Dendrolimus superans (Butler) occurred in the vast areas of Daxing'an Mountains forest. in Heilongjiang Province, in 1990. Stands damaged by D.Superans seriously, intermediately and lightly show patch shape dis...Dendrolimus superans (Butler) occurred in the vast areas of Daxing'an Mountains forest. in Heilongjiang Province, in 1990. Stands damaged by D.Superans seriously, intermediately and lightly show patch shape distribution within damaged area. By ordination analysis and correlation analysis between ordination factors and coordinate axis. It was found that occurrence of D. Superans in different extent is owing to the effect of forest age. composition and exposure. The tended young pure forests grown on the sunward slopes are most seriously damaged and non-tended middle-age mixing stands grown on the sunless slopes are most lightly damaged. Therefore, in order to prevent D.superans from seriously damaging larch forests. relatively large crown density (P>0. 7) should be kept,and broadleaftrees should be also properly preserved.展开更多
Introduction:Research on the effect of close-to-nature management(CTNM)on stand states and dynamics of forests is crucial for the evaluation of CTNM implemented and sustainable development of forestry.Outcomes:We anal...Introduction:Research on the effect of close-to-nature management(CTNM)on stand states and dynamics of forests is crucial for the evaluation of CTNM implemented and sustainable development of forestry.Outcomes:We analyzed and compared the stand states and dynamics of Masson pine(Pinus massoniana)plantations in the young,middle-aged,and near-mature stages under CTNM eight years after selective cutting and unmanaged control.Both paired-sample T-tests and RDA ordination results demonstrated that the overall stand states with CTNM were superior to the control treatment in all three stages.The interaction of the CTNM and stand age significantly affected The Shannon-Wiener index of diameter class and regeneration density.Discussion and Conclusion:CTNM and stand age jointly affected the stand state of forests and CTNM accelerated the forest development,which promoted an increase in the heterogeneity of stand parameters and shortened the formation time of a target stand.Greater tree size differentiation and adequate regeneration are particularly important aspects for improving the quality of Masson pineforests during the management processes.展开更多
A free standing film of polyaniline as large as 18 cm×18cm×0.002 cm can be obtained by evaporation of a solution of the chemically synthesized base in NMP. Its structure was examined by the elemental analysi...A free standing film of polyaniline as large as 18 cm×18cm×0.002 cm can be obtained by evaporation of a solution of the chemically synthesized base in NMP. Its structure was examined by the elemental analysis, IR, U.V.-visible spectra, XPS, DSC, SEM and X-ray scattering and its conducting behavior as well as electrochemical properties were studied. Results show that the composition, structure of main chain, physical properties of the free standing film of polyanilme is similar to that of the powder. However, some differences in its electronic structure, conductivity at room temperature and potential of redox couple between the flee standing film and powder are observed, which may be due to cross-linking of the film of polyaniline.展开更多
文摘Dendrolimus superans (Butler) occurred in the vast areas of Daxing'an Mountains forest. in Heilongjiang Province, in 1990. Stands damaged by D.Superans seriously, intermediately and lightly show patch shape distribution within damaged area. By ordination analysis and correlation analysis between ordination factors and coordinate axis. It was found that occurrence of D. Superans in different extent is owing to the effect of forest age. composition and exposure. The tended young pure forests grown on the sunward slopes are most seriously damaged and non-tended middle-age mixing stands grown on the sunless slopes are most lightly damaged. Therefore, in order to prevent D.superans from seriously damaging larch forests. relatively large crown density (P>0. 7) should be kept,and broadleaftrees should be also properly preserved.
基金This research has been supported by Science and Technology Project of Guizhou Province[QKHPTRC[2018]5261,QKHZC[2017]2520-1,and QKHJC[2019]1076]Natural Science Foundation of China[32001314].
文摘Introduction:Research on the effect of close-to-nature management(CTNM)on stand states and dynamics of forests is crucial for the evaluation of CTNM implemented and sustainable development of forestry.Outcomes:We analyzed and compared the stand states and dynamics of Masson pine(Pinus massoniana)plantations in the young,middle-aged,and near-mature stages under CTNM eight years after selective cutting and unmanaged control.Both paired-sample T-tests and RDA ordination results demonstrated that the overall stand states with CTNM were superior to the control treatment in all three stages.The interaction of the CTNM and stand age significantly affected The Shannon-Wiener index of diameter class and regeneration density.Discussion and Conclusion:CTNM and stand age jointly affected the stand state of forests and CTNM accelerated the forest development,which promoted an increase in the heterogeneity of stand parameters and shortened the formation time of a target stand.Greater tree size differentiation and adequate regeneration are particularly important aspects for improving the quality of Masson pineforests during the management processes.
文摘A free standing film of polyaniline as large as 18 cm×18cm×0.002 cm can be obtained by evaporation of a solution of the chemically synthesized base in NMP. Its structure was examined by the elemental analysis, IR, U.V.-visible spectra, XPS, DSC, SEM and X-ray scattering and its conducting behavior as well as electrochemical properties were studied. Results show that the composition, structure of main chain, physical properties of the free standing film of polyanilme is similar to that of the powder. However, some differences in its electronic structure, conductivity at room temperature and potential of redox couple between the flee standing film and powder are observed, which may be due to cross-linking of the film of polyaniline.
