The continued planting of Chinese fir caused decrease in trees growth, druing 15 years old forest of the 2nd and 3rd times cultivation less 6.3% and 24.3% respectively in comparing with the first time cultivation. From the clear cutting of evergreen broad-leaf forests by burn and soil preparation to 15 years old the first time cultivation of Chinese fir forest caused the change of the soil fertility over three rotations as follows; the total amount of soil organic matter decreased by 45%; the total amount of N, P and K decreased by 38%, 42% and 32% respectively; the availability of N, P and K lessened 28%, 38% and 18% by order in rotations.The 3rd time cultivation of trees growing more slow, during the fast growing stage. Because the soil nutrients had been used in first two rotations. Therefore the stands of the 3rd cultivation was more open, thus influenced the ground vegetation, and the raising of soil nutrients, during the pole stage.There are about 174 specise in the stands of Chinese fir as undergrowth. The interspecific correlation coefficients of growth in every stands and in a certain stands showed Positive relation. Correlation coefficents of some species reached 0.4—1.0. In fact, continued planting of this species could not changed ecological environment for plant growth. The environmental conditions suitable for natural regeneration of subtropical evergreen borad-leaf forests and for the growth of many plants species also. If take effective steps to stop buring organic matter of the site, and carry out proper soil preparation in patches as well as control of water and soil erosion the site productivity can be maintained.Finally, accoding to physico-chemical properties of soil and topographical factors applied mathematical statisies forecasting stands periodical productivity of continued planting of this species significant value reached 0.81 of partial correlation coefficient.

Through field model experiments and simulation methods; the shelterbelt porosity of shelter lattice for the China farmland plains was discussed in the paper. The results showed that the best shelterbelt porosity was between 0.3 and 0.5, the optimum porosity for the farmland protection was 0.35. The results also indicated that, if the vector composition simulation of wind speed was applied, it would be useful for the designing and planning of shelterbelts.

Through sixteen years of introduction and acclimatization and two years of experiments on provenance, the results of Larix principis-rupprechtii have been obtained in the forest region on the north slope of Qilian Mountains. The growth of Larix principis-rupprechtii is 1—2 times as fast as that of Picea crassifolia Kom. During the period of its early growth. It has proved that this species suitable to the shade or half-shade slopes in the forest region of Qilian Mountains at the altitude of 2000—3000m.

The provenances of Ulmus pumiea L. can be divided into six provenance regions in China by observating experimental forest for 8 years. The volume of prorenance breeding value (Z) increased by 150% selecting appropriate provenances. Family selections have been evaluated using selection index (I₁), and ecological adaptation movements of provenances by means of ecological adaptation index (q_(ij)). Meantime, the heritability stabilities of character and the areas of experimental plot have also been analized in this paper.

This paper makes an analysis on the weather condition and physical climate effects, which cause the formation of icing in Hunan mountainous forests. After making a study on the differences of leaf-canopies, leaf and needle shapes, quantities of leaf and needle, branch shapes, forest structures and heights of altitude of various forests, the author put forwards some views of preventing from the icing to forests.1. Chinese fir plantations should be made mainly plantations of smaller acreage and to build up seperate forest belts with broad-leaf tree species in between.2. To carry out final felling at proper time and adopt appropriate cutting method.3. Masson pine should be planted in the altitude range of 300—500m, Chinese fir 700—1000m, bamboo 900—1300m or below 400m.4. To speed up the re-built of existing coppice forests.

Schima superba was grown in greenhouse. The rate of photosynthesis and leaf conductance appeared to change in parallel in response to change of light intensity in lower photon quantum flux intensity. A photosynthetic rate of 10 μmol m^-2s^-1 was measured at 24 to 26℃ and leaves were light saturated by 0.7mmol m^-2s^-1. The photosynthetic optimum temperature was 24 to 27℃ and photosynthesis decreased more rapidly at leaf temperature above 30℃, which suggests that photosynthesis under field condition may be limited by the high temperature observed in summer.The rate of photosynthesis increases with increasing intercellular CO₂ concentration and the CO₂ compensation point of photosynthesis was with a value 35μl·l^-1.CO₂ exchange in Schima superba was sensitive to change in leaf to air water vapor gradient. The rate of photosynthesis and leaf conductance decreased from 10 to 6.1μmol m^-2s^-1 and 0.12 to 0.05 mol m^-2s^-1, respectively. The decrease in photosynthesis rate was attributable to a decrease in intercellular CO₂ concentration.These results showed that Schima superba is a tropical species with humidity sensitive stomates and this phenomenon is quite common in tropical plants.

A series of experiments with a newly finding nuclear polyhedrosis virus of the oak caterpillar (Cyclophragma undans Walker) have been carried out. This virus, causes the larvae of the oak caterpillar lose their appetite and become slow in movement and yellowish brown in color after infection. The inne tissues of the dead larvae were fluidized and flowed out from the damaged skins which were fragile. The laboratory virulence tests showed that the mortality of the 6—8th instar larvae come up to 94.7% trated with 0.4×10⁸ PIB/ml CuNPV.Under electronic microscope the polyhedral bodies of CuNPV are tetrangonal, pentagonal or irregularly polygonal, and are measured to be 1.8—2.9μm, sometimes up to 4.0μm in size. Their protein lattice is of a pattern of regular dots and rows. The distance of two neighouring grides of the lattice is 4.40nm. The dots of the protein lattice are about 2.5nm in diameter. The virus bundle is enveloped by lax protein capsule with a thickness of 15—20nm. The polyhedroses are MEV, most of them have 2—4 virions which are rod-shaped and are measured 250—300×30—40nm.The viral DNA released from virions of CuNPV are found to be the circular or open circular molecules with countour length of 36.1 μm on the average. The molecular weight of the viral DNA is 71.12×10⁶ daltons.This virus as an insecticide is safe to vertebrates by experiments.

The discoloration of Paulownia wood has been a serious problem in logs after felling and in lumber during storage and drying, which leads to considerable reduction with regard to utilization. The components responsible for the discoloration were extracted completely from the wood of Paulownia elongata S. Y. Hu with aqueous ethanol before discoloration. The extractive was separated into petroleum ether, chloroform, diethyl ether, ethyl acetate and water soluble fractions. Simulation tests of discoloration were conducted on filter paper and wood veneer with all of the fractions respectively. The results revealed that the water soluble fraction discolored seriously and is responsible for the color change of redish-brown. Color reactions of water soluble fraction indicated that leucoanthocyanins and proanthocyanins are the components responsible for the wood discoloration. Other factors affect wood discoloration were also discussed briefly.

Chinese fir (Cunninghamia lanceolate Hook.) is an important wood species in China. The essential oil obtained by steam distillation from the wood of Chinese fir has been investigated. The components of the essential oil was identified by GC/MS. It has been found that there are 39 compounds in the essential oil in which cedrol is major compound. The purpose of this work is to study the natural resistance of the extractives from Chinese fir against the termite and fungus. The qualitative and quantitative method of damage test and the ability against both the termite and fungus of both the Chinese fir wood and its extractives are detemined by Agar-plate toxicity test and sandblock method in the laboratory.The results of this study are as follows:1. The ability of natural resistance the fungi (Lenzites brabea Pers ex Fr.) and the termite (Reticulitermes chinensis snyder.) is rather considerable. The loss of wood samples in weight attacked by the fungi is 10.1%. According to the classification of the natural decay resistance this level lies between class Ⅰ and Ⅱ (very durable and durable). The rating scale of natural resistance of the wood samples against the termites lies between class Ⅱ and Ⅲ.2. It is shown that the property of the natural resistance against the fungus and termite attributed to the cedrol and the other components of the essential oil. However the ability of the resistance is lower than that of sodium pentachlorideophenate and WP-1.

Being agreeable to some basic ideas in the paper "A discussion on the basic theory of site classification in China", some comments are put forward:1. It is indicated that the review of research activities in the field of site classification in China is not fully presented. The research effort which should be unique, suitable to the national specific conditions, must be based on thorough studies of the world experiences in the same field and their broad utilization.2. It is considered that the afforestation division is not subordinate to the natural division, but a part of forestry division as a sectional economic division. It is recommended that the achievements of the forestry division can directly be used as the base of site. classification.3. It is considered that the rules presented in the paper to divide the site type group according to their topographic factors and to divide site types according to their soil factors are not acceptable in all conditions. It is indicated that the minor differences within a site type are also the objects of study.4. It is necessary to study the basic theory of site classification, but it must be done with more abundant contents and deepgoing exploration.

Using Abies georgei as the experimentary material, trials of different sowing date, different daylight intensity(shade)and overwintering under various covering materials were carried out in 1982—1984 at the experimentary nursery of Xiao-Zhongdian Forest Service of Yunnan province. The results were as follows:1. Shade in a certain extent was necessary for seedlings of Abies georgei in the subalpine regions of Yunnan province and 30—70% of natural daylight intensity showed better effects on survivals of seedlings. The seedlings grown in dry season were damaged by the direct sunshine exposure. But the lowered intensities which were less than 15% of the natural sunshine irradiation caused bad quality of seedlings due to the insufficient photo-energy which affected the photosynthesis of the seedlings and resulted in low biomass.2. The biomass and growing speed of sown in winter were highest than in spring and summer, and the value of NAR was higher too, because sown in winter had a longer growing season and the NAR peak value was moved up and appeared on the second ten days of June, while summer seeding the NAR peak value appeared on the third ten days of July. it should be preached to seed in winter.3. The overwintering of seedlings of Abies georgei showed quite low percentage of survival, only 24.7%. The higher survival rate 88.8% was obtained under the condition that the seedlings were coyered with rice straw with 5—7 cm deep. This measure is feasible.

This article discusses the influence of intermediate cuttings on growth in height, growth in thickness, forest yield, maturity and locality according to the 13 years' test of intermediate cuttings conducted in larch plantation. The results showed that through the resonable intermediate cuttings, the height increment was increased by 19—57%, the diameter increment was increased by 30—104%; the mature age was shortened to 20—25 years; the economic benefit was raised by 50—100%. The test also proved that intermediate cuttings could not heighten the forest yield during the same cutting.

This paper discussed two problems concerning with the mangrove as follows:1. The distribution of mangrove species in the world was described. In which, there are 81 species belonging to 30 genera in 24 families.2. The composition of mangrove in the southeastern coast of China including Taiwan and Hainan Islands was described.Among them, there are 31 species, that is Acanthus ebrecteatus, A. ilicifolius, Acrostichum aurenm, A. speciosum, Aegiceras corniculatum, Avicennia marina, Barringtonia raeemosa, Bruguiera cylindrica, B. gymnorhiza, B. sexangula, B. sexangula var. rhynchopetala; cerbera manghas, ceriops tagal, Excoecaria agallocha, Heritiera littoralis, Hibiscus tiliaceus, Kandelia candel, Lumnitzera littorea, L. raeemosa, Nypa fruticans, Pemphis acidula, Rhizophora apiculata, R. mucronata, R. stylosa, Scyphiphora hydrophyllacea, Sonneratia alba, S. caseolaris, S. hainanensis, S. ovata, Thespesia populnea and Xyiocarpus granatus.

1. Most of the poplar twig clearinwg moths Paranthrene tabanieormis Rottenburg are univoltine in Beijing area. They hibernate as larvae in the tannels of the tree trunk. No apparent diapause phenomena was found in the larvae stage. In the case of proper temperature. They could take food at any time. Through the feeding of artificial diet, the larvae has been proved to be eight instar. The sex pheromone mass trapping of adult showed that emergence time varied with atmospheric temperature in a year. emergence begins in the first ten days of May and ends in the second ten days of October. Thus, it lasts for five and a haif months. To make a check against previous report, emergence of adult occurred 20 days earlier and its duration is prolonged for two and half months. Female moths often attract male moths by the sex pheromone-(E, Z)-3, 13-Octadecadienol.2. The poplar twig clearwing moth can do harm to all kinds of cultivated poplars and sometimes to willows. The degree of harm depends on the morph adaptability and back woodify level of poplar; site class; canopy density and the number of insect's source.3. To spray a contact insecticide upon poplar repeatly during adult's emergence time was found to be effective. But this method influences the reproduction of the natural enemy and contaminates the environment. Therefore, sex pheromone was used to surround mass trapping, and spraying freaquency was decreased. In the area of a few insect's source only mass trapping of sex pheromone was used. In a good isolation area the trapping of male moths continues for years and the rate of harm was lowered greatly.

Macrotermes barneyi distributes in the provinces south of Changjiang River. It lives gregariously in caves underground. The depth and diameter of the nest is generally 50—200cm and 30—80cm respectively. The colony does not produce replacement reproductive. Eight years after the construction of the nest it begines to separate into smaller colonies, which is the main way to scatter. The longevity of the colony is over 30 years. Large, medium and small soldiers could be found in some colonies.The species eats variously. Because climate affects the damaging behaviour, the behaviour has three summit period, i. e. separating into smaller colonies, resurgence (out of nest to gather in rain) and storing food. The density of nests in forest has a close relationship to soil, but the damage index does not. It varies with vegetation, quantity of bush, the ingredient of the forest and forest management. Whether the afforested trees and main trees composing forest are eaten or not depends on if they contain good or superior nourishment.This termitecan be controlled with Baythion and other chemicals, or natural smoke agent such as Xanthium sibiricum. But the most effective lies in decreasing nourishment of the trees.

The fasciated disease of Chinese Toon (Toona sinensis (A. Juss.) Roem.) was found in Zi Yang county of Shanxi Province, China. Electron microscope studies showed that the mycoplasma-like organisms (MLO) exist in the phloem tissues of the diseased plants and not in those of healthy ones.

The resistant mechanism of Chinese fir [Cunnighmia lancelata(Lamb.) Hook] to spot anthrancnose (Colletotrichum gloeosporioides) was studied using localizations of POD and PPO. An activity increasing region of POD and PPO in front of the hyphae developed region was noticed and region moved outward continously as the lesion developing. This was a suggestion of host resisting the fungus infection.