Effects of mixed decomposition of Platycladus orientalis and Quercus variabilis fine roots on soil organic carbon sequestration
Fine root decomposition is an important source of soil organic carbon(SOC).Previous studies have mostly focused on individual species,whereas the impact of mixed fine root decomposition on soil carbon sequestration remains unclear.We conducted a 90 day container incubation experiment using soil from a C4 crop(maize)to investigate the impact of mixed fine root litter from Platycladus orientalis and Quercus variabilis on the turnover of"new"versus"old"soil carbon at the initial stage of root decomposition.The results showed that compared with single fine root decomposition,root mass loss was promoted by mixed fine root decomposition due to the increased activity of cellulose disaccharide hydrolase(CBH)(P＜0.01).Mixed fine roots decomposition formed more root-derived"new"carbon,but also promoted the"old"soil carbon loss(positive priming effect).Redundancy analysis showed that soil"old"carbon loss was positively correlated with β-glucosidase(βG)activity(P＜0.05),soil"new"carbon increase was positively correlated with fine roots mass loss(ML)(P＜0.05),and was highly positively correlated with CBH and β-N-acetylglucosaminidase(NAG)activity(P＜0.01).The gain of"new"soil carbon exceed"old"soil carbon loss,suggesting mixed root decomposition drive greater soil carbon sequestration than single fine roots.Overall,this study indicates that the impact of mixed root decomposition on soil organic carbon dynamics is different from that of single root decomposition,emphasizing the importance of mixed fine root research in accurately evaluating soil carbon dynamics in forest ecosystems.
fine rootmixed decompositionsoil organic carbonpriming effect
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