Zou Chun-jing

Effect of root derived organic acids on the activation of nutrients in the rhizosphere soil

Four types of soils, including brown coniferous forest soil, dark brown soil, black soil, and black calic soil, sampled from three different places in northeast China were used in this test. The functions of two root-derived organic acids and water were simulated and compared in the activation of mineral nutrients from the rhizosphere soil. The results showed that the organic acids could activate the nutrients and the activated degree of the nutrient elements highly depended on the amount and types of the organic acid excreted and on the physiochemical and biochemical properties of the soil tested. The activation effect of the citric acid was obviously higher than that of malic acid in extracting Fe, Mn, Cu, and Zn for all the tested soil types. However, the activation efficiencies of P, K, Ca, and Mg extracting by the citric acid were not much higher, sometimes wven lower, than those by malic acid. The solution concentration of all elements increased with increase of amount of the citric acid added.

The pH change in rhizosphere ofPinus koraiensis seedlings as affected by different nitrogen sources and its effect on phosphorus availability

Root mat method described by Kuchenbuch and Jungk was used to study the rhizosphere processes. The experiment was carried out on two years oldPinus koraiensis seedlings. Soil samples collected from the upper 20-cm soil layer in Changbai Mountain were treated with three different forms of nitrogen fertilizers: NO3−−N, NH4+−N and NH4NO3. The results showed that the soil pH and available P near the roots were all lower than in the bulk soil in control treatment. NH4+−N application greatly decreased the soil pH near the roots compared to the control treatment and promoted the absorption of phosphorus, which led to a more remarkable depletion region of available P. On the contrary, the rhizosphere soil pH was higher than in the bulk soil in treatments with NO3−−N and retarded the P absorption, which led to a nearly equal available P contents to the bulk soil. In treatment with NH4NO3, the rhizosphere soil pH was only a little lower than that in the control treatment and its effects on P absorption is mediate between the treatments with NH4+−N and NO3−−N.

Characteristics and dynamics of sandy natural forests in sandy forest-steppe ecotone in the northern area of China

The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980s. 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.

Turbulence regime near the forest floor of a mixed broad leaved/Korean pine forest in Changbai Mountains

The measurement and observation for this study were carried out by using a three-dimensional (u, v, w) Sonic anemometer (IAP-SA 485), at Forest Ecosystem Opened Research Station of Changbai Mountains (128°28’E and 42°24’N, Jilin Province, P.R. China) in August 2001. The basic characteristics of turbulence, such as turbulence intensity, atmospheric stability, time scales, and convection state, near the forest floor were analyzed. It is concluded that the airflow near forest floor is characterized by high intermittence and asymmetry, and the active and upward movement takes the leading position. Near forest floor, the vertical turbulence is retained and its time scale and length scale are much less than that ofu, v components. The eddy near forest floor shows a flat structure and look like a ‘Disk’. Buoyancy plays a leading role in the generation and maintenance of local turbulence.

Effect of elevated CO2 concentration on growth course of tree seedlings in Changbai Mountain.

One-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis, Phellodendron amurense were grown in open-top chambers (OTCs) with 700 and 500 ώmol/mol CO2 concentrations, control chamber and on open site (ambient CO2, about 350 ώmol/mol CO2) respectively at the Open Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, and the growth course responses of three species to elevated CO2 and temperature during one growing season was studied from May to Oct. 1999. The results showed that increase in CO2 concentration enhanced the growth of seedlings and the effect of 700 (ώmol/mol CO2 was more remarkable than 500 ώmol/mol CO2 on seedling growth. Under the condition of doubly elevated CO2 concentration, the biomass increased by 38% in average for coniferous seedlings and 60% for broad-leaved seedlings. With continuous treatment of high CO2 concentration, the monthly-accumulated biomass of shade-tolerantPinus koraiensis seedlings was bigger in July than in August and September, while those ofPinus sylvestriformis andPhellodendron amurense seedlings showed an increase in July and August, or did not decrese until September. During the hot August, high CO2 concentration enhanced the growth ofPinus koraiensis seedlings by increasing temperature, but it did not show dominance in other two species.

Response of seedlings growth ofPinus sylvestriformis to atmospheric CO2 enrichment in Changbai Mountain

The biomass and ratio of root-shoot ofPinus sylvestriformis seedlings at CO2 concentration of 700 μL·L−1 and 500 μL·L−1 were measured using open-top chambers (OTCs) in Changbai Mountain during Jun. to Oct. in 1999. The results showed that doubling CO2 concentration was benefit to seedling growth of the species (500 μL·L−1 was better than 700 μL·L−1) and the biomass production was increased in both above-ground and underground parts of seedlings. Carbon transformation to roots was evident as rising of CO2 concentration.

Effects of elevated CO2 concentrations on photosynthesis, dark respiration and RuBPcase activity of three species seedlings in Changbai Mountain

Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L−1, 500 μL·L−1) and ambient CO2 concentrations (350 μL·L−1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L−1 CO2 concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L−1 CO2, out that ofF. mandshurica decreased under both concentrations 700 μL·L−1 and 500 μL·L−1 CO2. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO2 concentrations.

Ecophysiological responses and carbon distribution of Pinus koraiensis seedlings to elevated carbon dioxide

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.

Recovery of species diversity after disturbance of broad-leaved Korean pine mixed forest in Changbai Mountain

Recovery of species diversity after catastrophic disturbance was influenced by a few factors, such as intensity of disturbance, availability of propagules, and the environmental conditions. In this paper, we examined pattems of species development after nearly 60a succession in burned broad-leaved Korean pine mixed forest on northem slope of Changbai Mountain. We assessed the recovery of plant species diversity in 3 types of forests under the condition with gradient of soil moisture. Results revealed that recovery of plant species diversity varied greatly under different environmental conditions. Species richness of secondary forests greatly related to the site condition. Secondary birch forest on mesic site had the greatest number of plant species and the following was poplar-birch forest and larch-birch forest. Most of characteristic taxa could be found in birch forest after 60a succession. For larch-birch forest on hydra site, most of climax species were still not able to invade, so it had the lowest species diversity.

Vegetation landscape structure and dynamics in sandy forest-steppe ecotone

Sandy forest-steppe ecotone in Baiyinaobao Natural Reserve of Inner Mongolia Autonomous Region of China is one of the special landscape types in forest-steppe vegetation zone in China. Vegetation landscape types, landscape patches, and patch size were measured by the field investigation, forest photograph, and airscape. The structure of landscape patches in sandy forest-steppe ecotone, including composition structure, and size structure, was studied and the dynamics and transformation of landscape patches were analyzed. The data obtained in this study could provide theoretical basis for the research on vegetation landscape in forest-steppe ecotones and other vegetation types.