Through a study on the effects of different types of natural forest in two districts of the Loess Plateau on physical properties of soil, research results indicated that (1) in both districts, average contents of coarse sand (1.0—0.5mm in diameter), medium (0.5—0.25mm) and fine (0.25—0.05mm) in the top layer of the soil showed the following sequnce: forest land>bush land>farm land; similar sequnce also obtained on the soil profile despite varying with soil depth; (2) average contents of coarse silt in the top layer of the soil were appeared in the following order: bush land>forest land, young stands>middle-aged stands>mature stands while the total contents of medium and fine silt were adversely; (3) average contents of physical particales of clay in the top layer of the soil were in the order of forest land>bush land, mature forest stands>middle-aged stands>young stands; (4) the contents of soil moisture were arranged in the following sequnce: forest land>bush land>farm land.

Through studing on physical characters of Sampium sebiferum in Guizhou by means of gas (liquid) chromatography, infrared and atomic absorption spectroscopy, and streening electron microscophy, 2 fine varieties have been screened out. The oil contained in S. sebiferum can be divided into two kinds: wax substance oil and stillingia oil. The research results show as follows:(1) The two kinds of oil are mainly triglyceride. Most of the fatty acids contained in the wax substancc oil are saturated fatty acids, while most of them in the stillingia oil are unsaturated one. There is a positive correlation between the oil content of whole seeds and the percentage of wax substance oil, and palmitic acid in the wax substance oil has a negtive correlation with oleic acid.(2) There are 14 hydrolytic amino acids in wax substance oil, which make up p.4—1.0% of the wax substance oil, 17 hydrolytic amino acids in stillingia oil, which account for 8.5—21.4%.(3) Many trace elements in the seeds and their coat oil (wax substance oil) are necessary for human bodies, among which K, Fe and Zn contents have significant correlations with the quality, species of S. sebiferum, as well as seed harvest time.(4) The seed microstructure of one S. sebiferum variety is different from that of other varieties.(5) The influences of seed harvest time and storage life on the qualities of the wax substance oil are obvious.

The male sterile plant of C. lanceolata Hook. was found by us in Zhejiang province in 1978. This paper descfibes a seties of studies on the morphology, physiology and biochemistry of the microstrobilus of the male sterile plant of C. lanceolata. The male sterility of C. lanceolata belongs to the pollen-free type. The direct causes of the male sterility of C. lanceolata may be that the tapetum disintegrates in advance and that the microspore mother cells call not finish meiosis. The female cone of the male sterile plant can blossom, pollinate and bear seeds normally. During the genesis and development of the microspore, the respiratory intensity of the microstrobilus in the male sterile plant is obviously lower than that of the microstrobilus in the male fertile plant. There is a significant difference in the charts of peroxidase isozyme between the male sterile and fertile plants. It shows that the bands of the former are always more than that of the latter It is suggested that there exists the male sterile cytopleam gene in the male sterile plants, which can influemces the normal function or/and regulates the expression of nucleal, genes that coded the peroxidase isozymes, and the discordance between nuclear gene and cytopleam gene can result in the male sterility

According to the rules of development of poplar canker, caused by Dothiorella gregaria Sacc., the multivariant linear stepwise regression prediction model was established using method of multivatiant statistics with factors as disease index (Dis), pathogens (F₁, F₂, F₃), collect temperature(CT), ratio of temperature to relative humidity (TH), ratio of temperature to raina ll(TR) and ratio of relative humidity to rainfall (HR):Dis=19.0-F₃^1/2.8+0.1F₁+0.0015(F₂)³+4.15TH-CT^1/0.042-0.4HR+1.5TR.The disease index of the following a month could be predicted with this equation what was proved to be reliable by examination using actual disease index obtained in the survey.

This paper describes a new species of Tenthredinidae, which is a serious pest of the maple Acer truncatum Bge in Taishan Mountain, Shandong Province. The type specimens are deposited in the collection of forest insects in the Forest Research Institute, the Chinese Academy of Forestry.Messa acericola n. sp.Female Head reddish yellow, shining; apices of mandibles black; palpi yellowish brown; apices of first and second antennae reddish yellow, the rest segments black; eyes black. Thorax piceous; posterior angles of pronotum, regulae yellowish brown; juneture of prescutum and scutum reddish yellow; wings translucent; veins black; pterostigma pale yellow(fig. 1—2); legs yellowish brown. Abdomen piceous; central part of terga 1 with a yellowish white band; lancet see fig. 1—1. Posterior part of prescutum and abdominal terga with very rare and fine punctuations. Anterior margin of clypeus straight; posterior tentorial pits very deep; median fovea round and deep; transversal suture and lateral sutures distinct and deep; coronal suture indistinct; median ocellar basin rather deep. OOL: POL: OCL=5:4.5:4.Body length 3.7mm; antennae 9 segments; 8th segment:9th segment=0.07:0.14. Male unknownHost Acer truncatum BgeHolotype ♀, Taian County, Shandong Province (Taishan mountain), 1990. 6. 14, Liu Jing leg., 300-800m. Paratypes 10 ♀♀, Same as Holotype.The species resambles Mess glaucopis(Konow), but differs from the latter by the following characters: 9th antennal segment is more than one and a half times as long as 8th; hind femur is completely yellowish brown; antenna except for the first segment and apex of the second segment is black; the host is the maple Acer truncatum.

Dioryctria rubella Hampson is an important insect pest of the piney shoot, bud, cone and trunk. According to field observation and laboratory rearing, this insect has 2 to 3 generation a year in Zhejiang Province with early or middle and late instar larvae hibernating in bud, dead shoot or infested shoot. The adults of the overwintering, first and second generation occur from late April to late June, mid-September and late September to mid-October respectively. The larval boring habits in bud, shoot, cone and trunk and the relationship between the occurrence of the pest and the natural enemies of Macrocentrus sp. etc. were observed in the seed orchards of Pinus massoniana, P. elliottii and P. taeda.Experimental results showed that blacklight trap, spraying omethoate in early spring and punch-driping SN-851 were effective.

Vestured pits on the vessel wall in 26 species belonging to 19 genera and 3 sub-families Chinese leguminosae woods were investigated by SEM. Among them vestured pits in vessel, except 4 species, have been observed, Present or absent, shape and distribution of vestures are some valuable features for the identificatin of genera and species of Leguminosae woods. When wood sections (14 species) were treated with 5% sodium hypochorite, vestures decreased mostly or could not be seen. When the ultrathin wood section of one species was studied using TEM, it indicated that the electron. density is different between the vestures and the second wall, namely, different chemcal composition was shown between them. In addition, the formation, function of vestures and its relations with warts were discussed too.

The results from ofthogonal cutting tests in 0-90, 90-0, 90-90 directions for 11 coniferous woods showed that: 1) the effects of chip thickhess, knife rake angle, and wood moisture content on the main cutting forces for various species were basically identical, but quantitatively there existed certain variations; 2) the variations of the ratios Rt, R₂, and R_w expressing respectively the effects of chip thickness, rake angle, and moisture content were not significant among various species; 3) there were certain interactions among the effects of the three factors, which varied in different cutting directions.

Heat transfer of wood with the moisture content below the fiber satuation point was analysed by the liner theory of non-equilibrium thermodynamics. The results showed that diffusion of water vapour and bound water contributed to the heat transfer and thermal conductivity of wood consisted of one coefficient of heat conduction and two equivalant coefficients arising from the diffusion of water vapour and bound water. The expressions of three coefficients were derived by extended Siau's theory on heat transfer of wood and the principle of water sorption and fluid diffusion. It was found that the theoretical valuesl coincided with the experimental valuesfor tangential thermal conductivity of thirty-six wood spicies and radial thermal conductivity of twenty-three, respectively. The methods that have been used to analyse the radial thermal conductivity are also suitable for the longitudinal thermal conductivity.

Cortical turpentine compositions of 69 individuals from 10 Pinus armandi seed sources originating throughout the range were analysed in a provenance test forest by a gas chromatography-mass spectra-computer combined instrument. The results showed that the turpentine contained in the farks of P. armandi were mainly monoterpene and sesquiterpene. The content of diterpene was detected as minor constituent. The significant geographic vatiations between total amounts of monoterpene and sesquiterpene, including a-pinene dipentaene and hop alkene, and the latitutes of its provenance origin were observed. The trees from the Yunnan-Guizhou plateau seed provenance contained mainly monoterpene. On the contrary, the sesquiterpene was mainly contained in Qinling-Daba mountain seed provenance.

The seedlings of Elaeagnus angustifolia were planted in the nature saline soil and the sand culture of artifical salinization in different levels. The growth, photosynthetic and transpiration rate as well as the Na⁺ and K⁺ contents in leaves were determined. The results of field experiments showed that it could grow and develop normally in the saline soil whose salt content was 0.8-1.2%. Its photosynthesis and transpiration were normal. The experiment results of sand culture showed that 100mM NaCl had no influence on the growth of the seedlings, the Na⁺ content increased and K⁺ content decreased as NaCl content increased above 100mM. This showed that E. angustifolia could not exclude salt, but it hadan ability to salt toleranee. Moreover, the degree of leaf succelence increased under salt stress conditions which was the expression of preventing salt.

I-69(Populus deltoides Bartr. cl. "Lux" (I-69/55)) as a female parent was crossed with three different male parents in 1983. Three hybrid combinations were: I-69×I-63 (P. deltoides Bartr. cl. "Harvard"(I-63/51)), I-69×P. x euram. cv. serotina, and I-69 ×P. nigra(from Xinjiang), numbered as No. 34, No. 37 and No. 32, respectively. After nursery test 21 hybrid clones of I-69 half-sib family were selected out to continue field test in Mian County of Shanxi Province in the fall of 1985. I-69 and local mainly-cultivated P. x euram. clone were used as two controls. After four growth seasons, the results indicated that: the height and DBH of the clones of combination No. 34 was significantly higher than that of combination No. 37, No. 32 and local P. x euram. clone from age 2 to age 5; based on all clones (23) tested and clones (21) of I-69 half-sib family, the estimated value of broad-sense heritability(h²) of height and DBH increased as age increaed, ranging from 0.50 to 0.56 at age 2 and from 0.85 to 0.95 at age 5; however, the estimated value of broad-sense heritability of height and DBH was low for full-sib clones(14) of hybrid combination No. 34. Twenty-three clones tested were divided into three groups using the method of systematic cluster analysis: (1) fast-growing and high resistance to B. horsfieldi(G1), including three clones such as 34-17, 34-135 and 34-314; (2) fast-growing but less resistant(G2), including twelve cottonwood clones such as I-69 and 34-301, etc.; (3) growing slowly and less resistant(G3), including eight eurameicana poplar clones. The difference of resistance rate to B. horsfieldi between G1 and either G2 or G3 is statistically significant. Mainly taking the resistance into account, clones 34-17 and 34-135 (resistance rate 100%) were combined together named Nan-kang No. 1, clone 34-314 (resistance rate 87.5%) was named Nan-kang No. 2.

Tilia amurensis Rupr. is a commercially valuable timber species in natural forest in northeastern China. The resources of this species have become seriously reduced because of over cutting and not regenerated properly. During the periods 1983—1985 and 1988—1990, the research was carried out on techniques for raising seedlings of this species, including seed quantity of sowing, density of seedlings on the bed, growth and development of seedling and nursery managment. The research results indicated that the proper quantity of the seed sown was 126—157.5kg/ha, the optimum density was about 420,000 seedlings/ha. The growing period of one-year old seedlings of T. amurensis was 130—140 days and the practice of nursery management was also suggested

In 1988, a nuclear polyhedrosis virus of Parocneria orienta Chao was isolated in Nanping, Fujian Province, China,by scanning electron microscopy. It was shown that the inclusion body was a hexahedron, with a diameter of 0.61-2.69 μm. The virus was singly embedded rod-shaped, with a size of 48—72×320—376 nm. The LC50 values for early second-instar to fifth-instar larvae were 5.455 × 10⁴, 2.036×10⁵ 2.933 × 10⁵ and 1.438 × 10⁶ PIB/ml, respectively. The LT50 decreased with the increasing virus concentration.

Predators were major mortality factor of natural population of the pine moth, Dendrolimus punctatus Walker during its latent period. Birds, spiders, ants, true bugs and preying mantids were primary predators of the pine moth. Eggs, mature larvae, pupae and adults were mainly attacked by birds as Parus major commixtus Swinhoe; immature larvae were mainly preyed by arthropod predators such as Oxyopes linealipes L. Koch., O. seriatus L. Koch., Poyrhachis dives F. Smith, Formica rufibarbis sinae Emery., Velinus nodipes (Uhied), Lsynadus obscurus (Dallas). The mortality caused by predators was so high(95—100%) that the life cycle of the pine moth was not completed under certain circumstances.

In order to investigate the effects of wood species and wood moisture contents on cutting force (P), sawing power (N) and specific power (K) of circular rip sawing, Nine wood species grown in northeast district in China were tested at constant cutting speed and feed speed. Quantitative comparison among the cutting indexes of the 9 species was made, and the defference between the effects of moisture contents of Picea jezoensis and Tilia amurensis was illustraed and discussed.