Ginkgo biloba L.is a deciduous woody plant.The female plants and maleplants have different uses.It is therefore advantageous to distinguish the sexof individual plant before at flowers. Experiments performed in 4 successive years in our laboratory show thatperoxidase isozyme patterns are sexassociated.There are more bands in theyoung leaves of the female plant than in the male.When examining theperoxidase isozyme patterns in the leaves of trees with unknown sex,wefound there exist only two types:one agrees with the male,the other agreeswith the female.There are no intermediate types. The esterase isozyme pattern has nothing to do with sexuality.It istherefore considered that peroxidase isozyme pattern can be used as abiochemical test to distinguish the sex of individual plant in Ginkgo biloba L.

The water relations to annual growth in seedlings of Populus × euramericana(Dode)Guinier cv.Ⅰ-214,P.× euramericana(Dode)Guinier cv.Sacrau 79,P.deltoides Bartr.cv."Lux"(ex.Ⅰ-69/55),P.× euramaricana(Dode)Guinier cv."san Martino"(ex.Ⅰ-72/58),P.× nigra var.italica(M(u|¨)ench)Koehne × Cathayana Rehd,P.nigra var.italica(M(u|¨)ench) Koehne× simonii Carr.,P.simoii Carr × nigra L.,P.× Opera Hs(u|¨),P.× pupoloris Hs(u|¨) and P.simoii Carr.were studied respectively under the controlled conditions both in greenhouse and field in 1979 and 1980.Special attention was paid to determine their diurnal and seasonal changes of transpiration rates, water consumption per hectare by calculation,water loss of excised leaves, and the ratio of transpiration to photosynthetic rates. Besides,stomatal size,frequency of distribution,and control of stomatal apertures were studied.Based on the results in the contents mentioned above,the studied species and hybrids were classified into five groups according to the capacity of their drought tolerance and the concerned physiological charateristics in water relations.

The present paper describes the process of meiotic division of pollen mother cells and microsporogenesis of Pinus koraiensis Sieb.et Zucc.The nonsynchronous phenomenon in meiotic division of PMCs has been observed andsome abnormal phenomena in the process of microsporogenesis are described and analysed.

The present paper deals with the role of the forest litter layer in Huanglun mountain of Shensi.The thickness of litter layer ranged from 3 to 9cm.The moisture content of the layer ranged from 70.47 to 137.07 m³/ha;consequently the surface runoff has been regulated and soil erosion reduced. By the end of growing season,soil watercontent of different vegetation types are as fllowing: It is quite clear that the forest vegetation plays an important role in regulating surface runoff.

This paper deals with the general situation of aerial sowing of trees,shrubs and herbs in Yanan prefecture,Shaanxi province,and discusses the basic considerations regarding the choice of species and determination of sowing time. The paper recommends the suitable species for the Loess Plateau such as Pinus tabulaeformis,Astragallus adsurgens as well as Caragana microphylla. The suitable sowing time is usually at the beginning of raining season,In case,if there will be a dry year according to the weather forecast,no aerial sowing should be carried out.

During the period of 1962—1980,experimental planting of naked-root ed seedlings of Pinus koraiensis under the canopy of low quality broadleaved secondary growth has been done after selective felling. It has been found that the total volume increment of the treated stands is 1—2 times higher than that of the untreated stand after 18 years.

The effect of insecticides are closely related to the composition of population and different physiological states of elm leaf beetle(Galerucella aeneseens F.)and to temperature and humidity changes in the field. (1) The insecticidal resistance in different physiological states is as follows:(a).larval stage—lst instar<2nd instar<3rd instar<ripe larval;(b),adult stage—newly emerging adult<over wintering adult in flight period<adult in stage of supplement of nutrjtion<adult in the preparatoryperiods for passing summer. (2) Influence of seasonal changes on temperature on insecticidal efficiency:at lower temperature,DDT have quicker killing effect and stronger in efficiency than Dipterex and vice versa;at higher temperature,effect of Rotenone a little weaker than that of Dipterex,although they are similar in nature. (3) Influence of diurnal changes in temperature and humidity on insecticidal effifiency:spray was made in the morning and at noon when temperatures and humidities were reversed respectively.During and after spraying the temperature and the humidity have a direct effect on killing speed of various insecticides,however,within certain range of temperature(20—30℃),it has little influence on final mortality.

The new species(Laecifer ruralis sp.n.)was collected from the branches of Mallotus philippinensis(Lam.)Muell.-Arg.in Yunnan Province,on June 10,1969.The type specimens are kept in the Institute of Zoology,Academia Sinica. It is quite similar to L.laeea Kerr.,But differs from the latter by the following characteristic:Biological characteristics;Resin salmon-coloured;Antennae; Dorsal spine;Anal tubercle and Brachial plate.

The mean microfibril angle of Pinus massoniana was measured by means of diffractometer technique using(002)reflection.The methods of X-ray diffraction are easy to measure.The wood samples can be free from the modification as a result of chemical treatment.The comparison between the mean microfibril angle measured by iodine staining and the values obtained by (002)reflection was studied.The former is somewhat smaller than the latter. Because the mean microfibril angle of Pinus massoniana is smaller than 20°,M₄₀ agrees well with M_(0.6t).Since the longer the tracheid the steeper will be the pitch of the helices of the microfibrils to the longitudinal axis of the fiber, the mean microfibril angle of latewood is smaller than the earlywood,and the mean value of sapwood is larger than the heartwood.

The framework of timber price in this country,after the original Soviet form,has been fixed for about thirty years since 50' and has never been changed essentially.The fundamental deficiencies of this form are as follows: 1) The stumpage price is based merely on labor costs of which the stumpage costs are formed.Factors like land and building are to be served as no charges and therefore no costs to be counted at all.The result shows that the returned costs might not be able to compensale the drains of production, even could not make up the wages they ought to offer,let alone the long range development of forest management. 2) Stumpage cost is twelve percent barely enough to the factory price of timber and two percent to the timber price of free market.The difference in percentage between stumpage cost and the price of free market is so large that any other commodity could not never be compared with. 3) The averaged increasing rate of timber price is only two percent, while the price index in this country has increased several times higher within the same thirty years. 4) The price has divorced from the use-value, the lawful purchasing prices of dimension stocks are abnormally lower than that of non-dimension stocks and fuelwoods. 5) The policy of timber price in this country has born no relation with the prices of international markets since 50'. In order to improve the current situation,the prime work we should do is to reform the framework of costs.Evidently,forest management must have an insurance and all the insurance must be counted into costs,and land rent as well.But,at present,we should better choice the model of "calculating price"according to the details we suggest above,then graduate into a model of "limited price" which is formed by the goal price of similar assortment prescribed by "International Commodity Contract of Timber",taking it as the upper limit of the price of timber and the calculating cost of the calculating price mentioned above as the lower limit. By means of this model,not only can we apply it to improve the managed level of our enterprises,but also can resettle the relationship between supply and demand and create a favourable condition for the lumber we held to enter into international.