Controls on the stability of soils and their functioning under land use and climate change

土壤为人类提供了许多功能，包括对粮食生产和减缓气候变化至关重要的碳储存和养分循环。然而，令人担忧的是，土壤及其提供的功能正受到一系列压力的威胁，包括集约化耕作方法和干旱等极端气候事件日益频繁。这些干扰不仅对土壤的功能构成直接威胁，而且还可能损害土壤抵抗未来进一步压力并从中恢复的能力。我们的项目将通过解决两个一般性问题来解决这个问题：第一，是什么使土壤能够承受干扰事件，如干旱，第二，我们如何利用这些知识来确保土壤能够缓冲未来的干扰？这些问题多年来一直困扰着土壤科学家，但到目前为止，仍未得到解决。然而，在解决这个问题方面，有一个领域提供了很大的希望，那就是食物网生态学。食物网是描述生态系统中无数生物中谁吃谁的相互作用网络。在土壤中，它们是驱动养分循环和能量流动过程的引擎，土壤和它们所支持的陆地生态系统的功能都依赖于这些过程。简单的食物网比复杂的食物网更难以抵御干扰事件（如干旱）并从干扰事件中恢复过来，这一观点已经提出多年，但迄今尚未在土壤中得到充分验证。我们想在土壤中验证这一理论，土壤中蕴藏着地球上一些最复杂，但也最敏感的食物网。我们通过实验和模型验证了这一观点，即土壤承受、恢复和适应干扰事件的能力取决于土壤食物网的结构和多样性，而土壤食物网控制着植物-土壤系统中养分和能量的转移速率。我们还提出，与集约土地利用相关的土壤扰动，如践踏和施肥，侵蚀了使土壤系统稳定的食物网结构，从而降低了土壤抵抗和从未来扰动（如极端天气事件）中恢复的能力。我们还将解决是什么使食物网稳定，并测试不同类型的生物在土壤中的作用，例如我们认为起主要作用的菌根真菌。最后，我们将开发新的模型，帮助我们更好地预测土壤将如何应对未来的威胁，并在快速变化的世界中指导有关可持续土壤管理的管理决策。这些问题是NERC土壤安全方案的核心，该方案寻求解决是什么控制着土壤的能力及其抵抗、恢复和最终适应扰动的功能，例如由土地利用和极端气候事件引起的扰动。

Soils provide many functions for humans, including the storage of carbon and nutrient cycling, which are crucial for the production of food and mitigation of climate change. However, there is much concern that soils, and the functions that they provide, are being threatened by a range of pressures, including intensive farming methods and increased frequency of extreme climatic events, such as drought. Not only do these disturbances pose an immediate threat to the functioning of soils, but they could also impair their ability to resist and recover from further stresses that come in the future. Our project will tackle this problem by addressing two general questions: first, what makes a soil able to withstand and recover from disturbance events, such as drought, and, second how can we use this knowledge to ensure soils can buffer disturbances in the future? These are questions that have puzzled soil scientists for many years, but so far, remain unresolved. An area that offers much promise, however, in tackling this issue is food web ecology. Food webs are the networks of interactions describing who eats whom amongst the myriad organisms within an ecosystem. And in soil, they are the engine that drives the very processes of nutrient cycling and energy flow on which the functioning of soil and the terrestrial ecosystems they support, depend. It has been proposed for many years, but so far not fully tested in soil, that simple food webs are less able to withstand and recover from disturbance events, such as drought than complex ones. We want to test this theory in soil, which harbours some of the most complex, but also sensitive, food webs on Earth. We test the idea, through experiments and models, that the ability of a soil to withstand, recover and adapt to disturbance events depends on the architecture and diversity of the soil food web, which governs the rate of transfer of nutrients and energy through the plant-soil system. We also propose that soil disturbances associated with intensive land use, such as trampling and fertiliser addition, erode the very food web structures that make the soil system stable, thereby reducing the ability of soil to resist and recover from future disturbances, such as extreme weather events. We will also resolve what makes a food web stable, and test the roles of different types of organisms in soil, such as mycorrhizal fungi, which we believe play a major role. And finally, we will develop new models to help us better predict how soils will respond to future threats and to guide management decisions on sustainable soil management in a rapidly changing world. These question are at the heart of the NERC Soil Security programme which seeks to resolve what controls the ability of soils and their functions to resist, recover and ultimately adapt, to perturbations, such as those caused by land use and extreme climatic events.