Han Shi-jie

Ecological functions of coarse woody debris in forest ecosystem

Coarse woody debris is an important structure and function unit in forest ecosystem. This review analyzed the ecological functions of coarse woody debris in forest ecosystem and introduced several hotspots and existing problems in coarse woody debris research field. It is suggested that quantitative research should be intensified in the ecological demands of coarse woody debris for providing a technical guidelines in management of productivity, biodiversity and other ecological processes.

Genetic diversity and genetic differentiation of natural Pinus koraiensis population

Genetic diversities and genetic differentiations of the four Pinus koraiensis populations (Gaofeng Forestry Farm at Tangwanghe in Yichun City, Erdaobaihe Town in the Changbai Mountains, Shengshan Forestry Farm in Heihe City, in China, and the suburb of Vladivostok City in Russia) were analyzed by using ISSR-PCR technique. The results of 15 primers amplification showed that the ratio of polymorphic site of P. koraiensis population was 60.7%. Each primer had 3.6 polymorphic sites. The diversity levels of the four P. koraiensis populations were rather higher compared with those of other Pinaceae species. The genetic diversity levels of P. koraiensis populations grown in the center region were higher than those grown in the edge zone. The genetic diversity of P. koraiensis mainly came from the interior of the population, accounting for 73% of total genetic diversity. There were no positive correlation between genetic distances and geographical distances for the four P. koraiensis populations. The gradual decrease of natural distribution region of P. koraiensis was due to anthropic destroy and environmental factors (i.e. fire and wind throw), rather than the lower genetic diversity.

Factors controlling N2O and CH4 fluxes in mixed broad-leaved/Korean pine forest of Changbai Mountain, China

Using the closed chamber technique, thein situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China, from June 1994 to October 1995. The relationships between fluxes (N2O and CH4) and some major environmental factors (temperature, soil water content and soil available nitrogen) were studied. A significant positive correlation between N2O emission and air/soil temperature was observed, but no significant correlation was found between N2O emission and soil water content (SWC). This result showed that temperature was an important controlling factor of N2O flux. There was a significant correlation between CH4 uptake and SWC, but no significant correlation was found between CH4 uptake and temperature. This suggested SWC was an important factor controlling CH4 uptake. The very significant negative correlation between logarithmic N2O flux and soil nitrate concentration, significant negative correlation between CH4 flux and soil ammonium content were also found.

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.

Comparisons of extraction and purification methods of soil microorganism DNA from rhizosphere soil

Microorganism DNA of rhizosphere soil from Pinus koraiensis and Pinus sylvestriformis were extracted by proteinase K based on SDS method, CTAB method, PVP (polyvinylpolypyrrolidone) method, and freezing and thawing method and the crude DNA from rhizosphere soil were purified by dialysis method, silver beads absorption method, and squeezing DNA gel method. The results of different extracting and purifying methods were compared and evaluated. Results indicated that the best method of extraction for microorganism DNA in rhizosphere soil was proteinse K based on SDS method with high salt concentration of 1.0% (w/v) NaCl, which could effectively eliminate humic acids and other impurities. The dialysis method was suitable to purify DNA from rhizosphere soil because of effectively removing brown matters and humic acids and the purified products were suited to PCR amplification. Squeezing DNA gel method was also a good purification method with the advantage of inexpensive in cost and efficient in use.

Indirect effects of precipitation variation on the decomposition process of Mongolian oak (Quercus mongolica) leaf litter

The effect of precipitation variation on the chemistry of Mongolian oak (Quercus mongolica) leaf litters was examined by analyzing litters of Mongolia oak saplings under four precipitation gradients. The decomposing process of these leaf litters in the Mongolian oak dominated forest was assessed using litter bag method. Compared with the litters of the Mongolian oak saplings from the natural precipitation site (A), litters produced by Mongolian oak from the driest precipitation gradient (A450) had significantly higher concentrations of nitrogen (N), phosphorus (P) and potassium (K) while lower acid-insoluble fraction (AIF) concentration. The decomposition study showed that A450 exhibited significantly higher decomposition rate, mineralization rates of N, P and K as well as much shorter N and P net immobilization periods. On the contrary, litters produced by seedlings from wettest gradient (A850) showed a totally opposite pattern. Litters from saplings that received comparable precipitation (A650) to those at the natural site (A) had significantly higher N concentration and faster decomposition rate as well as release rates of N, P and K. The mass loss patterns for the four litter types fitted the exponential model and the decay constant (k) can be well predicted by initial AIF/N. During the decomposition period, N concentration was best related to the percentage of mass remaining of the litters with relatively higher AIF concentrations and lower N concentrations, but the percentage of mass remaining of litters with lower AIF concentrations and higher N concentrations correlates strongly with AIF con centration. Our study proved that changes in precipitation significantly altered the litter quality, and therefore indirectly changed the decay process of leaf litters.

The rhizosphere pH change ofPinus koraiensis seedlings as affected by N sources of different levels and its effect on the availability and uptake of Fe, Mn, Cu and Zn

Dark brown forest soil was collected from the upper 20 cm soil layer in Changbai Mountain Research Station of Ecosystem, Chinese Academy of Sciences. The soil was amended with two different forms of nitrogen fertilizers: NO3 as Ca(NO3)2, NH4+ as NH4Cl at the concentrations of 50, 100, 200 and 400 mg kg−1respectively. The experiment was carried out with 2-yr-oldPinus koraiensis seedlings in pot. The pH change of rhizosphere soil and the contents of available Fe, Mn, Cu, and Zn in soil and leaves were analyzed. The result indicated that the addition of NH4-N decreased the rhizosphere pH value, while the addition of NO3-N increased the rhizosphere pH value in contrast with the control treatment. The direction and extent of the pH change mainly depended on N source and its concentrations applied. The rhizosphere pH change had a remarkable influence on the availability of the micronutrients in the rhizosphere, and thereafter affected the nutrient uptake by the seedlings. The contents of available mineral nutrients had a negative correlation with the pH value in the rhizosphere soil. The contents of available mineral nutrients in leaves were positively correlated to the levels of the available nutrients in the rhizosphere soils.

Stomatal response ofPinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

Four-year-oldPinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol−1) and high CO2 concentrations (500 and 700 μmol·mol−1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42°N, 128°E). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol−1 CO2. grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol−1CO2). High-[CO2]-grown plants exhibited lowerci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However,ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

Effect of biological agents on survival rate and root growth of Scots Pine seedlings

Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Balinyouqi, Inner Mongolia (180°12′13″E and 43°13′05″N). The effect and function of these biological agents on survival rate of seedlings were tested and analyzed by measuring the fine root growth and gross root growth. The results showed that the survival rates of the seedlings treated with Pt3, ABT, and HRC biological agents increased by 29.3%, 23.6%, and 16%, respectively. The regression analysis revealed that the length of fine roots (<2 mm) was positively correlated with seedling survival rate, which means that the Pt3 powder, ABT foot-growing powder and HRC water-absorbing powder increased the survival rates of the seedlings by promoting the growth of fine roots.

Fluxes of soil carbon dioxide, nitrous oxide and firedamp in broadleaved/Korean pine forest

To understand influence of litters on the emission/absorption of CO2, N2O and CH4 in broadleaved/Korean pine forest in Changbai Mountain, fluxes of soil CO2, N2O and CH4 were measured by closed static chamber technique, from Sept 3, 2002 to Oct 30, 2003 in two types of soil ecosystems, of which one was covered with litters on the surface soil, and the other had no litters. The results showed that litters had significant influences on CO2, N2O and CH4 fluxes (p<0.05). Their diurnal change patterns of plot with litters and litter-free plot were similar, and they all showed emission/absorption peak at 18:00. The diurnal change fluxes of CO2 and N2O of plot with litters were significantly higher than those of the litter-free plot, while the diurnal flux of CH4 of plot with litters was lower than that of litter-free plot. The fluxes of CO2, N2O, and CH4 showed the similar seasonal patternsfor both plots. The fluxes of CO2, CH4 showed their peak fluxes in June, but the fluxes of N2O showed its peak emissions in August. The annual fluxes of CO2 and N2O of plot with litters were significantly higher than those of the litter-free plot, while the annual flux of CH4 of plot with litters was lower than that of litter-free plot.