The net CO₂ assimilation rate, stomatal conductance, RuBPcase (ribulose 1,5-biphosphate carboxylose) activity, dry weight of aboveground and belowgroud part, plant height, the length and diameter of taproot ofPinus koraiensis seedlings were measured and analyzed after six-week exposure to elevated CO₂ in an open-top chamber in Changbai Mountain of China from May to Oct. 1999. Seedlings were planted in four different conditions: on an open site, control chamber, 500 μL·L⁻¹ and 700 μL·L⁻¹ CO₂ chambers. The results showed that the total biomass of the seedlings increased whereas stomatal conductance decreased. The physiological responses and growth to 500 μL·L⁻¹ and 700 μL·L⁻¹ CO₂ varied greatly. The acclimation of photosynthesis was downward to 700 μL·L⁻¹ CO₂ but upward to 500 μL·L⁻¹ CO₂. The RuBPcase activity, chlorophyll and soluble sugar contents of the seedlings grown at 500 μL·L⁻¹ CO₂ were higher than that at 700 μL·L⁻¹ CO₂. The concentration 500 μL·L⁻¹ CO₂ enhanced the growth of aboveground part whereas 700 μL·L⁻¹ CO₂ allocated more carbon to belowground part. Elevated CO₂ changed the carbon distribution pattern. The ecophysiological responses were significantly different between plants grown under 500 μL·L⁻¹ CO₂ and 700 μL·L⁻¹ CO₂.

For very sparse tree land individual tree was the basic element of interaction between atmosphere and the surface. Drag of isolated tree was preliminary aerodynamic index for analyzing the atmospheric boundary layer of this kind of surface. A simple pendulum method was designed and carried out in wind tunnel to measure drag of isolated tree models according to balance law of moment of force. The method was easy to conduct and with small error. The results showed that the drag and drag coefficient of isolated tree increased with decreasing of its permeability or porosity. Relationship between drag coefficient and permeability of isolated tree empirically was expressed by quadric curve.

The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980's. In this paper, we introduced the concept and origin, distribution and actuality, types and succession of sandy natural forests in the northern area of China. The conservation value and strategy for sandy natural forests were also discussed. We hope to supply some scientific basis for performing “the Natural Forest Protection Program” reasonably in China.

The photosynthetic response of 12-year oldPinus sylvestriformis to elevated CO₂ and its influential factors were tested and analyzed in the forest region of Changbai Mountain in 1999. Trees grown at the natural condition were controlled at three levels of CO₂ concentration (350 μL·L⁻¹, 500 μL·L⁻¹ and 700 μL·L⁻¹) by CO₂ rich settlement designed by us. Net photosynthetic rates (NPR), temperature, relative humidity, stomatal conductance, intercellular CO₂ concentration and photosynthetic active radiation (PAR) were measured at 6:00, 8:00, 10:00, 14:00, 16:00 and 18:00 hours a day. Experimental results showed that the NPR ofPinus sylvestriformis increased by 32.6% and 123.0% at 500 μL·L⁻¹ and 700 μL·L⁻¹ CO₂ concentration respectively, compared to ambient atmospheric CO₂ concentration (350 μL·L⁻¹). The relations between NPR and influential factors, including temperature, relative humidity, intercellular CO₂ concentration and photosynthetic active radiation, were analyzed respectively by regression analysis at different CO₂ concentrations.

Soil sample plots were specified and the soil in layer A₀, A₁ and AB were collected in Maoershan-Forest Experiment Farm of Northeast Forestry University for study of the effect of corylus clusters on soil in 1999. The result shows that the pH value, contents of organic matter, total nitrogen, alkali-discomposed nitrogen and total phosphorus under the corylus clusters are higher than that under the non-corylus clusters, except the available phosphorus content. The number of soil granular aggregates or the water stable aggregates under corylus clusters is more than that under the non-corylus clusters. The corylus clusters play an important role in improving the physicochemical properties of the soil, which should be conserved and developed in the forestry production.

The contributions of nitrification and denitrification to N₂O and N₂ emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C₂H₂ were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N₂O>nitrification N₂O>Denitrification N₂. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N₂O>Denitrification N₂.

The changes of fractal dimension ofPicea koraiensis seedlings under different light intensities in natural secondary forests was studied. The results showed that with the change of light environment, crown characters ofPicea koraiensis seedlings exhibited a greater plastic in lateral number, lateral increment, lateral dry weight, and specific leaf area. The range of calculated fractal dimensions of seedling crowns was confined between 2.5728 and 2.1036, but maximum of fractal dimension achieved in term moderate shading and in extreme low light conditions fractal dimension was least.

The species distribution frequency of communities from 700 m to 1900 m along northern slope of Changbai Mountain was studied by using Raunkiaer's frequency analysis methods in summer of 1999. The variation on composition and structure of communities with the increase of elevation was displayed from the point of view of frequency. The results showed that for all the species of community including tree, shrub and herb, the frequency presented a “L” shape even though there were difference among communities. The percentage of high frequency species increased with the increase of elevation. As one of important index in reflecting species spatial patterns, frequency not only show up the importance of species, but also the evenness of spatial distribution in community. Frequency figure could reveal the complexity and diversity of community at some extent.

Based on data from 210 meteorological stations in Northeast China and survey on zonal climax vegetation, the Kira's warmth index (W _l), coldness index (C _l), and Xu Wenduo's humidity index (H _l) were adopted to simulate and predict the dynamics of the vegetation eco-boundary under climate warming in Northeast China. The future vegetation eco-boundary alteration types of zonal climax vegetation could be divided into three types, such as extended vegetation eco-boundary species (W _l value range for 45–95°C · month) which would move northwards under climate warming, retreated vegetation eco-boundary species (W _l value range for 25–65°C · month) which would retreat from the present localities, and extinct population species (W _l value range for 5–35°C · month) which would be extinguished because the ecosystems they depend on disappeared. In Northeast China, there were differences for 15° latitudinal and 2600 m altitudinal. Based on our research results, the edificators would move northwards about 400–700 km, steppe vegetation would move eastwords 900 km, and the populations would move upwards about 260–360 m in mountains if the global temperature increases 2°C in the future. However, the moving distance would become shorter and shorter as the latitude and altitude increased. Therefore, the populations in alpine tundra zone at Daxing'an Mountains and Changbai Mountain might disappear. The results were expected to supply reference to local government when they set down strategies to respond to climate change in the future.

This paper studied the biomass distribution patterns ofLarix olgensis/swamp ecotones andBetula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these nature resources, by setting up sample belts, investigating initial data along the environmental gradients change, and establishing regression models. By means of regression models, the biomass of communities, layers, tree species and organs was calculated. In this system, it was found that the community biomass increased gradually along the environmental gradients change from swamp to forest in Changbai Mountain. Furthermore, the ecotoneal biomass distributed mainly over tree layer. The tree biomass distributed mainly in two or three dominate tree species.

Soil samples were taken from depth of 0–12 cm in the virgin broad-leaved/Korean pine mixed forest in Changbai Mountain in April, 2000. 20 μL·L⁻¹ and 200 μL·L⁻¹ CH₄ and N₂O concentration were supplied for analysis. Laboratory study on CH₄ oxidation and N₂O emission in forest soil showed that fresh soil sample could oxidize atmospheric methane and product N₂O. Air-dried soil sample could not oxidize atmospheric methane, but could product N₂O. However, it could oxidize the supplied methane quickly when its concentration was higher than 20 μL·L⁻¹. The oxidation rate of methane was increased with its initial concentration. An addition of water to dry soil caused large pulse of N₂O emissions within 2 hours. There were curvilinear correlations between N₂O emission and temperature (r²=0.706, p<0.05), and between N₂O emission and water content (r²=0.2968, p <0.05). These suggested temperature and water content were important factors controlling N₂O emission. The correlation between CH₄ oxidization and temperature was also found while CH₄ was supplied 200 μL·L⁻¹ (r²=0.3573, p<0.05). Temperature was an important factor controlling CH₄ oxidation. However, when 20 μL·L⁻¹ CH₄ was supplied, there was no correlation among CH₄ oxidization, N₂O emission, temperature and water content.

The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16^o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23^o.

Plant, insect and forest structures of 25 forest communities were investigated in Mao'ershan Experimental Forest Farm and Liangshui Experimental Forest Farm during 1994–1995. The paper used continuum index (C _i) as a parameter, to quantitatively describe forest community succession stage. Relationships between the biodiversity and continuum index of forest community were studied. The annual species and family diversities in forest plant community showed nonlinear correlation with continuum index, and the largest diversities were during the middle stage of succession. The diversities of total insect community and herbivorous insect group were negatively related withC _i, that of spide group and parasitic insect group was positively related. The pattern diversity and coverage weight diversity index foliage height increased with continuum index.

A systematic observation and intensive study on the parasitoids ofPissodes nitidus were made in Langxiang and Xin'qing Forestry Bureau in Xiaoing'an Mountain area in 1996–1999, including the diagnosis, life history, biological characteristics ofEurytoma sp. and parasitoid complex ofPissodes nitidus. There were about 70 species of parasitoids onPissodes nitidus, including Eurytomidae, Ichneumonidae and Braconidae etc. Among them,Eurytoma sp. is a dominant species and a braconid,Ipobracon sp. is a subdominant species, and they play an important role in controlling the pest.