Developing a general, predictive understanding of ecological systems requires knowing how much structural and functional relationships can cross scales and contexts. Here, we introduce the CROSSLINK project that investigates the role of forested riparian buffers in modified European landscapes by measuring a wide range of ecosystem attributes in stream-riparian networks. CROSSLINK involves replicated field measurements in four case-study basins with varying levels of human development: Norway (Oslo Fjord), Sweden (Lake Mälaren), Belgium (Zwalm River), and Romania (Argeş River). Nested within these case-study basins include multiple, independent stream-site pairs with a forested riparian buffer and unbuffered section located upstream, as well as headwater and downstream sites to show cumulative land-use impacts. CROSSLINK applies existing and bespoke methods to describe habitat conditions, biodiversity, and ecosystem functioning in aquatic and terrestrial habitats. Here, we summarize the approaches used, detail protocols in supplementary materials, and explain how data is applied in an optimization framework to better manage tradeoffs in multifunctional landscapes. We then present results demonstrating the range of riparian conditions present in our case-study basins and how these environmental states influence stream ecological integrity with the commonly used macroinvertebrate Average Score Per Taxon (ASPT) index. We demonstrate that a qualitative index of riparian integrity can be positively associated with stream ecological status. This introduction to the CROSSLINK project shows the potential for our replicated study with its panoply of ecosystem attributes to help guide management decisions regarding the use of forested riparian buffers in human-impacted landscapes. This knowledge is highly relevant in a time of rapid environmental change where freshwater biodiversity is increasingly under pressure from a range of human impacts that include habitat loss, pollution, and climate change.

Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed their polyunsaturated fatty acid (PUFA) content to quantify trophic connectivity. Specific PUFAs are exclusively produced by stream algae, and thus are used to track uptake of aquatic resources by terrestrial consumers. Riparian spiders were collected from 10 site pairs situated along agricultural streams, and from five forest sites (25 sites total). Each agricultural site pair comprised an unshaded site with predominantly herbaceous vegetation cover, and a second with a woody riparian buffer. Spider communities differed between site types, with web-building spiders dominating woody buffered sites and free-living spiders associated with more open habitats. PUFA concentrations were greatest overall in free-living spiders, but there was also evidence for increased PUFA uptake by some spider groups when a woody riparian buffer was present. Our results reveal the different roles of open and wooded riparian habitats in supporting terrestrial consumers and aquatic-terrestrial connectivity, and highlight the value of incorporating patches of woody vegetation within riparian networks in highly modified landscapes.

Prescribed fires are a common nature conservation practice. They are executed by several parties with limited coordination among them, and little consideration for wildfire occurrences and habitat requirements of fire-dependent species. Here, we gathered data on prescribed fires and wildfires in Sweden during 2011–2015 to (i) evaluate the importance and spatial extent of prescribed fires compared to wildfires and (ii) illustrate how a database can be used as a management tool for prescribed fires. We found that on average only 0.006% (prescribed 65%, wildfires 35%) of the Swedish forest burns per year, with 58% of the prescribed fires occurring on clearcuts. Also, both wildfires and prescribed fires seem to be important for the survival of fire-dependent species. A national fire database would simplify coordination and make planning and evaluation of prescribed fires more efficient. We propose an adaptive management strategy to improve the outcome of prescribed fires.

Intensive forestry practices have had a negative impact on boreal forest biodiversity; as a consequence, the need for restoration is pressing. Polypores (wood‐inhabiting fungi) are key decomposers of dead wood, but, due to a lack of coarse woody debris (CWD) in forest ecosystems, many species are under threat. Here, we study the long‐term effects on polypore diversity of two restoration treatments: creating CWD by felling whole trees and prescribed burning. This large‐scale experiment is located in spruce‐dominated boreal forests in southern Finland. The experiment has a factorial design (n = 3) including three levels of created CWD (5, 30, and 60 m3 ha−1) crossed with burning or no burning. In 2018, 16 years after launching the experiment, we inventoried polypores on 10 experimentally cut logs and 10 naturally fallen logs per stand. We found that overall polypore community composition differed between burned and unburned stands. However, only red‐listed species abundances and richness were positively affected by prescribed burning. We found no effects of CWD levels created mechanically by felling of trees. We show, for the first time, that prescribed burning is an effective measure for restoring polypore diversity in a late‐successional Norway spruce forest. Burning creates CWD with certain characteristics that differ from what is created by CWD restoration by felling trees. Prescribed burning promotes primarily red‐listed species, demonstrating its effectiveness as a restoration measure to promote diversity of threatened polypore species in boreal forests. However, because the CWD that the burning creates will decrease over time, to be functional, prescribed burns need to be applied regularly on the landscape scale. Large‐scale and long‐term experimental studies, such as this one, are invaluable for establishing evidence‐based restoration strategies.