中科院沈阳生态所根际激发效应研究获进展

根际激发效应（Rhizosphere priming effect）是指根际活动造成土壤有机质分解速率改变的现象，被认为是调控土壤碳氮循环的重要机制之一。目前，科研人员对根际激发效应开展了大量研究，发现激发效应可使土壤有机质分解速率降低50%或增加3.8倍，与温度、水分因子对土壤碳释放的影响程度相当。然而，这些研究结果还相对零散，限制了人们对根际激发效应的理解和应用。

中国科学院沈阳应用生态研究所地下生态过程学科组霍常富及其合作者，在研究员程维信的带领下，利用数据综合分析（Meta-analysis）的方法，对31篇有关根际激发效应的文献，进行了系统总结。研究结果表明：1）根际激发效应可使土壤有机质分解速率平均增加59%；2）激发强度受植物种类显著影响，木本>草本>农作物；3）土壤质地越细激发越强；4）激发强度与植物地上生物量显著正相关，而与根系生物量无相关性；5）根际激发效应与栽植时间显著正相关，意味着根际激发可以长期存在并可激发土壤中稳定的碳库。综上，该研究结果揭示了根际激发效应的方向、强度以及多种影响因子，今后应注重多因子尤其全球气候变化因子的试验，为模型模拟提供支撑。

以上研究成果，发表于美国土壤学会期刊《土壤生物学与生物化学》（Soil Biology & Biochemistry，(2017) 111: 78-84）。该研究受到中科院先导专项B、“973”项目和国家自然基金的资助。（来源：中科院沈阳应用生态研究所）

Rhizosphere priming effect: A meta-analysis

Abstract Rhizosphere priming is crucial for regulating soil carbon and nitrogen biogeochemical cycles. An appreciable number of studies have been conducted to quantify the rhizosphere priming effect (RPE), and have shown that the RPE is sensitive to changes of plant and soil conditions. These diverse results across individual studies offer us an opportunity to explore for potential general patterns and variability. In this study, we conducted a meta-analysis of RPE values taken from 31 publications. Our results showed that, on average, the RPE enhanced soil organic carbon mineralization rate by 59% across all studies. The magnitudes of the RPE significantly varied among plant types and soil texture. Within plant types, woody species showed the highest RPE followed by grasses while crops had the lowest level of the RPE, indicating that plant traits and physiology may exert important controls on the RPE. Soils with finer texture tended to produce stronger RPEs than soils with coarser texture, suggesting that interactions between the rhizosphere and the soil matrix may modulate the RPE. Furthermore, the level of the RPE is positively correlated with aboveground plant biomass, but surprisingly not with root biomass which is the commonly believed key variable for influencing the RPE. In addition, the RPE increased with the length of experimental duration, which implies that the RPE may persist much longer than previously believed because it impacts stabilized soil carbon more than labile carbon as the length of experimental duration increases. Overall, the results from this meta-analysis further illustrate several complex features of the RPE and call for future attentions to decipher this complexity.

原文链接：http://www.sciencedirect.com/science/article/pii/S0038071717304662