1. Unfertile flowers and low fruiting ratio are the important sources for low yield of C. Oleifera. The cause of low fruit ratio are to be found as following. (1) Dates of onset of blossoming period are not unified even in the same stand. (2) Date of blossoming in period is too late. (3) The existence of sterility plants.2. The fruiting ratio is affected by the characteristics of material parent, but difference in mating compatibility still exists. It follows that only pay attention to the characteristics of material parent, at primary selection, can not greatly influence yield.3. There is no selection particularity of fruitful plants to the pollens of male parent. Therefore, high yield is always obtained no matter what pollens of male parent mated with.4. There are some successive low yield plants with low fruiting ratio in the C. Oleifera population. They always gains lowest yield no matter what pollens of male parent, they mated with. It is considered that the low yields of this type of plants due to their poor heredity and fertility.5. Rainfall during the blossoming period greatly influences the yield of C. Oleifera fruit. Less raindays and lowe Precipitation of florescence then normal year will bring higher yield, while heavy rainfall cause lower production.6. The yield of C. oleifera is related to the date of onset of blossoming period. Plants with full florescence before early frost yield 2.9 times as those after early frost.

The purpose of this study was to research for a available method on the population dynamica and outbreak forecast of the pine caterpillar (Dendrolimus punctatus Walker).Based on the results of the prevenient studies, we made an integrated analysis on the relationships between population dynamics and the enviromental conditions which include habitat, climate, food and natural enemy factors, etc.The different conditions of injury of the host plant (Pinus massoniana Lamb.) intimately influence the gradation, mortality, fecundity, migration and parastic percentage of the present and subsequent generations. The results of all these influences were reflected in the reptoductive capacity.The mathematical model of the population dynamics is put foward as:Where N_t=population density at t generationsN₀=prime population densitye^k=reproductive rate from generation to generationt=number of generationsx=survival degree of pine needlesGenerally speaking, the precipitation in May (X₁) and the average temperature in Febuary (X₂) exerted a decisive effect on the occurence of outbreak in Jiangxi province. In addition, the back-cold in early spring, rainstorm and the long-lasting dry climate are the limited factors to the population dynamics. The criterion function Y=0.048X₁+0.341X₂ and the critical value Y_c=4.240.

Cunninghania lanceolata Hook is an important endemic timber species in China and has been widly planted in the subtropical region of China. The conditions of climate, topography, soils and growth rate, annual imcrement are quite difference in different areas. For properly extending of Chinese fir plantation, its commercial timber production areas suggested based on conditions of natural environment, its growth behavior and traditional production 3 zones and 6 regions have been recognized. They are northern zone; western region, eastern region; Central zone; eastern region, central region and western region; southern zone with one region. At the same time, the potential productivity is also estimated for different regions and zones.Accoding to the growth condition 14 main commercial timber production areas have been suggested.

Natural decay resistance of 161 Chinese timber species (136 hardwood species and 25 softwood species) against white rot fungus, Polyporus versicolor Fr. and brown rot fungus, Lenzites trabea Pers. ex Fr., was determined by sand-block method in laboratory. The classes of their natural decay resistance can be arranged as follows:Cryptmaeria fortunei, Cupressus funebris, Fokienia hodginsii, Larix gmelinii, Castanopsis hystrix, Cyclobalanopsis chungii, Homalium hainanenses, Madhuca haiannensis, Quercus chenii, etc. are designated as class of very durable.Ketelecria fortunei, Pinus yunnanensis, Tsuga dumosa, Albizzia julibrissin, Juglans mandshurica, Querous nongnolica, etc. are classi-fied as durable class.Picea koraiensis, Ailanthus altissima, Albizsia falcata, Betula alnoides, Camptotheca acuminata, Casuarina equisetifolia, etc. are classified as moderately durable class.Picea jezoensis, Alniphyllum fortunei, Castanopsis carlesii, Liquidambar formosana, Populus davidiana, etc. are classified as perishable class.From the results obtained here, the specimens weight losses caused by brown rot fungus (Lonsites trabea) appeared lower than those by White rot fungus (Polyporus versicolor).

As the relationship between the crop (wheat) yields and the microclimatic factors has been investigated, a multivariate regression equation of yield with these factors is established.The main points of analysis are as follows:(1) A reduction of 1m/s of wind speed at a given plot caused by the shelterbelts may increase the crop yield by 18.75gm/m² (25 in/mu) and raise the average weight of a thousand grains by 0.74gm/1000grains at that plot.(2) A reduction of the saturation deficit of the air by 1 mb caused by the shelterbelts may increase the crop yield by 6.81gm/m² (9.1jin/mu) and raise the average weight of a thousand grains by 0.17gm/1000 grains.(3) A reduction of 1% of solar radiation caused by the shadow of the shelterbelts may decrease the crop yield by 5.47gm/m² (7.4jin/mu) and decrease the average weight of a thousand grains by 0.07gm/1000 grains.(4) An increase in moisture content of soil by 1% (wt w. r. t. dry soil) due to the reduction of evaporation caused by shelterbclts will increase the crop yield by 17.27gm/m² (23 jin/mu) and the average weight of a thoundsnad grains by 0.42gin/1000 grains.

China has a large area. It's geographical environment (including reliefs climates etc)is very complex. So China abounds with forest types and soil types.According to natural condition, Chinese forest soils can be divided into three parts, namely: Eastern humid region, Meng-Xin arid region and Qing-Zang plateau.Ⅰ. In the Eastern region, the distributive rules of forest types and soils are: (from north to south)1. Brown coniferous forest soils under larch forests in Daxinganling mountainous forest areas.2. Dark brown forest soils under mixed forests of pine and deciduous broad-leaved trees in eastern part of Northeast forest areas.3. Cinnamon soils, brown forest soils under deciduous broad-leaved forests and xerophilous pine forests in Northern China forest areas.4. Yellow brown forest soils under mixed forest of everygreen and deciduous trees in Qinling and Daiba mountainous forest areas.5. Red soils and yellow earths under evergreen broad-leaved forests in Southern China forest areas.6. Laterite, mountain lateritic soils under the tropical monsoon forests and mountain rain forests in Hainan island and the southern Yunnan province.Ⅱ. Meng-Xin arid region, its forest types and soils are:1. Mountain gray forest soils under larch forests in the southwestern aspect Aertaishan mountainous forest areas.2. Mountain gray cinnomonic forest soils under spruce forest in the northern aspect of Tianshan and Helanshan etc. mountainous forest areas.Ⅲ. Qing-Zang plateau is a special natural geographical area with complex forest types and soils, such as mountain gray-cinnamonic forest soils, Mountain dark brown forest soils, mountain brown dark-coniferous forest soils under dark needle-leaved forests. Mountain yellow earths under evergreen broad leaved forests.In this paper, discussions about the evaluation of productivity of forest soils in main forest areas of China are also presented.

Phyllostaohys bambusoides is a native in central and southeast China. It was introduced from China as an economic plant into Japan, Korea, United states of America, Britain and Soviet Union in different times. In recent times, the massive flowering cycle of this bamboo took place all over those areas. Bamboo blossomed in Japan earlier than those in other countries. In 1959, flowering began from the northern part of that country, and progressively widespread southward, than terminated in the early 1970. The flowering period lasts more than 10 years. In central and northwest China, flowering began in 1963 gradually spreading from northwest to southeast until 1979.After the gregarious flowering, the culms and old rhizomes soon withered completely, While the young rhizomes and the butt of young culms will still keep growing and maybe used for rejuvenation, and the new bamboo gradually recovered. By means of artificial stands have improvement of the growing condition, we can make the production of bamboos to reach the normal level within about 10 years.

This paper describes a new species of the genus Matsucoccus, collected from Pinus sylvestris var. mongolica at Tahe virgin forest in Heilongjiang province in June, 1980.Matsucoccus dahuriensis Hu et Hu sp. nov.Adult female mounted specimens enlongate evoid, length 3.7—4.3mm; greatest width 0.18—0.19mm. Mouthparts wanting. Antennae 9—segmented, with pairs of sensory spines on segments 6th to 9th inclusive. Eyes small. Nine pairs of spiracles, two thoracic and seven abdominal. Thoracic spiracles 0.25—0.028mm in diameter, the 1st abdominal spiracles 0.010—0.015mm and 7th abdominal spiracles 0.008—0.013mm. In adjacent to the thoracic and abdominal spiracles each with a small prominence. Dorsal cicatrices 0.006—0.010mm, in 4 transverse bands on the dorsum of 3rd to 6th abdominal segments, total mumber 91—131. Multilocular disk pores 37—51 in number, 0.013—0.015mm in diameter, with peripherical loculi 10—12 in number.Locality:Tahe Bureau of Forestry in Heilongjiang province of China. 20. June. 1980.This new species is closely related to Matsucoccus pine (Green) and M. insignis Borchs.,but can be separated from the latter in the follwing table:The holotype and one paratype were preserved in North-Eastern College of Forestry and 2 paratypes in Shanghai Institute of Entomology, Academia Sinica.

In this paper, Sphecia siningensis n. sp. (figs. 1—7) from Qinghai province of China is described.This species closely resembles S. oberthiiri Le Cerf, but may esily be distinguished from it in the following characters:hairs on vertex of the male almost cinereous, posterior hairs on vertex of the female cinereous. Metathorax thickly with green-yellow hairs. Tergum of the 3rd abodominal segment with broader yellow band, no narrow erythroic margin. The ventral side of the abdo-minal segment yellow, with cinereous margins to each segment. The genitalia is as shown in figs. 5—7.Holotype: ♀, Sining, 1978. Ⅷ. 15; Allotype: ♂, Sining, 1978. Ⅷ. 15; Paratype:16♂♂, 19♀♀, Sining. The specimens are deposited in the insect collection of the Forest Research Institute, Qinghai Academy of Agriculture and Forestry.

Dothiorella gregaria Sacc. Attacked poplars severely. The canker disease distributed widely in China. Usually, the disease forms blister-type patches and cankers on the stems and branches of poplar, and may yet cause dieback and kill adult trees in a few years.The disease starts in early of May, and reaches its high peaks of occurrence twice in the year, i. e. the first peak comes in July, and the second in September. The pathogen overwinters from November up to next April. The mycelia hibernate in the old disease patches and become the primary sources of infection.A temperature of 18—25℃, and a relative humidity above 80% will be favourable for development of the disease. As mentioned above, the optimum tempereture and relative humidity were the main enviromental factors which influenced the development of this epidemic.The fungus has a wide hostrange. There is a significant difference on the resistance and susceptibility among poplar species. Poplus usbekistanica cv. 'Afghanica', and P. pyramidalis×P, berolinensis are severely susceptible; P. 'Pekinensis', P. usbekistanica cv. 'Afghanica'×hopeinsis P. simonii are middle; and P. tomentosa, P. pyramidalis, P. alba cv. Pyramidalis, P. 'Opera', P. dakuanensis, P. euramericana cv. 'Robusta', P. euramericana cv. 'Marilandica', poplar 15A (Populus sp.), P. euramericana cv. 'Gelrica' are lightly suscepitable; and P. euramericana (P. canadensis), P.×euramericana cv. 'Regenrata', P. pyramidalis×nigra, and so on are resistant.

Growth and net assimilation rate (NAR) were measured periodilly during the first year of growth of masson's pine seedlings grown in wooden boxes under field conditions. The main tesults obtained are as follows:1. Two distinct maxima of the NAR curve were shown in the annual growth of the seedlings. The first maximum appeared during the rapid growth stage of root system between May 1 and June 8; the second, during the rapid growth staye of stem and lateral roots between July 8 and August 7. NAR and roots growth were positively correlated.2. The vegetative organs showed differentes in growth rate in different seasons of the year. From May 11 to June 8, root growth was foster than height growth of the stem. From June 8 to August, stem growth exceeded that of the root. After August the growth rate of leaves, stem and tap root decreased to a low level, while that of the lateral roots increased.3. Before early August, much of photosynthetic products was utilized to form the root system and leaves. After that period photosynthetic products were mostly used for the growth and development of the lateral roots and stem.