Vegetation C–N–P accumulation and allocation patterns at the community level in early restored plantations in the loess hilly-gully region

Accumulation of vegetation biomass is a crucial process for carbon fixation in the early stage of afforestation and a primary driving force for subsequent ecological functions.Accurately assessing the storage and allocation of elements in plantations is essential for their management and estimating carbon sink capacity.However,current knowledge of the storage and allocation patterns of elements within plant organs at the community level is limited.To clarify the distribution patterns of elements in plant organs at the community level,we measured the biomass within plant organs of five typical plantations in the early stage of afforestation in the loess hilly-gully region.We assessed the main drivers of element accumulation and distribution by employing redundancy analysis and random forest.Results revealed significant differences in biomass storages among plantations and a significant effect of plantation type on the storages of elements within plant organs.Furthermore,the dominant factors influencing C–N–P storage and allocation at the community level were found to be inconsistent.While the storage of elements was mainly influenced by stand openness,total soil nitrogen,and plant diversity,the allocation of elements in organs was mainly influenced by stand openness and soil water content.Overall,the spatial structure of the community had an important influence on both element storage and allocation,but soil conditions played a more important role in element allocation than in storage.Random forest results showed that at the community level,factors influencing element storage and allocation within plant organs often differed.The regulation of elemental storage could be regulated by the major growth demand resources,while the allocation was regulated by other limiting class factors,which often differed from those that had a significant effect on element storage.The differences in plant organ elemental storage and allocation drivers at the community level reflect community adaptation strategies and the regulation of resources by ecosystems in combination with plants.Our study provides valuable insights for enhancing plantation C sink estimates and serves as a reference for regulating element storage and allocation at the local scale.

Estimation of leaf area index from high resolution ZY-3 satellite imagery in a catchment dominated by Larix principis-rupprechtii,northern China

Leaf area index(LAI) is a key factor that determines a forest ecosystem's net primary production and energy exchange between the atmosphere and land surfaces.LAI can be measured in many ways, but there has been little research to compare LAI estimated by different methods. In this study, we compared the LAI results from two different approaches, i.e., the dimidiate pixel model(DPM) and an empirical statistic model(ESM) using ZY-3 high-accuracy satellite images validated by field data. We explored the relationship of LAI of Larix principis-rupprechtii Mayr plantations with topographic conditions. The results show that DPM improves the simulation of LAI(r = 0.86,RMSE = 0.57) compared with ESM(r = 0.62, RMSE =0.79). We further concluded that elevation and slope significantly affect the distribution of LAI. The maximum peak of LAI appeared at an aspect of east and southeast at an elevation of 1700–2000 m. Our results suggest that ZY-3 can satisfy the needs of quantitative monitoring of leaf area indices in small-scale catchment areas. DPM provides a simple and accurate method to obtain forest vegetation parameters in the case of non-ground measurement points.

Distribution of Vascular Plants along Altitudinal Gradients in Hoang Lien National Park, Vietnam

The present study was conducted to examine the distributional characteristics of floral communities along the altitudinal gradients in Hoang Lien National Park (HLNP), located in Lao Cai province, Vietnam. We recorded the relatively abundant flora system with 3252 species (including 361 endemic species and 237 endangered species), belonging to 1126 genera, 230 families and 6 different phyla. Methodology of sampling, specimen collection and identification, statistical analysis are simultaneously used for investigating the complex changes of composition and richness of plant assemblages. The study results indicated the divisions in quantity and composition, especially differentiation of endemic and rare species in accordance with altitudinal gradients.

分级多孔N,P共掺杂rGO改性隔膜增强锂硫电池的循环稳定性

多硫化物(LiPSs)的穿梭效应和低硫利用率会导致电池容量的快速衰减,这严重阻碍了锂硫电池的商业化进程.为了抑制LiPSs的穿梭效应和提高硫的利用率,本工作采用一步高温还原法合成了具有分级多孔结构的N,P共掺杂还原氧化石墨烯(NPG),并将其用于锂硫电池的隔膜改性.高导电性NPG具有丰富的分级多孔结构,提供了大量的LiPSs锚定位点和丰富的离子/电子传输通道,实现了可溶性中间体的快速转化,高效抑制了LiPSs的穿梭效应.归因于以上优点,NPG改性聚丙烯隔膜(NPG/PP)能够有效抑制LiPSs的穿梭并提高硫的利用率.结果表明,NPG/PP改性隔膜的电池展现出优异的循环性能(在1 C的电流密度下,循环500圈以后容量仍保持在612.5 mAh·g−1,每圈的衰减仅为0.052%)和出色的倍率性能(在2 C的电流密度下容量仍保持在617.9 mAh·g−1).这种构建分级多孔N,P共掺杂rGO改性隔膜的思路为锂硫电池的研究提供了新的方向.

Bi/3DPG composite structure optimization realizes high specific capacity and rapid sodium-ion storage

As an anode material for sodium-ion batteries(SIBs),bismuth(Bi)has attracted widespread attention due to its suitable voltage platform and high volumetric energy density.However,the severe volume expansion of Bi during charging and discharging leads to a rapid decline in battery capacity.Loading Bi on the graphene can relieve volume expansion and improve electrochemical performance.However,excessive loading of Bi on graphene will cause the porosity of the composite material to decrease,which leads to a decrease of the Na+transmission rate.Herein,the Bi/three-dimensional porous graphene(Bi/3DPG)composite material was prepared and the pore structure was optimized to obtain the medium-load Bi/3DPG(Bi/3DPG-M)with better electrochemical performance.Bi/3DPG-M exhibited a fast kinetic process while maintaining a high specific capacity.The specific capacity still remained at 270 mA·h·g^(−1)(93.3%)after 500 cycles at a current density of 0.1 A·g^(−1).Even at 5 A·g^(−1),the specific capacity of Bi/3DPG-M could still reach 266.1 mA·h·g^(−1).This work can provide a reference for research on the use of alloy–graphene composite in the anode of SIBs.