Search

Ecologists are challenged by the need to bridge and synthesize different approaches and theories to obtain a coherent understanding of ecosystems in a changing world. Both food web theory and regime shift theory shine light on mechanisms that confer stability to ecosystems, but from different angles. Empirical food web models are developed to analyze how equilibria in real multi-trophic ecosystems are shaped by species interactions, and often include linear functional response terms for simple estimation of interaction strengths from observations. Models of regime shifts focus on qualitative changes of equilibrium points in a slowly changing environment, and typically include non-linear functional response terms. Currently, it is unclear how the stability of an empirical food web model, expressed as the rate of system recovery after a small perturbation, relates to the vulnerability of the ecosystem to collapse. Here, we conduct structural sensitivity analyses of classical consumer-resource models in equilibrium along an environmental gradient. Specifically, we change non-proportional interaction terms into proportional ones, while maintaining the equilibrium biomass densities and material flux rates, to analyze how alternative model formulations shape the stability properties of the equilibria. The results reveal no consistent relationship between the stability of the original models and the proportionalized versions, even though they describe the same biomass values and material flows. We use these findings to critically discuss whether stability analysis of observed equilibria by empirical food web models can provide insight into regime shift dynamics, and highlight the challenge of bridging alternative modelling approaches in ecology and beyond.

Ecologists are challenged by the need to bridge and synthesize different approaches and theories to obtain a coherent understanding of ecosystems in a changing world. Both food web theory and regime shift theory shine light on mechanisms that confer stability to ecosystems, but from different angles. Empirical food web models are developed to analyze how equilibria in real multi-trophic ecosystems are shaped by species interactions, and often include linear functional response terms for simple estimation of interaction strengths from observations. Models of regime shifts focus on qualitative changes of equilibrium points in a slowly changing environment, and typically include non-linear functional response terms. Currently, it is unclear how the stability of an empirical food web model, expressed as the rate of system recovery after a small perturbation, relates to the vulnerability of the ecosystem to collapse. Here, we conduct structural sensitivity analyses of classical consumer-resource models in equilibrium along an environmental gradient. Specifically, we change non-proportional interaction terms into proportional ones, while maintaining the equilibrium biomass densities and material flux rates, to analyze how alternative model formulations shape the stability properties of the equilibria. The results reveal no consistent relationship between the stability of the original models and the proportionalized versions, even though they describe the same biomass values and material flows. We use these findings to critically discuss whether stability analysis of observed equilibria by empirical food web models can provide insight into regime shift dynamics, and highlight the challenge of bridging alternative modelling approaches in ecology and beyond.

Access to ecosystem services and influence on their management are structured by social relations among actors, which often occur across spatial scales. Such cross-scale social relations can be analysed through a telecoupling framework as decisions taken at local scales are often shaped by actors at larger scales. Analyzing these cross-scale relations is critical to create effective and equitable strategies to manage ecosystem services. Here, we develop an analytical framework –i.e. the ‘cross-scale influence-dependence framework’- to facilitate the analysis of power asymmetries and the distribution of ecosystem services among the beneficiaries. We illustrate the suitability of this framework through its retrospective application across four case studies, in which we characterize the level of dependence of multiple actors on a particular set of ecosystem services, and their influence on decision-making regarding these services across three spatial scales. The ‘cross-scale influence-dependence framework’ can improve our understanding of distributional and procedural equity and thus support the development of policies for sustainable management of ecosystem services., The Voeren research was sponsored by the Flemish Land Agency . MFL was granted by the Spanish National Research Council ( JAE-Pre-2010-044 ). EMB was supported by NSERC EWR Steacie Fellowship . AN and GP were supported by the Swedish Research Council Formas (project 2012-1058 ). MGL was supported by the Spanish National Institute for Agriculture and Food Research and Technology (INIA) . SL and BL were funded by OPERAs FP7-ENV-2012 -two-stage- 308393 .

Increasingly, ecosystem services have been applied to guide poverty alleviation and sustainable development in resource-dependent communities. Yet, questions of access, which are paramount in determining benefits from the production of ecosystem services, remain theoretically underdeveloped. That is, ecosystem assessments typically have paid little attention to identifying real or hypothetical beneficiaries and the mechanisms by which benefits may be realized. This limits their ability to guide policy and interventions at the local scale. Through a qualitative mixed methods approach, this article analyzes how access to different aspects of the production of provisioning services is negotiated in Bribri communities (Costa Rica) of small-scale plantain farmers with alternative modes of agricultural production. The analysis considers access to land, labour, knowledge, tools, markets, and credit. Our analysis reveals how institutions of access are organized differently in traditional vs. conventional systems of agriculture and how these shape power dynamics and pathways to well-being. We conclude that understanding institutions regulating access to ecosystem services provides more useful insights for poverty alleviation than approaches that assume homogeneous access to benefits.

Ecosystems influence human societies, leading people to manage ecosystems for human benefit. Poor environmental management can lead to reduced ecological resilience and social-ecological collapse. We review research on resilience and collapse across different systems and propose a unifying social-ecological framework based on (i) a clear definition of system identity; (ii) the use of quantitative thresholds to define collapse; (iii) relating collapse processes to system structure; and (iv) explicit comparison of alternative hypotheses and models of collapse. Analysis of 17 representative cases identified 14 mechanisms, in five classes, that explain social-ecological collapse. System structure influences the kind of collapse a system may experience. Mechanistic theories of collapse that unite structure and process can make fundamental contributions to solving global environmental problems.

Cascading effects of regime shifts The potential for regime shifts and critical transitions in ecological and Earth systems, particularly in a changing climate, has received considerable attention. However, the possibility of interactions between such shifts is poorly understood. Rocha et al. used network analysis to explore whether critical transitions in ecosystems can be coupled with each other, even when far apart (see the Perspective by Scheffer and van Nes). They report different types of potential cascading effects, including domino effects and hidden feedbacks, that can be prevalent in different systems. Such cascading effects can couple the dynamics of regime shifts in distant places, which suggests that the interactions between transitions should be borne in mind in future forecasts. Science , this issue p. 1379 ; see also p. 1357

Ecosystems are shaped by natural processes such as predator–prey interactions and climate, as well as by human activities such as harvesting and pollution. Resilient ecosystems are able to absorb disturbances, but chronic stressors may reduce the capacity of an ecosystem to cope with change (Trends Ecol Evol 15:413–417, 2000). The ability of ecosystems to absorb disturbance and at the same time maintain their structure, processes, and function is known as resilience (sensu Ann Rev Ecol Evol Syst 4:1–23, 1973). Accumulated evidence from many systems (e.g., coral reefs, forests, rangelands, and shallow lakes) suggests that when pushed past a threshold (i.e., beyond their resilience), ecosystems can undergo a regime shift to an alternative state (Resilience thinking: sustaining ecosystems and people in a changing world, Washington, DC, 2006; Am Zool 32:674–682, 1992; J Anim Ecol 59:1147–1164, 1990; Trends Ecol Evol 8:275–279, 1993; Ecol Soc 6:17–28, 2011). From an anthropocentric perspective these alternative states may be less desirable than the initial state depending on the ecosystem goods and services they produce (Ecol Econ 29:215–233, 1999). Strong feedbacks in the alternate state may also make recovery to the original state difficult, even after the original stressors are removed (Nature 413:591–596, 2001; Ecosystems 15:695–710, 2012). Human dimensions such as opportunity and governance also comprise an important aspect of resilience because they influence how sustainably resources are used (Science 325:419–422, 2009; Curr Biol 19:206–212, 2009), thereby shifting the resilience threshold. The objectives of this lab are to.

Environmentalists have argued that ecological degradation will lead to declines in the well-being of people dependent on ecosystem services. The Millennium Ecosystem Assessment paradoxically found that human well-being has increased despite large global declines in most ecosystem services. We assess four explanations of these divergent trends: (1) We have measured well-being incorrectly; (2) well-being is dependent on food services, which are increasing, and not on other services that are declining; (3) technology has decoupled well-being from nature; (4) time lags may lead to future declines in well-being. Our findings discount the first hypothesis, but elements of the remaining three appear plausible. Although ecologists have convincingly documented ecological decline, science does not adequately understand the implications of this decline for human well-being. Untangling how human well-being has increased as ecosystem conditions decline is critical to guiding future management of ecosystem services; we propose four research areas to help achieve this goal.

Ecosystem management that attempts to maximize the production of one ecosystem service often results in substantial declines in the provision of other ecosystem services. For this reason, recent studies have called for increased attention to development of a theoretical understanding behind the relationships among ecosystem services. Here, we review the literature on ecosystem services and propose a typology of relationships between ecosystem services based on the role of drivers and the interactions between services. We use this typology to develop three propositions to help drive ecological science towards a better understanding of the relationships among multiple ecosystem services. Research which aims to understand the relationships among multiple ecosystem services and the mechanisms behind these relationships will improve our ability to sustainably manage landscapes to provide multiple ecosystem services.

Ecological resilience has been proposed to be generated, in part, in the discontinuous structure of complex systems. Environmental discontinuities arereflected in discontinuous, aggregated animal body massdistributions. Diversity offunctional groups within body mass aggregations (scales) and redundancy of functional groups across body mass aggregations (scales) has been proposed to increase resilience. We evaluate that proposition by analyzing mammalian and avian communities of Mediterranean-climate ecosystems. We first determined that body mass distributions for each animal community were discontinuous. We then calculated the variance in richness of function across aggregations in each community, and compared observedvalues with distributions createdby 1000simulations using a null of random distribution of function, with the same n, number of discontinuities and number of functional groups as the observed data. Variance in the richness of functional groups across scales was significantly lower in real communities than in simulations in eight of nine sites. The distribution of function across body mass aggregations in the animal communities we analyzed was non-random, and supports the contentions of the cross-scale resilience model.

Managing ecosystems for multiple ecosystem services and balancing the well-being of diverse stakeholders involves different kinds of trade-offs. Often trade-offs involve noneconomic and difficult-to-evaluate values, such as cultural identity, employment, the well-being of poor people, or particular species or ecosystem structures. Although trade-offs need to be considered for successful environmental management, they are often overlooked in favor of win-wins. Management and policy decisions demand approaches that can explicitly acknowledge and evaluate diverse trade-offs. We identified a diversity of apparent trade-offs in a small-scale tropical fishery when ecological simulations were integrated with participatory assessments of social–ecological system structure and stakeholders’ well-being. Despite an apparent win-win between conservation and profitability at the aggregate scale, food production, employment, and well-being of marginalized stakeholders were differentially influenced by management decisions leading to trade-offs. Some of these trade-offs were suggested to be “taboo” trade-offs between morally incommensurable values, such as between profits and the well-being of marginalized women. These were not previously recognized as management issues. Stakeholders explored and deliberated over trade-offs supported by an interactive “toy model” representing key system trade-offs, alongside qualitative narrative scenarios of the future. The concept of taboo trade-offs suggests that psychological bias and social sensitivity may exclude key issues from decision making, which can result in policies that are difficult to implement. Our participatory modeling and scenarios approach has the potential to increase awareness of such trade-offs, promote discussion of what is acceptable, and potentially identify and reduce obstacles to management compliance.

Ecosystem services have become a mainstream concept for the expression of values assigned by people to various functions of ecosystems. Even though the introduction of the concept has initiated a vast amount of research, progress in using this knowledge for sustainable resource use remains insufficient. We see a need to broaden the scope of research to answer three key questions that we believe will improve incorporation of ecosystem service research into decision-making for the sustainable use of natural resources to improve human well-being: (i) how are ecosystem services co-produced by social–ecological systems, (ii) who benefits from the provision of ecosystem services, and (iii) what are the best practices for the governance of ecosystem services? Here, we present these key questions, the rationale behind them, and their related scientific challenges in a globally coordinated research programme aimed towards improving sustainable ecosystem management. These questions will frame the activities of ecoSERVICES, formerly a DIVERSITAS project and now a project of Future Earth, in its role as a platform to foster global coordination of multidisciplinary sustainability science through the lens of ecosystem services. Fil: Bennett, E. M.. McGill University; Canadá Fil: Cramer, Wolfgang. Aix Marseille Université; Francia. Avignon Université; Francia Fil: Begossi, Alpina. Universidade Estadual de Campinas; Brasil. Universidade Santa Cecília; Brasil Fil: Cundill, Georgina. Rhodes University; Sudáfrica Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Egoh, Benis N.. University of KwaZulu-Natal; Sudáfrica Fil: Geijzendorffer, Ilse R.. Aix Marseille Université; Francia. Avignon Université; Francia Fil: Krug, Cornelia B.. Université de Paris XI; Francia Fil: Lavorel, Sandra. Université Grenoble Alpes; Francia. Centre National de la Recherche Scientifique; Francia Fil: Lazos, Elena. Universidad Nacional Autónoma de México; México Fil: Lebel, Louis. Chiang Mai University; Tailandia Fil: Martín López, Berta. Universidad Autónoma de Madrid; España. Universidad de Copenhagen; Dinamarca Fil: Meyfroidt, Patrick. Université Catholique de Louvain; Bélgica Fil: Mooney, Harold A.. University of Stanford; Estados Unidos Fil: Nel, Jeanne L.. Council for Scientific and Industrial Research; Sudáfrica Fil: Pascual, Unai. Basque Centre for Climate Change; España. University of Cambridge; Reino Unido Fil: Payet, Karine. Aix Marseille Université; Francia. Avignon Université; Francia Fil: Pérez Harguindeguy, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Peterson, Garry D.. Stockholms Universitet; Suecia Fil: Prieur Richard, Anne Hélène. Museum National D; Francia Fil: Reyers, Belinda. Council for Scientific and Industrial Research; Sudáfrica Fil: Roebeling, Peter. University of Aveiro; Portugal Fil: Seppelt, Ralf. Helmholtz Centre for Environmental Research; Alemania. German Centre for Integrative Biodiversity Research; Alemania Fil: Solan, Martin. University of Southampton; Reino Unido Fil: Tschakert, Petra. State University of Pennsylvania; Estados Unidos Fil: Tscharntke, Teja. Georg August University; Alemania Fil: Turner II, B. L.. Arizona State University; Estados Unidos Fil: Verburg, Peter H.. University of Amsterdam; Países Bajos Fil: Viglizzo, Ernesto Francisco. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: White, Piran C. L.. University of York; Reino Unido Fil: Woodward, Guy. Imperial College London; Reino Unido

Human action is driving worldwide change in ecosystems. While some of these changes have been gradual, others have led to surprising, large and persistent ecological regime shifts 1-4. Such shifts challenge ecological management and governance because they substantially alter the availability of ecosystems services 5, while being difficult to predict 6 and reverse2. Assessing whether continued global change will lead to further regime shifts, or has the potential trigger cascading regime shifts has been a central question in global change policy 7-9. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases or types of regime shifts 9-11. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. We demonstrate that the drivers of regime shifts are diverse and widely shared among regime shifts, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose tight links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts 8,12. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers.

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.

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance.

An ecological threshold is the point at which there is an abrupt change in an ecosystem quality, property or phenomenon, or where small changes in an environmental driver produce large responses in the ecosystem. Analysis of thresholds is complicated by nonlinear dynamics and by multiple factor controls that operate at diverse spatial and temporal scales. These complexities have challenged the use and utility of threshold concepts in environmental management despite great concern about preventing dramatic state changes in valued ecosystems, the need for determining critical pollutant loads and the ubiquity of other threshold-based environmental problems. In this paper we define the scope of the thresholds concept in ecological science and discuss methods for identifying and investigating thresholds using a variety of examples from terrestrial and aquatic environments, at ecosystem, landscape and regional scales. We end with a discussion of key research needs in this area.

Human well-being depends on ecosystem services such as food and clean water. Yet ecosystems and the services they provide are changing, often in ways we cannot anticipate. How can we cope with surprises and uncertainties when we cannot predict them? One approach is to make decisions that are robust to a number of different futures. Those interested in global environmental issues have used scenarios – sets of stories about the future – to help discuss those issues and to identify policy alternatives. To date, most global environmental scenarios have treated ecological dynamics as the product of large-scale anthropogenic drivers and have not considered ecological feedbacks to these drivers. Global scenarios could benefit from the input of ecologists, as this would lead to the incorporation of more realistic ecosystem dynamics. Similarly, ecology could benefit from involvement in scenario planning. Unlike many technical models, scenarios, easily understood as stories, can be used for communication and outreach, to build public appreciation of ecological science and the ecological dilemmas we face.

We use a simple model of ecosystem management to demonstrate that apparently rational management approaches can lead to ecological collapse. Our model of the ecosystem management of lake eutrophication integrates lake dynamics, management decision-making, and learning in a framework that is deliberately simplified to highlight the role of model uncertainty. The simulated lake can switch between alternate eutrophic and oligotrophic states. Managers consider two management models of the lake, one for an oligotrophic lake and the other for a eutrophic lake. As managers observe the lake varying from year to year, they estimate how well each of the two management models is supported by the observed data. Management policies maximize the expected net present value of the lake. Even under optimistic assumptions about environmental variation, learning ability, and management control, conventional decision theory and optimal control approaches fail to stabilize ecological dynamics. Rather, these methods drive ecos...

Landscapes are strongly shaped by the degree of interaction between pattern and process. This paper examines how ecological memory, the degree to which an ecological process is shaped by its past modifications of a landscape, influences landscape dynamics. I use a simulation model to examine how ecological memory shapes the landscape dynamics produced by the interaction of vegetative regrowth and fire. The model illustrated that increased ecological memory increased the strength and spatial extent of landscape pattern. The extent of these changes depended upon the relative rates of vegetative recovery and fire initiation. When ecological memory is strong, landscape pattern is persistent; pattern tends to be maintained rather than destroyed by fire. The generality of the simulation model suggests that these results may also apply to disturbance processes other than fire. The existence of ecological memory in ecosystems may allow processes to produce ecological pattern that can entrain other ecosystem variables. The methods presented in this paper to analyze pattern in model ecosystems could be used to detect such pattern in actual ecosystems.

A key challenge of ecosystem management is determining how to manage multiple ecosystem services across landscapes. Enhancing important provisioning ecosystem services, such as food and timber, often leads to tradeoffs between regulating and cultural ecosystem services, such as nutrient cycling, flood protection, and tourism. We developed a framework for analyzing the provision of multiple ecosystem services across landscapes and present an empirical demonstration of ecosystem service bundles, sets of services that appear together repeatedly. Ecosystem service bundles were identified by analyzing the spatial patterns of 12 ecosystem services in a mixed-use landscape consisting of 137 municipalities in Quebec, Canada. We identified six types of ecosystem service bundles and were able to link these bundles to areas on the landscape characterized by distinct social–ecological dynamics. Our results show landscape-scale tradeoffs between provisioning and almost all regulating and cultural ecosystem services, and they show that a greater diversity of ecosystem services is positively correlated with the provision of regulating ecosystem services. Ecosystem service-bundle analysis can identify areas on a landscape where ecosystem management has produced exceptionally desirable or undesirable sets of ecosystem services.

Ecosystem management that attempts to maximize the production of one ecosystem service often results in substantial declines in the provision of other ecosystem services. For this reason, recent studies have called for increased attention to development of a theoretical understanding behind the relationships among ecosystem services. Here, we review the literature on ecosystem services and propose a typology of relationships between ecosystem services based on the role of drivers and the interactions between services. We use this typology to develop three propositions to help drive ecological science towards a better understanding of the relationships among multiple ecosystem services. Research which aims to understand the relationships among multiple ecosystem services and the mechanisms behind these relationships will improve our ability to sustainably manage landscapes to provide multiple ecosystem services.

Attached algae play a minor role in conceptual and empirical models of lake ecosystem function but paradoxically form the energetic base of food webs that support a wide variety of fishes. To explore the apparent mismatch between perceived limits on contributions of periphyton to whole-lake primary production and its importance to consumers, we modeled the contribution of periphyton to whole-ecosystem primary production across lake size, shape, and nutrient gradients. The distribution of available benthic habitat for periphyton is influenced by the ratio of mean depth to maximum depth (DR = z/ z(max)). We modeled total phytoplankton production from water-column nutrient availability, z, and light. Periphyton production was a function of light-saturated photosynthesis (BPmax) and light availability at depth. The model demonstrated that depth ratio (DR) and light attenuation strongly determined the maximum possible contribution of benthic algae to lake production, and the benthic proportion of whole-lake primary production (BPf) declined with increasing nutrients. Shallow lakes (z < or =5 m) were insensitive to DR and were dominated by either benthic or pelagic primary productivity depending on trophic status. Moderately deep oligotrophic lakes had substantial contributions by benthic primary productivity at low depth ratios and when maximum benthic photosynthesis was moderate or high. Extremely large, deep lakes always had low fractional contributions of benthic primary production. An analysis of the world's largest lakes showed that the shapes of natural lakes shift increasingly toward lower depth ratios with increasing depth, maximizing the potential importance of littoral primary production in large-lake food webs. The repeatedly demonstrated importance of periphyton to lake food webs may reflect the combination of low depth ratios and high light penetration characteristic of large, oligotrophic lakes that in turn lead to substantial contributions of periphyton to autochthonous production.

Agricultural expansion and intensification have altered the quantity and quality of global water flows. Research suggests that these changes have increased the risk of catastrophic ecosystem regime shifts. We identify and review evidence for agriculture-related regime shifts in three parts of the hydrological cycle: interactions between agriculture and aquatic systems, agriculture and soil, and agriculture and the atmosphere. We describe the processes that shape these regime shifts and the scales at which they operate. As global demands for agriculture and water continue to grow, it is increasingly urgent for ecologists to develop new ways of anticipating, analyzing and managing nonlinear changes across scales in human-dominated landscapes.

"The Millennium Ecosystem Assessment (MA) scenarios address changes in ecosystem services and their implications for human well-being. Ecological changes pose special challenges for long-term thinking, because of the possibility of regime shifts that occur rapidly yet alter the availability of ecosystem services for generations. Moreover, ecological feedbacks can intensify human modification of ecosystems, creating a spiral of poverty and ecosystem degradation. Such complex dynamics were evaluated by a mixture of qualitative and quantitative analyses in the MA scenarios. Collectively, the scenarios explore problems such as the connections of poverty reduction and ecosystem services, and trade-offs among ecosystem services. Several promising approaches are considered by the scenarios, including uses of biodiversity to build resilience of ecosystem services, actively adaptive management, and green technology. Although the scenarios do not prescribe an optimal path, they illuminate the consequences of different policies toward ecosystem services."

The models investigated in this lab demonstrate how an ecological system can exist in alternative stable states and how the dynamics of alternative stable states change when moving from a site to an entire landscape. In this exam-ple, a site could persist as either a young, frequently burned site (dominated by longleaf pine) or an old, infrequently burned site (dominated by oaks). In-terestingly, however, the dynamics of a particular site changed when the site was placed within the context of its landscape, and the dynamics of a site greatly depended on the specific landscape context in which it was placed. Also, the dynamics of any single site were quite different from those of the entire landscape. When sites were grouped together to create a landscape, a site tended to push its neighboring sites toward its own particular state, re-ducing the range of system parameters for which alternative stable states could persist. In the forests of northern Florida, the ability of fire to spread, and conse-quently the rate at which patches of hardwood or pine either grow or shrink, is influenced by the pattern of hardwoods and pine across the landscape. The combination of spatial heterogeneity and positive feedbacks makes the dy-namics of forests difficult to predict from the study of a local site, since the processes that control a site can be affected by the properties of its neighbors. However, the use of models allows one to examine how the configuration of habitats across a landscape can affect the resilience of landscapes in the face of disturbance. Furthermore, while the models used in this lab are based on the forest dynamics of northern Florida, many ecosystems exhibit alternative stable states (Dublin et al., 1990; Knowlton, 1992; Scheffer et al., 1993). The dynamics of these ecosystems can be analyzed using similar models and techniques.

The environmentalist's paradox refers to two apparently contra-dictory trends: declining supplies of ecosystem services and increasing human well-being. If humans are truly dependent on nature, then human well-being should deteriorate as ecosystem services are degraded. Our article (Raudsepp-Hearne et al. 2010) examined the evidence for and against four proposed explanations of this paradox. By evaluating multiple explanations, we aimed to contribute to a stronger science of sustainability by encouraging dialogue among the disciplines that address sustainability but emphasize different ways of explaining this paradox. In our article, we critically reviewed empirical evidence from a broad multidisciplinary literature about the relationship between human well-being and ecosystem services and identified areas for future research to address the important gaps in our understanding of this relationship. Consequently, we broadly agree with both Nelson and Duraiappah (see Viewpoints, this issue) that more research and data at multiple scales are needed to resolve the environmentalist's paradox. However, our perspectives differ from theirs in terms of trends in well-being, stocks and flows of ecosystem services, and the role of technology in mediating the relationship between ecosystems and human well-being.

Ecosystem services (ES) is a valuable concept to be used in the planning and management of social–ecological landscapes. However, the understanding of the determinant factors affecting the interaction between services in the form of synergies or trade-offs is still limited. We assessed the production of 16 ES across 62 municipalities in the Norrström drainage basin in Sweden. We combined GIS data with publically available information for quantifying and mapping the distribution of services. Additionally, we calculated the diversity of ES for each municipality and used correlations and k-means clustering analyses to assess the existence of ES bundles. We found five distinct types of bundles of ES spatially agglomerated in the landscape that could be explained by regional social and ecological gradients. Human-dominated landscapes were highly multifunctional in our study area and urban densely populated areas were hotspots of cultural services. Electronic supplementary material The online version of this article (doi:10.1007/s13280-014-0601-0) contains supplementary material, which is available to authorized users.

The arctic tundra and boreal forest were once considered the last frontiers on earth because of their vast expanses remote from agricultural land-use change and industrial development. These regions are now, however, experiencing environmental and social changes that are as rapid as those occurring anywhere on earth. This paper summarizes the role of northern regions in the global system and provides a blueprint for assessing the factors that govern their sensitivity to social and environmental change.