To explore the fruiting rule in natural stand of Larix olgensis Henry in Zhanbei Mountain Range,the author made a comparison study on four different types of its cones.Comparison analysis has also been conducted on the basis of the four types of canes. Rules on the interrelationship between fruiting and a few acting factors have been discovered.Both the amount of cones yielded and the quality of seeds from the four different types of cone stands have been proved to have a lot to dō with the site of the stands,the developmental stages as well as several other biological factors,while the color,shape,size,structure of seed scale and number of scales of those types of cones have had nothing to do with the factors mentioned above.

This paper deals mainly with the relation of forestry characters of Chinese pine to the effectiveness of aerial sowing in the Loess Areas.Experiments and observations were made on the germination of seeds,survival percentage of young seedlings,rules of growth and development as well as the ability of drought-resistance and cold tolerance which conducted in order to find out the influence of these biological and ecological characters upon the effectiveness of aerial sowing of Chinese pine in these areas. Results showed that the seeds of Chinese pine were small enough to have a close contact with the soil and thus germinated easily.If there were 80mm of rainfall and 7 cloudy or rainy days succeedingly,the seeds sowed would germinate quickly and successfully.The seedlings have a strong geotropism so that they have deep and well-developed root system. These fine forestry characters of Chinese pine made it possible to be a nice tree species for successful aerial sowing in the Loess Areas.

Eight forest tree species,namely,Pinus bungeana Zucc.,Pinus tabulaeformis Carr.,Salix babylonica L.,Populus tomentosa Carr.,Eucommia ulmoides Oliv.,Paulownia elongata S.Y.Hu,Sophora japonica L.,and Ulmus pumila L.,representable conifers,diffuse-porous and ring-porous hardwoods respectively,were studied based on the samples collected periodically from trunk and crown branch of every tree during 1979 and 1980.Rhythm of periodical differentiation in cambial zone and sychronization with the characteristics of tissues and cells developed within a growth ring both in phloem and xylem were founded on facts of developmental anatomy.The trend of quantity and rate of tissue elements produced at different periods,the relations to phenology and environmental effects were analysed.All the studied typical ring-porous trees showed quite a different pattern of development as compared with others.Among the differences attracted attention,they resumed cambial activity in spring at the lower portion of trunk apparently much preceded the crown branch.Some problems on cambial study and its role in the control of shoot growth,and growth coordination in trees were discussed briefly.Besides,this general comparative study offers some indications that investigation on cambium,the formation of phloem and xylem,and relationship to tree growth should be integrated.The trend of this integration is worthy to be developed, because it will not only get a better understanding of cambium,but also help to forest practice for better production of wood and a part of bark.

In accordance with the species indentification,and the determination of the physical and chemical properties and ages as well as the on-the-spot examination,it was found that the so called buried wood(jianchang board),a precious wood of Cunninghamia unicanaliculata Wang et Liu was buried under the ground for many years because of local earth crust changed.In the ground it had undergone changes in its chemical composition and therefore possessed a high resistance to rot. It is suggested that Dechang county area is the ancient natural distribution region of the species.

The author of this paper has given an assumption that the log dropout process may be divided into two stagges.In april,1981,the experiment was conducted in the laboratory of the North-Eastern College of Forestry and proved that there exist two stages. On the basis of the experiment,the author further presents the theory of three stages in the log dropout process as follows: 1. The first stage:the toggles are tilted and turned around one track of the conveyor(Fig.1,b).The tilt of the toggles gives the log a selfdropout power. 2. The second stage:the toggles are rotated around the pull organ (chains or wire rope,Fig.l,c).It gives the proper condition to drop the log. 3. The third stage:the log rolled down from the toggles. This paper points out that the first and the second stages are most important for log dropout. Finally some parameters for determing the log dropout performance,such as log dropout time consumption,log diameter,log eccentricity and the log curvature are discussed in the paper.The experiment and analysis show this type of the log dorpout system by gravity with collapse of the toggles gives a minimum dropout time consumption and all kinds of logs can be discharged from the conveyor.

Through the analysis of the present production situation and timber hauling to log yard in north-east forest area of China,the method "double lines with three steps" has been put forward for all round year operation.This is an approach for the study on calculation of the minimum reserve of tree length in ensuring the balanced production in log yard.Based on the statistical chart of timber hauling to yard,the paper gives methods and steps and indexes for calculating the minimum storing volume of tree length,the formulae for calculation,which is of great significance for balanced production in yard.

Adventitious bud primordia were formed by culturing isolated embryos of Pinus sylvestris on media containing a relatively high cytokinin to auxin ratio. Further development of the bud Primordia required transfer to media lacking growth regulators.Adventitious buds with a visible stem were isolated from the initial tissue and cultured individually.On the average 10% of the vigorous adventitious shoots formed roots spontaneously after about 10 months in culture.These rooted shoots were transferred to unsterile conditions in the greenhouse.The capacity of forming adventitious buds varied among different seed lots.

A duel infection of mycoplasmalike organisms (MLO)and bacterialike organisms(BLO)was observed in leaf tissue of Melia azedaraoh with witches'-broom symptoms.MLO were present in mature sieve elements of the phloem.BLO appeared to have a Gram-positive type wall structure and were found in tracheary elements of the xylem and in some parenchyma cells.