Plant diversity effects on soil glomalin -related proteins

• 1、Key Laboratory of Forest Plant Ecology Ministry of Education，Northeast Forestry University， Harbin 150040

Abstract：GGlomalin-related soil protein (GRSP) is a metabolic byproduct of soil AM fungi, which has been studied on the regulation of soil physical structure and soil aggregation, but possible influence from plant composition diversity has not been reported to date. In this study, 72 plots of experimental forest farm of Northeast Forestry University at Harbin were selected as the research objects, the plant species diversity(Simpson, Shannon-wiener, richness and evenness indices) and key species important values(top 8 abundant tree species) were calculated, and we also collected soil samples from 0-100 cm (5 layers) for the measurement of soil EEG (easily extracted GRSP), TG (total GRSP), EEG / TG (composition ratio), EEG-C / SOC (contribution of EEG carbon to soil organic carbon), TG-C / SOC (contribution of TG carbon to soil organic carbon), EEG-N / TN (contribution of EEG nitrogen to soil nitrogen), TG-N / TN (contribution of TG nitrogen to soil nitrogen), and other soil physical and chemical properties (bulk density, pH, electrical conductivity, and water content).Through correlation analysis, redundancy ordination and variance partitioning analysis, the effects of soil physical and chemical properties, plant diversity and dominant species on GRSP characteristics were identified. The results showed that: (1) soil carbon and nitrogen had a positive correlation with GRSP characteristics, but a negative correlation with pH and electrical conductivity. Total 1m soil profile had the similar trend, which was consistent with previous reports. (2) Compared with soil properties, plant diversity showed much weak association with EEG and TG without statistical significance (p >0.05). Simpson index, Shannon-Wiener index, species richness negatively correlated with EEG-C / SOC, EEG-N / TN, TG-C / SOC, TG-N / TN; Species evenness was positively correlated with EEG-N / TN. (3) Top 8 tree\'s important values (IV) showed stronger relations with GRSP parameters. The higher IV of Pinus tabuliformis, the smaller IV of Phellodendron amurense and Ulmus pumila, accompanied with the increased EEG, and GRSP-C/SOC, and GRSP-N/TN and EEG / TG; The higher IV of Juglans mandshurica, Phellodendronamurense and Ulmus pumila positively associated with the increase of TG. (4) Variationpartitioning analysis showed tree biological factors showed 2.6-fold higher explanatory power for GRSP variations than soil factors; Of them, dominant species IV was the largest (57.1%), while species diversity\'s contribution was only 1.4%. Redundancy ordination manifested that the higher IV of evergreen coniferous species but lower IV of broad-leaved species, was aligned with the higher GRSP content and its contribution to carbon and nitrogen. In the past, most studies found that importance of soil physical and chemical properties on GRSP, and this study was the first to highlight importance of tree composition diversity on GRSP variation statistically, providing new data support for degraded soil management and ecological evaluation via plant-species-oriented GRSP regulation.

Keywords： Glomalin-related soil protein species diversity important value of key species soil physical and chemical properties redundancy ordination and variation partitioning