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Large woody debris (LWD) have been used successfully for managing stream flow, hyporheic exchange and residence time as well as trapping fine sediment and adding a potential source of autochthonous organic carbon, removal excess nutrients in nutrient rich agricultural streams. We here integrate the results of several spatially nested field and controlled laboratory studies investigating how the use of LWD in different types of river restoration strategies can help to effectively ameliorate excess nutrient pollution across different spatial scales. At a river reach scale, we evidence using smart tracer additions that microbial metabolic activity and associated nutrient turnover rates were substantially enhanced in stream reaches with naturally accreted woody debris, which was shown to increase stream residence time, causing nutrient attenuation at multi-kilometre scales. Spatially nested within this, we show how individual engineered LWD structures have the potential to substantially increase the transformation of nitrogen, causing enhanced denitrification rates that lead to a net-removal of nitrate from stream water but also increased the emissions of nitrous oxide as a potent greenhouse gas. These results point towards the risk of unintended consequences arising from the nature-based solutions designed to engineer environmental conditions favourable to a specific ecosystem function, in this case the attenuation of nitrogen pollution. We therefore in a third approach test in mesocosm and reach-scale tracer experiments how small-scale wood-bundles frequently used in river restoration can be adapted to better trap fine sediments and release step-limiting bioavailable organic carbon to facilitate complete denitrification in streambed environments.

The 2018–2021 wildfire seasons were a glimpse of the future: deadly damaging fires in Mediterranean regions and high fire activity outside the typical fire season, also in temperate and boreal areas. This challenge cannot be solved with the traditional mono-disciplinary approach of fire suppression. There is a critical need to change fire management from fire resistance to landscape resilience: Living with fire. Climate change thereby creates an urgency for understanding the integrated drivers of fire impacts and risks, and for designing creative and effective risk reduction, management and communication strategies. We argue that achieving this integrated fire management requires inter- and transdisciplinary research based on four axes of diversity: combining cross-geography, cross-risk, and cross-sector approaches while embracing social diversity. This requires a new way of training our future experts, a broader way of defining scientific excellence, and stimulation of opportunities for people from various disciplines and sectors to meet and learn.