Understanding plant roots induced changes in soil organic matter (SOM) decomposition, the rhizosphere effect, is critical to predict soil carbon and nutrient cycling within and across biomes. However, the root-centered mechanisms regulating such rhizosphere effect remain unclear. In this study, the rhizosphere effect on SOM decomposition was measured by incubating rhizosphere and bulk soils sampled from 14 hardwood species with distinct mycorrhizal associations (Arbuscular mycorrhizal, AM vs. Ectomycorrhizal, ECM). Further, root traits (related to chemistry, morphology and physiology), soil enzymes related to carbon, nitrogen and phosphorous cycling and soil physico-chemical properties were measured to determine potential mechanisms that regulate interspecific variation of the rhizosphere effect on SOM decomposition. The results indicated that the rhizosphere effects on SOM decomposition and soil enzymes showed relatively large interspecific variation, and were not influenced by mycorrhizal associations. Root traits showed stronger correlations with the rhizosphere effect on SOM decomposition across the 14 hardwood species than bulk soil physico-chemical properties. Specifically, the rhizosphere effect on SOM decomposition was correlated positively with root nitrogen concentration, and negatively with root carbon/nitrogen ratio and root diameter, respectively. These three root traits were the three most important predictors for the interspecific variation of the rhizosphere effect on SOM decomposition amongst all variables. Moreover, the rhizosphere effect on SOM decomposition tended to increase with increasing root exudationn rates. Taken together, we showed strong evidence that the rhizosphere effect on SOM decomposition tended to increase along the root economics spectrum from conservative species to acquisitive species in woody plants. Our findings thus contribute to a better mechanistic link between root traits and rhizosphere effect across species, which could be incorporated into land surface models to predict ecosystem scale consequences of root induced changes in SOM decomposition.

了解植物根系引起的土壤有机质（SOM）分解变化（根际效应）对于预测生物群落内部和整个生物群落中的碳和养分循环至关重要。但是，调节这种根际效应的以根为中心的机制仍然不清楚。在这项研究中，根际对SOM分解的影响是通过孵育根际和从14种硬木树种中取样的具有不同菌根联系的块状土壤（丛枝菌根，AM与。外生菌根，ECM）。此外，测量了根性状（与化学，形态和生理有关），与碳，氮和磷循环有关的土壤酶以及土壤理化性质，以确定调节根际对SOM分解的种间变化的潜在机制。结果表明，根际对SOM分解和土壤酶的影响表现出较大的种间差异，不受菌根协会的影响。与14种硬木树种相比，根系性状与根际效应对SOM分解的相关性强于整体土壤的理化特性。具体而言，根际对SOM分解的影响与根氮浓度呈正相关，根碳/氮比和根直径分别为负。这三个根性状是所有变量中根际对SOM分解的种间变化的三个最重要的预测因子。此外，根际渗出速率的增加，根际对SOM分解的影响趋于增加。两者合计，我们显示出有力的证据表明，根际经济对SOM分解的影响趋向于从木本植物的保守经济学到习性物种的整个根系经济学谱增加。因此，我们的发现有助于根系性状与跨物种的根际效应之间建立更好的机械联系，可以将其纳入陆地表面模型以预测根系引起的SOM分解变化的生态系统规模后果。这三个根性状是所有变量中根际对SOM分解的种间变化的三个最重要的预测因子。此外，根际渗出速率的增加，根际对SOM分解的影响趋于增加。两者合计，我们显示出有力的证据表明，根际经济对SOM分解的影响趋向于从木本植物的保守经济学到习性物种的整个根系经济学谱增加。因此，我们的发现有助于根系性状与跨物种的根际效应之间建立更好的机械联系，可以将其纳入陆地表面模型以预测根系引起的SOM分解变化的生态系统规模后果。这三个根性状是所有变量中根际对SOM分解的种间变化的三个最重要的预测因子。此外，根际渗出速率的增加，根际对SOM分解的影响趋于增加。两者合计，我们显示出有力的证据表明，根际经济对SOM分解的影响趋向于从木本植物的保守经济学到习性物种的整个根系经济学谱增加。因此，我们的发现有助于根系性状与跨物种的根际效应之间建立更好的机械联系，可以将其纳入陆地表面模型以预测根系引起的SOM分解变化的生态系统规模后果。