The paper deals with the growth performances of different ecotypes of Pinus tabulaeformis in three different elevation sites in Beijing mountain area. The 7-year-old results show that there are significant differences in growth performances among the ecotypes and the interaction between ecotype and site is also significant. In the sites below the elevation of 800 metres, the eastern ecotype is best because of its fast-growth and stable performances. The eastern ecotype, the central ecotype and the central-western ecotype are suitable for the sites with the elevation of 800-1200 metres. In the sites above the elevation of 1200 metres, the eastern ecotype and the north-eastern ecotype grow fast and have better performances. According to the results, it was put forward that the elevation differences between both the sites and the seed origins may not be considered if the seeds from the eastern ecotype are adopted in Beijing mountain area. Additionally, the seeds from the central ecotype and the central-western ecotype could be adopted in the sites with the elevation of 800-1200 metres as well as the seeds from the north-eastern ecotype in the sites above the elevation of 1200 metres on the condition that the seeds are in short supply.

Poplar 741 is a clone of hybrid from 4 different species: Populus alba ×(P. davidiana+P. simonii)×P. tomentosa. The regional tests and character analysis for 741 show that it possesses the following advantages: fast growing, high quality, straight and round trunk. its average volume of 4-9 year-odd trees is 240% higher than that of P. tomentosa and 12—169% higher than that of P. tomentosa f. yixianensis. Its wood basic density, compressive strength parallel to the grain, bending strength and hardness are much better than those of P. tomentosa f. fixianensis. Its adaptability is also studied in this paper.It is conasidered that 741 can be used to plant forest for wood and get the genetic gain.

The amount of pests on high trees is very difficult to be detected accurately. Thus the accuracy of prediction and forecast of the pests will be greatly affected by this reason. A vibrator which was developed by the forest Machinery Research Section of Nanjing Forestry Univesity was used to detect the amount and instars of the pine caterpillar of the overwintering generation in 1989. The height of the tested pine trees are from 5.0 to 10.2 meter and the diameter of them are from 15.0 to 25.0 centimeter. The vibrator mounted on the trunk was about 1.0 meter above the ground. After starting the vibrator, the trees were vibrated 5 times, each vibration lasted 30 seconds. and the interval between two vibrations was 5-10 minites. The average vibration fall rate of the pests was 85.4% with the highest rate up to 94.8%. The pests were easily to fell by vibration at the middle of fine days when the caterpillar were eating on the pine needles. The vibration fall rate could be used to calculate accurately the amount of the pine caterpillars on high trees. This method has many metits such as simplicity, accuracy, reliability etc. Hitting trees5.5-8.7 meters in height, and 13.3-19.7 centimeters in diameter with big stone for 10 times, the vibration fall rates are only 4.7-19.0%; and the method of calculating the larval amount by feces, is more complex and time-consuming than this method. In laboratory the frequency of the best effect was 20-30 Hz; starting instantaneous electrical current was 0.31 A; vibrating acceleration was 11.5 g.

The experiments of six different densities of artificial asphalt felt nest-boxes areas showed that the distribution patterns of laying nest-boxes of great tit (Parus major) deviated from random expectation in the direction of uniformity (R=1.1 to 1.4), as the same as the distribution patterns of established nest-boxes (R=1.2 to 1.6). The correlation between the densities of laying nest-boxes and the densities of established nest-boxes was not obvious (r=0.30). The suitable distance between established nest-boxes was about 30 to 50 m.It is easy to make asphalt felt nest-boxes and its cost is lower than that of the wooden nest-boxes The process of making asphalt felt nest-boxes was introduced and its suitabilities for great tits were discussed in the aspects of the average clutch-size and the survival of eggs and nestlings of great tits.

It is overelaborated in calculation and unconvenient for application to use the traditional working stress methed for calculation of loaded rope. This study suggests a admissible load designing method, which leads out a series of calculating formulas based on the parabola theory and works out a value table for loaded rope to establish a systematic admissible load designing method.

The effect of bacteria on the gas permeability of the air-dired sapwood and heartwood of refractory spruce (Picea, jezoensis var. komarovii) was investigated by pretreatment-ponding. The axial gas permeability of wood samples was measured with rising-water volume-displacement method. The results showed that a ponding period of 10 weeks in stagnant water not only notably improved the permeability of sapwood, but also increased the petmeability of heartwood, whereas the permeability of heartwood samples was not improved uniformly. Only 50 percent of heartwood samples was increased after ponding. The increase in permeability of sapwood and a part of heartwood were probably due to the attack of bacteria such as Bacillus brevis etc. Scanning electron microscopy suggested that tori in most of the bordered pits in sapwood tracheids were degraded, with the presence or the bacteria in the vicinity of the bordered pits in heartwood.

An increase in the bowing rate or slendereness raito of the member resulted in a decrease in the compression strength parallel to grain of the crooked log. The influence coefficient of the bowing rate on the strength between the species was different and showed a curve relation. It may be calculated by a formula of K=98d/(785h+98d)×a, where a is a function of the bowing rate C. The value of a can be confirmed by testing of different species. In this trial, the results are:In the case of C>2.5%, for Eucalyptus exserta a=C(0.61-0.04C), and for Pinus elliottii a=C(0.22+1.42/C). When C<2.5%, for E. exserta a=ln(1.8+1.22C), and for p. elliottii a=ln(2.1+2C)

The relationship between wood density and cutting resistance of 11 Chinese coniferous woods was studied. The main results obtained were: 1. The density-cutting correlation within the species was more significant in 90-90 cutting direction than in 0—90 and 90-0. The regression coefficient of the dellsity-cutting resistance relation within the species increased with an increase of the density of the species. 2. The density-cutting correlation among the species was more significant than that within the species. The regression coefficient of the relation among the species was close to the mean values of those within the species. 3. The effects of chip thickness, knife rake angle, and wood moisture content on the density-cutting resistance relation among the species showed a common tendency: the larger the mean value of the cutting resistance, the larger the regression coefficient. 4. Some phenomena were noted during the tests indicating certain characteristics of the scatter of the density-cutting resistance relation.

Soil temperature in or outside the humid evergreen broad-leaved forest in the Ailao Mountain of Yunnan Province were analysed comparitively in this paper. It was found that at the 0—80cm depth the average soil temperature, the daily and the annual ranges of the temperature were lower in the forest than that outside of the forest. It was particularly clear that at the surface layer, the effects of forest on decreasing the extreme maximum temperature and increasing the extreme minimum temperature were prominently. It was also shown that there were very close relationships between forest soil temperature (D) and air temperatures both in (T₁) and outside (T₂) of forest, and summarized into linear regression equations, in which correlation coefficionts were significant at the 0.01 or less level.

The development of understory in the Chinese fir stand in the Dagangshan, and the law of its biomass accumulation and allocation have been discussed in this paper. The relations of understory, the growth of Chinese fir trees, and site types have been expounded. The results indicate that understory develops quickly and its biomass could accumulate 4—5 t/ha in 4—5years. Therefore, it provides the scientific basis for further investigating how to use the understory and conserve and increase the Chinese fir forestland capablity.

The influence of aluminum in forest soil on the growth of Pinus massokiana was investigated in a tree farm by a new method in which three kinds of soil column were put in the holes near masson pine root system which would grow in it. The results showed that the pH values of soil column added aluminum sulphate to it were very low less roots were found and most of it had died. Whereas the pH values were increased in the soil column of adding calcium carbonate, and total aluminum and active aluminum were decreased, much more lateral roots and root hairs were found Some more related investigation should be continued further.

The indices of nutrient diagnosis of N, P, K elements in leaves of walnut tree grown in Qi county, Shan Xi Province were studied from 1985—1990. The results indicate that actording to the nutrient element contents of leaves, the nutrient indices are as follows: For nitrogen, optimum content is 3.82—4.76%, latent deficient content 3.06—3.76%, severe deficient content<3.06%, for potassium they are 2.59—2.61%, 1.94—2.49%,<1.94% respectively, for phosphorous optimum content 0.21—0.24%, deficient content<0.19%, luxurious content>0.24%. Therefore, the annual optimum requirements for N, P, K each tree growning in this experimental site are 0.75kg, 2.5kg and 0.25kg respectively.

The diurnal variations in the rates of net photosynthesis and respiration of Camellia sinensis grown under different environmental conditions were measured with GH—Ⅱ analyser. The results revealed that the diurnal variation in Pn in the intercropping system on sunny days in spring and summer was in the shape of an monopeak curve pattern and the maximum value was 10.44mg CO_2·dm^-2)·h^-1. However, in the control (monocultural tea system) Pn showed a bipeak pattern and the maximum value was 8.36mgCO_2·dm^-2h^-1. The daily average of Pn was 7.35mgCO₂·dm^-2)·h^-1 from April to July, which was 8.4% greater than that in the control. Light intensity was the most important ecological factor affecting Pn. The light saturation point of Pn was about 40—50 klx under natural condition. The rate of respiration of the leaves of C. sinensis was largely controlled by cemperatue. The temperature coefficient of respiration (Q₍₁₀₎) was about 1.5, and the maximum temperature about 32℃. The daily average respiration inteneity was 4.39mgCO₂·dm^-2)·h^-1, which was 14.0% less than that in the control.The daily average of transpiration rate of the leaves of C.sinensis was 4.04 g.g^-1(FW), and 23.6% less than that in the control. It was greatly varied with the light intensity and temperature. In the intercropping tea plantation, the chlorophyll b content of the leaves and the ratlo of spongy tissue to palisade tissue were higher. The leaves of the tea trees in intercropping tea plantations are thinner and with less stomata. However, the content of chlorophll (a+b) and SLA were not greatly varied with shade. Therefore, it was demonstrated that Camellia sinensis is a light-demanding plant and has fairly shade-tolerant capacity.

The contact toxicities of several pyrethroids and conventional organo-phosphates to Dendrolimus punctatus were tested by using microcapillary topical application methods. The results are as follows; pyrethroids showed very high toxicity, such as deltamethrin are 600 times and 1096 times more than dichlorvos and malathion; They are, so far, the most effective and economic insecticides for controlling the pine caterpillares. The pyrethroids are widely used in controlling forest pests in China from the beginning of 1980's. The resistance of Dendrolimus punctatus to pyrethroids has not appeared by 1989. But a tolerant difference was shown. Experimental showed that doses of initial applying compounds could be continually used in the forest area.

The pine sawfty, Acantholyda posticalis Mastsumura, is a destructive pest of Pinus sylvestris, P. tabulaeformis and P. koraiensis. It was found that Formica fukaii is an important predato of the sawfly in Heilongjiang Province. The nests are built on the ground, but some nests are built on Carex sp. About 1340 larvae can be predated by the ants in a nest per day. The habits, nesting means, and relocation of the nests are discussed.