How to Maximally Support Local and Regional Biodiversity in Applied Conservation? Insights from Pond Management

Biodiversity and nature values in anthropogenic landscapes often depend on land use practices and management. Evaluations of the association between management and biodiversity remain, however, comparatively scarce, especially in aquatic systems. Furthermore, studies also tend to focus on a limited set of organism groups at the local scale, whereas a multi-group approach at the landscape scale is to be preferred. This study aims to investigate the effect of pond management on the diversity of multiple aquatic organism groups (e.g. phytoplankton, zooplankton, several groups of macro-invertebrates, submerged and emergent macrophytes) at local and regional spatial scales. For this purpose, we performed a field study of 39 shallow man-made ponds representing five different management types. Our results indicate that fish stock management and periodic pond drainage are crucial drivers of pond biodiversity. Furthermore, this study provides insight in how the management of eutrophied ponds can contribute to aquatic biodiversity. A combination of regular draining of ponds with efforts to keep ponds free of fish seems to be highly beneficial for the biodiversity of many groups of aquatic organisms at local and regional scales. Regular draining combined with a stocking of fish at low biomass is also preferable to infrequent draining and lack of fish stock control. These insights are essential for the development of conservation programs that aim long-term maintenance of regional biodiversity in pond areas across Europe.

人为景观(anthropogenic landscapes)中的生物多样性与自然价值，通常取决于土地利用方式与管理举措。然而，针对管理与生物多样性之间关联的评估仍相对匮乏，在水生生态系统(aquatic systems)中这一问题尤为突出。此外，现有研究往往仅聚焦于局部尺度下有限的生物类群，而景观尺度下的多类群研究方法才是更优选择。
本研究旨在探究池塘管理对局部与区域空间尺度下多种水生生物类群（例如浮游植物(phytoplankton)、浮游动物(zooplankton)、多类大型无脊椎动物(macro-invertebrates)、沉水植物(submerged macrophytes)与挺水植物(emergent macrophytes)）多样性的影响。为此，我们针对涵盖5种不同管理类型的39处浅人工池塘开展了野外调查。
研究结果表明，鱼类种群管理与定期池塘排水是维持池塘生物多样性的关键驱动因素。此外，本研究还阐明了富营养化池塘(eutrophied ponds)的管理方式如何助力水生生物多样性保护。定期排水与维持池塘无鱼状态相结合的方式，似乎对局部及区域尺度下多数水生生物类群的多样性极为有益。定期排水搭配低生物量鱼类放养的方案，同样优于不定期排水且未实施鱼类种群管控的管理模式。这些研究结论对于制定旨在长期维持欧洲全境池塘区域生物多样性的保护规划至关重要。