We investigated the effect of fire disturbance on short-term soil respiration in birch （Betula platyphylla Suk.） and larch （Larix gmelinii Rupr.） forests in Greater Xing’an range, northeastern China for further u...We investigated the effect of fire disturbance on short-term soil respiration in birch （Betula platyphylla Suk.） and larch （Larix gmelinii Rupr.） forests in Greater Xing’an range, northeastern China for further understanding of its effect on the carbon cycle in ecosystems. Our study show that post-fire soil respiration rates in B. platyphylla and L. gmelinii forests were reduced by 14%and 10%, respectively. In contrast, the soil heterotrophic respiration rates in the two types of forest were similar in post-fire and control plots. After fire, the contribution of root respiration to total soil respiration was dramatically reduced. Variation in soil respiration rates was explained by soil moisture （W） and soil tem-perature （T） at a depth of 5 cm. Exponential regression fitted T and W models explained Rs rates in B. platyphylla control and post-fire plots （83.1% and 86.2%） and L. gmelinii control and post-fire plots （83.7%and 88.7%）. In addition, the short-term temperature coefficients in B.展开更多
Fire disturbance pattem of Liangshui Nature Reserve was studied by investigating fire scar tree and analyzing distribution of charcoal particle in soil-layer. The results show that : fire disturbance regular is relate...Fire disturbance pattem of Liangshui Nature Reserve was studied by investigating fire scar tree and analyzing distribution of charcoal particle in soil-layer. The results show that : fire disturbance regular is related with the accumulation and disposition of fuels in space pattern. rye fire protection measures wers put forward for Liangshui Nature Reserve.展开更多
Using static chamber gas chromatography, we determined the seasonal dynamics, controlling factors, and distribution patterns of forest swamp CH4 levels and related environmental factors (temperature, water level) afte...Using static chamber gas chromatography, we determined the seasonal dynamics, controlling factors, and distribution patterns of forest swamp CH4 levels and related environmental factors (temperature, water level) after fire disturbance in the Xiaoxing’an Mountains. The results showed the following: during the growing season, the annual CH4 emission distribution ranged from - 0.001 ± 0.012 to 22.373 ± 3.650 mg m^-2 h^-1;mild fire caused the swamp CH4 emission flux of tussock, shrub, Alnus sibirica and birch swamp to increase by 56.0–524.7%;at low water levels, temperature had a significant influence on the swamp type, and the correlation between the methane emission flux and temperature was significantly strengthened;after a fire disturbance, methane emissions from all types of marsh were highest in summer and second highest in autumn, with a weak absorption in spring;and along the water environment gradient of the transition zone, the CH4 emission flux presented a decreasing trend in its spatial distribution pattern.展开更多
Grassland ecosystems in North America have been significantly altered through various disturbances from past to present. This paper has identified and examined major disturbances in the grassland ecosystems, which inc...Grassland ecosystems in North America have been significantly altered through various disturbances from past to present. This paper has identified and examined major disturbances in the grassland ecosystems, which include grazing, fire and drought. A brief history of each disturbance is reviewed and its impact on the grassland ecosystem is discussed, by synthesizing previous research efforts available in the current literature. The paper intends to understand the grassland ecosystem from a comprehensive perspective and particularly tries to articulate the compound effect of the major disturbances in the same context instead of viewing them in isolations. It is concluded that a holistic understanding of the interaction between disturbances and plant communities is essential for sustainable grassland management, which demands comprehensive research effort in this area. The paper also points out the challenges we are facing in the current researches and suggests potential future improvement.展开更多
In order to make an efficient analysis of muzzle disturbance influenced by projectile mass, mass eccentricity, dynamic unbalance, load deviation, and clearance between projectile and bore, the orthogonal test method i...In order to make an efficient analysis of muzzle disturbance influenced by projectile mass, mass eccentricity, dynamic unbalance, load deviation, and clearance between projectile and bore, the orthogonal test method is extended to analyze the launch dynamics. Taking a tank as the research object, the launch dynamics equations of a tank system are established. Based on the stochastic simulation principle, the tank launch dynamic simulation system is constructed and through the development of the orthogonal test method, the influence of projectile on muzzle disturbance is studied. The study results provided both theoretical foundation and simulation approaches for improving the firing dispersion of the tank.展开更多
基金supported by the National Basic Research Program of China(973 Program)(No.2011CB403203)the National Natural Science Foundation(No.31070544)+3 种基金the Fundamental Research Funds for the Central Universities(No:DL12CA07)the Huoyingdong Education Foundation(No.131029)Postdoctoral Science-Research Foundation(LBH-Q12174)the CFERN&GENE Award Funds for Ecological Papers
文摘We investigated the effect of fire disturbance on short-term soil respiration in birch （Betula platyphylla Suk.） and larch （Larix gmelinii Rupr.） forests in Greater Xing’an range, northeastern China for further understanding of its effect on the carbon cycle in ecosystems. Our study show that post-fire soil respiration rates in B. platyphylla and L. gmelinii forests were reduced by 14%and 10%, respectively. In contrast, the soil heterotrophic respiration rates in the two types of forest were similar in post-fire and control plots. After fire, the contribution of root respiration to total soil respiration was dramatically reduced. Variation in soil respiration rates was explained by soil moisture （W） and soil tem-perature （T） at a depth of 5 cm. Exponential regression fitted T and W models explained Rs rates in B. platyphylla control and post-fire plots （83.1% and 86.2%） and L. gmelinii control and post-fire plots （83.7%and 88.7%）. In addition, the short-term temperature coefficients in B.
文摘Fire disturbance pattem of Liangshui Nature Reserve was studied by investigating fire scar tree and analyzing distribution of charcoal particle in soil-layer. The results show that : fire disturbance regular is related with the accumulation and disposition of fuels in space pattern. rye fire protection measures wers put forward for Liangshui Nature Reserve.
基金supported by postdoctoral grant of HeiLongJiang(Grant No.LBH-Z17002)
文摘Using static chamber gas chromatography, we determined the seasonal dynamics, controlling factors, and distribution patterns of forest swamp CH4 levels and related environmental factors (temperature, water level) after fire disturbance in the Xiaoxing’an Mountains. The results showed the following: during the growing season, the annual CH4 emission distribution ranged from - 0.001 ± 0.012 to 22.373 ± 3.650 mg m^-2 h^-1;mild fire caused the swamp CH4 emission flux of tussock, shrub, Alnus sibirica and birch swamp to increase by 56.0–524.7%;at low water levels, temperature had a significant influence on the swamp type, and the correlation between the methane emission flux and temperature was significantly strengthened;after a fire disturbance, methane emissions from all types of marsh were highest in summer and second highest in autumn, with a weak absorption in spring;and along the water environment gradient of the transition zone, the CH4 emission flux presented a decreasing trend in its spatial distribution pattern.
文摘Grassland ecosystems in North America have been significantly altered through various disturbances from past to present. This paper has identified and examined major disturbances in the grassland ecosystems, which include grazing, fire and drought. A brief history of each disturbance is reviewed and its impact on the grassland ecosystem is discussed, by synthesizing previous research efforts available in the current literature. The paper intends to understand the grassland ecosystem from a comprehensive perspective and particularly tries to articulate the compound effect of the major disturbances in the same context instead of viewing them in isolations. It is concluded that a holistic understanding of the interaction between disturbances and plant communities is essential for sustainable grassland management, which demands comprehensive research effort in this area. The paper also points out the challenges we are facing in the current researches and suggests potential future improvement.
基金funded by the Natural Science Foundation of China Government(11472135)
文摘In order to make an efficient analysis of muzzle disturbance influenced by projectile mass, mass eccentricity, dynamic unbalance, load deviation, and clearance between projectile and bore, the orthogonal test method is extended to analyze the launch dynamics. Taking a tank as the research object, the launch dynamics equations of a tank system are established. Based on the stochastic simulation principle, the tank launch dynamic simulation system is constructed and through the development of the orthogonal test method, the influence of projectile on muzzle disturbance is studied. The study results provided both theoretical foundation and simulation approaches for improving the firing dispersion of the tank.
