Managing biodiversity and trophic cascades to enhance forest functioning and restoration

全球生物多样性下降将如何影响自给自足的生态系统的维持和人类生活的质量？迫切需要解决这一问题，以便预测并减轻人类驱动的自然界变化的后果。森林是研究这一环境挑战的理想环境，因为它们是生物多样性的极其重要的储存库，并提供人类所依赖的许多生态系统服务，如提供食物、土壤安全以及捕获和储存二氧化碳。此外，由于森林作为地球上许多物种的家园的重要性，以及树木消除空气中碳的能力，在大片土地上重新植树造林是扭转生物多样性下降和减缓气候变化的关键战略。有鉴于此，国际倡议承诺到2030年在面积几乎是澳大利亚一半的土地上建立森林，英国政府承诺到2022年在英国种植1100万棵树。土壤无脊椎动物和微生物对碳固存至关重要，因为它们在碳和营养循环中发挥关键作用，这是幼苗建立和树木生长的基础。我们知道，地上植被物种种类更多的生态系统生产力更高，捕获的碳更多，但我们不知道地下群落的多样性如何影响这些生物多样性与生态系统生产力的关系。此外，对于目前欧洲各地鹿和麋鹿数量的增加将如何影响土壤生物群落以及森林生态系统的功能和再生，我们的理解仍然存在差距。因此，在没有必要的生态知识来最有效地实现保护和社会目标的情况下，正在实施影响地球表面大片地区的森林恢复倡议。为了弥补这些认识上的差距，我的研究旨在：i)确定复杂地下群落的多样性如何影响碳和养分循环、树木生长和再生；以及2)量化大型哺乳动物食草动物如何影响地上和地下生物群落、生态系统过程和森林恢复。土壤群落极其复杂和多样，数百万物种和数十亿个体生活在一个生态系统中。然而，由于土壤中的生命如此之小和众多，研究地下食物网是极其具有挑战性和耗时的。因此，这项工作的一个重要成果将是使用尖端基因测序技术，首次确定这些难以研究的生物的多样性如何影响碳封存，从而影响气候变化缓解战略。此外，我将在欧洲广泛的森林类型和气候中建立一个哺乳动物排斥实验，以调查地上和地下对停止浏览的反应。这将帮助我们了解大型哺乳动物觅食的变化如何影响森林再生和土壤过程，并将形成长期、大规模野外实验的基础，这对未来旨在了解生态系统如何工作的研究将非常有价值。此外，我的研究将帮助我们：1)了解并缓解全球生物多样性下降对支持人类的生态系统服务的影响；2)产生有助于管理森林恢复的数据，以扭转生物多样性的下降趋势，帮助缓解全球变暖。对于所有被生态相互作用的错综复杂所吸引的人来说，生物多样性的侵蚀是一个巨大的损失；我的工作将提高我们描述这些复杂性的能力，并通过这样做，加深我们对我们正在解开自然世界的方式的理解。

How will declining global biodiversity affect the maintenance of self-sustaining ecosystems and quality of human life? There is an urgent need to address this question in order to predict and therefore mitigate the consequences of human-driven changes to the natural world. Forests are an ideal setting in which to investigate this environmental challenge because they are hugely important reservoirs of biodiversity and provide many ecosystem services upon which humanity relies, such as the provision of food, soil security and the capture and storage of CO2. Furthermore, because of the importance of forests as homes for many of Earth's species and the ability of trees to remove carbon from the air, reforesting vast areas of land is a key strategy in reversing declines in biodiversity as well as the mitigation of climate change. In light of this, international initiatives have pledged to establish forests on a land area almost half the size of Australia by 2030 and the UK government is committed to planting 11 million trees in the UK by 2022.Soil invertebrates and microbes are vitally important for carbon sequestration because of their key role in carbon and nutrient cycling, which underpin seedling establishment and tree growth. We know that ecosystems with a greater variety of above-ground vegetation species are more productive and capture more carbon, but we don't know how diversity in below ground communities effects these biodiversity-ecosystem productivity relationships. Furthermore, there remain gaps in our understanding of how current increases in deer and elk populations across Europe will influence soil biotic communities and the functioning and regrowth of forest ecosystems. Therefore, forest restoration initiatives that affect huge areas of the Earth's surface are being implemented without the necessary ecological knowledge to most effectively realise conservation and societal goals. To redress these gaps in our understanding, my research aims to: i) determine how the diversity of complex below-ground communities affects carbon and nutrient cycling, tree growth and regeneration; and 2) quantify how large mammalian herbivores affect above and below-ground biotic communities, ecosystem processes and forest restoration. Soil communities are extremely complex and diverse, with millions of species and billions of individuals living within a single ecosystem. However, because life in soil is so small and numerous, studying below-ground food webs is extremely challenging and time consuming. Therefore, an important outcome of this work will be the use of cutting-edge genetic sequencing techniques to determine, for the first time, how the diversity of these difficult to study organisms influences carbon sequestration and therefore climate change mitigation strategies. Furthermore, I will establish a mammal exclusion experiment across a broad range of forest types and climates in Europe, to investigate above and below-ground responses to the cessation of browsing. This will help us to understand how changes in browsing by large mammals affects forest regeneration and soil processes, and will form the basis of a long-term, large-scale field experiment, which will be extremely valuable for future studies aimed at understanding how ecosystems work.Together, my research will help us to: 1) understand and mitigate the consequences of declines in global biodiversity for the ecosystem services that support humanity; and 2) generate data that will help manage the restoration of forests to reverse the decline in biodiversity and help mitigate global warming. The erosion of biodiversity represents a great loss to all those who are captivated by the intricacy of ecological interactions; my work will increase our ability to describe these complexities, and in doing so, deepen our understanding of the ways in which we are unravelling the natural world.