The role of complementarity and facilitation in influencing tree community resilience

全球变化因素，如昆虫和病原体的外来入侵以及气候变化，正在对世界许多地区许多树种的生长和生存以及许多森林生态系统的运作产生不利影响。目前的研究表明，树种的混合可以更好地科普压力环境事件。然而，在什么样的林分和环境条件下使用什么类型的混合物，以最大限度地提高森林对自然和人为压力的恢复力，大多是未知的。在这个发现的研究计划，我打算测试几个假设，关于森林的组成和结构是如何相互作用的基本共存机制，以促进（或不）树和森林的阻力和恢复（两种措施的弹性），许多不同的永久性和/或间歇性的压力单独或联合行动。我将结合受控的野外实验和在管理和未管理的森林中设置的永久地块来调查这些问题。我将与研究生和博士后密切合作，并与来自世界各地的科学家合作，以回答这些问题。一个雄心勃勃的新的实地实验，在不同密度和空间安排的树种的各种混合物，目前正在建立在加拿大魁北克的里彭附近，以测试这些假设在一个受控的设置。来自25个以上国际树木多样性实验的数据也将用于测试树木多样性如何影响森林在各种气候条件和树种混合物中对各种压力的恢复力。来自60多个国家的在各种环境条件下的管理和天然森林中建立的小型和大型永久性地块将用于增加我们研究结果的实际相关性，并测试我们研究结果的一般性。在树木和地块尺度的生长和死亡率将研究与已知的最近发生的气候和生物压力的关系，这项研究的结果将被用来设计新的管理方法，以提高树木的弹性和生存面临全球变化，从城市公园和花园，农作物，管理森林，以广大保护区的林地。更好地了解保持或增加树木多样性和林分复杂性的好处，开辟了许多可能的应用，因为我们面临着越来越多的挑战，管理和恢复日益新颖和紧张的生态系统。

Global change factors such as non-native invasion of insects and pathogens as well as climate change are negatively affecting the growth and survival of many tree species and functioning of many forest ecosystems in a great number of regions in the world. Current studies indicate that mixtures of tree species can better cope with stressful environmental events. However, what types of mixtures to use under what types of stand and environmental conditions to maximise forest resilience to natural and human-induced stressors are mostly unknown. In this discovery research program, I intend to test several hypotheses regarding how forest composition and structure are interacting with basic coexistence mechanisms to promote (or not) both tree and forest resistance and recovery (both measures of resilience) to many different permanent and/or intermittent stressors acting alone or in conjunction. I will use a combination of controlled field experiments and permanent plots set in managed and unmanaged forests to investigate these questions. I will work closely with graduate students and Post-Docs and collaborate with scientists from around the world to answer these questions.An ambitious new field experiment where various mixtures of tree species grown in different densities and spatial arrangements is currently being established near Ripon in Quebec, Canada, to test some of these hypotheses in a controlled setting. Data from more than 25 international tree-diversity experiments will also be used to test how tree diversity affects forest resilience to various stressors in a wide set of climatic conditions and tree species mixtures. Small and large scale permanent plots established in managed and natural forests in a wide range of environmental conditions from more than 60 countries will be used to increase the practical relevance of our findings and to test the generality of our findings. The growth and mortality at the tree and plot scales will be studied in relation to known recent climatic and biotic stressors that have occurred.The results of this study will be used to design novel management approaches for increasing the resilience and survival of trees facing global change from urban parks and gardens, agricultural crops, and managed forests to vast protected areas of forested land. A better understanding of the benefits of maintaining or increasing tree diversity and stand complexity opens up many possible applications as we face the increasing challenge of managing and restoring increasingly novel and stressed ecosystems.