Enhancing the resilience of ecosystem services (ES) that underpin human well-being is critical for meeting current and future societal needs, and requires specific governance and management policies. Using the literature, we identify seven generic policy-relevant principles for enhancing the resilience of desired ES in the face of disturbance and ongoing change in social-ecological systems (SES). These principles are (P1) maintain diversity and redundancy, (P2) manage connectivity, (P3) manage slow variables and feedbacks, (P4) foster an understanding of SES as complex adaptive systems (CAS), (P5) encourage learning and experimentation, (P6) broaden participation, and (P7) promote polycentric governance systems. We briefly define each principle, review how and when it enhances the resilience of ES, and conclude with major research gaps. In practice, the principles often co-occur and are highly interdependent. Key future needs are to better understand these interdependencies and to operationalize and apply the principles in different policy and management contexts.

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

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Anadromous fishes achieve most of their lifetime growth at sea before returning to spawn in freshwater. However, populations of some species enter freshwater many months before spawning, apparently compromising growth opportunities at sea to access spawning grounds in conjunction with specific seasonal patterns of flow and temperature along the migratory route. The nutritional benefits of overwintering in the ocean may also be outweighed by a relatively dormant winter in colder river habitats. Modification of the thermal and hydrologic regimes of rivers (such as the Columbia River during the 20th century) might be expected to affect the abundance and life history patterns of such populations. This study reviews information on the migratory timing, abundance, and composition (wild versus hatchery) of summer‐run (upriver) populations of steelhead Oncorhynchus mykiss in the Columbia River basin with reference to environmental changes. Despite pronounced changes in the river's environment, the late summer migration‐spring spawning persists as an overall pattern as it passes Bonneville Dam (the lowest on the Columbia River). However, the historic summer run's distinct bimodality (with early and late components) has gradually become unimodal. Upriver, other complex changes have taken place in migration timing: it now occurs earlier through some reaches of the river and periods of time, reflecting both the uneven physical changes over time and the complex behavior and population structure of steelhead. We were unable, therefore, to isolate the causal mechanisms or disentangle natural from anthropogenic influences. However, our research suggests that the change in the migration pattern for summer‐run steelhead reflects a response to the challenges presented by a changing environment (temperature and flow) to genetically controlled life history patterns, the relative abundance of component populations, and the relative proportion of populations derived from hatchery production (which lately (1984‐1999) accounted for an average 74% of the early run and 85% of the late run).

Human activities are altering many factors that determine the fundamental properties of ecological and social systems. Is sustainability a realistic goal in a world in which many key process controls are directionally changing? To address this issue, we integrate several disparate sources of theory to address sustainability in directionally changing social-ecological systems, apply this framework to climate-warming impacts in Interior Alaska, and describe a suite of policy strategies that emerge from these analyses. Climate warming in Interior Alaska has profoundly affected factors that influence landscape processes (climate regulation and disturbance spread) and natural hazards, but has only indirectly influenced ecosystem goods such as food, water, and wood that receive most management attention. Warming has reduced cultural services provided by ecosystems, leading to some of the few institutional responses that directly address the causes of climate warming, e.g., indigenous initiatives to the Arctic Council. Four broad policy strategies emerge: (i) enhancing human adaptability through learning and innovation in the context of changes occurring at multiple scales; (ii) increasing resilience by strengthening negative (stabilizing) feedbacks that buffer the system from change and increasing options for adaptation through biological, cultural, and economic diversity; (iii) reducing vulnerability by strengthening institutions that link the high-latitude impacts of climate warming to their low-latitude causes; and (iv) facilitating transformation to new, potentially more beneficial states by taking advantage of opportunities created by crisis. Each strategy provides societal benefits, and we suggest that all of them be pursued simultaneously.adaptability ͉ Alaska ͉ climate change ͉ resilience ͉ vulnerability T he world is undergoing rapid change in many of the factors that control the properties of ecosystems. In the last 50 years, humans have changed ecosystems more rapidly and extensively than during any comparable period of human history, with even more rapid and extensive changes projected for the next half century and beyond (1, 2). For example, human activities have substantially altered climate, the hydrologic cycle, biodiversity, land cover, the use of biological productivity, and the cycling of nitrogen at global scales (3). People have always profoundly influenced their environment (4). However, the recent increase in the magnitude and extent of these impacts raises serious challenges to sustaining earth's life support systems, the services that ecosystems provide to society (5). These ecosystem services contribute fundamentally to human well-being, i.e., the basic material needs for a good life, freedom and choice, good social relations, and personal security (6).Given the importance and difficulty of fostering sustainability in a world with an uncertain future, many approaches are being explored (7-10). In this article, we integrate several of these approaches. We argue that, by understanding the linka...