Exploring links in the root trait - soil organic matter continuum

土壤是陆地上最大的碳储存库，它既是大气碳的潜在源，也是大气碳的汇。在以前通过集约利用或退化而失去有机质（和C）的土壤中，未来封存过量大气C的潜力最大;这些退化的土壤代表了全球范围内的巨大土地面积。例如，最近的综合研究表明，平均而言，全世界的农业土壤可以螯合50吨公顷的补充。然而，为了有效地利用这种封存潜力，我们需要更好地了解地上和地下植物凋落物（特别是根凋落物）的命运和路径，与不同的已知土壤稳定机制（土壤团聚体的保护;与矿物表面的化学反应）。目前的一系列研究将集中在多样性（具体和功能）和“效果”功能性状（植物的形态特征）如何通过叶片影响土壤碳储存，特别是根系（根组织化学;根土壤开发性状;生根深度等），在森林生态系统和草地系统中（与法国合作）。在目前的实验中，草原土壤种植单一作物，我们测量了物种和根性状对土壤团聚体的影响，指出确定特定的根性状，可能促进保护土壤C的可能性。这一观察结果将被证实沿着梯度的树木多样性，假设增加多样性（丰富度或功能）将与增加土壤团聚和化学保护的C。我们还将探讨性状对微生物群落结构和功能的反馈;性状对土壤过程的间接影响可能由该隔室介导。在亚寒带森林社区，我们将测量八个林下植物的性状，并将通过测量质量损失的一个共同的基板在生根区的分解率进行测试。这一系列的研究将增加我们对生物多样性对生态系统功能（几个生态系统）的影响和特定的根性状（效应性状）对土壤碳稳定相关过程的作用的理解。土地管理者有能力确定土壤碳储存潜力最大的情况（地点，土壤，化学），也就是说，土壤距离碳饱和更远。如果像这里提出的研究也可以开始，以确定根性状的组合，可以最大限度地提高长期C存储在不同的土壤类型和生态系统，我们可以提出管理系统，可以隔离C在更大的规模，在森林和农业生态系统。这一进展对于减少全球变化的潜在影响以及维持和恢复生产性生态系统至关重要。

Soils represent the largest terrestrial pool of stored carbon (C); this pool is important both as a potential source and also sink for atmospheric C. The future potential to sequester excess atmospheric C is greatest in soils which have previously lost organic matter (and C) through intensive use or degradation; these degraded soils represent an enormous land area on a global basis. For example, recent syntheses have suggested that on average, agricultural soils worldwide could sequester a supplemental 50 t ha-1. However, to effectively exploit this sequestration potential, we need to have a better understanding of the fate and paths of above and belowground plant litter (especially root litter) in relation to the different known mechanisms of stabilization in the soil (recalcitrance; protection in soil aggregates; chemical reactions with mineral surfaces). The current series of studies will focus on how diversity (specific and functional) and «effect» functional traits (morphological characters of plants) may influence soil C storage via the leaves, but especially root systems (root tissue chemistry; root soil exploitation traits; rooting depth etc), in both forest ecosystems and in grassland systems (collaboration with France). In current experiments with grassland soils planted with monocultures, we measured species and root trait effects on soil aggregation, pointing to the possibility of identifying specific root traits that may promote protection of soil C. This observation will be verified along gradients of tree diversity, with the hypothesis that increasing diversity (richness or functional) will be related to increasing both soil aggregation and chemical protection of C. We will also explore the feedback of traits on microbial community structure and function; indirect effects of traits on soil processes may be mediated by this compartment. In sub-boreal forest communities we will measure traits of eight understory plants, and decomposition rate in relation to traits will be tested by measuring mass loss of a common substrate in the rooting zone. This series of studies will increase our understanding of biodiversity effects on ecosystem function (several ecosystems) and the role of specific root characters (effect traits) on processes related to soil carbon stabilization. Land managers have the capacity to identify the situations (site, soil, chemistry) where the potential for soil C storage is greatest, that is, where the soils are further from carbon saturation. If studies such as proposed here can also begin to identify the combination of root traits that can maximize long term C storage in different soil types and ecosystems, we can propose management systems that could sequester C on a much larger scale, across both forest and agro-ecosystems. This progress is critical to reducing the potential impacts of global change and to maintaining and restoring productive ecosystems.