Interacting impacts of land use and climate changes on ecosystem processes: from cyclic herbivores to predators of conservation concern.

近年来，有证据表明，在气候变化和人类引起的土地利用变化的共同影响下，整个欧洲的生态系统过程和功能正在发生戏剧性变化。最引人注目的变化之一与田鼠和飞蛾等关键食草动物物种的数量有关，这些物种的数量在20世纪90年代几乎同时在欧洲大部分地区发生(IMS等人，2008年)。小型食草动物动态的变化有可能导致生态系统重新组织，因此对生物多样性的保护构成了挑战，为此必须迅速解决明确的管理和政策。事实上，几种高度受保护的欧洲物种以及许多猛禽与周期性波动的猎物密切相关。该项目涵盖了拉普兰苔原、挪威泰加森林、英国高地草原、法国农业平原和西班牙农业草原等不同的生态系统，在西班牙，小型啮齿动物被广泛视为各种捕食者协会的关键物种，包括高度保护的物种，如北极狐、母鸡和蒙塔古的隼或红风筝。有趣的是，在过去几十年中，北部地区(挪威、英国、法国)的田鼠或旅鼠的动态已经失去了它们的大幅度和规律周期，而南部(西班牙)最近记录到了第一次暴发。啮齿动物循环的影响很可能通过间接相互作用在这些生态系统的食物网中传播，例如，通过通用捕食者将猎物切换到替代猎物，并可能导致捕食者、寄生虫和植物群落的深刻重组。营养级联确实可能在营养级别之间传播和放大初级生产者物候的微妙变化，以应对气候变化。了解生态系统过程如何受到小型食草动物动态变化的连锁效应的影响是一个具有巨大保护意义的知识鸿沟。除了人口和社区动态理论上感兴趣的悬而未决的问题外，这项建议的主要目标是解决随之而来的保育问题。更好地了解这些复杂的相互作用似乎对于为顶级捕食者和它们所属的群落设计有效的保护倡议至关重要。这个欧洲合作项目围绕五个嵌套的工作包进行设计，从基本问题到明确的应用问题都取得了进展。首先，我们将检验以下四组嵌套假设：1.目前存在地理上广泛的环境驱动(气候和土地利用)、特定季节的欧洲生态区域小型草食动物动态变化的综合症；2.这些变化对利用周期性波动的草食动物猎物的捕食者的人口参数产生不成比例的(非线性)影响；3.这些人口变化反过来直接影响捕食者的种群生存能力；4.并通过级联效应间接影响食物网中的其他物种。因此，改变啮齿动物动态的问题在欧洲范围内至关重要，对保护和生态系统管理具有深远的意义。在最后的一揽子工作(5)中，我们将系统地探讨与气候和土地利用变化对生物多样性的影响以及面对全球变化的已开发和原始生态系统的养护管理有关的假设的保护推论。这些措施包括通过改变土地利用的季节模式来缓解和适应变化的范围，以及积极管理有影响的物种。我们将与政策制定者和利益攸关方一起，探讨我们的发现、替代管理做法和高度相关的政策影响在生态系统层面的后果。

In recent years, evidence has emerged that dramatic changes in ecosystem processes and functioning are taking place across Europe under the joint impact of climate change and human-induced shift in land use. One of the most spectacular change concerns the populations of keystone herbivore species such as voles and moths with cyclical dynamics that took place nearly simultaneously in much of Europe in the 1990s (Ims et al 2008). Changes in small herbivore dynamics have the potential to lead to ecosystem re-organisation and therefore represent a challenge for the conservation of biodiversity, for which clear management and policy have to be addressed quickly. Indeed several European species of high conservation concern, as well as many birds of prey, are intimately linked to cyclically fluctuating prey. This project encompasses ecosystems as diverse as Lapland tundra, Norwegian taiga forest, UK upland grassland, agricultural plains of France, and agro-steppe in Spain, where small rodents are widely seen as key-stone species for a diverse guild of predators, including species of high conservation concern such as Artic fox, hen and Montagu's harrier or red kite. Interestingly, the dynamics of voles or lemmings have lost their large amplitude and regular cycles in northern areas during the last decades (Norway, UK, France), while the first outbreaks were recently recorded in the south (Spain). The impact of the rodent cycle is likely to be transmitted in the food web of these ecosystems by indirect interactions through, for instance, prey-switching by generalist predators to alternative prey and might lead to a profound re-assembly of predator, parasite and plant communities. Trophic cascades might indeed propagate and amplify between trophic levels subtle changes in primary producer phenology in response to climate change. Understanding how ecosystem processes are affected by the cascading effects of changing small herbivore dynamics is a knowledge gap with tremendous conservation implications. Along with outstanding issues of theoretical interest in population and community dynamics, the main objective of this proposal is to tackle the corollary conservation issues. Acquiring a better knowledge of these complex interactions appears to be essential for designing effective conservation initiatives for top predators and the communities to which they belong. This European collaborative project has been designed around five nested work packages progress from fundamental to decidedly applied issues. First, we will test the following nested set of four hypotheses: 1. that there is currently a geographically extensive syndrome of environmentally-driven (climate and land use), season-specific, changes in small herbivore dynamics across widely different eco-regions in Europe; 2. that these changes have disproportionate (non-linear) impacts on demographic parameters of predators that exploit cyclically fluctuating herbivore prey; 3. that these demographic changes, in turn, impact directly on population viability of predators; 4. and indirectly influence other species in the food web through a cascading effect. The issue of changing rodent dynamics is thus critically important at the European scale, with implications of profound importance to conservation and ecosystem management. Within the last work package (5), we will systematically explore the conservation corollaries of the hypotheses tested that pertain to the impacts of climate and land use changes on biodiversity and to the conservation management of exploited and pristine ecosystems in the face of global change. These include the scope for mitigating and adapting to the changes through alterations of seasonal patterns of land use, and active management of influential species. Together with policy makers and stakeholders, we will explore the ecosystem-level consequences of our findings, alternative management practices and highly-relevant policy implications.