祁连山南麓不同植被类型土壤碳氮磷及其化学计量比特征OA

Exploring the relationship between soil carbon(C),nitrogen(N),and phosphorus(P),their stoichio-metric characteristics,and soil physicochemical properties under different vegetation types on the southern slope of the Qilian Mountains is important for assessing regional soil nutrient status and guiding vegetation restoration.In this study,shrubland,broadleaved forest,mixed coniferous-broadleaved forest,and coniferous forest on the southern slope of the Qilian Mountains were selected as research objects.The soil content of C,N,and P and their stoichiometric ratios(C:N,C:P,N:P)were measured in the top 30 cm of soil(divided into depths of 0-10 cm,10-20 cm,and 20-30 cm),along with soil physicochemical properties,including pH and bulk density(BD).One-way ANOVA with LSD multiple comparison,Pearson correlation analysis,and redundancy analysis were used to characterize the soil stoichiometric ratios under different types of vegetation and their relationships with soil phys-icochemical properties.The following results were obtained:(1)Among different vegetation types,soil C and N contents were highest in the mixed coniferous-broadleaved forest and lowest in the coniferous forest,and soil P content was highest in the coniferous forest among the three tree-dominated forest types but was highest in the shrubland of all vegetation types.(2)In the 0-20 cm soil layer,the C:N ratio in broadleaved forest and mixed for-est was significantly higher than that of the other types and the C:P and N:P ratios generally followed the order broadleaved forest>mixed forest>shrubland>coniferous forest.Broadleaved forest and mixed forest exhibited higher C:P and N:P ratios but lower total P content,indicating a higher risk of phosphorus(P)limitation in these two forest types.(3)Correlation analysis showed that,across all vegetation types,soil C and N contents and C:P and N:P ratios were significantly positively correlated with belowground biomass(BGB)and significantly nega-tively correlated with pH and BD.(4)RDA found that soil pH was the most important common factor driving changes in soil stoichiometric characteristics in this region,although its explanatory power mainly originated from surface soil differences;additionally,the stoichiometric ratios of mixed forests were significantly regulated by litter amount(PL),whereas those of coniferous forests were regulated by BD.In summary,the mixed conifer-ous-broadleaved forest performed best in soil C and N accumulation and should be recommended as the domi-nant vegetation type for the restoration of regional vegetation.However,broadleaved forest and mixed forest face a higher risk of P limitation,necessitating the special consideration of phosphorus supply in nutrient manage-ment.The results of this study provide a scientific basis for vegetation restoration and soil nutrient management in the ecologically fragile southern slope of the Qilian Mountains.