NSFDEB-NERC:Mycorrhizal drivers of SOM formation and decomposition

自然温带生态系统中的土壤以土壤有机质的形式储存了大量的碳。这代表了这些生态系统（包括森林、草原和湿地）的一项重要服务，因为这些有机物质储存库是由腐烂的植被建立起来的，这些植被以前从大气中的二氧化碳中固定了生物量中的碳。由于气候的影响和土地利用的变化，土壤中这种碳库的持久性存在很大的不确定性。温度对植物生物量形成和腐烂过程的影响已经得到了很好的研究，但迄今为止主要是单独考虑。最近，人们发现植被与土壤中微生物相互作用方式的根本差异对土壤有机质中碳的储存有重大影响。植物与特定形式的真菌（菌根）的共生关系是特别感兴趣的。这些真菌在植物营养供应中的作用已经确立，但最近的发现强调了这些生物对有机物形成和分解的重要影响。植被形态的变化可以极大地影响土壤中真菌（即菌根）多样性的类型，直接影响有机质的形成和腐烂。然而，植被形态、真菌结合力与土壤有机质储量之间的相互作用尚未得到系统的研究。这项研究解决了植被变化的方式，也改变了菌根真菌关联的类型，导致有机物储存的变化。具体来说，我们将调查从草原到针叶林的转变。这种植被变化在温带地区相对常见，这是由于气候变暖导致树线附近树木的侵蚀，以及土地利用的管理变化，在这些变化中，高地牧场可能会种植商业林业或进行“野生化”努力。我们的方法将实验分解研究与生态系统模型开发相结合，使新一代预测模型（基于现有建模工具）能够纳入植物与微生物的相互作用。土地管理者和决策者都需要充分了解这种植被变化对土壤碳储量的影响，因为植被对碳吸收的明显好处可能会被相应的土壤碳储量损失所抵消。

Soils in natural temperate ecosystems store substantial amounts of carbon in the form of soil organic matter. This represents a vital service by these ecosystems (including forest, grasslands as well as wetlands), as these organic matter reservoirs have been built up from decaying vegetation that previously fixed carbon in its biomass from atmospheric CO2. There is significant uncertainty regarding the persistence of this reservoir of carbon in soils, both from climatic influences and changes in land use. The influence of temperature on the formation of plant biomass as well as decay processes are well researched, but have so far been largely considered separately. More recently, it has emerged that fundamental differences in the way in which vegetation interacts with microbial organisms in the soil have significant impact on the storage of carbon in soil organic matter. The symbiotic relationship of plants with particular forms of fungi (mycorrhizas) is of particular interest. The role of these fungi in the supply of nutrients to plants is well established, but recent findings highlight important influences of these organisms also on the formation and decomposition of organic matter. Changes in vegetation form can drastically influence the type of fungal (i.e. mycorrhizal) diversity in the soil, with direct implications for organic matter formation and decay. However, the interaction between vegetation form, fungal association and soil organic matter storage has not been investigated systematically.This research addresses the way in which changes in vegetation that also alter the type of mycorrhizal fungal association results in changes in organic matter storage. Specifically, we will investigate a switch from grasslands to coniferous forests. This kind of vegetation change is relatively common in temperate regions due to an encroachment of trees near treelines, following a warming climate, and managed land use changes where upland pasture may be planted with commercial forestry or for 'rewilding' efforts. Our methodology combines experimental decomposition studies with ecosystem model development to enable a new generation of predictive models (based on existing modelling tools) able to incorporate plant-microbial interactions. Land managers and policy makers alike require a full understanding of the consequences of this kind of vegetation change on soil carbon storage, as apparent benefits in carbon uptake by vegetation may be annulled by corresponding losses in storage within the soil.