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Nitrogen retention and recycling are topics of enduring interest in ecosystem ecology, yet we lack a mechanistic field-tested model of how these processes work in unpolluted, old-growth temperate forests. Forests of the Cordillera Piuchué Ecosystem Study (CPES) in southern Chile provide an opportunity to examine nitrogen cycling and retention in a forest that is virtually free of human disturbance. We applied15N pool dilution and pulse-chase tracer techniques as complementary approaches within small plots to understand flows of inorganic nitrogen in the surface soil of an evergreen mixed-angiosperm forest. We also followed separate pulses of15NH4 +and15NO3 -for two years to gain insights into how short-term mechanisms of inorganic nitrogen cycling translate into long-term patterns of ecosystem nitrogen retention. Strong consumption appears to limit losses of NH4 +and NO3 -from this forest, and predominantly by the same mechanisms for both forms of nitrogen. As a result, the extent of15NH4 +and15NO3 -retention were also similar, yet ∼44-fold higher rates of gross NH4 +production leads to the dominance of NH4 +over NO3 -in soil and stream waters. Microbial biomass played a key role in the short-term assimilation of15N tracers, but retention was only transient. Turnover of15N through microbial biomass was rapid and appeared to be only weakly retained in soil exchangeable pools, fine roots, and soil organic matter, resulting in substantial losses of15N from soils within weeks of tracer additions. Assimilation of15N into fine roots was a much larger sink (13%) than has been reported for other forested ecosystems (1-3%), and the transport of15N from microbial biomass to aboveground sinks in vegetation may explain the observed loss of15N from surface soils over time. Losses of15N from microbial biomass did not enter the extractable pool of dissolved organic nitrogen (DON), suggesting that DON losses do not originate directly from active microbial turnover, and also that microbial activity may not exert as much control over hydrologic losses of DON as compared to losses of NH4 +and NO3 -. Our results also suggest an additional rapid and extremely transient (1 d) mechanism of NO3 -retention via incorporation into extractable-DON. The long-term retention of15N at the whole-plot level did not differ significantly between15NH4 +and15NO3 -treatments, and averaged 65% after two years. The lack of an appreciable change in15N recovery for ∼1.5 yr following the initial assimilation, redistribution, and loss of15N suggests that the majority of15N was not recycled over the long term through inorganic nitrogen pools and microbial biomass via mineralization/immobilization pathways. Instead, long-term retention of inorganic15N appeared to be dominated by rapid and possibly direct assimilation into a slow-turnover pool of soil organic matter. Elevated15N contents in fine-root and microbial pools for up to two years after15N additions, however, also indicated sustained biotic retention of inorganic nitrogen. Our results suggest very similar retention of NH4 +and NO3 -that is dominated by rapid assimilation and turnover through microbial biomass in the short term (weeks), and transfer from microbial biomass into nitrogen-conserving plant (and to a lesser extent soil organic matter) pools in the long term (years). These processes result in efficient long-term retention of nitrogen in unpolluted old-growth temperate forests.

With increasing pressure placed on natural systems by growing human populations, both scientists and resource managers need a better understanding of the relationships between cumulative stress from human activities and valued ecosystem services. Societies often seek to mitigate threats to these services through large-scale, costly restoration projects, such as the over one billion dollar Great Lakes Restoration Initiative currently underway. To help inform these efforts, we merged high-resolution spatial analyses of environmental stressors with mapping of ecosystem services for all five Great Lakes. Cumulative ecosystem stress is highest in near-shore habitats, but also extends offshore in Lakes Erie, Ontario, and Michigan. Variation in cumulative stress is driven largely by spatial concordance among multiple stressors, indicating the importance of considering all stressors when planning restoration activities. In addition, highly stressed areas reflect numerous different combinations of stressors rather than a single suite of problems, suggesting that a detailed understanding of the stressors needing alleviation could improve restoration planning. We also find that many important areas for fisheries and recreation are subject to high stress, indicating that ecosystem degradation could be threatening key services. Current restoration efforts have targeted high-stress sites almost exclusively, but generally without knowledge of the full range of stressors affecting these locations or differences among sites in service provisioning. Our results demonstrate that joint spatial analysis of stressors and ecosystem services can provide a critical foundation for maximizing social and ecological benefits from restoration investments.

In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting-edge, meaningful and integrated knowledge. Consideration of the below-ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below-ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below-ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine-root vs coarse-root approach; (2) considering the specificity of root research to produce sound laboratory and field data; (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage); and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I–VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers’ views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning.

Significance Adaptive governance (AG) has been suggested as a suitable approach for ecosystem management in changing environments. It rests on the assumption that landscapes and seascapes need to be understood and governed as complex social–ecological systems rather than as ecosystems alone. We compared three AG initiatives and their effects on natural capital and ecosystem services. In comparison with other efforts aimed at conservation and sustainable use of natural capital, adaptive governance developed capacity to manage multiple ecosystem services and respond to ecosystem-wide changes and enabled collaboration across diverse interests, sectors, and institutional arrangements. Internal and external pressures continuously challenge the adaptive capacity of the initiatives. To gain insights into the effects of adaptive governance on natural capital, we compare three well-studied initiatives; a landscape in Southern Sweden, the Great Barrier Reef in Australia, and fisheries in the Southern Ocean. We assess changes in natural capital and ecosystem services related to these social–ecological governance approaches to ecosystem management and investigate their capacity to respond to change and new challenges. The adaptive governance initiatives are compared with other efforts aimed at conservation and sustainable use of natural capital: Natura 2000 in Europe, lobster fisheries in the Gulf of Maine, North America, and fisheries in Europe. In contrast to these efforts, we found that the adaptive governance cases developed capacity to perform ecosystem management, manage multiple ecosystem services, and monitor, communicate, and respond to ecosystem-wide changes at landscape and seascape levels with visible effects on natural capital. They enabled actors to collaborate across diverse interests, sectors, and institutional arrangements and detect opportunities and problems as they developed while nurturing adaptive capacity to deal with them. They all spanned local to international levels of decision making, thus representing multilevel governance systems for managing natural capital. As with any governance system, internal changes and external drivers of global impacts and demands will continue to challenge the long-term success of such initiatives.

Which indicators of ecosystem structure and function must be measured to assess ecosystem health? People generally equate health with a long and active life, but when it comes to ecosystems there is no agreement on what it means to be healthy. On page 1438 of this issue, Woodward et al. ( 1 ) show that different conclusions on the health of stream ecosystems can be reached depending on which combinations of metrics are used to assess them. The work points to an urgent need for a general framework for assessing ecosystem health.

Recent calls for ocean planning envision informed management of social and ecological systems to sustain delivery of ecosystem services to people. However, until now, no coastal and marine planning process has applied an ecosystem-services framework to understand how human activities affect the flow of benefits, to create scenarios, and to design a management plan. We developed models that quantify services provided by corals, mangroves, and seagrasses. We used these models within an extensive engagement process to design a national spatial plan for Belize’s coastal zone. Through iteration of modeling and stakeholder engagement, we developed a preferred plan, currently under formal consideration by the Belizean government. Our results suggest that the preferred plan will lead to greater returns from coastal protection and tourism than outcomes from scenarios oriented toward achieving either conservation or development goals. The plan will also reduce impacts to coastal habitat and increase revenues from lobster fishing relative to current management. By accounting for spatial variation in the impacts of coastal and ocean activities on benefits that ecosystems provide to people, our models allowed stakeholders and policymakers to refine zones of human use. The final version of the preferred plan improved expected coastal protection by >25% and more than doubled the revenue from fishing, compared with earlier versions based on stakeholder preferences alone. Including outcomes in terms of ecosystem-service supply and value allowed for explicit consideration of multiple benefits from oceans and coasts that typically are evaluated separately in management decisions. Significance Oceans and coasts provide people with diverse benefits, from fisheries that sustain lives and livelihoods to recreational opportunities that generate tourism. However, translating appreciation of these benefits into changes in management and policy is not trivial. We report on a ground-breaking effort to use ecosystem-service values and models within a coastal planning process. By accounting for spatial variation in the influence of human activities on services, our results allowed stakeholders and policymakers to refine zones of human use, reduce risk to ecosystems, and enhance delivery of multiple ocean and coastal benefits. Application of our approaches and tools will enable planners worldwide to bring ecosystem-service science to bear on real-world decisions, thus directing actions that protect ecosystems and their benefits for people.

Disturbance regimes are changing rapidly, and the consequences of such changes for ecosystems and linked social-ecological systems will be profound. This paper synthesizes current understanding of disturbance with an emphasis on fundamental contributions to contemporary landscape and ecosystem ecology, then identifies future research priorities. Studies of disturbance led to insights about heterogeneity, scale, and thresholds in space and time and catalyzed new paradigms in ecology. Because they create vegetation patterns, disturbances also establish spatial patterns of many ecosystem processes on the landscape. Drivers of global change will produce new spatial patterns, altered disturbance regimes, novel trajectories of change, and surprises. Future disturbances will continue to provide valuable opportunities for studying pattern-process interactions. Changing disturbance regimes will produce acute changes in ecosystems and ecosystem services over the short (years to decades) and long term (centuries and beyond). Future research should address questions related to (1) disturbances as catalysts of rapid ecological change, (2) interactions among disturbances, (3) relationships between disturbance and society, especially the intersection of land use and disturbance, and (4) feedbacks from disturbance to other global drivers. Ecologists should make a renewed and concerted effort to understand and anticipate the causes and consequences of changing disturbance regimes.

We investigated the effects of land use and cover and surface geology on soil properties in Baltimore, MD, with the objectives to: (i) measure the physical and chemical properties of surface soils (0-10 cm) by land use and cover; and (ii) ascertain whether land use and cover explain differences in these properties relative to surface geology. Mean and median values of each variable measured across all plots showed that soil properties varied considerably. Chemical properties generally varied more than physical properties. A subset of the variables measured showed a pattern with land use and cover. Potassium, P, and bulk density were the most discerning variables differentiating forest cover from land uses dominated by turfgrass cover. Soil pH differentiated residential land use and cover from the other turfgrass types. This separation may reflect differences in management, e.g., additions of fertilizer, although additional research is needed to assess the importance of management on soil properties. Differences in surface soil properties among land use and cover types could be useful when conducting urban soil surveys, at least to spatially differentiate remnant soils from highly disturbed and managed soils. Other soil properties (Al, Mg, V, Ti, Mn, Fe, Ni, and soil texture) were related to surface geology and thus unique to the Baltimore region. The importance of surface geology was contrary to our expectation that urban factors would be more important in determining the distribution of surface soil characteristics. Heavy metal concentrations did not differentiate land use and cover, suggesting that these elements are more related to other factors.

The traditional view of forest dynamics originated by Kira and Shidei [Kira T, Shidei T (1967) Jap J Ecol 17:70–87] and Odum [Odum EP (1969) Science 164(3877):262–270] suggests a decline in net primary productivity (NPP) in aging forests due to stabilized gross primary productivity (GPP) and continuously increased autotrophic respiration (R ₐ). The validity of these trends in GPP and R ₐ is, however, very difficult to test because of the lack of long-term ecosystem-scale field observations of both GPP and R ₐ. Ryan and colleagues [Ryan MG, Binkley D, Fownes JH (1997) Ad Ecol Res 27:213–262] have proposed an alternative hypothesis drawn from site-specific results that aboveground respiration and belowground allocation decreased in aging forests. Here, we analyzed data from a recently assembled global database of carbon fluxes and show that the classical view of the mechanisms underlying the age-driven decline in forest NPP is incorrect and thus support Ryan’s alternative hypothesis. Our results substantiate the age-driven decline in NPP, but in contrast to the traditional view, both GPP and R ₐ decline in aging boreal and temperate forests. We find that the decline in NPP in aging forests is primarily driven by GPP, which decreases more rapidly with increasing age than R ₐ does, but the ratio of NPP/GPP remains approximately constant within a biome. Our analytical models describing forest succession suggest that dynamic forest ecosystem models that follow the traditional paradigm need to be revisited.