillate floral primordia, where the ratio of pistillate floral bud was "+/-" or 3.0,and vegetative bud was "-/+" or 1.2.In this paper, the practical significance of the endogenous hormone pattern, and the nature of juvenility for walnut were also discussed.

This study focused on the effects of different spacings of Paulownia elongata on energy balance and yield of intercropped wheat in paulownia-wheat intercropping field. Results showed that the net radiation (Rn) and its components were reduced in the intercropped wheat field compared to the control plots. However, the proportion of sensible heat flux(H) to Rn decreased while those of the latent heat flux(LE) and soil heat flux (G) increased. At the same time, water relative deficit in the intercropped plots decreased.Effects of paulownia trees on these parameters depended on its density, growth stage, the modified energy balance was favorable to wheat growth during jointing, heading and flowering stages in all paulownia spacings. However, the reduced Rn in denser paulownia spacings caused less favorable effect on wheat growth during grain filling and mature stages. The yield of intercropped wheat was found to vary with paulownia density and with the wheat plants' relative distance from the paulownia tree rows. Paulownia did not affect wheat yield in spacings larger than 5×20m but caused a decrease in spacings of less than 5×20m at the 7th intercropping year.

The origin of the chief cellulose digesting enzyme, C_X-Cellulase, in longhorn beetles was investigated. Homogenate of alimentary canals of 18 species of female adults, 16 species of male adults and 12 species of larvae of two subfamilies (Lamiinae and Cerambycinae) were tested with the isoelectric-focusing PAGE method.The zymograms of cellulase isozymes were quite different in various developmental stages and larval instars. The origin of C_X-Cellulase in digestive tract (mid-gut, hind-gut) of cerambycid beetles was discussed in detail.The author inclined to draw a conclusion that most species of cerambycid beetles are able to secrete their own C_X-Cellulase.

The research was carried out at Beijing Milu Reserve in 1985-1986 and at Da Feng Milu Reserve from April 1987 to March 1990.For the first time 263 plant species eaten by Milu are recorded. The plant species belong to 49 families and 164 genera with 39 families 86 genera 118 species at Beijing Milu Reserve and 42 families 133 genera 194 species at Da Feng Milu Reserve. Fifty one plant species eaten by Milu are the same at the two Reserves. It was suggested that the vegetations could satisfy Milu's needs of living and reproduction and the mean annual increasing rate at the two sites were more than 20% in the last years.Monthly number of plant species eaten by Da Feng Milu herd and ground vegetation biomass (Data from 30 samples taken monthly) are shown in figure 2 and figure 1 respectively. Habitat vegetations have deteriorated in the two sites because of heavy grazing and Milu's Underfoot trample as well as simple flora, young development of plant comunity and rapid succession of vegetation. It would be a good way if one third of Milu in the two sites were removed to new suitable habitats.

Since 70's, a great progress of forest fertilization and nutrient diagnosis has been made in restoring and raising forest soil fertility of plantation, and rational fertilization has become an important technical measure for directive cutivating short-rotation industrial timber plantation.The study on systematic fertilization network nutrient diagnosis is the prerequisite for national fertilization and raising the fertilizer efficiency. Soil analysis, plant tissue analysis and field trial are the major means to nutriant diagnosis. Because of some technical problems existed in nutriant diagnosis method, so it is somewhat limeted in guiding forest fertilization. This article makes a brief comment on the history of forest fertilization research, trend of its applications in forestry production, and some related problems.Integrated environmental factors should be applied to the study on nutrient diagnosis, carrying out systematic fixed location trials and working out rational fertilization schemes for various tree species.

In this article, we have analysed the traditional mechanical model of the double mass spring system of the YG-5 chainsaw, found the contradiction between this mechanical model and former experimental results of other people, and demonstrated through experiment that it is inaccurate to simplify the vibration of YG-5 chainsaw as a double mass spring system.

The Juniperus rigida open wood is the initial plant community on bare area of forest-steppe zone in the Loess Plateau of northern Shaanxi Province. There are two succession periods: xeromorphic steppe plants are dominant in the earlier period, such as Stipa sp, Festuca ovina, Thymus mongolicua and Atemisia frigida, etc.; xero-mesophytes are dominant in the later period, such as Atemisia giraidii, A, gmelinii and Lespedeza davurica, etc. Since soil condition is improved by the plant communty of earlier period, the plants of later period are developing, which is accompanied by soil change from drought to mesophytezation, so the fundamental driving force of the succession is a dynamic of edaphic internal cause succession under the action of plant communities.

the results from this study show that the contents of Mieyouniaosanhao insecticide (l-"4-chlorophenyl"-3-"2-chlorobenzoyl"urea) in soil under poplar and pine woods dicreased continually, with time and its half life was 12 days. Bacteria and fungi were isolated from forest soil. Bacteria identified to be Pseudomonas testoeteroni, Acinetobacter calcoacticus from poplar forest soil, P. alcaligenes and Acinetobacter calcoaceticus from pine woods soil, as well as fungi were all able to degrade Mieyounaosanhao so that soil microorganism played an important role in degradation of Mieyouniaosanhao. The two metabolites of 4-chlorophenyurea and 4-chloroaniline can be produced from the degradation of this insecticide, and can be also further degraded by soil microorganisms. Therefore, it was concluded that the Mieyouniaosanhao insecticide was easily degraded by soil microorganisms, and it can be used safely without pollution in soil enviroment.

BY the systematic anatomical observation of the uniting process of walnut grafting branch, the results indicate that the uniting process of walnut grafting branch consists of 5 stages: non-formation of callus, callus initiation, callus junction between stock and scion, cambium differentiation and union, vascullar tissue differentiation and union. Meanwhile, the main factors affecting the uniting process of walnut grafting branch were analysed and discussed.

Two years old early-fruiting walnut seedling were water stress in early July. As the water stress increased, net photosynthesis rate of the leaves decreased from the maximum state slowly first than, rapidly later on, and ultimately completely inhibited. The relations of net photosynthesis and leaf water potential soil water content, leaf water content, stomatal diffusion resistance, and the angle between the first couple leaflets at the top of compound lesf were studied and discussed in this paper. It was shown that the angle and the leaf water potential were the better indexes to indicate the water state of trees than soil water contant. When the angle was more than 90° and the leaf water potential was more than- 1.20MPa, the net photosynthesis rate of leaves could be maintained at higher level. Whereas leaf water content and stomatal diffusion resistance could not be used as the water indexes for early-fruiting walnut. Critical water potential of early-fruiting walnut for stomatal closure was-1.35MPa.

Investgations were carried out from 1979 to 1981 on the natural regeneration of the alpine pine in Gengzhang Gully, Xizang. The results show that the stand types are mainly pteridophyta, alpine oak, and alpine pihe, and that their distrbution areas are comparatively large. Alpine pines grown on flood land and in the middle-lower parts of the slopes are mostly Ⅱ and Ⅲ age-dasses, their increments are high with good, and natural regeneration As a resoult of poor seed sources in the forest, there only 1—10 year-old young seedlings and trees, about 2000—115000 plants per hectare, and grow badly. We suggest that some measures should be token to promote the natural regeneration, such as by strip clear cutting, heavy selective fellings, direct seeding and forest cleaning.

According to the researches on the population dynamics and effective accumulated temperature of Dendrolimus tabulaeformis, a Leslie matrix model of this pest insect is established. After the vector of population on some time are imputed, the development of the population can be showed. The simulation results basically fits what occurred in the field.

This paper deals with the use of spatial autocorrelation method to estimate the insect population density on a comparatively large area through a survey on several small sample plots, basing on the spatial correlation of insect population. The estimated formula of autocorrelation variance is : r^*=∑(z(x_i+h)-z(x_i))²/2N. The linear estimated coefficient equation is : A(?)=M. The residuals of estimation have been worked out while the calculation of the population density of Dendrolimus punctatus is conducted as example. This method may be used to estimate the population density of agricultural and forest insects, the level of damage, etc.

In this study, main noise resource in CAB of the caterpillar skidding tractor 50 were identified by "elimination" and "spectrum analysis". According to analysed results, the multiple input/single output models with ear-side noise for output and other noise resources for input were respectively set up, programmed and calcutated by a computer to Solve the influence degrees of various noise resurces inputted on driver's ear-side noise. Some measures for reducing main resources were adopted, so that the value of driver's ear-side noise is decreased by 5.5dB(A). The restults can provide effective means for reducing the noise in the CAB.

This paper mainly analyses the causes of making Populus davidiana small-diameter timber collapse. Scanning electron microscope was used to examine the change laws of the structure of timber collapsed. The results support the hydrostatic theory of collapse.