Based on determinations of the four microelements, including Cu, Zn, Fe,and Mn, whthin Dahurian larch plantation ecosystem in the eastern part of no-rthern China, analyses of nutrient concentrations, distribution, accumulation,removement and cycle through the ecosystem were conducted. The results wereas follows, The total amount of the microelements accumulated in the ecosystemwas 173493.368kg/ha, in which nearly 99% was stored in the soil pool, whileno more than 1% in the vegetation system; The annual absorption of the mic-roelements was 6. 4483kg/ha, in which the annual retention and the annual re-turn were 3.3250kg/ha and 3. 1233kg/ha, respectively, and the return/absorp-tion ratio was 48.440; The input thrfough hydrologic way into the ecosystemand the output through runoff out of the ecosystem were 0.8720kg/ha·a and0.4114kg/ha, respectively, and thus the net gains of the system was 0.4606kg/ha·a and the average net change ratio was 52.8% with the highest value of77.8% for Cu; The circulation diagram of microelemental cycle within the eco-system was described and the dynamic models were established.

According to the morphological and anatomical characteristics, the sampledmycorrhiza of Populus tomentosa from the central China are divided into 14types. Their anatomical characteristics indicate that most of them have a bador worse symbiotic relationship with the host plant. Statistical results from distri-bution characteristics index of the mycorrhiza show that the beneficial ectomy-corrhizal fungi exist rarely in the forest soil of Populus tomentosa. The majo-rity of them occur in the soils whose pH value are less than 7.5.On the con-trary the mycorrhiza with the bad or worse symbiotical relation or pseudom-ycorrhiza are dominant in the alkaline soils. In the alkaline nursery soils, onlya few of the ectomycorrhizal types have been discovered in roots of the nur-sery stock and the pseudomycorrhiza, type 5, makes up the majority of them.The tree ages seem to have no effect on the mycorrhiza formation in Populus tomentosa plantation.

This paper studied the effect of ethylene on adventitious root initiation ofstem cuttings with the experiment materials of shoot, semi-hardwood and one-year-old hardwood of I-69 Poplar. Auxins treatments could induce the cuttingsto release ethylene, and the amount of ethylene released from cuttings tre-ated with auxins was higher than that from cuttings without auxins treatment(CK) during the whole process of cutting and rooting, meanwhile the ethylenestimulated the initiation of adventitious root. But the amount of ethylene rele-ased from cuttings treated with GA₃ ABA, and KT was egual to that from CKtreatment, which did not stimulate, even inhibited or intensely inhibited theadventitious root initiation. The treatment with ethylene gas at a concentrationof 25-1000ug·ml^-1 could stimulate the adventitious root initiation and buddingof I-69 Poplar hardwood cuttings. The initiation of adventitious roots could bepromoted in treatment with ethrel at a low concentration(<25ug·ml(-1)), whichcould be reduced and inhibited as the concentration of ethrel increased Theamount of ethylene released from cuttings increased magnificently when cuttingstreated with a high concentration of ethrel. The morphological changes ofcuttings treated with high concentrations of ethrel, ABA, and NAA were si-milar. In all of experimental results, the effect of ethylene on the initiationof adventitious roots of I-69 Poplar cuttings is similar to that of auxins, whichis stimulated at low concentration and inhibited at high concentration. Theseeffects on adventitious root initiation are related to the production of ethylenedirectly as a result of their cooperation.

12 nunoff plats were set up in mountain timber yards at four classes ofslope (e, g. 8,19, 24, 32), the fired position observations of the cultural land ofChinese fir had been continued for 4 years after control burning. The laws ofseasonal and annual changes in water,soil and nutrient losses of the forest landwere analysed from the control burning to canopy closure of Chinese fir cu-ltural land. The periods of soil and water losses were divided. The relation-ship between slope and loss was also analysed. The results indicated that run-off, soil and nutrient losses were most serious in the first year after controlburning, in which the amount of soil erosion was up to 24.81t/ha, then thelosses decreased yearly, and tend to[steadiness until the fourth year, which wassimilar to]that in the sites not to be burned. The common measure of culturaloperations aggrevated the amount of soil erosion. The authors suggest to adjustthe fashion and season of cultural operations, and adopt necessary biologicalmeasures.

Present paper, with optical light microscope and scanning electron micris-cope, deals with the morphological characters of eggs, mature larvae and pu-pae of main parasites of Dryocosmus kuriphilus Yasumatsu (Torymus sinensis Kamijo, T. geranii Walker, Eurytoma rosae Nees, E. setigera Mayr, Decatoma concinna (Bob. ), Eupelmus urozonus Dalman, Ormyrus sp. ). Preliminary resu-lts show that the differences of morphological characters in eggs, mature lar-vae and pupae are obvious. We also dicussed characteristics of mature larva,such as number and length of chaetae in epicranium and body surface, ante-nna shape, morph of mandible, structure of body surface, and the character-istics of egg, such as its colour, egg petiolule and its length, morph of eggbody. So the classification on groups of chalcidoidea by means of morphologi-cal characters of mature larvae is feasible.

From 1988 to 1989, the authors conducted fixed-site observation on thelarch cone fly complex (Strobilomyia spp. ) in the Da Xingan and the Xiao Xi-ngan Mts. In the Da Xingan Mts., the complex is composed of S. laricicola(Karl), S. baicaleneis (Elberg), S. infrequens (Ackland) and S. melaniola(Fan). S. melaniola is the prominent species. In the Xiao Xingan Mts., thecomplex is composed of S. luteoforceps (Fan & Fang),S. baicalensis(Elberg),S. infrequens (Ackland) and S. melaniola (Fan). S. infrequens is the domi-nant species. Yellow-glue paper trapping shows that each species has different emergingperiod and so the larval developing period is different from each other; alsothe developing period is accordant with the cone development.

The control over knife sharpness is of great importance in determiningwood cutting resistance For this control, it is necessary to develop a methodof simply and effectively determining knife sharpness In this paper, the effe-ctiveness of the method to determine and control knife sharpness by means oftrail cutting with wood samples in the determination of main cutting force inorthogonal cutting is demonstrated, and the basis for its reasonable applicationis provided through investigations on the variation of wood cutting resistancewithin wood samples, and that of the difference in cutting resistance whichrepresents that in knife sharpness under various conditions.

This paper is a review of a new theory about a colloidal concept of UFresin presented with American scholars. In the paper, their evidancess aboutthe theory are introduced, as well as high strures and morphology of UF re-sin, being further support. After that, potential significances of the theory inUF resin are discussed.

The variations among populations within species for Populus ussuriensis arevery rich. The study on population selection in its whole distribution regionhas been conducted for selecting best population which can be used in forest-ation directly. Firstly, the main economic characters of Populus ussuriensis populations collected form 9 places of origin, such as growth, rooting ability,cold and rust resistance have been determined in Daxinganling, then evaluatingthese economic characters comprehensively, finally the best population has beenselected.

The hydrological function of litter on woodland is closely connected withits amount. It is determined that the existing amount of litter in plantation of Pinus tabulaeformis at the age of 27-29 is 17.95t/ha; the annual litterfall am-ounts to 3.24t/ha. The changes of grand total litterfall (Y) with time (t)conform to functional equation: Y=-203.10+773.65t-113.60t²+6.32t³; andthe annual litter decomposition adds up to 3.23t/ha, its decomposition processchanges with seasons, more fast in rainly season and more slowly in winter.Thus at the present age and construction state, the litterfall and its decompo-sition of Pinus tabulaeformis are in balance, and the total amount of litter isrelatively constant.

Based on a series of plantation experiments with Keteteeria tree speciesfrom 1978 to 1989, which studied site selection, species comparision, density,mixed forest and tending, as well as artificial plantation growth, a set ofartificial reproduction techniques and measures for Keteleeria tree species hadbeen sumed up. Up to now, the trees have been planted more than 600ha inGuang Xi. The average height of 9-11-years-old trees is 7.66m, and theaverage diameter at breast height is 9, 91cm, growing stock volume 81.9m³/ha.The benefits of artificial reproducting Keteleeria tree species are striking, therefore which provides a main kind of forestation tree species for south China.

The weevil Curculio hippophes Zhang is a seed bores of Hippophae rhamn-oides L. , which usually causes serious damage to it. It widely distributes in H.rhamnoides forests in Liaoning Gansu and Shaanxi Provinces. There is one ge-neration a year, pupation occurs as full-grown lavral in mid-June. Emergencebegins in early July with a peak from late July to early August. The just ha-tched larvae occur in mid-August. Hibernation takes place in mid-October. Theadults are very active from 11-20 hours. Copulation and oviposition occur from16-19 hours. Stubbing the trees of seriously infected H. rhamnoides fover inwinter or spraying 2.5% decis at a dilution of 1:5000 to the adults during thepeak emergence period may obtain significant effectiveness.

The box-tree pyralid, Diapania perspectalis, is one of the main pests ofthe box tree, Buxus sinica, and seriously injures the tree. The spatial distri-bution model of the larvae is cluster distribution. It has three generations ayear in Xian and the larva has six instars. Overwintering takes place as secondinstar larva in white cocoon by leaf-tier;The larvae feed on the leaf sep-arately after third instar; The fifrh and sixth instars are able to feed on entireleaf; The mean leaf-eating capacity of each leava is 82.3 tablets. Plukingthe cocoon or spraying fenitrothin, 50% dichlorvos. 50% phoxim, 80% tri-chlorphon emulsions at a dilution of 1:800 reached a mortality of over 93.5%.

From April of 1989 to April of 1990, the effects of two kinds of pyreth-roid on the insect community (including spiders) were studied combining withthe work of controlling the pest Dendrolimus punctatus conducted by QianshanCounty, Anhui Province. The results indicate that the species in the commu-nity is more abundent during the period of the pest's outbreaks but the evenessand diversity index of the community are lower than those of the communityof the control plots. After the pest was effectively controlled by the insectici-des, the pest was difficult to return to a high population density; though thespecies in the community was less abundent at this time, the diversity index was higher because the eveness had incresed greatly; each kind of measure-ment index for community shows a similar change tendency with that of thecontrol plots. Chemical control not only decreased the pest's population den-sity but also killed a lot of natural enemies of the community. But the effectsof insecticides on different groups of natural enemies (beneficial insectsand spiders) were different. Beneficial insects were greatly affected by insec-ticides, and the species and individuals in this group decreased rapidly afterchemical control; spiders were little affected and showed great resistance to the insecticides. Beneficial insects are more dependent on the population den-sity of the pest than spiders in both species and individuals.

The allowable rebound deflection is main criteria for pavement design offorest highway. The peper analyses the each coefficient and calculated formulaof the allowable rebound deflection. Based on results surveying highway andtest ug data at home and abroad, and thinking over the conditions of foresthighway the author puts forward a suggestion value of grade coefficient ofhighway to calculate the allowable rebound deflection. It is also carried on asolution of pavement thickness calculation with the suggested grade coefficient.This article showed that it is possible to achieve a larger reliability for desig-ning forest highway with the suggested coefficient.

The paper probes into the concept and characteristics of forestry projects.Basing on the actual conditions of forestry production in China, the paperbuilds the estimating methods system for efficiency and social parameters. Thenit points that we should pay attention to dealing with medial products, lifecircle and so on.