Scaling and thresholds in earthworm abundance and diversity in grassland agricultural systems

“即使在同一块土地上，蠕虫在某些地方比在其他地方更频繁，土壤的性质没有任何明显的差异”达尔文，1881年达尔文在130多年前写下了这句话，然而，尽管进行了大量的研究，我们仍然不能用最广泛的术语来解释为什么，当你从一块土地的两个不同地方挖土壤时，蚯蚓可能出现在一个地方，但不存在于另一个地方。鉴于蚯蚓在环境中的重要性，这不是一件小事。蚯蚓被称为“生态系统工程师”。它们摄取大量的土壤，在这个过程中分解有机物质，混合土壤，并通过洞穴保持土壤通气。由于这些活动，蚯蚓帮助它们所在的生态系统提供各种利益或服务。这些所谓的生态系统服务包括粮食生产（植物在蚯蚓的存在下生长得更好）和洪水控制（有大量蚯蚓洞穴的土壤可以储存更多的水，并且水通过洞穴土壤更快地流失，从而减少洪水的机会）。鉴于蚯蚓在环境中的有益作用，以帮助蚯蚓繁殖的方式管理土壤是有意义的。只有了解土壤性质和土地管理对蚯蚓分布的影响，我们才能做到这一点。在英国，半天然草地约占土地利用和管理的16%，营养丰富的草地占另外20%。这些草地用于粮食生产;用于奶制品和肉类生产的动物在上面吃草。传统的农业管理集中在提高草的营养质量，以最大限度地提高产量。但随着社会越来越重视环境所能提供的各种服务，如生物多样性和水储存以及粮食生产，值得一问的是，管理策略对蚯蚓的影响是什么，蚯蚓对如此多的重要服务做出了如此强烈的贡献。我们的研究旨在研究蚯蚓是如何沿着草地集约化的梯度分布的，从低投入、低放牧强度的草地到高投入，高放牧强度草地。我们特别关注了解蚯蚓在这些草原的空间分布，以及这与土壤特性和草原管理的关系。通过在一系列空间尺度上对蚯蚓和土壤特性进行采样，从农田到农场再到整个英国，我们将能够确定是否存在农业集约化的临界阈值，超过这些阈值，蚯蚓以及它们提供的生态系统服务，我们会邀请市民参与我们的工作，协助我们进行抽样调查，并学习如何识别车间里的蚯蚓我们收集的蚯蚓记录将用于正在进行的蚯蚓记录计划和生物记录中心的工作。这两项活动将使我们的工作在项目生命周期之外留下持久的遗产。例如，重复调查可以突出显示环境变化对生物多样性的影响。我们采集的蚯蚓和土壤样本也将存档，供未来研究使用。我们将让我们采样蚯蚓的土地所有者参与讨论，并与他们以及政策制定者，自然资源保护主义者和生态学家讨论我们的结果和模型，以确保它们用于帮助保护并可能增加蚯蚓数量，以保护草原提供的各种生态系统服务，同时保持必要的粮食生产水平。

"Even on the same field worms are much more frequent in some places than in others, without any visible difference in the nature of the soil" Darwin, 1881Darwin wrote these words over 130 years ago and yet, despite much research, we still can't explain in anything but the broadest terms why, when you dig up soil from two different places in a field, earthworms may be present in one place but not in another. Given the importance of earthworms in the environment, this isn't a trivial matter. Earthworms have been termed "ecosystem engineers". They ingest a vast amount of soil and in the process break down organic matter, mix up soil and, via their burrows, keep soils aerated. Because of these activities earthworms help the ecosystems in which they occur to provide various benefits or services. These so called ecosystem services include food production (plants grow better in the presence of earthworms) and flood control (soils with lots of earthworm burrows can store more water and also water drains more rapidly through burrowed soil thereby reducing the chances of flooding).Given the beneficial role of earthworms in the environment it makes sense to manage soils in a way that helps earthworms flourish. We can only do this if we understand what impact soil properties and land management practises have on the distribution of earthworms. In the UK semi-natural grasslands account for about 16% of land use and managed, nutrient-enriched grasslands account for an additional 20 %. These grasslands are used for food production; animals used for dairy and meat production graze on them. Traditionally agricultural management has focussed on improving the nutrient quality of the grass so as to maximise production. But as society increasingly appreciates the various services that the environment can provide such as biodiversity and water storage as well as food production it is worth asking what impact management strategies have on the earthworms that contribute so strongly to so many vital services.Our research aims to look at how earthworms are distributed along a gradient of grassland intensification, from low input, low grazing intensity grasslands to high input, high grazing intensity grasslands. We are particularly concerned with understanding the spatial distribution of earthworms in these grasslands and how this relates to soil properties and grassland management. By sampling earthworms and soil properties at a range of spatial scales, from fields to farms to the whole of the UK, we will be able to determine whether there are critical thresholds of agricultural intensification beyond which earthworms, and hence the ecosystem services that they provide, are lost from grassland systems.Members of the public will get involved in our work by helping us with the sampling and learning how to identify earthworms at workshops. The records of earthworms we collect will feed into the ongoing earthworm recording scheme and the work of the Biological Records Centre. Both of these activities will give our work a lasting legacy beyond the life of the project. For example, repeat surveys could highlight changes in earthworm numbers in response to environmental change. The earthworms and soils that we sample will also be archived for future research. We will involve the land owners where we sample earthworms in our discussions and discuss our results and models with then as well as policy makers, conservationists and ecologists to ensure that they are used to help protect and potentially increase earthworm numbers in order to protect the varied ecosystem services that grasslands provide whilst maintaining necessary levels of food production.