Populus bollena was very seriously subject to the broken and rotten trunks which urgently needed to be overcomed in forestry operations. Through investigation, it was found that there was a strong disease resistant variant of Populus bollena which was characterized by smooth bark with smaller lenticels on it.Combined with cultivation experiments, analyses were carried out to identify the structure, physiological and biochemical properties of the variant, including water status, permeability of protoplasmic membrance of cells, pH, quntity of phenal, carbohtdrate, cellulose, protein's fat and activity of phenaloxidase, hydrogen peroxide ensyme, and peroxidase.The result of analysis showed that the variant of Populus bollena with smaller lenticelle was more resistant to cold conditions and disease than those with larger lenticelle. It would be a new way select and to use the natural variant to solve the problem of broken and rotten trunks of Populus bollena.

Successive cultivation of Chinese fir (Cunninghamia lanceolata) monoculture has resulted in site degradation, productivity decrease and widespread of diseases and pest in South China. Thus in 1977, we introduced a dozen of tree species to Zhuting, Hunan Province, in order to select the appropriate species for planting. This report is based on the research results from a part of the project. Data on growth, structure, biomass and ecological parameters of three stands were collected in 1989 and 1990. The results showed that Chinese fir interplanted with Fokienia hodginsii, (Fukien cypress) on poor sites helps maintain soil fertility and site productivity in long-term, promote its growth and establish a stable, man-made forest ecosystem, The total biomass of a 14-year-old mixed stand is 79.58t/ha, 22.9 percent higher than that of pure stand of Chinese fir. In the view of economics, ecology and aesthetics, the mixed stands have several advantages over the pure stands of either Chinese fir or of Fukien cypress.

According to the observations in Xishan Area of Beijing in 1985—1991, the population of Dendrolimus tabulae formis was in a state of low density successively with an average of 0.4—11.7 larvae/plant:4. 2 larvae/plant in 1985; 11.7 in 1988; 0.5 in 1991. During the past 7 years, the average annual parasitism of Casinaria nigripes was 25. 22± 11.14%. The parasitism rate was negatively proportional to the host density, y= 34.406 1.909x, r= -0.925. If the parasitism rate was high than 25% in this year, the population density of D. tabuiaeformis would lower down in the following year. There were two parasitism peaks, which appeared in 1986 and 1990 respectively with an interval of 3 years. There was an interspecific competition existing between C. nigripes and Carcelia matsukarehae, In the year when the parasitism rate of C. nigripes was high, that of C, matsukarehae would be rather low or even zero. The number of overwintering larvae of D. tabuiaeformis parasitized by C. nigripes, which began to be active earlier after hibernation, was more than that of the parasitized D. tabuiaeformis, which began to be active later after hibernation. The alternate hosts of C. nigripes in the field are Malacosoma neustria testacea, Lymantria dispar and Ivela ochropoda. It has 4—5 generations in a year in different species of hosts. Its overwintering host is D. tabuiaeformis. The population of C. nigripes was influenced by these factors such as alternate hosts, hyperparasitism and high temperature in summer. The seasonal population dynamics is like this:its population is more in spring, and it decreased significantly in summer, and it rises again in autumn. According to the observations, it has exerted an obvious suppressive function on the number of D. tabuiaeformis at low density.

Curculio hippophes Zhang, sp. nov.Body longishoval. Rostrum, antennae, elytra, tibiae and tarsi reddish brown; pronotum sepia. Rostrum of male much shorter than body (1:1.93), and of female shorter than body (1:1.49). Rostrum with several carinae from ante nnal scrobe to the base. Antennae inserted in the middle () or in the basal third () of rostrum. Antennae with scape thinly long, as long as 6 () or 7 () basal segments of funicle combined, funicle with first segment 1.2 times as long as second, third to seventh equal in length, half as long as first, club as long as four apical segments of funicle combined. Vertex thinly clothed with whitish hairy scales, with a little wider scales along inner margin of eyes. Prothorax transverse (1.34:1), widest at the base, basal. margin bisinuate, without median carina; pronotum covered with internally directing whitish and pale reddish brown hairy scales. Prosternum transverse canaliculated shallowly, densely covered with directing to transverse groove milky whitish scales a little wider. Mesepisterna, metasternum and legs thinly covered with yellowish white hair, mesepimera densely covered with whitish hairy scales. Scutellum evidently, densely covered with whitish scales. Elytra much wider than pronotum at the prominent rounded shoulders, and narrowing behind, and with broader striae, half of the intervals, elytra variegated with whitish and reddish brown hairy scales, several irregular oblique band formed of which respectively. Apical of all hairy scales cutback. Apical of pygidium with yellowish white setae. Legs with femora dentate.Length 2.67—2.83mm, breadth 1.21—1.50mm.Holotype , allotype, paratypes 2, 4. Long County (34.9 N, 106.8 E), Shaanxi, taken on 10. Ⅷ. 1989, by Chen Xiaoda and Dang Xinde.This new species is closed to C. hilgendorfi (Harold), but differs from it in length of body much shorter (C. hilgendorfi, 6-9mm); antennae with longer scape; elytra variegated with whitish and reddish brown hairy scales, forming several irregular oblique band.The type specimens are deposited in the Institute of Zoology, Academia Sinica

The determination of the mechanical behavious of the flakes in compression stress, from three popular species—hybrid Populus spp., Populus tomentosa, Populus euramericana cL'cima' showed that some different rheological characteres tics of significance existed among them. It could be consideral that the different rheological characteristics resulted in the different properties of particleboard from these popular species. The 0.35mm thickness flakes of hybrid popular with mechanical behaviour characerized by weak strength of spring back resulted in rapid increase of MOR and no considerable increase of IB with increase of board based on compression ratio from 1.2 to 1.5. In the range of high density of board, the dimensional stability decreased. When the thickness of the flakes were changed to 1.2mm, MOR and IB increased synchronously because of their stronger spring back strength. However, thicker flakes resuled in lower E-module and poor dimensional stability. The flakes of the other two species performanced rather better elastic behavour and lower engagement coefficient in compression stress than that of hybrid popular flake. The density of particleboard from the other two species with 0.35mm thickness increased in a wide range of compression ratio, both MOR and IB increased considerably, and the dimensional stability still keep in a stable level.

Forest recreation benefit is main part of forest public benefits. Affe analyzeing systematically the main measurement methods in the world the visitors were divided into 22 origin zones according to the different distance and the principle that the visitation ratio of each origin zone is 2 at least based on one year's sample survey, and one polynomial regression model of the population, average mouth income, travel cost and travel time versus the visitation ratio was established. Besides, the effect of each factor on the visitation ratio was also discussed, Both the Consumer Surplus Theory and the opinion proposed by Marx that the accumulation of working time is equal to the add of free time, were applied to obtain the recreation benefit of 16.9430 million yuan of the park in 1988. The benefit of five main tour lines of the park was also calculated.The research results not only provided a scientific basis for the exploration, investment and comprehensive economic evaluation of the park, but also had the practical meaning for the further benefit evaluation of the forest tourism.

The climate change prediction in China based on OCU model as well as summary analysis of GFDL, GISS, NCAR, OCU and UKMO models are used for discussing the approaches to predict the response of the forests in China under double concentration of atmospheric carbon dioxide after about 2020. The growth, production and distribution boundary of Chinese fir (Cunninghamia lanceolata), the tree composition and their growth in cold temperate Oaxingan Mountain region, and potential forest zones in China as examples are discussed in this paper.

Results of the study on productivity of plantation system of Castanopsis kawakamii at age 23 showed that stand biomass was 169.302 t/ha and 107.530 t/ ha for plantations with closed canopy on site class Ⅰ and Ⅱ, respectively. The biomass of tree layer for site class Ⅰ was 168.67 t/ha accounting for 99.57%, while, on class Ⅱ it was 105.47 t/ha accounting for 98.08% of the total. Index of leaf area of plantations on site class Ⅰ was 7.712 m²/m² and 5.74lm²/m² on site class Ⅱ. Within plantation trees with large diameter ed to have greater values in the distribution of organ biomass, especially in plantations for which early thinning were done on site class Ⅰ. It was also found that competitive index of individual trees was larger in plantations than that in natural forest stands. Theoretical value of stem biomass of intermediate trees in plantations was 124 kg that was 0.122—0.236 times of that for trees in natural stands, trees in plantations started rapidly growing 9 to 22 years earlier than those in natural stands. In plantations on site class Ⅰ the net production of individual trees was around 7000 kg/ha.a after age 13 and 5000kg/ha.a after age 16 on site class Ⅱ, but both appeared to be increased after age 23. Curves of annual and average net production did not crossed each other.

Based on interception process of forest canopy to rainfall, this paper derived a series of predictive interception models, including theoretical models, rainfall models, and seasonal models. Impact of last rainfall event on current interception loss was considered in these models. The concept of "interception per unit canopy area" was introduced, which might be helpful to compare interception abilities of different tree species, different developmental stages of one species, or the same stage/species in different climate conditions. At the end of this paper, the seasonal model has been tested with the data observed in plantations of Pinus tabulaeformis in Hebei province, northern China, and the calculated values fit quite well with the observed date.

The reliability, optimum age and genetic gain of early selection were studied on the basis of analysis of individual growth process, the competition and the differentiation in the plantations of Pinus tabulaefortnts Carr. By using 263 sample stem data. 85 % of over-15 years old dominants in the plantations and 81 % in natural stands reached or passed the age when the growth rate was maximum in the process. Differentiation in sample plots was most violent at the age of 3 to 9. All the correlations between ages after 15 were prominent. The suitable age for selection was later than 12-15.

In order to improve the quantity and quality of white poplar seeds produced by sexual hybridization, the branches of maternal plant were treated with rare-earth. The results indicate that there is a significant promotive effect on seed setting rate in the branches soaked with rare-earth at 200ppm or 500ppm concentration. The length and thickness of fruite ear are also promoted slightly at these concentrations. The effects of rare-earth treatments on the weight of 1000 seeds and germination rate are not obvious.

This paper deals with the control threshold of Ceracris kiangsu Tsai(CKT), a serious pest of Phyllostachys heterocycla var, pubescens(Mazel) Ohwi(PHPO), which is widely planted as an important economic tree in the south China.The leaf number and quantity of PHPO in different breast diameters and different life stages and the feeding quantity of CKT in one generation and different life stages was studied. The damage of CKT to PHPO was tested. Based on the oringinal data and the control economic factors, the control threshold of CKT was established. The main result was as follows, when defoliated rate of PHPO reach 10%, the damage of the growth and development of PHPO would take place, so when the density of CKT population reached that level, which could cause 10% lost of PHPO leaves, then the control to CKT was necessary. The CKT density that cause 10% lost of PHPO leaf can be calculated out according to the technique introduced in this paper, which coneides bamboo grove appearance, CKT quantity per m² or per individual bamboo tree and the investigation time to CKT respectively.

This paper deals with a set of techniques using trees [Morus alba L., Broussonetia kazinoki S, et Z., B. papyrifera (L, )Vent] as baits to control the adults of Apriona germari (Hope), which can prevent poplar plantation from being damaged. The methods, simple, economical and easily conducted, can segregate poplar plantation with pest and kill them before oviposition outside the poplar plantation. In the stands sprayed with insecticide there were at most 19 death adults in one clump of bait one day. It costed 0.084 Yuan (RMB) per mu. The mean yearly rate of trees injured reduced by 1.89%, The pest density stabilized with no increase or decrease. But in control stand the average rates of trees damaged and pest density enhanced 31.53% and 1.07 respectively compared with the stands sprayed with insecticide. The difference is very significant (statistical analysis).

In this paper presented is a new method to describe stem form of trees. A stem could be divided into sections in equal length and volume could be worked out for each section, then "relative stem ratio" (RSR) was defined as the ratio between volume of each section and the total volume of whole stem.This new concept, relative stem ratio, implicates not only volume, but also diameter. RSR could be used as an index of tapering degree, because it was reduced progressively in the direction of stem length. The most important founction of RSR is to denote various forms of tree stems as series of diagram in quite uniform, therefore the changes of stem form and volume structure can obviously seen from the diagram. 8 major species of hardwoods in Changbai Mountain were analysed using this new methodology, the results were coincident wich those obtained from multivariate analysis.

The diffusion coefficient D and the surace emission coefficient S are the essential physical parameters characterizing the water transport in lumber drying and storage. By using the separating method from a single drying ourve of wood specimens (Fraxinus mandshurica) in the same thickness, the time-variation parameters D and S were obtained in the study.The experiment visualized that both D and S were dependent on the moisture content of wood.The method suggested in the paper is easy in experiment and can obtain satisfactory results. Therefore, the method has the potential of applications in research and practical engineering problems.

In this paper a computerized database inquiry system for Identification, Properties and Uses of Tropical Wood from Southeast Asia has been established. The hardware environment for using this system is a set of IBM PC microcomputer or it's compatibles with MS-DOS. The programs of the system are written in Turbo Pascal 4.0 (Borland International, 1987) with English and Chinese two versions. 201 species of hardwood are included with the names (Chinese name, Latin name, Trade name and Local name), geographic distribution, wood anatomical features, wood properties (physical and mechanical properties, seasoning, nature durability and working qualities) and uses, the total 244 features belong to 18 categories for each species have been stored. The database inquiry system has the following main functions,1. Retrieval of tree species according to wood anatomical features,2. Retrieval of suitable wood species according to uses.3. Retrieval of provenances, properties and uses according tree species.4. Mutual retrieval of latin name, trade name and local name.5. Display or printing of the tree species collected and all the relating information.6. Remote international communication.