Mesoclosures – increasing realism in mesocosm studies of ecosystem functioning

1. Experimental studies linking community composition to functioning are typically confined to small and closed micro- or mesocosms. Such restricted conditions may affect both species’ biology and their environment. Yet, targeting simple features in the behaviour of species may circumvent these constraints. Focusing on ecological functions provided by dung beetles, we test whether large, open-top cages – MESOCLOSURES – will intercept the flight trajectories of beetles, thereby allowing manipulation of local community composition. 2. MESOCLOSURES were built in both tropical forest (Brazil) and temperate grasslands (Finland), thus testing their general efficiency. Within the respective environments, we varied different aspects of MESOCLOSURE design: in the tropical forest, we examined the impact of MESOCLOSURE dimensions on exclusion efficiency, whereas in the temperate grassland, we assessed the potential for selectively excluding and including community members by different mesh sizes. ...1. 探讨群落组成与生态系统功能关联的实验研究，通常局限于小型封闭的实验微宇宙（microcosms）或实验中宇宙（mesocosms）。这类受限的实验条件，既会影响物种的生物学特性，也会改变其生存环境。然而，针对物种行为的简单特征开展研究，或可规避上述约束。本研究以蜣螂（dung beetles）所提供的生态功能为研究对象，旨在验证大型开放式顶盖中封闭装置（MESOCLOSURES）是否能够拦截蜣螂的飞行轨迹，从而实现对本地群落组成的人为操控。 2. 研究团队分别在热带森林（巴西）与温带草原（芬兰）搭建了MESOCLOSURES装置，以此检验该装置的通用效能。在各自的生境中，我们对MESOCLOSURE的设计参数进行了差异化调整：在热带森林样地中，我们考察了装置尺寸对物种排除效率的影响；而在温带草原样地中，我们评估了通过调整不同网孔尺寸，选择性排除或纳入群落成员的可行性。