南亚热带典型森林土壤可交换性阳离子的垂直分布格局OA

[Objective]This study aims to explore the vertical distribution patterns of exchangeable cations in southern subtropical forest soils and identify their potential influencing factors,so as to provide theoretical support for the conservation and sustainable development of southern subtropical forest ecosystems.[Method]Three representative southern subtropical forests in the Dinghushan National Nature Reserve,Guangdong Province were selected for this study.These forests include the monsoon evergreen broadleaved forest(broadleaved forest/primary forest),mixed Pinus massoniana/broadleaved forest(mixed forest/secondary forest),and P.massoniana forest(pine forest/planted forest).The exchangeable cations(H+,Al3+,K+,Na+,Ca2+,Mg2+and Fe3+),cation exchange capacity(CEC),aluminum saturation(Al-S),base saturation(BS),and pH in different soil layers[0,10),[10,20),[20,30),and[30,40)cm of three forests were analyzed.[Result]The results indicated that pH was generally lower than 4.2,BS was below 8％,and Al-S was typically higher than 60％across the three forests.Along the soil profile,the concentrations of exchangeable cations,CEC,BS,and exchangeable acidity generally decreased with increasing soil depth,while soil pH and Al-S showed an increasing trend.Overall,the broadleaved forest had significantly higher CEC,BS,Al-S,and exchangeable cation contents(except for H+)than the other two forests,but had lower soil pH.The mixed and coniferous forests exhibited similar patterns in exchangeable cation distribution.[Conclusion]In conclusion,the southern subtropical forests of China are acid-sensitive ecosystems characterized by nutrient-poor soils within an aluminum buffering system.Exchangeable cations are predominantly concentrated in the upper soil layers.Land-use history and its legacy effects contribute to the varying soil acidification status among these three forests.Given the global change,it is essential to prioritize the replenishment of key cations like calcium and magnesium,rather than focusing solely on aluminum toxicity,in forest restoration and management efforts.