Biodiversity on farms: a complex systems approach

背景技术背景：过去50年来，可耕地农业的集约化与生物多样性的大量丧失有关，人们相当关注集约化农业与生物多样性的保护不相容。此外，令人不安的是，对农田鸟类等指标群体的研究并没有提供促进生物多样性所需的信息。我们的目标是为有机农场构建一个大型生态网络，展示物种之间的联系，然后使用复杂系统方法来预测物种损失和物种恢复的影响。为什么要研究这一领域？如果生态学家、土地管理者和政策制定者要可持续地管理农田生物多样性，那么他们就需要了解物种之间的联系方式。复杂系统理论预测，仅仅几个高度关联的物种的灭绝就可能导致一系列次级灭绝，这可能导致网络的完全崩溃。简而言之，像农场食物网这样的复杂系统可能非常容易受到相当小的灾害的影响。提案：我们将建立一个农场规模的网络，其中包括植物，昆虫，鸟类和哺乳动物以及昆虫害虫物种和农民。一旦我们构建了网络，我们预计将在一个网络中将大约1000个物种相互联系起来，我们将模拟物种灭绝的影响。我们将通过使用计算机来模拟网络中主要物种的损失（通过从网络中逐个删除物种）并根据随后的二级保护的数量和程度来测量网络的鲁棒性。极少量的初级营养不良就能引起营养级联。例如，在一个154个物种的网络中，模拟10%的物种损失足以引发一系列导致网络崩溃的二次破坏。让农民加入我们的网络，将使我们能够询问她如何影响网络结构和弹性。最后，由计算机生成的退化网络将被用来模拟农场的恢复使用DEFRA的新的农业环境计划，环境管理。我们将能够发现恢复构成农场生物多样性的物种之间相互作用网络的最佳方法。虽然这些计划旨在增加农田生物多样性，但很少对农业环境计划的环境影响进行测试。鉴于欧洲联盟每年在此类计划上花费27亿英镑，因此迫切需要评估农业环境计划效力的工具。为什么这是令人兴奋的，有趣的和重要的？食物网和其他生态网络尚未广泛应用于可持续农业领域。考虑到网络建设（例如，生态信息学）的实际进展，理论进展（例如，复杂系统方法）和生物多样性丧失的持续威胁与雄心勃勃的农业环境计划相结合，现在是一个非常令人兴奋的时刻，开始使用生态网络作为管理生物多样性的实用工具，我们77%的土地被农田占用。对社会更广泛的好处是什么？了解管理景观的生态是实现更可持续农业和保护农田生物多样性的基础。自然和管理的栖息地的健康运作提供了对人类至关重要的免费“生态系统服务”。这些措施包括授粉、虫害防治和水过滤等。这些生态系统服务的提供取决于生物多样性，因此，生物多样性的进一步减少可能会威胁到这些服务，很可能也威胁到人类。

BACKGROUND: The intensification of arable agriculture over the last 50 yrs has been associated with substantial losses of biodiversity and there is considerable concern that intensive agriculture is incompatible with the conservation of biodiversity. Moreover, there is disquiet that studying indicator groups such as farmland birds is not providing the information needed to foster biodiversity. Our aim is to construct a large ecological network for an organic farm showing how species are linked to each other and then to use a complex systems approach to predict the impact of species loss and species restoration. WHY STUDY THIS SUBJECT AREA? If ecologists, land managers and policy makers are to manage farmland biodiversity sustainably, then they need to understand the ways in which species are linked to each other. Complex systems theory predicts that that the extinction of just a few highly-linked species could lead to a cascade of secondary extinctions, which could cause a complete collapse of the web. Put simply, complex systems such as a farm food web can be very vulnerable to rather small disasters. THE PROPOSAL: We will construct a farm-scale network, which contains plants, insects, birds and mammals as well as insect pest species and the farmer. Once we have constructed the web, which we expect will link about 1000 species to each other in a single network, we will model the impact of species extinction. We will do this by using a computer to simulate primary species loss in the web (by removing species one by one from the network) and measuring the network's robustness in terms of the number and extent of secondary extinctions that follow. A remarkably small number of primary extinctions can cause a trophic cascade. For example, the simulation of a 10% species loss in a 154 species network was sufficient to elicit a cascade of secondary extinctions which led to network collapse. Having the farmer in our network will allow us to ask how she affects network structure and resilience. Finally, the degraded webs generated by the computer will be used to model the farm's restoration using DEFRA's new agri-environment scheme, Environmental Stewardship. We will be able to discover the best way to reinstate the network of interactions between the species that make up the farm's biodiversity. Although they are designed to increase farmland biodiversity, very little testing of the environmental impact of agri-environment schemes takes place. Given that £2.7 billion is spent annually on such schemes in the European Union, tools for assessing the efficacy of agri-environment schemes are badly need. WHY IS THIS SUBJECT EXCITING, INTERESTING AND IMPORTANT? Food webs and other ecological networks have not yet been widely applied to the field of sustainable agriculture. Given the practical advances being made in network construction (for example, in eco-informatics), the theoretical advances (for example, complex systems approaches) and the ongoing threat of biodiversity loss combined with ambitious agri-environment schemes, now is a very exciting time to begin to use ecological networks as a practical tool for managing biodiversity on the 77% of our land occupied by farmland. WHAT ARE THE WIDER BENEFITS TO SOCIETY? Understanding the ecology of managed landscapes is fundamental for achieving more sustainable agriculture and for the conservation of biodiversity on farmland. The healthy functioning of natural and managed habitats provides free 'ecosystem services' essential to mankind. These include, for example, pollination, pest control and water filtration. The delivery of these ecosystem services is dependent on biodiversity, and consequently the services, and very probably mankind, could be threatened by further reductions in biodiversity.