Linkages among stem xylem transport, biomechanics, and storage in lianas and trees across three contrasting environments.

PREMISE: Stem xylem transports water and nutrients, mechanically supports aboveground tissues, and stores water and nonstructural carbohydrates. These three functions are associated with three types of cells-vessel, fiber, and parenchyma, respectively. METHODS: We measured stem theoretical hydraulic conductivity (Kt), modulus of elasticity (MOE), tissue water content, starch, soluble sugars, cellulose, and xylem anatomical traits in 15 liana and 16 tree species across three contrasting sites in Southwest China. RESULTS: Lianas had higher hydraulic efficiency and tissue water content, but lower MOE and cellulose than trees. Storage traits (starch and soluble sugars) did not significantly differ between lianas and trees, and trait variation was explained mainly by site, highlighting how environment shapes plant storage strategies. Kt was significantly positively correlated with vessel diameter and vessel area fraction in lianas and all species combined. The MOE was significantly positively correlated with fiber area fraction, wood density, and cellulose in lianas and across all species. The tissue water content was significantly associated with parenchyma area fraction in lianas. Support function was strongly linked with transport and storage functions in lianas. In trees, transport and support functions were not correlated, while storage function was tightly linked with transport and support functions. CONCLUSIONS: These findings enhance our understanding of the relationship between stem xylem structure and function in lianas and trees, providing valuable insights into how plants adapt to environmental changes and the distinct ecological strategies employed by lianas and by trees to balance the demands of hydraulic transport, mechanical support, and storage.

[Optimize extraction process of polysaccharide in Trillium tschonoskii].

OBJECTIVE: To optimize the extraction process of polysaccharide in Trillium tschonoskii. METHODS: The influence of temperature, time, solid-liquid ratio and extraction times on extraction yield of the polysaccharide in fleshy roots of Trillium tschonokii were discussed with orthogonal test method. RESULTS: The impact sequence of the factors on the extraction rate of polysaccharide in Trillium tschonoskii was as follows: extraction times > time > solid-liquid ratio > temperature; The optimal extraction condition was extraction temperature of 80 degrees C, extraction time of 4.5h, solid-liquid ratio of 1:40 and extracted three times. CONCLUSION: Under these optimal conditions, the extracting rates of polysaccharide in Trillium tschonoskii is 6.75%. The content of polysaccharide is high which can be exploited and utilized as another new ingredient.

[Study on the characteristics of three-dimensional fluorescence excitation-emission spectra of methanol and ethanol].

For the purpose of revealing the spectra characteristics of methyl and ethanol, and establishing a method for distinguishing each other, the fluorescence features of methyl and ethanol were studied by three-dimensional fluorescence excitation-emission matrix spectra. The results obtained showed that there were two peaks in the three-dimensional fluorescence excitation-emission matrix spectra of methyl, and the intensities of the two peaks were positively related to the concentration of methyl when it was less than 15%. On the other hand, a whole fluorescence peak was only observed in the three-dimensional fluorescence excitation-emission matrix spectra of ethanol, and the intensity of the peak was positively correlated to the content of ethanol when it was less than 50%. There was a higher fluorescence efficiency for the methanol as compared to the ethanol. When the methyl was used for organic solvents to study the fluorescent nature of the organic matter, the fluorescence emitted by the methyl should be deduced. The locations of the fluorescence peaks of the methyl and ethanol were different. The peaks of the methyl were located at 225/350 nm and 250/375 nm, while the peak of the ethanol was characterized by 240/310 nm. Therefore, the fluorescence peak locations of the two alcohols could be applied to discriminate each other.

[Structure and dynamic characteristics of Betula luminifera populations in different regions of Southwest Hubei Province, China]. / 鄂西南不同区域亮叶桦种群结构与动态特征.

We investigated Betula luminifera populations in three regions (Mulinzi, Qizimei Mountains, and Jinzi Mountains) in the southwest Hubei Province, China. Population structure was divided by age classes and height classes. Population structure figures were drawn. The static life tables of B. luminifera populations in different regions were analyzed using the method of substitution of space for time. The survival curve, mortality rate curve and disappearance rate curve were created. Four functions of survival analysis were used to analyze the dynamics of B. luminifera population in different regions. The results showed that the B. luminifera populations in three regions were the increasing type. The height class structures were relatively complete. Some age classes were absent from the age structures of B. luminifera populations in Qizimei Mountains and Jinzi Mountains. Although the dynamic index of trees number Vpi＞0, but it was sensitive to external disturbance. The survival of B. luminifera of different age classes varied greatly in static life table, which gradually decreased with increasing age class, with Deevey-type 2 survival curve. The trend of mortality rate changed similarly to the disappearance rate, but fluctuated differently. All B. luminifera populations in different regions appeared to decrease in the early stage and keep dynamically stable in the medium-late stage.

Variation in three community features across habitat types and scales within a 15-ha subtropical evergreen-deciduous broadleaved mixed forest dynamics plot in China.

The evergreen and deciduous broadleaved mixed forests (EDBMFs) belong to one of the ecosystems most sensitive to environmental change, however, little is known about the environmental determinants for their plant diversity and forest structure at different habitat types and spatial scales. Here, we used data from a 15-ha (300 × 500 m) forest dynamic plot (FDP) of an old-growth EDBMF to examine the patterns and determinants of the three community features (stem abundance, rarefied species richness and basal area [BA]) in three habitat types (ridge, hillside and foothill) and at three spatial scales (20 × 20 m, 50 × 50 m, and 100 × 100 m). We found that the three community features significantly changed with habitat type, but only one of them (rarefied richness) changed with scale. Among spatial scales, the principle environmental factors that widely affected community features were pH, soil organic matter, and total phosphorus, while these effects only taken place at certain habitat. Variations in the three community features explained by soil conditions were generally greater than those explained by topographical conditions. With changes in habitat type, the proportion of variations explained by environmental conditions was 31%-53%, 8%-25%, and 18%-26% for abundance, rarefied richness, and BA, respectively. With increasing spatial scale, the variations explained by environmental conditions were 44%-75% for abundance, 28%-95% for rarefied richness, and 18%-86% for BA. Our study demonstrated that environmental factors had great impacts on the plant diversity and forest structure in the EDBMFs, especially the soil factors such as pH. In addition, the importance of the environmental determinants on these community features was highly related to the spatial scale.