植物群落与土壤养分共同调控对黄土塬区沟坡土壤团聚体稳定性的影响OA

[Objective]The effects of plant communities and soil nutrients on the stability of soil aggregates on gully slopes in the gully region of the loess tableland were investigated in order to provide a theoretical basis for regional ecosystem restoration and sustainable vegetation reconstruction.[Methods]Four typical herb communities with dominant species of Artemisia gmelinii,Artemisia argyi,Artemisia frigida,and Stipa bungeana were selected as the study objects.Through field investigation and laboratory analysis,the variation of plant diversity,root system,soil nutrient properties,and water-stable aggregate composition with soil depth was investigated.[Results]① The A.argyi community showed the highest species diversity.Its Patrick richness index and Shannon-Wiener index were significantly higher than those of other communities,whereas its Simpson index was the lowest.The Pielou evenness index showed no significant difference among the communities.② The root length density(RLD)and root mass density(RMD)of all communities decreased significantly with increasing soil depth.The RLD and RMD in the surface layer(0-20 cm)were 2.71-10.80 times of those in the deep layers.③ Soil organic carbon(SOC),total nitrogen(TN),and their stoichiometric ratios(C:N,C:P,and N:P)decreased significantly with soil depth,whereas total phosphorus(TP)showed no significant change.The SOC,TN,and TP contents in the A.argyi community were significantly higher than those in the other communities across all soil layers,with average values being 1.07-1.84 times of those of the A.gmelinii community,1.12-1.43 times of those of the A.frigida community,and 1.14-2.81 times of those of the S.bungeana community.④ The A.argyi community exhibited the significantly highest proportion of>0.25 mm water-stable aggregates and the aggregate stability indices(MWD and GMD),which were 1.15-1.55 times and 1.27-2.98 times of those of the other communities,respectively.The partial least squares path model(PLS-PM)revealed that soil nutrients were the strongest direct driving factor for aggregate stability(path coefficient 0.850,p<0.01).Root distribution indirectly affected aggregate stability by significantly increasing soil nutrient content(path coefficient 0.817,p<0.01),with an indirect effect of 0.695.[Conclusion]Higher species diversity promotes soil nutrient accumulation through well-developed roots,thereby synergistically enhancing the formation and stability of soil aggregates through the'root-soil nutrient'pathway.