The evaluation model(E=E_d+E_e+E_s) of the synthetical efficiency of water conservation forest in the Qilian mountains has been built up with the theory of Marxist differential land rent, taking the retio of E to I as the efficiency index T of water reservoir forest, T=E/I where I is production invesment. The material observed at the Qilian Mountains fix-position Research Station of Forest ecosystem and the data investigated from social are regarded as the metrological valuation parameters. The economic evaluation index and the metrological system have been determined. The results show that the index of the synthetical efficiency of water conservation forest in the Qilian Mountains is 11.93, among which ecological efficiency and social efficiency are 4.51 and 6.05 times as much as the immedinate economic efficiency respectively.We have affirmed that the management policies of protection, development and synthetical utilization are right at present, and various profitable departments in HeXi should return sum over 0.5% of total income from water efficiency to forestry department as reproduction cost in order to ensure the long-term development of national economic construction.

The authers researched the relations of photosynthetic rates with light intensity, CO₂ concentration and leaf age in P. deltoides (Ⅰ-69) and P. tomentosa by infared-CO₂-analysis method, and the daily and yearly progresses of photosynthetic rate of P. deltoides(Ⅰ-69) by improving dry weight method, as well as the yearly progresses of changes in chlorophyll content, specific leaf weight, single leaf area. It is shown that the light saturation point of P.deltoides(Ⅰ-69)is similar to that of P. tomentosa, but light compensation point is higher, CO₂ compensation point is lower than that of P. tomentosa. The higher net photosynthetic rate, more founction leaves and longer period of founction leaf of P. deltoides are the bases of more rapid growth. The two-peak curve of daily photosynthetic progress of P. deltoides even during the period of high temperature and moisture (July and August) indicates that P. deltoides is sensitive to water deficit. The yearly photosynthetic progress is also in two-peak curve, which appears in June to July and October respectivly. The lower photosynthetic rate of P. deltoides in August is related to its larger single leaf area, lower chlorophll content and smaller specific leaf weight. Otherwise, the lower mineral and nitrogenous nutration during quick growth period are the external causes for it.

According to the researches by the writer since 1983, relative data of 26 Chinese fir seed orchards throughout the country and scientific reports of other members of the high and stable yield cooperative research group of Chinese fir seed orchard in Zhejiang Province, discussion is made on selections of seed orchard site, genetic material and density of stocks and managing techniques before and after fruitage in this paper.The best site is the ordinary production region of this species, where there is not too much rainfall in pollination and frost damage in winter and where the sunny gentle-sloped low hill, well iso lated conditions, deep and mid-fertile soil, suitable moisture and well water drainage must be considered. The clones which have fruitage capacity above middle level and high genetic gains with the match of anthesis should be selected as the genetic materials. The density of stocks should be proper. It is necessary to concentrate on keeping high percentage of survival and straight stem of graft trees, and develop wide and light-penetrative crown by soil mana gement and make proper branch-cutting before fruitage. And pay much attention to soil and pollen management, thinning in time and controlling insects and diseases after fruitage. The seed orchard should be regenereted and reformed in time when the seed yield highly degenarate.

After the investigations for several years, it was found that the vertical distributional zones of pathomycetes in the forest plants of the Mr. Taibai,the highest peak in the Qingling Mountains, may be divided into four zones: 1) the lower mountainous and low-middle mountainous zone of leaf spots(Phyllosticta spp.) and powdery mildew on broadleaf forests; 2) middle mountainous and high-middle mountainous zone of rusts and saprogenic fungi on broadleaf forests; 3) middle-high mountainous zone of leaf casts diseases (Lophodcrmium spp.) on coniferous forests; 4) high mountainous zone of lacquerspot diseases (Rhytisma spp.) on bush-woods.

The larch sawfly Pristiphora erichsonii(Htg) is an impartant pest in North China larch(Larix principis rupprechtii Mayr). It has one generation a year in Ulanqab League, Inner Mongolia Autonomous Region and overwinters as prepupa in the soil or under the litter. When the canopy density of the larch stand is above 0.6, the use of aerosol at the rate of 0. 75kg/mu to control the larvae of 2—3 instars reached 70.1—83.2% mortality. The use of 25% Diflubenzuron Ⅲ at 20—30 g/mu by low volume spray in controlling 2—3 instars larvae reached 81.1—95.5% mortality. Digging the soil around the base of the tree in order to expose the overwintering prepupae reached 95.9% mortality.

The rheological behaviour in compression perpendicular to the surfaces of the flakes from three species-aspen(hybrid Populus), Larch (Larix spp.)and mongolian oak(Quercus mongolica) were studied in terms of the parameters including elastic deformation, instantaneous plastic deformation, retarded elastic deformation and time-dependent plastic deformation, as well as the engagement coefficient of the flake surfaces by the method of separating the rheological parameters. The measures of the creep, retarded elastic deformation and time-dependent plastic deformation showed that both of them were the functions of the logarithmic time lasting stress in compression, respectively. The measures of the elastic deformation and retarded clastic deformation had no considerable difference among various species flaks under the condition in same level of constant compression stress indicated by the stress-strain spectrum over a wide range of the stress levels. The engagement coefficient of flake surfaces showed that there were three turning points resulting in a max. value existing in some stress level and the parameter of the time-dependent plastic deformation had some differences among these three species flakes. The performances of the various compressbility of various species flakes were mainly attributed to the difference of the instantaneous plastic deformations of them.

The Electron spin Resonances of the stained wood infected by mold and blue-stain fungi were investigated. The results revoaled that pigments in the stained wood were originated from pigment radicals of fungi displaying very strong and stable ESR signals with g=2.0040±0.0002. They drowned signals of other free radicals originated from the same piece of wood. Their line shapes are lorentzian and homogeneously brodened. The pigmentations are correlated with free radical contents in both stained wood and fungi associated with proteins. These pigments have all the characteristics of biological melanins. Therefore the stains in wood infected by mold and blue-stain fungi were supposed to be due to the presence of melanins secreted by these fungi.

The principle of permeability control of wood was studied. The results showed that the main factors affecting permeability of wood were the effective radius and the number of pit membrane openings. The permeability of wood which has large and many pit membrane openings is high. The smaller an opening is, the bigger the capillary tension at the gas-liquid interface in the opening is and the more difficult the impregnation of wood with liquid is. An impregnation pressure which is equal to the capillary tension at the gas-liquid interface in the pit membrane opening and enough to overcome the tension must be applied to the wood when the deep impregnation of wood with liquid is needed. One effective measure to improve the impregnation of wood seems to increase the radius of pit membrane openings and their number in order to reduce the capillary tension and the applied impregnation pressure, and subsequently to increase the flow rate and the permeability.

Through a colaborative forestry project (ACIAR 8848)between the Chinese Academy of Forestry (CAF) and the Australian Centre for International Agricultural Research, a species trial was established in Southeast China in 1986 with 7 species of Casuarinaceae, Allocasuarina littoralis, A. torulosa, Casuarina cristata, C. cunnighamiana, C. equisetifolia, C. glauca and C. junghuniana, with 14 seedlots from Australia and 2 local lots. The trial was designed 4×4 square lattice with 3 replicates and 5×5 trees in a square plot. As land races, the two local seedlots of C. equisetifolia and C. glauca were used as controls. It was found from the research results that there were considerably significant differences in growth rates and survival between C. junghuniana and the other 6 species. Introduced to China for the first time, C, junghuniana has reached average height of 10.2m and dbh 9.7 cm at age 4.5, in comparison with stright stem form, dense crown and abounded litter, and started fruiting at age 3.C. cunninghamiana performed as well as the land races, C. glauca and C. equisetifolia around 6.0m tall and dbh 5.6cm. ,A. littoralis, A. torulosa and C. cristata ranged 4.5 to 5.2m in height and 4 to 6 cm in dbh with lower survival percentage of 20% to 60%. Perspectively C. junghuniana is of great importance in large scale planting, A. littoralis and A. torulosa will be possibly used as associates in plantations.

A pruning test has been carried out in a 12-year-old seed orchard of Pinus koraiensis clonal for heightening per unit yield of seeds at Cao He kou since 1981. The pruning technique which promoted fruitage obviously had been used in a intermediate trial. The results indieated that the pruning conducted one month before flowing of sap, cutting out the main shoot and maintaining 3 to 5 leteral branches among the upper branches to be used as future multi-branch of maternal tree, can yaise the fructification amount up 40% than that of the trees which were not pruned at that stage.

There is a large area suitable for high yield plantation of poplar in the cold semi-arid area in North China. But the wide utilization of good clones of P. euramericana and P. deltoides introduced in this area is restricted by the dry and cold climate. We have recently introduced 45 poplar clones from the high latitudes of Europe and America in order to bring the potential ability of this land into full play.We have selected 4 clones of P. eurmericana and 1 clone of P. deltoides through isolated raising seedlings, disease-resistant and coldresistant selection, as well as cluster analysis of growth figures of these clones. The average tree height of the selected clones is 14.5—16.8m in the 6-year-old plantation, the average DBH, 19. 5—22. 9cm, the average volume per tree, 0.1956—0.3126m, and the form figureof the stem, 0.4476—0.4650. The average volume increment per hectare per year of these clones is 46.3%—134.2% higher than that of control cultivar, P. Beijingensis.The yields level of poplar plantation in this area will be increased in a large degree as a result of the extension of these cold-resistant and fast growing clones.

Tilia amurensis and Fraxinus mandshurica are mainly natural associated tree species in Pinus koraiensis stands, Pinus koraiensis trees often develop into stand under the crown of these broadleaved trees.Therefore, study on the influence of mainly associated tree species on the growth of Pinus koraiensis is very important for understanding the community function of these tree specie and properly selecting associated tree species in building mixed forest of Pinus koraiensis. A lot of pot incubation tests were conducted in this study, in which Pinus koraiensis seedlings were incubated with leaf extracts of Tilia amurensis, Fraxinus mandshurica, Picea koraiensis, Pinus koraiensis or their leaf powder mixed in pot soil. Experimental results showed that leaves of Tilia and Fraxinus broad-leaved species could promot the growth of Pinus koraiensis seedlings obviously in comparison with needles of Pinus koraiensis and Picea koraiensis. For this reason, Tilia and Fraxinus were suggested as important associated tree species in planting Pinus koraiensis coniferous-broadleaved forest.

Determining the cutting age classes at each cutting time for maximum economic benifit of a planted forest within a planted period can be cosidered as an optimal control problem of an discrete system. According to the timber price, tending cost,reforestation cost, interest rate of bank, as well as the changes of these economic indexes during the whole planning period, each optimal cutting age can be ditermined by appling maximum principle, and the influence of these indexes on the cuttong ages can be also analysed.

Megastigmus sabinae Xu et He is the most injurious insect pest of the seeds of Sabina. It has one generation a year in Qinghai Province. The larva feeds on the embryo of seeds and overwinters as third instar larva. The peak of emergence of the adult is at last ten days of July. The temperature is an important factor directly influencing the growth and development of the pest. The insect den-sity are complete positive correlation with embryo numbers.

The dye Sudan Ⅱ 670 was used to spray on the pine needles for feeding the 4-instar larvae of Dendrolimus punctatus and D. tabulaeformis in the marking test. After the feeding, the fat bodies of the larvae appeared to be of blue colour obviously. Not only the marking blue remained in the fat bodies from larvae to pupae and adults of the present generation,but also they remained in the eggs and newly emerged larvae of the following generation. It can be distinguished by naked eyes. The marking agent does not affect reproduction and lifespan of the pine moth. It appears that this method can be used in the study of insect population dynamics caused by dispersal and migration.

It is considered more reasonable to form the three-letter abbreviation of woody plant family names by; (1) Using the first three letters of a family name; (2) using the first letter adding the following two consonant letters with the vowols ignored; (3) doulbllig the first letter followed by the letter before the aceae towards the end of a family name.