Plant Composition Effects On Soil Glomalin-related Proteins In Harbin Experimental Forest Farm

Glomalin-related soil protein(GRSP)is a metabolite of soil arbuscular mycorrhizal fungi(AMF),which has been studied on the regulation of soil physical structure and pollution.However,the effect of plant community composition and species diversity on Glomalin-related soil protein was rarely studied.In this study,72 plots of experimental forest farm of Northeast Forestry University were selected as the research objects,The plant species diversity and dominant species important values were calculated,and the soil physical and chemical properties of 0-100 cm and 5 layers of soil easily extracted Glomalin associated soil protein(EEG),total Glomalin associated soil protein(TG),composition ratio(EEG/TG),contribution of EEG carbon to soil carbon(EEG-C/SOC),contribution of TG carbon to soil carbon(TG-C/SOC),contribution of EEG nitrogen to soil nitrogen(EEG-N/TN),contribution of TG nitrogen to soil nitrogen(TG-N/TN),and soil physical and chemical properties(bulk density,pH,electrical conductivity,and water content)were measured.Through correlation analysis,redundancy ranking and variance decomposition analysis,the effects of soil physical and chemical properties,plant diversity,community structure and important value of dominant species on GRSP characteristics were identified.The results showed that:(1)The average value of EEG was 0.71 mg·g-1,TG was 8.59 mg·g-1,and ratio of EEG/TG was 9%.The contribution value of TG to carbon was larger than that of nitrogen.The contribution value of TG to soil carbon and nitrogen is relatively higher in the deep layer,while the contribution value of EEG nitrogen was higher in the surface layer.The content of EEG in Pinus tabuliformis and Pinus sylvestris forest was higher than that in Phellodendron amurense forest,Juglans mandsh.urica forest and Ulmus davidiana forest.The proportion of EEG/TG was higher in evergreen coniferous species forest,e.g.,Pinus sylvestris.EEG-C/SOC,TG-C/SOC and TG-N/TN accounted for the highest proportion in Pinus tabuliformis forest,while EEG-N/TN was higher in Pinus tabuliformis forest and Pinus sylvestris forest.(2)The average DBH of arbors was 10.57 cm,the height of arbors was 8.02 m,the height under branches of arbors was 3.57 m,the DBH of shrubs was 2.22 cm,and the height of shrubs was 3 m.Among the community structure indexes,the correlation between shrub indexes and GRSP was stronger than that of tree indexes,the correlation between DBH of shrub was stronger than that of height,and the correlation between DBH of arbor was stronger than that of height and height under branch.Arbor’s height was negatively correlated with EEG,and positively correlated with TG-N/TN(p<0.01).TG content was negatively correlated with tree height,tree branch height was negatively correlated with EEG-N/TN,shrub DBH and TG content were negatively correlated.In terms of soil physical and chemical properties,GRSP characteristics were positively correlated with soil carbon and nitrogen,but negatively correlated with pH conductivity,positively correlated with water content,and not significantly correlated with bulk density.In the vertical distribution of 1 m profile,the contents of EEG and TG decreased significantly with soil depth.The content of EEG and TG in the surface layer was higher than that in the deep layer,and gradually decreased with the deepening of the soil layer.(3)The average Simpson index was 0.59,the Shannon-Wiener index was 1.13,the species richness was 4.97,and the average evenness index was 0.81.EEG was not correlated with all diversity indices,but TG was positively correlated with species richness;the contribution of EEG and TG to soil carbon and nitrogen was negatively correlated with species diversity index(Simpson index,Shannon-Wiener index,species richness),indicating that with the increase of species diversity,the contribution of EEG and TG to organic carbon and total nitrogen decreased,and species evenness was positively correlated with EEG-N/TN,these coupling relationships have similar trends in different layers of 1 m soil.The higher the important value of Pinus tabuliformis,the smaller the important value of Phellodendron amurense and Ulmus pumila,the more conducive to the accumulation of EEG,and the contribution of GRSP to soil carbon and nitrogen and the EEG/TG increased;Juglans mandshurica,Phellodendron amurense and Ulmus pumila were more conducive to the accumulation of TG,while Pinus tabuliformis,Larix gmelinii and Pinus sylvestris were not conducive to the accumulation of TG.(4)Variance decomposition analysis showed that the biological factors(species diversity,importance value of dominant species and community structure)could explain the change of GRSP much more than soil factors,and the importance value of dominant species could explain 50.1%of GRSP,while the impact of species diversity on GRSP was very small,only explained 0.4%.The more evergreen coniferous species(Pinus tabuliformis and Pinus sylvestris)and less broad-leaved species,the higher GRSP content and its contribution to carbon and nitrogen(p<0.01).In the past,most studies found that there is important effect of soil physical and chemical properties on GRSP.This study provided the important impact of dominant species and species diversity on GRSP from a statistical point of view,and provided data support for degraded soil management and ecological evaluation based on species composition and GRSP regulation.In conclusion,the important value of dominant species has a great impact on GRSP.In the future Afforestation Measures,we can pay more attention to key species rather than only soil properties,so as to improve soil carbon sequestration function and soil physical structure.