Three major steps toward the conservation of freshwater and riparian biodiversity

J.M. and J.H. thank Stiftelsen Längmanska kulturfonden for funding travel to the conference. As.L. and K.R. thank the Estonian Research Council (grant 1121) for financial support, and A.M. acknowledges the Leverhulme Trust (RPG-2019-402). H.H. was supported by the European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Actions (grant agreement 860800): RIBES (river flow regulation, fish behaviour, and status), and V.A. acknowledges the support from the Leibniz Competition project Freshwater Megafauna Futures. E.J. received support through the National Laboratory for Health Security (RRF-2.3.1-21-2022-00006), Centre for Ecological Research, Budapest, Hungary, and thanks Z. Molnár for support.Freshwater ecosystems and their bordering wetlands and riparian zones are vital for human society and biological diversity. Yet, they are among the most degraded ecosystems, where sharp declines in biodiversity are driven by human activities, such as hydropower development, agriculture, forestry, and fisheries. Because freshwater ecosystems are characterized by strongly reciprocal linkages with surrounding landscapes, human activities that encroach on or degrade riparian zones ultimately lead to declines in freshwater–riparian ecosystem functioning. We synthesized results of a symposium on freshwater, riparian, and wetland processes and interactions and analyzed some of the major problems associated with improving freshwater and riparian research and management. Three distinct barriers are the lack of involvement of local people in conservation research and management, absence of adequate measurement of biodiversity in freshwater and riparian ecosystems, and separate legislation and policy on riparian and freshwater management. Based on our findings, we argue that freshwater and riparian research and conservation efforts should be integrated more explicitly. Best practices for overcoming the 3 major barriers to improved conservation include more and sustainable use of traditional and other forms of local ecological knowledge, choosing appropriate metrics for ecological research and monitoring of restoration efforts, and mirroring the close links between riparian and freshwater ecosystems in legislation and policy. Integrating these 3 angles in conservation science and practice will provide substantial benefits in addressing the freshwater biodiversity crisis.Peer reviewe

Forests, Functions, and Food Webs : Riparian processes through an ecological and molecular lens

Riparian systems are critical ecological interfaces that have a significant impact on the surrounding aquatic and terrestrial ecosystems. The riparian and surrounding systems have significant roles in regulating energy flow, providing essential nutrients, and supporting unique species, making them important for ecosystem function. Both the aquatic and terrestrial ecosystems are reliant on the reciprocal exchange of energy subsides to maintain productive and stable food webs. Retention of forested buffers along streams during tree felling operations is a common management technique used to protect aquatic resources and conserve the surrounding ecosystem processes. Measuring the effects of forestry practices on the function and food webs of riparian predators is vital to making forest management decisions that strengthen and protect these fundamental services. Insight into predator function and predator-prey interactions using powerful molecular techniques can further the understanding of these complex systems and help to mitigate the effects of forestry practices. This thesis explores the functional diversity, food webs, and predator-prey interactions in riparian systems impacted by forestry felling practices. I have studied the effects of clear-cutting and forested buffer zones on riparian functional diversity through the assessment of functional richness and redundancy of spider and plant communities. In addition, I have both validated and used stable isotope analysis and DNA metabarcoding to investigate the primary food sources and prey choices of riparian predators. Riparian buffer size had no direct effect on the functional richness or redundancy of riparian spiders and vascular plants. However, riparian buffer variables such as canopy closure, buffer density, and vegetation coverage did have direct impacts on both spider and plant function. Most riparian spiders and brown trout received a significant majority of their food source from the terrestrial environment and the presence or absence of a riparian buffer did not effect this outcome. However, web-weaving spiders in unbuffered systems were more likely to exploit aquatic resources as a primary food source. Overall, the responses of predator function and food webs to forestry practice are site-specific.This thesis investigates the role of riparian systems impacted by forestry practices, examining their functional diversity, food webs, and predator-prey interactions. Clear-cutting and forested buffer zones' effects on riparian functional diversity, as well as the primary food sources of riparian predators, were studied using stable isotope analysis and metabarcoding. While buffer size did not directly impact the functional diversity of riparian spiders, brown trout, or plants, factors such as canopy closure and vegetation coverage did. Additionally, unbuffered systems impacted the prey source of web-weaving spiders

Effekt av avstånd till bebyggda områden på vedlevande skalbaggar i urbana skogsområden

Urban forests play key roles in animal and plant biodiversity and provide important ecosystem services.  Habitat fragmentation and expanding urbanization threaten biodiversity in and around urban areas.  Saproxylic beetles can act as bioindicators of forest health and their diversity may help to explain and define urban-forest edge effects.  I explored the relationship between saproxylic beetle diversity and distance to an urban area along nine transects in the Västra Götaland region of Sweden.  Specifically, the relationships between abundance and species richness and distance from the urban-forest boundary, forest age, forest volume, and tree species ratio was investigated Unbaited flight interception traps were set at intervals of 0, 250, and 500 meters from an urban-forest boundary to measure beetle abundance and richness.  A total of 4182 saproxylic beetles representing 179 species were captured over two months.  Distance from the urban forest boundary showed little overall effect on abundance suggesting urban proximity does not affect saproxylic beetle abundance.  There was an effect on species richness, with saproxylic species richness greater closer to the urban-forest boundary.  Forest volume had a very small positive effect on both abundance and species richness likely due to a limited change in volume along each transect.  An increase in the occurrence of deciduous tree species proved to be an important factor driving saproxylic beetle abundance moving closer to the urban-forest.  Overall, analysis showed inconsistent effects on both abundance and richness as functions of proximity to the urban-forest boundary.  Urban edge effects, forest volume, forest age, and forest tree species make up are all variables that may effect saproxylic abundance and species richness.  Forest managers should consider these variables when making management decisions

Forests, Functions, and Food Webs : Riparian processes through an ecological and molecular lens

Riparian systems are critical ecological interfaces that have a significant impact on the surrounding aquatic and terrestrial ecosystems. The riparian and surrounding systems have significant roles in regulating energy flow, providing essential nutrients, and supporting unique species, making them important for ecosystem function. Both the aquatic and terrestrial ecosystems are reliant on the reciprocal exchange of energy subsides to maintain productive and stable food webs. Retention of forested buffers along streams during tree felling operations is a common management technique used to protect aquatic resources and conserve the surrounding ecosystem processes. Measuring the effects of forestry practices on the function and food webs of riparian predators is vital to making forest management decisions that strengthen and protect these fundamental services. Insight into predator function and predator-prey interactions using powerful molecular techniques can further the understanding of these complex systems and help to mitigate the effects of forestry practices. This thesis explores the functional diversity, food webs, and predator-prey interactions in riparian systems impacted by forestry felling practices. I have studied the effects of clear-cutting and forested buffer zones on riparian functional diversity through the assessment of functional richness and redundancy of spider and plant communities. In addition, I have both validated and used stable isotope analysis and DNA metabarcoding to investigate the primary food sources and prey choices of riparian predators. Riparian buffer size had no direct effect on the functional richness or redundancy of riparian spiders and vascular plants. However, riparian buffer variables such as canopy closure, buffer density, and vegetation coverage did have direct impacts on both spider and plant function. Most riparian spiders and brown trout received a significant majority of their food source from the terrestrial environment and the presence or absence of a riparian buffer did not effect this outcome. However, web-weaving spiders in unbuffered systems were more likely to exploit aquatic resources as a primary food source. Overall, the responses of predator function and food webs to forestry practice are site-specific.This thesis investigates the role of riparian systems impacted by forestry practices, examining their functional diversity, food webs, and predator-prey interactions. Clear-cutting and forested buffer zones' effects on riparian functional diversity, as well as the primary food sources of riparian predators, were studied using stable isotope analysis and metabarcoding. While buffer size did not directly impact the functional diversity of riparian spiders, brown trout, or plants, factors such as canopy closure and vegetation coverage did. Additionally, unbuffered systems impacted the prey source of web-weaving spiders

Small stream predators rely heavily on terrestrial matter energy input in the fall, regardless of riparian buffer size

Stream ecosystems are reliant on the reciprocal exchange of terrestrial and aquatic energy subsides to maintain a productive and stable food web. Land use around streams can have strong effects on the size and availability of resource subsidies for stream and riparian predators such as fish and spiders. A common forestry technique around streams is the establishment of forested buffers to protect aquatic and riparian ecosystems from upland disturbances. Buffer size may determine prey abundance, richness, and spatial extent of prey reach into both the aquatic and terrestrial systems. To test the effects of forested buffers subsidy direction, we explored the carbon and nitrogen stable isotope signatures of brown trout (Salmo trutta), Tetragnathidae and Lycosidae spiders, and their aquatic and terrestrial prey sources around twelve streams in southern Sweden. For both predator groups, buffer presence showed no effect on resource subsidy source. We found that both brown trout and spiders are significantly reliant on terrestrial sources of prey for their diets in the fall. To support the terrestrial subsidy into small streams it is vital to maintain ecologically functional riparian zones by conserving complex surrounding habitats that optimize habitat and both terrestrial and aquatic prey diversity

Greater than the sum of your parts : Nonlethal stable isotope sampling methods in spiders

As top consumers and generalist predators, spiders are ideal organisms to study food webs and complex ecological functions using stable isotopes. Most researchers use whole-body samples to analyze stable isotope ratios in spiders. Spiders can regrow lost legs and produce multiple molts during a life cycle, and nonlethal sampling utilizing legs and molts may provide a useful alternative to whole-body sampling especially in larger bodied or threatened species. Furthermore, removing spider abdomens and thus leftover prey in the gut contents may provide a more accurate isotopic value. We tested the hypothesis that the delta N-15, delta C-13, or delta H-2 isotopic values in spider legs are reliable proxies for spider prosomas, abdomens, or whole bodies. We used laboratory-reared large-bodied spiders (Pterinochilus murinus) and field-collected Lycosidae to compare lethal and nonlethal tissue isotopic values. We found that nonlethal samples of spider legs and molts are acceptable alternatives to lethal whole-body samples to determine delta C-13 and delta N-15 stable isotope signatures. Nonlethal samples are not suitable proxies for whole-body samples to determine delta H-2 isotopic values. Using nonlethal leg or molts samples in stable isotope investigations of spiders will allow researchers to promote conservation efforts and study threatened species while ensuring accurate and repeatable results

Forested riparian buffer environmental variables are more important than size for species functional diversity in production forests

Retention of forested buffers around streams following forest cutting operations is a common managementtechnique used to protect aquatic resources and conserve the surrounding ecosystem services. Species richness,or α-diversity, is commonly used as an indicator of the effects of forestry management although it provides verylittle information about those effects on ecosystem processes and function. Functional diversity links speciestraits and ecosystem function incorporating species diversity, community composition, and functional guild andis more suitable to investigate the direct and indirect effects of forestry on ecosystem function. We sampledspiders and vascular plants in buffered and unbuffered stream-forest systems in southern Sweden and used atrait-based approach to assess the effects of buffer size and environmental variables on functional diversity. Weused structural equation modeling (SEM) to explore the effects of buffer size and condition on spider and vascularplant diversity. We found no effect of buffer size on the functional richness or functional redundancy for spidersor vascular plants. Buffer size had a slight effect on the α-diversity of spiders within small buffers and fullyforested sites but the effect was small. Other buffer variables including canopy closure, buffer density, bareground coverage, and soil fertility had direct effects on spider and vascular plant functional diversity. The maindriver of functional richness was α-diversity, but our SEM analysis illustrated other environmental variablesworking jointly to drive functional diversity. Using a trait-based approach, we showed that forested buffers havea minimal overall impact on spider and vascular plant functional diversity. However, it is important to maintainhigh levels of α-diversity to preserve and promote both spider and plant functional richness in production forestsand we suggest that forest management conserves and encourages high levels of α-diversity to increase overallfunctional diversity