Riparian zones extend from the edges of water bodies to upland communities in areas influenced by fresh water. The high biodiversity of riparian areas is created and maintained by inherent nutrient, sediment and biogeochemical processes, variable energy-flow and disturbance regimes, complex habitat, herbivory and other biotic processes. Riparian zones intercept and retain nutrients from upland runoff, as well as intercept and retain nutrients from adjacent streams and floodplains. Effectiveness of riparian buffering depends on soil and vegetative characteristics, as well as on river-riparian connectivity. Riparian zones are energy sources for adjoining aquatic systems via plant litter and arthropods falling into streams. Under natural conditions, large animals significantly influence nutrient and energy flows by altering physical characteristics and by herbivory. Connectivity – both the timing and extent of flows as well as the movements of animals – is fundamental for maintaining biodiversity and ecological services. Riparian zones are among the most vulnerable ecosystems facing global environmental change. Hence, preserving their biodiversity and the associated services is urgent.

Food web analyses offer useful insights into understanding how species interactions, trophic relationships, and energy flow underpin important demographic parameters of fish populations such as survival, growth, and reproduction. However, the vast amount of food web literature and the diversity of approaches can be a deterrent to fisheries practitioners engaged in on‐the‐ground research, monitoring, or restoration. Incorporation of food web perspectives into contemporary fisheries management and conservation is especially rare in riverine systems, where approaches often focus more on the influence of physical habitat and water temperature on fish populations. In this review, we first discuss the importance of food webs in the context of several common fisheries management issues, including assessing carrying capacity, evaluating the effects of habitat change, examining species introductions or extinctions, considering bioaccumulation of toxins, and predicting the effects of climate change and other anthropogenic stressors on riverine fishes. We then examine several relevant perspectives: basic food web description, metabolic models, trophic basis of production, mass‐abundance network approaches, ecological stoichiometry, and mathematical modeling. Finally, we highlight several existing and emerging methodologies including diet and prey surveys, eDNA, stable isotopes, fatty acids, and community and network analysis. Although our emphasis and most examples are focused on salmonids in riverine environments, the concepts are easily generalizable to other freshwater fish taxa and ecosystems.

Humans are changing the Earth's surface at an accelerating pace, with significant consequences for ecosystems and their biodiversity. Landscape transformation has far-reaching implications including reduced net primary production (NPP) available to support ecosystems, reduced energy supplies to consumers, and disruption of ecosystem services such as carbon storage. Anthropogenic activities have reduced global NPP available to terrestrial ecosystems by nearly 25%, but the loss of NPP from wetland ecosystems is unknown. We used a simple approach to estimate aquatic NPP from measured habitat areas and habitat-specific areal productivity in the largest wetland complex on the USA west coast, comparing historical and modern landscapes and a scenario of wetland restoration. Results show that a 77% loss of wetland habitats (primarily marshes) has reduced ecosystem NPP by 94%, C (energy) flow to herbivores by 89%, and detritus production by 94%. Our results also show that attainment of habitat restoration goals could recover 12% of lost NPP and measurably increase carbon flow to consumers, including at-risk species and their food resources. This case study illustrates how a simple approach for quantifying the loss of NPP from measured habitat losses can guide wetland conservation plans by establishing historical baselines, projecting functional outcomes of different restoration scenarios, and establishing performance metrics to gauge success.

Water quality is strongly related to a river's ecosystem composition at landscape scale. Key water/sediment interfaces, referred to here as functional compartments (FCs), are the epilithic biofilm, the fine sediment at the bottom of the river and the macroporous medium or hyporheic zone, which is primarily located in the active channel where subsurface flow occurs. The function of each FC (consumption or production of organic matter and nitrate) at river reach scale was examined through modelling and calibrated within field measurements to quantify the regulation service for water quality improvement. These functions were tested on a river reach of a dominant interface function (DIF) river, the Garonne River in south-west France. It was found that: a) functions differed between the FCs as a result of biotic (organisms involved) and abiotic (hydrological and morphological) conditions, b) functions varied within each FC over time (measured, but not discussed) and c) FCs acted as transient storage zones and contributed to the development of the river's self-purification capacity. It was concluded that in relation to the concept of river continuum, the upper reaches in the catchment were dominated by epilithic biofilm, where the main function was the production of organic matter (OM) (mean of 0.3 g.m(-2).d(-1), range from 0.08 to -1.7), the middle course was dominated by the hyporheic zone, where the most important function was to serve as a nitrate sink (-1.25 g.m(-2).d(-1), range from -45.6 to -0.19), and the downstream parts of the river, whose main function was the degradation of OM within the fine sediment FC (mean of - 1000 g.m(-2).d(-1), range from - 960 to - 1440). Hence, the morphological heterogeneity of rivers that mimic the natural mosaic of functional compartments with exchanges of water, organic matter and nutrients between compartments could contribute to enhancing their self-purification function and thus to improving water quality and system health. This study is a first step in testing the influence of the different FCs on the water quality regulation service provided by a river reach. The final objective was to be able to upscale the modelling of the different interfaces involved in a watershed's water quality regulation service. The present study demonstrates the need to take the biophysical diversity of reaches into account in order to accurately model this regulation service. Thus the BIODIF concept of BIO-physical (biological and physical) Diversity for rivers Dominated by river-bed Interface Functions (DIF rivers) was investigated for its ability to identify the theoretical relationships between the structure and the function of regulation of a river.

Flow regimes are fundamental to sustaining ecological characteristics of rivers worldwide, including their associated floodplains. Recent advances in understanding tropical river–floodplain ecosystems suggest that a small set of basic ecological concepts underpins their biophysical characteristics, especially the high levels of productivity, biodiversity and natural resilience. The concepts relate to (1) river-specific flow patterns, (2) processes ‘fuelled’ by a complex of locally generated carbon and nutrients seasonally mixed with carbon and nutrients from floodplains and catchments, (3) seasonal movements of biota facilitated by flood regimes, (4) food webs and overall productivity sustained by hydrological connectivity, (5) fires in the wet/dry tropical floodplains and riparian zones being major consumers of carbon and a key factor in the subsequent redistribution of nutrients, and (6) river–floodplains having inherent resilience to natural variability but only limited resilience to artificial modifications. Understanding these concepts is particularly timely in anticipating the effects of impending development that may affect tropical river–floodplains at the global scale. Australia, a region encompassing some of the last relatively undisturbed tropical riverine landscapes in the world, provides a valuable case study for understanding the productivity, diversity and resilience of tropical river–floodplain systems. However, significant knowledge gaps remain. Despite substantial recent advances in understanding, present knowledge of these highly complex tropical rivers is insufficient to predict many ecological responses to either human-generated or climate-related changes. The major research challenges identified herein (for example, those related to food web structure, nutrient transfers, productivity, connectivity and resilience), if accomplished in the next decade, will offer substantial insights toward assessing and managing ecological changes associated with human alterations to rivers and their catchments.

In response to major water-related challenges, the Chinese government is preparing to significantly expand river restoration efforts. The high level of development in many Chinese river basins requires that this work be undertaken strategically. This article identifies current global challenges to river restoration and presents a framework for strategic river restoration, together with a set of eight 'golden rules'. The framework and rules were developed specifically to address the Chinese situation, but are relevant elsewhere, particularly for heavily developed and highly contested river basins.

We contend that traditional approaches to forest conservation and management will be inadequate given the predicted scale of social-economic and biophysical changes in the 21st century. New approaches, focused on anticipating and guiding ecological responses to change, are urgently needed to ensure the full value of forest ecosystem services for future generations. These approaches acknowledge that change is inevitable and sometimes irreversible, and that maintenance of ecosystem services depends in part on novel ecosystems, i.e., species combinations with no analog in the past. We propose that ecological responses be evaluated at landscape or regional scales using risk-based approaches to incorporate uncertainty into forest management efforts with subsequent goals for management based on Achievable Future Conditions (AFC). AFCs defined at a landscape or regional scale incorporate advancements in ecosystem management, including adaptive approaches, resilience, and desired future conditions into the context of the Anthropocene. Inherently forward looking, ACFs encompass mitigation and adaptation options to respond to scenarios of projected future biophysical, social-economic, and policy conditions which distribute risk and provide diversity of response to uncertainty. The engagement of science-management-public partnerships is critical to our risk-based approach for defining AFCs. Robust monitoring programs of forest management actions are also crucial to address uncertainty regarding species distributions and ecosystem processes. Development of regional indicators of response will also be essential to evaluate outcomes of management strategies. Our conceptual framework provides a starting point to move toward AFCs for forest management, illustrated with examples from fire and water management in the Southeastern United States. Our model is adaptive, incorporating evaluation and modification as new information becomes available and as social-ecological dynamics change. It expands on established principles of ecosystem management and best management practices (BMPs) and incorporates scenarios of future conditions. It also highlights the potential limits of existing institutional structures for defining AFCs and achieving them. In an uncertain future of rapid change and abrupt, unforeseen transitions, adjustments in management approaches will be necessary and some actions will fail. However, it is increasingly evident that the greatest risk is posed by continuing to implement strategies inconsistent with current understanding of our novel future. (C) 2015 Elsevier B.V. All rights reserved.

doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art1To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region.

A table showing the years, scale, type, and sources of the photo series used in the GIS analysis.

A table presenting soil characteristics and site and vegetation descriptions.

Photographs illustrating the natural history of large logs in the Queets River, Washington, USA.

Accelerating environmental change is perhaps the greatest challenge for natural resource management; successful strategies need to be effective for decades to come. Our objective is to identify opportunities that new environmental conditions may provide for conservation, restoration, and resource use in a globally recognized biodiversity hotspot in southwestern Australia. We describe a variety of changes to key taxonomic groups and system-scale characteristics as a consequence of environmental change (climate and land use), and outline strategies for conserving and restoring important ecological and agricultural characteristics. Opportunities for conservation and economic adaptation are substantial because of gradients in rainfall, temperature, and land use, extensive areas of remnant native vegetation, the ability to reduce and ameliorate areas affected by secondary salinization, and the existence of large national parks and an extensive network of nature reserves. Opportunities presented by the predicted environmental changes encompass agricultural as well as natural ecosystems. These may include expansion of aquaculture, transformation of agricultural systems to adapt to drier autumns and winters, and potential increases in spring and summer rain, carbon-offset plantings, and improving the network of conservation reserves. A central management dilemma is whether restoration/preservation efforts should have a commercial or biodiversity focus, and how they could be integrated. Although the grand challenge is conserving, protecting, restoring, and managing for a future environment, one that balances economic, social, and environmental values, the ultimate goal is to establish a regional culture that values the unique regional environment and balances the utilization of natural resources against protecting remaining natural ecosystems.

The Columbia Basin once supported a diversity of native fishes and large runs of anadromous salmonids that sustained substantial fisheries and cultural values. Extensive land conversion, watershed disruptions, and subsequent fishery declines have led to one of the most ambitious restoration programs in the world. Progress has been made, but restoration is expensive (exceeding US$300M/year), and it remains unclear whether habitat actions, in particular, can be successful. A comprehensive approach is needed to guide cost-effective habitat restoration. Four elements that must be addressed simultaneously are (1) a scientific foundation from landscape ecology and the concept of resilience, (2) broad public support, (3) governance for collaboration and integration, and (4) a capacity for learning and adaptation. Realizing these in the Columbia Basin will require actions to rebalance restoration goals to include diversity, strengthen linkages between science and management, increase public engagement, work across traditional ecological and social boundaries, and learn from experience.

Biotic communities are shaped by adaptations from generations of exposure to selective pressures by recurrent and often infrequent events. In large rivers, floods can act as significant agents of change, causing considerable physical and biotic disturbance while often enhancing productivity and diversity. We show that the relative balance between these seemingly divergent outcomes can be explained by the rhythmicity, or predictability of the timing and magnitude, of flood events. By analyzing biological data for large rivers that span a gradient of rhythmicity in the Neotropics and tropical Australia, we find that systems with rhythmic annual floods have higher-fish species richness, more stable avian populations, and elevated rates of riparian forest production compared with those with arrhythmic flood pulses. Intensification of the hydrological cycle driven by climate change, coupled with reductions in runoff due to water extractions for human use and altered discharge from impoundments, is expected to alter the hydrologic rhythmicity of floodplain rivers with significant consequences for both biodiversity and productivity.