The length and maximum width of leaf blades of 8 clones of Populus spp. were measured with Li—ocr 3000A area meter, and 8 types of regression models were established to predict leaf area (Y) from leaf length (L),maximum width (W) or the product of L and W. The result showed thatthe best models were: (1) lgY = a + bx + clgx, where X for L ×W; (2) Y =a+bx+cx², in which X was for W. But a poor relationship existed with the leaf length. Therefore, the above models for the 8 clones i. e. lgY=-0.450826 + 0 000771 + 0.976335lgx and Y=-1.697387 + 0.733497x-0.001253x², were established, and might fit to other too.

Based on data obtained from 37 sampled plots, the phytoxoenological features of the forests of Larix chinensis in Qinling Range were systematically analysed. The natural forests were classidied into 3 forest-type groups,i. e. Lariceta fruticosa, Lariceta herbosa, Lariceta bryophyteta, and 16 stand types by means of K-means clustering. The ground-flora was analysed with NMDS ordination to understand the relationship between the stand types and environmental factors, which procided a scientific basis for conservation of this rare phytocommunity.

A study on techniques to enhance cold resistance of seedlings of Pinus bungeana was coducted for over 9 years.The experimental results showed that the chloroplast,mitochondrum and the membraneous System in cells were often damaged and caused serious water—lose in shenyang region during winter hence pine seedlings could not survive properly, however, vinyl-film or straw curtain in addtion were proved to be the best materials to protect the seedlings from the cold and 81%~97.5% seedlings could survive.The key measures of raising seedlings of P.bungesna in Shenyang region inclued the storage of seed mixed with sand under temperature 0—3℃ after hot water soaking; transplanting of seedlings not at age 4 years and paying attention to water management; and covering the seedlings with vinyl—flim for the first two years after sowing and transplanting. The 6—7 years old seedlings or those which had been trasplanted over3—4years might safely survive the cold winter.In addition,seed was soaked with Brassonolide(0.01μg/mL),see germination percentage could be increased by 47%. BR(0.01μg/mL) was sprayed in growing Stage to increase winter survival rate by 10.6%~14.5% Under rice-straw cover.

The provenance differences of Pinus massoniana Lamb. Between the Rongxian, in Guangxi Province and the Longli in Guizhou Province in stand structure and growth effect are analysed comparatively.Based on the stand growing stock volume at present, combining the predict model of timber assortment yield and technically economic target in the studing region, the economic effcts are evaluated by a dynamic analysis method. The results show that the species introduced from Rongxian County is feasible, the stand productivity of the Rongxoan provenance is higher than that of the Longli provenance under the same site conditions, among which the height, DBH, and growing stock are 15.0—21.7%, 5.4-19.1% and 28-40% higher respectively,the economic benefit and net present value (NPV) increase 38.96-61.28% and 69.78-91.76% respectively. The differences in single tree timber volume enhance with the increase of stand ages, but the increasing percentage decrease.With the increment of site index, the economic benefit, NPV,and benefitcost ratio increase.

In north Taihang Mountain, Shanxi Province, the forest site of water reservoir forest subregion in Wutai Mountain were classified and evaluated by the cluster analysis method. On the basis of biological characteristics of main tree species harmoniziog with site factors, similarities of site production property were discribed quantitatively by the cluster method. According to the results, the region was classified into 12 site types at a fixed similarity level, which were named by three-section name method (heat, water and nutrient). The results of growth forecast of Larix principis-rupprectii and Pinus tabulaeformis at 12 site types were coordinate with the growth status of the existing forest.

Beaver's diet in Xinjiang contains about 49 species of plants including 15species of woody plants. The key foods of beavers are willows. Beavers mainly feed willow sprigs in summer. In fall, beavers forage a large number of trees to make a food cache weighing about 1000~2000kg for winter use. The foraging period lasts about one month. Food intake in fall is the largest of a year, which is about two times larger than in winter.

This paper deals with 4 species of the Triozidae from Liaoning province of China, all of which are described as new to science. Type specimens are deposited in the Insect Collection of Beijing Agricultural University.1 Trioza celastrae Li, sp. n. (fig. 1 )Holotype ♀, Qingyuan Co. (County) (270m) Liaoning, Prov. (Province),1992-V-12) paratypes 1, 1♀, same data as holotype.Host plant: Celastrae orbiculatus Tunb. (Celastraceae)This new species' genitalia resembles Trioza obional Loginova 1964, but differs from the latter in venation and appearance of wings; it also differs from T.nigra Kuwayama, 1910, in genal cones yellow-brown and length of genal cones as long as vertex.2 Trioza rhamnisuga Li, sp. n. (fig. 2)Holotype ♀, Qingyuan Co. (270m) Liaoning prov., 1992-VI-5.Host pjant: Rhamnus davurica Pall. (Rhamuaceae)This new species is similar to Trioza atkasookensis Hodkinson, 1978, but distinguished from it by the tibia with 4 spur at apex and by different body colour.3 Eubactericera tiliae Li, sp.n. (fig. 3)Holotype , Xifeng Co. (240m) Liaoning Prov., 1992-V-5.Host plant: Tilia mandschurica Rupr. et Maxim. (Tiliaceae). This new species' parameres in caudal view resembles Eubactcricera salicigra Li (in press), but is well separable from it by parameres' difference in lateral view and meracanthus finger-like.,4 Eubactericera curroata Li et Sun, sp. n. (fig. 4)Holotype , Qingyuan Co. (270m) Liaoning Prov., 1991-VⅧ-2.Host plant: Rhamnus davuricae Pall.This species is similar to Trioza arctica Hodkinson, 1978, but differs clearly in genitalia' features and Rs longer and sinuation.

The Control Method, as an intensive management method used in uneven -aged forest, was firstly experimented in China. A method of the integration of one modified parameter prediction model (MPPM) and one linear programming method was proposed to be used for predicting and simulating standing stock growths and selective cuttings of uneven-aged stands. Because diameter distributions of stands were fitted by Weibull distribution, the MPPM was much suited to growth predictions of uneven-aged stands. Results of predictions and simulations to the experimental uneven-ages stands locoted at Wangqing Forest Enterprise of Jilin Province showed that not only stable timber harvests but also sustained standing stock growths could be gotten with 5 year selective cutting cycle and suitable selective cutting intensities in longterm selection systems. By selective cutting simulations to the five experimental stands, suitable selective:cutting intensities of them were determined and recommended.

The article, by using system an alysis, presents the characteristics of timeliness and space, continuity, servce, controllment and economy of tree length flow in forest harvesting system. To minimize the production cost and storage cost of tree length flow and balance the tree length transportation and operation in log yard as the objective, the macrocontrol and microcontrol mathematical models of tree length flow are developed. The practical examples show that the economic results of “two-step hauling”are more significant than that of “hauling in summen and storage in winter (flow)”.

Twenty 11-13-year-old trees and seven 17-19-year-old trees of Tectona grandis L. f. were taken from Hainan Island to study some characteristics of wood specific gravity and fibre length, and to test the standard physical and mechanical properties.With the weighted mean of the breast height disc as the unit, specific gravity varied from 0.466 to 0.588, averaging 0.516, and fibre length varied from 0.878 to 1.230 mm, averaging 1.063 mm. A slight negative relationship was observed between ring width and specific gravity (r=-0.029), also and fibre length (r=-0.108). There were significant correlations between the 1st ring and the ninth ring for both properties.Variations in the two properties among sample plots were insignificant while those between trees within sample plot were highly significant.Radial variation Fibre length increased rapidly outward from the pith in the few rings; after the eighth ring the rate of increase slowed down. Specific gravity showed similar increasing trend to that of fibre length at first and more fluctuations after the eighth ring.Axial variation This analysis was based on seven trees, from each of which discs at 0.2, 1.3, 3.6, 5.6 and 7.6m height levels of the trunk were removed, then every growth ring in the southern and northern radii from each of these discs were further sampled. 1. Core sequence (six growth rings from the pith outward) In the ring nearest the pith, fibre length varied very little up the tree, and in the outer rings, either it decreased gradually or showed some fluctuations. Specific gravity in the six rings at the base were the greatest, then decreased rapidly to the 1.3m height, after which they varied differently up the trunk. 2. Sheath sequence (six growth rings from the bark inward) Fibre length and specific gravity in the six rings all decreased rapidly from the base upward. The main factors affecting the two sequences of axial variation in fibre length were discussed.The result of the standard physical and mechanical properties tested was presented.

Using the ellips-parabolid log model with the four practical measurable parameters, it is measured that the exact volume of all the uncut-boards and clabs cut by the multi-bit ripping edger. The loss of the saw Kerf and recovery have be accurately calculated. By the theroies, a quite simple NC detecting system of the multi-bit ripping eddger will be desinged which made the numerical control for the maching of short cycle wood for timber industry realizable.

Gravitarmata margarotana Heinemann and Petrova cristata walsingham are serious forestinsect pests in Cuizhou province, they mainly injure the cones of pine trees, sometimes damage the shoots too. In recent years they have frequently occurred in the seed orchard of masson pine of Henpo forest farm in Huangping county, the large amount losses of cones are caused by them every yrear. From 1990 to 1992, their mixed population saptial distribution pattern and sampling technique in the seed orchard had been examined by means of seven aggregation indices, and regression analysis methods of Iwao, Taylor,and Lan Xingping etc. in Henpo forest farm of Huangping county. The results show that the distribution pattern of mixed population of pine seed borers belong to the aggregation. The reasons of aggregation are caused by borers biological characteristics and environmental factors. The linear related degree of La-m regression model is optimum among the five models.According to the saptial distribution pattern of cone borers, the sequential sampling equations and determining maximum sampling number for cone borers of pine tree seed orchard were presented by authors in this paper.