Towards evidence-based conservation of subterranean ecosystems

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.Peer reviewe

Current cave monitoring practices, their variation and recommendations for future improvement in Europe: A synopsis from the 6th EuroSpeleo Protection Symposium

This manuscript summarizes the outcomes of the 6th EuroSpeleo Protection Symposium. Special emphasis was laid on presenting and discussing monitoring activities under the umbrella of the Habitats Directive (EU Council Directive 92/43/EEC) for habitat type 8310 "Caves not open to the public" and the Emerald Network. The discussions revealed a high level of variation in the currently conducted underground monitoring activities: there is no uniform definition of what kind of underground environments the "cave" habitat should cover, how often a specific cave has to be monitored, and what parameters should be measured to evaluate the conservation status. The variation in spatial dimensions in national definitions of caves further affects the number of catalogued caves in a country and the number of caves to be monitored. Not always participants are aware of the complete national monitoring process and that data sets should be freely available or easily accessible. The discussions further showed an inherent dilemma between an anticipated uniform monitoring approach with a coherent assessment methodology and, on the contrary, the uniqueness of caves and subterranean biota to be assessed – combined with profound knowledge gaps and a lack of resources. Nevertheless, some good practices for future cave monitoring activities have been identified by the participants: (1) Cave monitoring should focus on bio- and geodiversity elements alike; (2) Local communities should be involved, and formal agreements envisaged; (3) Caves must be understood as windows into the subterranean realm; (4) Touristic caves should not be excluded ad-hoc from regular monitoring; (5) New digital tools and open FAIR data infrastructures should be implemented; (6) Cave biomonitoring should focus on a large(r) biological diversity; and (7) DNA-based tools should be integrated. Finally, the importance of the 'forgotten' Recommendation No. 36 from the Bern Convention as a guiding legal European document was highlighted

Current cave monitoring practices, their variation and recommendations for future improvement in Europe: A synopsis from the 6th EuroSpeleo Protection Symposium

This manuscript summarizes the outcomes of the 6th EuroSpeleo Protection Symposium. Special emphasis was laid on presenting and discussing monitoring activities under the umbrella of the Habitats Directive (EU Council Directive 92/43/EEC) for habitat type 8310 "Caves not open to the public" and the Emerald Network. The discussions revealed a high level of variation in the currently conducted underground monitoring activities: there is no uniform definition of what kind of underground environments the "cave" habitat should cover, how often a specific cave has to be monitored, and what parameters should be measured to evaluate the conservation status. The variation in spatial dimensions in national definitions of caves further affects the number of catalogued caves in a country and the number of caves to be monitored. Not always participants are aware of the complete national monitoring process and that data sets should be freely available or easily accessible. The discussions further showed an inherent dilemma between an anticipated uniform monitoring approach with a coherent assessment methodology and, on the contrary, the uniqueness of caves and subterranean biota to be assessed – combined with profound knowledge gaps and a lack of resources. Nevertheless, some good practices for future cave monitoring activities have been identified by the participants: (1) Cave monitoring should focus on bio- and geodiversity elements alike; (2) Local communities should be involved, and formal agreements envisaged; (3) Caves must be understood as windows into the subterranean realm; (4) Touristic caves should not be excluded ad-hoc from regular monitoring; (5) New digital tools and open FAIR data infrastructures should be implemented; (6) Cave biomonitoring should focus on a large(r) biological diversity; and (7) DNA-based tools should be integrated. Finally, the importance of the 'forgotten' Recommendation No. 36 from the Bern Convention as a guiding legal European document was highlighted