Forecasting land management and extreme weather effects on earthworm populations, soil function and ecosystem services

土壤构成了陆地生命的基本基质。它们通过支持粮食、燃料和纤维的生产，并通过促进土壤形成和养分循环等基本服务来调节气候、疾病和水资源，从而造福于人类。对于人口呈指数级增长的人口来说，关键是土壤为农业提供的基础。生态系统工程师的活动对土壤功能至关重要，土壤功能是提供生态系统服务的基础。蚯蚓在土壤中扮演生态系统工程师的角色，既直接通过消化和挖掘活动，也间接通过鼓励其他有益的土壤有机体。优化土壤环境条件(如土壤有机碳(SOM)和土壤水分)的管理措施也能刺激蚯蚓生物量的产生。反过来，蚯蚓活动对土壤团聚体稳定性、养分循环和土壤碳动态的影响会提高作物产量。尽管土地管理的变化可能会增加土壤生物的丰度，但这些影响取决于管理实践和环境因素的具体组合。这使得实验场研究的结果很难根据不同的情景进行推断，比如在极端天气下。因此，需要工具来更好地预测管理做法如何通过对重要的生态系统工程师的影响来影响生态系统服务的提供。现有的关于人口如何应对人为环境变化的人口模型忽视了潜在的机制。许多只关注种群或个体的水平，而不是代表连接两个生物组织水平的过程。需要机械模型来捕捉支撑系统运行的关键生物、生理和生态机制。这样的模型将有更好的预测能力。在这份提案中，我将展示如何开发和验证蚯蚓的机械模型，这些模型在一系列栖息地提供重要的土壤功能。一旦这些模型表明它们真实地捕捉到了田间蚯蚓的种群动态，它们将被应用于许多农业情景，其中包括土壤和天气条件、作物管理做法(例如耕作)和极端天气(洪水和干旱)事件的不同组合。模型结果将通过预测这些不同情景下的蚯蚓数量来显示不同农业系统的生态后果。人们对蚯蚓如何应对洪水和干旱知之甚少。这项提议将通过改进机械模型来确定支撑机制，以匹配这些极端天气条件下的新数据。我将通过回顾相关的科学文献，将蚯蚓作为生态系统工程师的角色与土壤功能和生态系统服务(如作物生产和产量)联系起来。这些知识将被用来提供新的方法来量化蚯蚓作为生态系统工程师的价值，从而能够更好地对不同的土地管理制度进行成本效益分析，并促进将蚯蚓作为一种自然资源供土地管理者使用。

Soils form the basic substrate for terrestrial life. They benefit the human population by supporting the production of food, fuel and fiber and regulating the climate, disease and water resources by facilitating essential services such as soil formation and nutrient cycling. Crucial for an exponentially growing human population are the foundations that soils provide for agriculture.The activities of ecosystem engineers are important to the soil functions that underpin the provision of ecosystem services. Earthworms act as ecosystem engineers in soils both directly through digestion and burrowing activities and indirectly by encouraging other beneficial soil organisms. Management practices which optimise soil environmental conditions (e.g. soil organic carbon (SOM) and soil moisture) also stimulate earthworm biomass production. In turn the effects of earthworm activity on soil aggregate stability, nutrient cycling and soil carbon dynamics improve crop yields.Although changes in land management may increase the abundance of soil organisms, these effects depend on specific combinations of management practices and environmental factors. This makes the results of experimental field studies hard to extrapolate for different scenarios, such as in extreme weather. Thus, tools are needed to better forecast how management practices affect the provision of ecosystem services through their effects on important ecosystem engineers. Existing population models of how populations will respond to anthropogenic environmental change ignore the underlying mechanisms. Many focus only on the level of populations or individuals, rather than representing the processes which link both levels of biological organisation. Mechanistic models are needed that capture key biological, physiological and ecological mechanisms underpinning system functioning. Such models will have much better predictive power.In this proposal I show how I will develop and validate mechanistic models of earthworms which deliver important soil functions in a range of habitats. Once the models have demonstrated that they realistically capture earthworm population dynamics in the field, they will be applied to numerous agricultural scenarios, with different combinations of soil and weather conditions, crop management practices (e.g. tillage) and extreme weather (flood and drought) events. Model results will indicate the ecological consequences of the different agricultural systems by forecasting earthworm populations in these different scenarios. Relatively little is known about how earthworms respond to flood and drought. This proposal will identify the underpinning mechanisms by refining the mechanistic models to match new data under these extreme weather conditions. I will relate the role of earthworms as ecosystem engineers to soil functions and ecosystem services such as crop production and yield, by reviewing the relevant scientific literature. This knowledge will be used to provide new methods for quantifying the value of earthworms as ecosystem engineers which will allow better cost-benefit analysis of contrasting land management systems and promote the use of earthworms as a natural resource to land managers.