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.

Performance test of organic planting bags for woody plant seedlings

Organic planting bag has been developed to overcome both weaknesses of plastic polybags,contaminating the soil and damaging the plant’s root when transplanting.The improvement in this stage was achieved by inserting coconut fiber to strengthen a bag.The main purpose of this study was to investigate the effectiveness of seedling and transplanting by using organic planting bags,employed,three woody plants,i.e.,Albizia(Albizia julibrissin),Cadam(Neolamarckia cadamba)and Gmelina(Gmelina arborea).Performance testing of organic plant bags was conducted on three compositions of coconut fiber and water hyacinth.Two stages of experiments were conducted to know bag performance.First,the testing of organic plant bags during the nursery was conducted for 50 d from day 0 to day 50.Second,the testing of organic plant bags after transplanting and observed on days 60,70,and 80,after transplanted on the field.The parameters in this study were plant height,a total of roots that penetrate the organic plant bags and a total of leaves and stem diameters of plant grown in the organic bag and transplanting on land.The results showed that organic planting bag with the composition 155 g of coconut fiber and 505 g of water hyacinth(A3B3)has 0.020 kg/cm^(2) compressive strength and provides the best plant growth rates.Compressive strength affects the number of roots which penetrate the organic bag.Generally,the growth of seed in organic bags is faster than that in polybags.Albizia shows a higher growth rate(0.379 cm/d)compared to Cadam and Gmelina.

Variation of carbon and nitrogen stoichiometry along a chronosequence of natural temperate forest in northeastern China

Aims Carbon(C)and nitrogen(N)stoichiometry contributes to under-standing elemental compositions and coupled biogeochemical cycles in ecosystems.However,we know little about the temporal patterns of C:N stoichiometry during forest development.The goal of this study is to explore the temporal patterns of intraspecific and ecosystem components’variations in C:N stoichiometry and the scaling relationships between C and N at different successional stages.Methods Along forest development in a natural temperate forest,northeastern China,four age gradients were categorized into ca.10-,30-,70-and 200-year old,respectively,and three 20 m×20 m plots were set up for each age class.Leaves,branches,fine roots and fresh litter of seven dominant species as well as mineral soil at depth of 0-10 cm were sampled.A Universal CHN Elemental Analyzer was used to determine the C and N concentrations in all samples.Important Findings Intraspecific leaf C,N and C:N ratios remained stable along forest development regardless of tree species;while C,N concentrations and C:N ratios changed significantly either in branches or in fine roots,and they varied with tree species except Populus davidiana(P<0.05).For ecosystem components,we discovered that leaf C:N ratios remained stable when stand age was below ca.70 years and dominant tree species were light-demanding pioneers such as Betula platyphylla and Populus davidiana,while increased signifi-cantly at the age of ca.200 years with Pinus koraiensis as the dom-inant species.C:N ratios in branches and fresh litter did not changed significantly along forest development stages.C concentrations scaled isometrically with respect to N concentrations in mineral soil but not in other ecosystem components.Our results indicate that,leaf has a higher intraspecific C:N stoichiometric stability compared to branch and fine root,whereas for ecosystem components,shifts in species composition mainly affect C:N ratios in leaves rather than other components.This study also demonstrated that C and N remain coupled in mineral soils but not in plant organs or fresh litter during forest development.