The biomass structure and soil fertility in 29 years old Chinese fir stands of 5 different densities were studied. The results show that the biomass of mean individual and its each organ tend to decrease with the increasing of density; The biomass and the productivity per unit area tend to consistant; The amount of litter per unit area increases with the increasing of density, but the development of the ground vegetation and its biomass are at the contrary. The soil moisture content, maximum water-holding, and capillary water-holding capacities of stands with 2805 and 3750 trees per hectare are greater than others, the soil porosity increases with the increasing of density, and the content of soil organic substances, total nitrogen (N), total phosphorous (P), available nitrogen and available phosphorous are decreasing with the incerasing of density, but the tendency of available potassium content is not evident. The planting density of Chinese fir must be confined from 2805 to 3750 trees per hectare in order to raise the yield and maintain the soil fertility.

The experiment was conducted in Laoshan Experimental Station of Maoershan Experimental Forest Farm, Northeast Forestry University. The results are as follows: The mass-loss rate of Mongolian Scots pine dead needles in the first and third year after falling are 34.67% and 63.75% respectively; the mass-loss ratio of dead cone, bark scales and branches in the first year after falling are 36.69%, 33.66% and 30.12% to that of dead needles respectively; and the mass-loss ratio of Korean pine dead needles and Mongolian oak, spring ulm and Manchurian ash dead leaves in the first and third year after falling are 58.70% and 84.71 %, 81.60% and 80.55 %, 134.94% and 156.55%, 124.26% and 147.71 % to that of dead needles of Mongolian Scots pine respectively. The mass-loss in the first year after falling is 26.61 % to total litter mass, in which 20.50% and 58.29% mass-loss are provided by broadleafed litter (its litter mass is 11.85% to total) and dead needles of Mongilian Scots pine (ite litter mass is 43.64 % to total); whereas only 10.92 %, 5.28% and 3.37 % mass-loss are provided by dead bark scales, branches and cones of Mongolian Scots pine (their litter mass is 24.28%, 13.10% and 6.89% to total respectively). The releasing ratio and amounts of nutrient elements in different litters varies seasonally. Generally speaking, the net releasing ratio of major nutrient elements (N, P, K, Ca, Mg, and Fe) in broadleafed litter is relatively high, whereas the releasing ratio of major and minor nutrient elements in litters of Mongolian Scots pine is relatively low. The net releasing ratio of K, Mg, N, Zn, Mn, P, Ca, Fe and Cu in first year after falling is 58.50%, 40.13%, 12.84%, 7.24%, 5.13%, 4.64%, 1.13%, -4.20% and -65.27% respectively. The-broadleaved litter (its litter mass is 11.85% to total) provided 44.58%, 54.92% and 80.40% net release of N, K and Mg respectively, as well as total net release of P and Ca.

The biomass accumulation and nutrient cycle in the plantations of oiltea camellia, Camellia oleifera, were studied. Results showed that the biomass accumulation differed from one growth period to another. In the full fruit period the biomass accumulation amounted to 16.139t/hm², including 1.798t/hm² of economic biomass. The productivity of the plants was also varied with each growth period. In the full fruit period, the plant made the best use of solar energy, resulting in a photosynthetic efficiency of 0. 2 percent. The distributive ratio of the photosynthate in the plant's various organs changed with the growth period, too. The study also revealed that the amount of the nutrient elements, N, P, K, Ca and Mg, in terms of their absorption, retained, return and leaching varied with the growth periods. Accordingly, a minimum dosage of fertilizers to be applied is recommended.

The collapsed area of coal mine was filled with coal ash from thermal power plant, and covered with a surface soil layer of 30cm, then the area was reformed into "artificial soil". In 1990, Populus×euramericana cv. 'Neva' plantation was set up. The main measures are: (1) Treatment of different soil depth (0, 30, 55cm, and mixing soil and ash); (2) Treatment of fertilization (orthogonal design totally 16 treatments); (3) Treatment of appling green manure (planting 4 species of green manure crops or manuring with the same crops). The method for computer simulation is: firstly, pre-evluating the model's controlling point, then, using logistic equation to simulate the growth process of tree height and DBH, net present value(NPV) and internal receiving rate(IRR) used as the evaluation indexes for evaluating superior model. The results show that the first-class model is on the basis of covering 30cm soil layer, 0.5kg/hole P fertilzer applied as basal fertilzer, soaked irrigation once, and planting Sesbania in the row inter space or manuring Amorpha fruticosa in successive years. The maximum economic benefit can be achieved by it, and its IRR can reach over 18%. If taking the improvement of ecological envirnment as the main purpose, and increasing input to pursue even higher production of plantation, the best combination will just be the combinations of best ones in each single item experiment.

Permanent sample plots were set up in windfall area in western slope of Changbai mountain to investigate regeneration successively and determine changes in ecological habitats. The results indicate that the composition of regeneration population is a mixture of shade-tolerant and intolerant tree species. Abundance of shade-tolerant trees tends to decrease and that of intolerant trees increases year by year. Contents of soil water, C, N and organic material in windfall plots decrease. Tendings of forest promote the restoration of habitats.

In this paper the genetic variations of ring density component traits of new clones in Populus deltoides×P. simonii were studied. The results show that each trait value of ring density components is obviously different among the clones. The broad heritability of ring density, earlywood density, minimum wood density, maximum wood density and gradient of wood density were high (h²=0. 41-0. 58);but the broad heritability of latewood density, latewood density/earlywood density and variation range of wood density were low (h²=0. 15-0. 25). At different ages the broad heritability of same trait was different.

48 genera 122 species of tree legumes were examined for nodulation in field and seedling nursery. Among them, 82 species were found to be nodulated. 123 strains of root nodule bacteria from nodules of the trees were isolated following the method suggested by Vincent (1970). Isolates of rhizobia were purified and maintained on YEMA slants. Strains of rhizobia obviously differ from one another in characteristics of colonies and growth rate.

Cellulase extract preparation from intestinal tracts of the Apriona germari Hope (Lamiinae, feeding in phloem, sapwood and duramen of mulberry trees), Anoplophora chinensis Forster (Lamiinae, feeding in the sapwood and duramen of various host plants) and Nedezhdiella cantori (Hope) (Cerambyciinae, living in the heartwood of citrus trees) were tested to determine the hydrolytic abilities of digestive enzymes on various subtracts: microcrystalline cellulose (MC), sodium carboxymethyl cellulose (CMCNa) and salicin. It revealed that all of the three species could hydrolyze all the subtracts mentioned. The results indicated that the three species of cerambycids all did have cellulolytic enzyme complex: exo-β-1, 4-glucanase (C₁-ase), endo-β-1, 4 glucanase (C_x-ase) and β-1, 4-glucosidase in the gut, and possess a real cellulolytic capacity. Moreover, the C₁-ase activity of the heartwood feeding species N. cantori would be higher than that of phloem and sapwood feeding species A. germari and A. chinensis. All the Borers examined are living in healthy trees, and they rarely encounter or consume fungus-infected wood; from the cultures of intestinal fluid on MC or CMC-Na selecting medium, no cellulolytic fungi was found on MC medium and only few bacteria on CMC-Na medium. In the tissue and microsection of dissected intestinal tracts there were not any special myctocytes or structure for harboring extracellular microorganisms.Comparing with the cellulases' characters between the common cellulolytic fungi and the cerambycid Borers, difference was very evident. Based on these facts, it was suggested that at least some of cerambycids would be able to secret cellulases and the cellulase complex should be endogenous rather than exogenous.

A new method for the identification of key factors from life table data of insects is proposed, i. e. the analytic method of grey sequence. The method possesses the integral, asymmetric, sequential, dynamic, and simple and convenient merits. It can accurately identify key factors and show the relative importance of other factors, An illustrative study was made with the life table data of Seperda populnea L. Using the life table data of some insects, the grey sequence was compared with other analytic methods of sequence. The result shows that analytic method of grey sequence is correct and practicable. The method is a new one for the identification of key factors affecting population dynamics of insect pests.

Cellulase extract preparation from intestine tract of the longicorn borer (Apriona germari Hope) were tested to determine the cellulolytic abilities. It was revealed that the borers had cellulolytic enzyme complex: exo-β-1, 4-glucanase (C_x-ase), endo-β-1, 4-glucanase (C_x-ase)and β-1, 4-glucosidase in their gut. After comparison of the kinetic properties among cellulases of A. germari, it was showed that the C_x-ase had wider range of adaptability than β-glucosidase. For C_x-ase, the optimun pH was at pH4. 4, whereas β-glucosidase had an optimun pH of 5. 6; C_x-ase had a fairly wide optimun temperature range between 30℃-45℃, but β-glucosidase had a range between 45℃-50℃. Treated with salts of different concentrations and under the same assay condition to test the activity of C_x-ase and β-glucosidase, inactivating effect was observed with Ca⁺⁺, Mg⁺⁺, Co⁺⁺, Cu⁺⁺, Zn⁺⁺, Mn⁺⁺, Ag⁺⁺, Hg⁺⁺ and Pb⁺⁺ under high concentrations (0. 1mol/L). While under low concentrations (0. 005mol/L), the effects showed very slight with Ca⁺⁺, Mg⁺⁺ and Co⁺⁺, but very strong with Hg⁺⁺ and Pb⁺⁺. It is very interesting to note that the Mn⁺⁺ and Cu⁺⁺ are important trace elements for plant growth and also common fungicides and sterilizing agents, they were also proved to be strong cellulase activity inhibitors. It would be possible to develop new devices in control of cerambycid borers.

The radial variation patterns of wood density in 7 Pinus caribaea provenances from an experimental plantation in Guangxi Province were studied by X-ray wood densitometry. The main results obtained are: 1) The general trends of the density profiles of the trees were similar, while there existed a certain degree of variations among provenances and among individual trees. Therefore, the indefiniteness in describing the variation patterns is inevitable. The variance analysis showed more significant differences in average ring density among provenances in mature wood than in juvenile wood. The differences in the parameters related to the variation patterns among provenances were nonsignificant. 2)The juvenile to mature age-age correlations of the average ring density among provenances and among individual trees with relatively large differences in between were significant. 3)The significance of the correlations between density components and between density components and ring width components related to the effect by provenances partly differed from those related to the effect of ages. The negative correlations between wood density and ring width were mainly shown in the variation related to the effect of age other than that related to provenances.

A normal wood and a tension wood (lean angle of the stem was 10°) were drawn from natural stands of Langya mountains, Anhui province, whose wood properties were analyzed and compared. At a result, three portions in tension wood were divided, which were tension wood (T), far away from the pith, opposite wood (O), near the pith, and flank side wood (S), between T and O. Compared with the properties of S and O, more quantities of glutinous fiber, higher fiber tissue propotion, lower compressive strength parallel to the grain, larger shrinkage coefficent and higher basic density were found.Apart from fiber tissue propotion, the other properties of normal wood were better than that of three portions in tension wood. The properties of normal wood were partly samilar to that of S, but the difference between them were still very large.

A study on the allelic nature of random amplified polymorphic DNA (RAPD) Marker was made with femalegametophytes of half-sib seeds from single tree of Masson's Pine. On the basis of screening the primers for amplification effects, the Mendelian 1: 1 segregation was tested for amplified products of 40 seeds from C-16 tree of Zhong Yi population with 17 primers. The results showed that the number of amplified fragments for each primer ranged from 7-22, and the total number of amplified fragments over 17 primers was 201. Among these, there were 129 heterozygous bands which occupied 64 percent of total fragments. Through χ² test (P < 0. 05), 55 fragments (Loci) fit the 1: 1 segregation of Mendelian, which were 27 percent of total amplified fragments, These research results will provide the Mendelian RAPD marker for testing genetic variation analysis of single tree or populations and linekage map construction in Masson's Pine.