Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale, UMR 7263, Aix Marseille Université, Université d'Avignon, CNRS, IRD, Campus l'Etoile, Site de Saint-Jérôme, Avenue escadrille Normandie-Niemen, 13 397 Marseille Cedex 20, France.
Aix Marseille Université, CNRS, Spectropole Campus St Jérôme, Fédération des Sciences Chimiques de Marseille, FR 1739, 13397, Marseille, France.
Sci Total Environ. 2017 Jul 15;590-591:676-685. doi: 10.1016/j.scitotenv.2017.03.023. Epub 2017 Mar 10.
This study investigated how oak abundance in pine stands (using relative Oak Basal Area %, OBA%) may modulate soil microbial functioning. Forests were composed of sclerophyllous species i.e. Quercus ilex mixed with Pinus halepensis Miller or of Q. pubescens mixed with P. sylvestris. We used a series of plots with OBA% ranging from 0 to 100% in the two types of stand (n=60) and both OLF and A-horizon compartments were analysed. Relations between OBA% and either soil chemical (C and N contents, quality of organic matter via solid-state NMR, pH, CaCO) or microbial (enzyme activities, basal respiration, biomass and catabolic diversity via BIOLOG) characteristics were described. OBA% increase led to a decrease in the recalcitrant fraction of organic matter (OM) in OLF and promoted microbial growth. Catabolic profiles of microbial communities from A-horizon were significantly modulated in Q. ilex and P. halepensis stand by OBA% and alkyl C to carboxyl C ratio (characteristic of cutin from Q. ilex tissues) and in Q. pubescens and P. sylvestris stands, by OBA% and pH. In A-horizon under Q. ilex and P. halepensis stands, linear regressions were found between catabolic diversity, microbial biomass and OBA% suggesting an additive effect. Conversely, in A-horizon Q. pubescens and P. sylvestris stands, the relationship between OBA% and either cellulase activities, polysaccharides or ammonium contents, suggested a non-additive effect of Q. pubescens and P. sylvestris, enhancing mineralization of the OM labile fraction for plots characterized by an OBA% ranging from 40% to 60%. Mixing oak with pine thus favored microbial dynamics in both type of stands though OBA% print varied with tree species and consequently sustainable soil functioning depend strongly on the composition of mixed stands. Our study indeed revealed that, when evaluating the benefits of forest mixed stand on soil microbial functioning and OM turnover, the identity of tree species has to be considered.
本研究调查了油松林中橡木丰度（使用相对橡木基面积百分比，OBA%）如何调节土壤微生物功能。森林由硬叶物种组成，即混有 Quercus ilex 的 Pinus halepensis Miller 或混有 Q. pubescens 的 P. sylvestris。我们使用了一系列在两种林型中 OBA% 从 0 到 100%的样地（n=60），并分析了 OLF 和 A-层。描述了 OBA%与土壤化学特性（C 和 N 含量、通过固态 NMR 测定的有机质质量、pH 值、CaCO）或微生物特性（酶活性、基础呼吸、生物量和通过 BIOLOG 测定的代谢多样性）之间的关系。OBA%的增加导致 OLF 中难分解有机质（OM）的减少，并促进微生物生长。A-层土壤微生物群落的代谢谱在 Q. ilex 和 P. halepensis 林分中被 OBA%和烷基 C 与羧基 C 比值（Q. ilex 组织角质的特征）显著调节，在 Q. pubescens 和 P. sylvestris 林分中，被 OBA%和 pH 值调节。在 Q. ilex 和 P. halepensis 林分的 A-层中，发现代谢多样性、微生物生物量和 OBA%之间存在线性回归，表明存在附加效应。相反，在 Q. pubescens 和 P. sylvestris 林分的 A-层中，OBA%与纤维素酶活性、多糖或铵含量之间的关系表明，Q. pubescens 和 P. sylvestris 的作用是非附加的，增强了 OM 易分解部分的矿化，对于 OBA%在 40%至 60%之间的样地。因此，橡木与松树混交有利于两种林型中的微生物动态，尽管 OBA%的影响因树种而异，因此，混合林分的组成强烈依赖于可持续的土壤功能。我们的研究确实表明，在评估森林混合林分对土壤微生物功能和 OM 周转的益处时，必须考虑树种的身份。
