FROBENIUS INTEGRABLE DECOMPOSITIONS FOR TWO CLASSES OF NONLINEAR EVOLUTION EQUATIONS WITH VARIABLE COEFFICIENTS

Frobenius integrable decompositions are introduced for partial differential equations with variable coefficients. Two classes of partial differential equations with variable coefficients are transformed into Frobenius integrable ordinary differential equations. The resulting solutions are illustrated to describe the solution phenomena shared with the KdV and potential KdV equations, the Boussinesq equation and the Camassa–Holm equation with variable coefficients. </jats:p

Short-term effects of thinning on the understory natural environment of mixed broadleaf-conifer forest in Changbai Mountain area, Northeast China

Background The understory natural environment is critical in affecting the succession and recovery process of vegetation, stand structure, and species composition of forest. The thinning intensity could significantly change the forest microclimates and soil properties, therefore, to analyze the effects of thinning intensity on the understory natural environment of forest is of important significance for promoting the ecological benefits of thinning. Methods A total of 16 fixed sample plots with different thinning intensities were established in the mixed broadleaf-conifer forest in Jiaohe, situated in Changbai Mountain area, Northeast China, and the forest microclimates and soil properties were investigated after 4 years since the establishment of the sample plots. Results The results showed that the high intensity thinning significantly decreased the leaf area index from 4.13 (unthinned plot) to 2.21 (high intensity thinned plot), and the air temperature was increased by thinning from May to July. Comparing with the unthinned plot, thinning caused a rise of temperature (ranging from 2.11 to 6.74 °C, depending on the intensity of thinning) in May. However, it showed cooling effect in September and October. Besides, the air moisture of thinning plots was lower than the control plot in May and October, when the density of leaves is lower in the forest, and it even decreased 20.27% after thinning. The thinning intensity had no significantly effect on water content and organic carbon in forest soils, and only the bulk density in the top-layer soils in high intensity thinning plot was remarkably increased. Total nitrogen in soil was increased by different intensities of thinning, and the availability of nutrients for nitrogen, phosphorus and potassium in some soils were also affected

Short-term effects of thinning on the understory natural environment of mixed broadleaf-conifer forest in Changbai Mountain area, Northeast China

Background The understory natural environment is critical in affecting the succession and recovery process of vegetation, stand structure, and species composition of forest. The thinning intensity could significantly change the forest microclimates and soil properties, therefore, to analyze the effects of thinning intensity on the understory natural environment of forest is of important significance for promoting the ecological benefits of thinning. Methods A total of 16 fixed sample plots with different thinning intensities were established in the mixed broadleaf-conifer forest in Jiaohe, situated in Changbai Mountain area, Northeast China, and the forest microclimates and soil properties were investigated after 4 years since the establishment of the sample plots. Results The results showed that the high intensity thinning significantly decreased the leaf area index from 4.13 (unthinned plot) to 2.21 (high intensity thinned plot), and the air temperature was increased by thinning from May to July. Comparing with the unthinned plot, thinning caused a rise of temperature (ranging from 2.11 to 6.74 °C, depending on the intensity of thinning) in May. However, it showed cooling effect in September and October. Besides, the air moisture of thinning plots was lower than the control plot in May and October, when the density of leaves is lower in the forest, and it even decreased 20.27% after thinning. The thinning intensity had no significantly effect on water content and organic carbon in forest soils, and only the bulk density in the top-layer soils in high intensity thinning plot was remarkably increased. Total nitrogen in soil was increased by different intensities of thinning, and the availability of nutrients for nitrogen, phosphorus and potassium in some soils were also affected. </jats:sec

Sexual dimorphism in reproductive and vegetative allometry for two dioecious Rhamnus plants in north-eastern China

The dimorphism in reproductive allometry has received much attention, while rather little is known about the sexual dimorphism in the vegetative allometry of a dioecious species. This study presents vegetative and reproductive allometries for two dioecious tree species of the genus Rhamnus in north-eastern China. A power function and a linear model were found suitable for describing different components of the vegetative allometry. In addition, a linear regression was used to estimate the number of flowers and/or fruits based on observed stem size. R. davurica being the taller species of the two shows highly significant correlations for all selected combinations of different vegetative components. These correlations are much less pronounced and sometimes even nonsignificant in R. schneideri, which occupies a great variety of niches at the understory with diverse crown shapes. Component biomass was highly correlated with tree diameter for both sexes, but the allometries changed with sex and species. Both females and males show consistent patterns of reproductive size dependency. However, the slope of the linear relations differs between the sexes again indicating gender-related differences in reproductive size. According to theory, females allocate more biomass to reproduction than males, which negatively affects their vegetative growth. However, in this study, flowering females did not show less vegetative growth than males suggesting that the two Rhamnus species behave contrary to expectation. Further studies are required to test the assumption that photosynthesis by reproductive organs may substantially contribute to vegetative growth

Ultrahigh Malleability of the Lithiation-Induced LixSi Phase

Through in situ transmission electron microscopy (TEM) observation, the lithiation behaviors of carbon-coated silicon (Si) nanostructures are investigated. Our experimental results reveal that the carbon (C) coating can not only mediate the lithiation kinetics and volume expansion, leading to the retardation or even complete suppression of the lithiation process, but also determine the morphological evolution and final shape of the lithiation products. The lithiation behaviors of C-coated Si nanostructures are further corroborated by chemo-mechanical simulations. Our study consistently demonstrates that the effect of C coating layer on the lithiation behaviors of Si nanostructures is closely related to the ultrahigh malleability and deformability of the lithiation-induced LixSi phase. The finding of this study sheds light on the rational design of high-performance Si–C composite electrode materials