The paper reports the changes in carbohydrates contained in organic matter of soil in decomposition process of forest litters under laboratory conditions for 730 days. The results show that carbohydrates belonging to humus, existed in soil partiapate in decomposition and have been renewed, besides part of the organic remainders to be decomposed in this process. The amount of decomposition and renew deponds on the component of litters. Secondly, when the organic remainders decompose towards humification, the percentage of fucose, ribose, rhamnose and galactose orginated from microbe in humus fraction is higher than that in non-humus fraction, where as the percentage of xylose and arabinose originated from plants in humus lower than that in non-humus.

After a 5-year (1982-1986) experiment on the planting of Populus×xiaozhuanica cv 'popularis' in different time (planting once every 5 days during the month of April) in the dry-irrigated area in Dengkou county, the result shows that the most appropriate planting time is from 5-15 April. The effect of planting will be unsatisfactory, if it is planted after the date of 20 April. The differences for each item for planting in different times are as follows:1. Populus×Xiaozhuanica cv 'popularis' has acquired a property of sprouting, so that if it is planted earlier or later, the survival rate from 97% to 77%, the preserving rate from 95% to 74% respectively. However, there is no significant difference between them. But the different periods to carry out the planting has a very significant influence on the variation of sprouting rate (4.0-62.0%).2. The yield of wood volume per hectare for early planting (1-10 April) is 12.8-6.9m~3, whereas for later planting (20—30 April) is only 3.8-0.9m~3.3. It is important to handle the proper time for planting. We take the start of blossoming time of apricot as the forecast of the end of planting.

A preliminary study on the relation of the macronutrients in the bark of Populus tomentosa Carr., P.×euramericana(Dode) Guinier, P. nigra var. thevestina to Dothiorella gregaria Sacc. was carried out by using statistical analysis. The results of correlation analysis as well as principal component analysis show that the percentage of conidia germination of D. gregaria Sacc. and colony growth appear to be negative correlation with nitrogen, sulphur, phosphorus, calcium and magnesium, and to be positive correlation with potassium, nitrogen the effect of which is the most significant. Futhermore, the results from two-dimensoinal classification of samples show that there are significant differences in the contents of six macronutrients and the resistance to D. gregaria Sacc. amoug various poplar species, thus providing the theoretical basis for selecting poplar varieties with strong resistance to D. gregaria Sacc. In the early stage.

The inoculation of potted transplants with different water contents in the greenhouse showned that water deficiency was a predisposition of the development of the poplar canker. A close correlation was found to exist among phenolics, phenylalanine ammonia-lyase(PAL) and host resistance. In the healthy transplants with high relative turgidity values, phenylalanine ammonia-lyase activity increased, meanwhile, the contents of some phenolic acids measured by high pressure liquid chromatography were high. The results of plate test and inoculation experiments of potted transplants injected with catechol solution demonstrated that catechol was a major inhibitor in living bark.

Bioassay of JDS-CPV was conducted on the 3rd instar and 5th instar larvae of pine caterpillar D. punctatus. The regression equations between concentration and mortality for 3rd instar and 5th instar were Y=2.44+0.49x and Y=1.83+0.57x, LC₍₅₀₎ value were 1.6×10⁵PIB/mL and 3.3×10⁵PIB/ml respectively. The regression equation between the count of PIB and mortality for 3rd instar larvae is Y=1.72×0.98x, LD₍₅₀₎ value is 2.1×10³PIB/larvae. For example as 1×10⁸PIB/ml, the LT₍₅₀₎ value for 3rd instar and 5th instar larvae were 8.5 days and 13 days respectively. The results showed that the JDS-CPV has higher virulence to pine caterpillar.

This inverstigation, as a part of the plant and animal survey in the project on tropical forest ecosystem in Jianfenling mountain, Hainan Island, was conducted in 1981—1983. About 4000 insects have been collected, of which the Lepidoptera accounts for 50% and the Coleoptera and Diptera accounts for 13% and 11% respectively. The rest belongs to the other 17 orders. Take 26 families of moths for an example, the species of Noctuidae, Geometridae and Pyralidae are the dominant families, which accounts for 69% of the total collected moths. One character in population quantity is large in small population and small in large population. There are 17 dominant species, among which 10 species are in pyralidae, 4 species in Hypsidae, 2 species in Arctiidae and 1 species in Uraniidae. Most sp les of Acrdiidae and Pentatomidae have been found in tropical semidecidous monsoon forest and most species of Thrips and Moths in tropical mountainous rain forest. According to the composition of fauna, most species of Thripidae, Phlothripidae, Pentatomidae and Sphingidae are distributed in Oriental region. Some species local species in Hainan Island obtained are Antillothrips flavicornis Zhang, Dinothrips hainanensis Zhang, Agaeus tessellatus Dallas, Dabessus albovittatus Hsiao et Cheng and Rhagastis mongoliana pallicosta Mell. It may be concluded that the charateristics of tropical forest insects are abundant in species, less quantity for each species, more than one generation and no dormancy but diapause for widespread species.

Based on the matrix model of the growth of uneven-aged forest stand, the problem of the dynamic optimization of uneven-aged forest harvesting regulations is studied and a computer model associated is established for its simulation in this paper. The shortest and greatest-in-benefit cutting path for finding the ideal state from the current one of uneven-aged forest state can be determined in the computer model by means of a method extending regulation period. An associated software is then developed in the medium-size computer FACOM M-340S. In solving the problem of the dynamic optimization of uneven-aged forest harvesting regulations, the obvious advantage of the approach given here is centred on the determination of the feasible region and the shortest regulation time. The approach and software are considerably worth to the forest-managers in the harvesting decision-making and forecasting.

Based on some experiments, this paper has inspected the effects of the variations of the cutting parameters of the chain saw, such as the cutting speed, the thickness of cutting pieces of wood, the cutting length and the angle of the cutting. On the cutting targets and found the variance analysis results that the cutting parameters may affect some cutting targets such as the cutting force, the cutting power, the cutting productivity and the unit cutting work. In addition, by means of the stepwise regression analysis, a regression formula for only containing mainly affecting factors of each cutting targets has been defined. The formula is very important for the chain saw design and calculation.

For determining cutting properties of a certain wood species, the effects of related factors should be comprehensively analysed. The effects of related factors on cutting resistance and surface roughness within Korean pine and Manchurian ash were analysed with the linear modelling method and the relationships between cutting resistance, surface roughness and wood density were preliminarily studied.

Under 3-point sustained, un-symmetrical cyclic loading at constant temperature (18℃) and humidity (45—65% rh) condition but at various stress level from 20% to 100%, a group of experiments has been carried out on the creep behavior of birch laminated boards (LB) with 3 types of distinct assembly, which are employed in gymnastic vaulting-board. Results show that dynamic creep curves of LB are much analogous to those of many wood materials under static load. Using an iterative least squares computer program written by ourselves, the dynamic creep curves based on 3-and 4-element rheological model have been fitted to the 17 sets of data from specimens. Until 10⁵ cyclings, the 4-element model always provides the better overall fit to the data, for which the multiple correlation R² is more than 0.99 at each condition. The 3-element model seems appliable within the duration of delayed elastic stage, i.e. the primary creep region, in general.

Through the study and analsis to the forest standard cut in the past five years in Huitong County in Hunan Province, this paper proved that the Age-Class-Space theory and the Gentan probability method are of use for predicting yield of the collective-owned forest in China. A result of linear programming was provided in order to prove the feasibility of the Gentan probability method. The result proved there are not remarkable differences between standard cut from linear programming and standard cut from the Gentan probability when the planning period lasts a long time. Finally, the paper deals with some problems about the Gentan probability.

The research-work is carried out by stages generally, one stage per 3 to 4 years. The results of the 1st stage are as follows:The Pn of leaves of bamboos with different ages doesn't come out different obviously. But the Pn of leaves of different ages is notable changes. The Pn shows great changes during different periods within a day. In summer it is lower in the morning, while at 10—11 a. m. it rises to the highest, and it falls at noon. After noon it appears hollow and noontime snooze. In spring and autumn, the max. number of Pn in a day appears right at noon and without snooze. The influence of the density of light quantum on Pn is closely related to the time during a day, the positions of leaves and the physiological state of leave0s themselves. By means of measurements we can see that the light compensating point of bamboos is about 30 to 50μmole. The Pn is the lowest in winter, and the highest in automn. This is identical with the growth of bamboos and the increase of biomass.

The relationship between leaf area of crown(L. A. C.) and growth indices in a poplar plantation had been investigated from 1983 to 1986. The leaf area of crown and the volume increment raise with the increasing of water supply. The leaf area of crown is highly correlated with height(H), diameter(D), volume(V) and D²H of the tree. The heighest correlation is presented between leaf area of crown and volume (D²H). Some related problems were discussed in this paper.

The result of the test comparing Camellia oleifera clones is showed in this paper. The test was established on 13th, March, 1980 planting the nurse seed graftings grafted two months ago. There are 24 clones in the tost with offsprings from one clone as a control. Every clone has six plants in a spot, and there are six spots containing 36 plants for each clone. The distance from one plant to another is about 1.67 meters. The experiment field is about 0.5 hectares all together.The test indicates that the graftings generally began to flower in the second year after planting, about one or two years earlier than seedlings. There are a lot of differences between the graftings and the seedlings, even on the growth period and on the appearance of the plant. At the same time, it is easily to recorgnize one clone from the others. Most of the clones began to bear fruit aboundently in 1984. From 1984 to 1987, the average yield for clones was higher than the yield of seedling by 12.4%. Seven of them got much higher, even over 30%. Except that two clones were more sensitivity to some deseases, five clones were recommended as the better ones for the oil production. They are 51-27, 817, 12-6, 3-3, and 9-8. Their average yield reached 498. 21 kilogrames a hactare each year during the past four years.According to the test, we find that it is possible to select the best clones by noticing their growth characteristics, flower period, and the rate of oil containing in whole fruit if they bear fruit normally and free of the main deseases.

In a multivariate population, all the observed and studied indexes were expressed with marks, and all the marks were restricted with the rule of equal probability for equal mark. The quality and its ordering of a unit in a population were assessed according to the mark gained. The procedure was mainly used to establish a marking standard for a unit in a multivariate population.