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Ecosystem Benefits of Large Dead Wood in Freshwater Environments  

Ellen Wohl

Large wood in freshwater environments is downed, dead wood pieces in river channels, floodplains, wetlands, and lakes. Large wood was historically much more abundant in freshwaters, but decades to centuries of deforestation and direct wood removal have decreased wood loads—volumes of large wood per unit area—in freshwaters around the world. The widespread public perception that large wood is undesirable in freshwater environments contrasts with scientific understanding of the beneficial effects of large wood. Large wood tends to increase the spatial heterogeneity of hydraulics, substrate, channel planform, and the floodplain and hyporheic zone in rivers. This equates to greater habitat diversity and refugia for organisms, as well as energy dissipation and storage of materials during floods, which can increase the resilience of the river to disturbances such as wildfire, drought, and flooding. Similarly, wood in lakes increases lakeshore and lakebed heterogeneity of hydraulics, substrate, habitat, nutrient uptake, and storage of particulate organic matter and sediment. Large wood in rivers and lakes provides an array of vital ecosystem functions, and both individual species and biotic communities are adversely affected by a lack of wood in rivers and lakes that have been managed in a way that reduces wood loads. River and lake management are now more likely to include protection of existing large wood and active reintroduction of large wood, but numerous questions remain regarding appropriate targets for wood loads in different environmental settings, including potential threshold wood loads necessary to create desired effects. Large wood can also directly and indirectly enhance carbon storage in freshwater environments, but this storage remains poorly quantified.

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Integrated Water Resource Management as an Organizing Concept  

Mohamed Ait-Kadi and Melvyn Kay

This is an immersive journey through different water management concepts. The conceptual attractiveness of concepts is not enough; they must be applicable in the real and fast-changing world. Thus, beyond the concepts, our long-standing challenge remains increasing water security. This is about stewardship of water resources for the greatest good of societies and the environment. It is a public responsibility requiring dynamic, adaptable, participatory, and balanced planning. It is all about coordination and sharing. Multi-sectoral approaches are needed to adequately address the threats and opportunities relating to water resources management in the context of climate change, rapid urbanization, and growing disparities. The processes involved are many and need consistency and long-term commitment to succeed. Climate change is closely related to the problems of water security, food security, energy security and environment sustainability. These interconnections are often ignored when policy-makers devise partial responses to individual problems. They call for broader public policy planning tools with the capacity to encourage legitimate public/collective clarification of the trade-offs and the assessment of the potential of multiple uses of water to facilitate development and growth. We need to avoid mental silos and to overcome the current piecemeal approach to solving the water problems. This requires a major shift in practice for organizations (governmental as well as donor organizations) accustomed to segregating water problems by subsectors. Our experience with integration tells us that (1) we need to invest in understanding the political economy of different sectors; (2) we need new institutional arrangements that function within increasing complexity, cutting across sectoral silos and sovereign boundaries; (3) top down approaches for resources management will not succeed without bottom-up efforts to help people improve their livelihoods and their capacity to adapt to increasing resource scarcity as well as to reduce unsustainable modes of production. Political will, as well as political skill, need visionary and strong leadership to bring opposing interests into balance to inform policy- making with scientific understanding, and to negotiate decisions that are socially accepted. Managing water effectively across a vast set of concerns requires equally vast coordination. Strong partnerships and knowledge creation and sharing are essential. Human civilization – we know- is a response to challenge. Certainly, water scarcity can be a source of conflict among competing users, particularly when combined with other factors of political or cultural tension. But it can also be an inducement to cooperation even in high tension areas. We believe that human civilization can find itself the resources to respond successfully to the many water challenges, and in the process make water a learning ground for building the expanded sense of community and sharing necessary to an increasingly interconnected world.