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Gsell, Alena Sonia, Ulrike Scharfenberger, Deniz Özkundakci, Annika Walters, Lars-Anders Hansson, Annette B. G. Janssen, Peeter Nõges i in. "Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems". Proceedings of the National Academy of Sciences 113, nr 50 (22.11.2016): E8089—E8095. http://dx.doi.org/10.1073/pnas.1608242113.
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Ecosystems can show sudden and persistent changes in state despite only incremental changes in drivers. Such critical transitions are difficult to predict, because the state of the system often shows little change before the transition. Early-warning indicators (EWIs) are hypothesized to signal the loss of system resilience and have been shown to precede critical transitions in theoretical models, paleo-climate time series, and in laboratory as well as whole lake experiments. The generalizability of EWIs for detecting critical transitions in empirical time series of natural aquatic ecosystems remains largely untested, however. Here we assessed four commonly used EWIs on long-term datasets of five freshwater ecosystems that have experienced sudden, persistent transitions and for which the relevant ecological mechanisms and drivers are well understood. These case studies were categorized by three mechanisms that can generate critical transitions between alternative states: competition, trophic cascade, and intraguild predation. Although EWIs could be detected in most of the case studies, agreement among the four indicators was low. In some cases, EWIs were detected considerably ahead of the transition. Nonetheless, our results show that at present, EWIs do not provide reliable and consistent signals of impending critical transitions despite using some of the best routinely monitored freshwater ecosystems. Our analysis strongly suggests that a priori knowledge of the underlying mechanisms driving ecosystem transitions is necessary to identify relevant state variables for successfully monitoring EWIs.
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Derks, Milou, Frank Berkers i Arnold Tukker. "Toward Accelerating Sustainability Transitions through Collaborative Sustainable Business Modeling: A Conceptual Approach". Sustainability 14, nr 7 (23.03.2022): 3803. http://dx.doi.org/10.3390/su14073803.
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Sustainability transitions are purposeful and require deliberate collective action from multiple organizations, leading to the necessity to adopt new business models and redesign value networks. In both business model and sustainability transition research, the explicit activities needed to re-shape value creation and capture systems of organizations are largely unaddressed. We aim to fill this gap by proposing collaborative sustainable business modeling (CSBMing) as a participative multi-actor approach aimed at value network innovation to accelerate sustainability transitions. To do this, we first conceptualize a sustainability transition as a business ecosystem change. We then introduce the value network as the interceding level connecting the individual business to the wider ecosystem, which upon scaling, can change the ecosystem, leading to transition. CSBMing aims to redesign value networks and may thus be used as an actionable approach to accelerate transitions. Second, through the multi-level perspective, we explain how CSBMing can scale, influence other value networks, and change the ecosystem. Third, we recognize that scaling value networks might need more than just implementation of a CSBM and show how elements of CSBMing can complement executing transition management activities. We illustrate the potential role of CSBMing in accelerating transitions through two examples from the Dutch energy transition. In all, we show that CSBMing can be a fruitful approach to innovate and scale value networks, create collective action needed for sustainability transitions, and contribute to transition management activities.
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Zelnik, Yuval R., Ehud Meron i Golan Bel. "Gradual regime shifts in fairy circles". Proceedings of the National Academy of Sciences 112, nr 40 (11.09.2015): 12327–31. http://dx.doi.org/10.1073/pnas.1504289112.
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Large responses of ecosystems to small changes in the conditions—regime shifts—are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water–vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts.
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Batllori, Enric, Miquel De Cáceres, Lluís Brotons, David D. Ackerly, Max A. Moritz i Francisco Lloret. "Compound fire‐drought regimes promote ecosystem transitions in Mediterranean ecosystems". Journal of Ecology 107, nr 3 (19.12.2018): 1187–98. http://dx.doi.org/10.1111/1365-2745.13115.
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Levine, Naomi M., Ke Zhang, Marcos Longo, Alessandro Baccini, Oliver L. Phillips, Simon L. Lewis, Esteban Alvarez-Dávila i in. "Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change". Proceedings of the National Academy of Sciences 113, nr 3 (28.12.2015): 793–97. http://dx.doi.org/10.1073/pnas.1511344112.
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Amazon forests, which store ∼50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale die-back of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size- and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem’s resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest’s response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.
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Komninos, Nicos. "Transformation of Industry Ecosystems in Cities and Regions: A Generic Pathway for Smart and Green Transition". Sustainability 14, nr 15 (6.08.2022): 9694. http://dx.doi.org/10.3390/su14159694.
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This research paper focuses on pathways towards a digital and green transition. We assess a generic pathway for the transformation of industry ecosystems in cities and regions based on processes of prioritisation, ecosystem identification, and platform-based digital and green transition. We start with problem definition and hypotheses; review related works on transition pathways, such as digital transition, green transition, system innovation, industry ecosystems, and multi-level perspective of transformation; assess the generic pathway with case studies; and conclude with a discussion of findings, outline of conclusions, and policy implications. Overall, the paper investigates pathways, priorities, and methods allowing public authorities and business organisations to master the current industrial transformation of cities and regions introduced by the twin digital and green transitions as an opportunity for radical change of city ecosystems, innovation leapfrogging, and system innovation.
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Weaver, I. S., i J. G. Dyke. "Early warning signals in complex ecosystems". Earth System Dynamics Discussions 6, nr 2 (27.11.2015): 2507–42. http://dx.doi.org/10.5194/esdd-6-2507-2015.
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Abstract. Given the potential for elements of the Earth system to undergo rapid, hard to reverse changes in state, there is a pressing need to establish robust methods to produce early warning signals of such events. Here we present a conceptual ecosystem model in which a diversity of stable states emerge, along with rapid changes, referred to as critical transitions, as a consequence of external driving and non-linear ecological dynamics. We are able to produce robust early warning signals that precede critical transitions. However, we show that there is no correlation between the magnitude of the signal and magnitude or reversibility of any individual critical transition. We discuss these findings in the context of ecosystem management prior to and post critical transitions. We argue that an understanding of the dynamics of the systems is necessary both for management prior and post critical transitions and the effective interpretation of any early warning signal that may be produced for that system.
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Yoon, Changhee, Seungyeon Moon i Heesang Lee. "Symbiotic Relationships in Business Ecosystem: A Systematic Literature Review". Sustainability 14, nr 4 (16.02.2022): 2252. http://dx.doi.org/10.3390/su14042252.
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The business ecosystem shares many unique features with the biological ecosystem due to its origins. Similar to the biological ecosystem, the business ecosystem also emphasizes symbiotic relationships among symbionts (i.e., participants of a business ecosystem). In this study, we have broadened and deepened our knowledge of symbiosis in a business ecosystem, focusing on how each relationship develops and evolves through the interaction between keystone species and symbionts. We have introduced the typology of symbiotic relationships and highlighted the significant role of keystone species in business ecosystems. We defined three symbiosis types based on the analysis results: mutualism, commensalism, and parasitism. The findings indicated that each relationship continuously transitions into different symbiotic relationships as the relationship between the participants changes. The results also showed that a keystone species, a leader of a business ecosystem, can contribute to the success of a business ecosystem by strategically managing their relationship with symbionts.
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Larson, Danelle Marie, Wako Bungula, Casey McKean, Alaina Stockdill, Amber Lee, Frederick Forrest Miller i Killian Davis. "Quantifying ecosystem states and state transitions of the Upper Mississippi River System using topological data analysis". PLOS Computational Biology 19, nr 6 (7.06.2023): e1011147. http://dx.doi.org/10.1371/journal.pcbi.1011147.
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Aquatic systems worldwide can exist in multiple ecosystem states (i.e., a recurring collection of biological and chemical attributes), and effectively characterizing multidimensionality will aid protection of desirable states and guide rehabilitation. The Upper Mississippi River System is composed of a large floodplain river system spanning 2200 km and multiple federal, state, tribal and local governmental units. Multiple ecosystem states may occur within the system, and characterization of the variables that define these ecosystem states could guide river rehabilitation. We coupled a long-term (30-year) highly dimensional water quality monitoring dataset with multiple topological data analysis (TDA) techniques to classify ecosystem states, identify state variables, and detect state transitions over 30 years in the river to guide conservation. Across the entire system, TDA identified five ecosystem states. State 1 was characterized by exceptionally clear, clean, and cold-water conditions typical of winter (i.e., a clear-water state); State 2 had the greatest range of environmental conditions and contained most the data (i.e., a status-quo state); and States 3, 4, and 5 had extremely high concentrations of suspended solids (i.e., turbid states, with State 5 as the most turbid). The TDA mapped clear patterns of the ecosystem states across several riverine navigation reaches and seasons that furthered ecological understanding. State variables were identified as suspended solids, chlorophyll a, and total phosphorus, which are also state variables of shallow lakes worldwide. The TDA change detection function showed short-term state transitions based on seasonality and episodic events, and provided evidence of gradual, long-term changes due to water quality improvements over three decades. These results can inform decision making and guide actions for regulatory and restoration agencies by assessing the status and trends of this important river and provide quantitative targets for state variables. The TDA change detection function may serve as a new tool for predicting the vulnerability to undesirable state transitions in this system and other ecosystems with sufficient data. Coupling ecosystem state concepts and TDA tools can be transferred to any ecosystem with large data to help classify states and understand their vulnerability to state transitions.
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Rietkerk, M., V. Brovkin, P. M. van Bodegom, M. Claussen, S. C. Dekker, H. A. Dijkstra, S. V. Goryachkin i in. "Local ecosystem feedbacks and critical transitions in the climate". Biogeosciences Discussions 6, nr 5 (28.10.2009): 10121–36. http://dx.doi.org/10.5194/bgd-6-10121-2009.
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Abstract. Global and regional climate models, such as those used in IPCC assessments, are the best tools available for climate predictions. Such models typically account for large-scale land-atmosphere feedbacks. However, these models omit local vegetation-environment feedbacks that are crucial for critical transitions in ecosystems. Here, we reveal the hypothesis that, if the balance of feedbacks is positive at all scales, local vegetation-environment feedbacks may trigger a cascade of amplifying effects, propagating from local to large scale, possibly leading to critical transitions in the large-scale climate. We call for linking local ecosystem feedbacks with large-scale land-atmosphere feedbacks in global and regional climate models in order to yield climate predictions that we are more confident about.
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Ohman, Mark, Katherine Barbeau, Peter Franks, Ralf Goericke, Michael Landry i Arthur Miller. "Ecological Transitions in a Coastal Upwelling Ecosystem". Oceanography 26, nr 3 (1.09.2013): 210–19. http://dx.doi.org/10.5670/oceanog.2013.65.
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Munson, Seth M., Sasha C. Reed, Josep Peñuelas, Nathan G. McDowell i Osvaldo E. Sala. "Ecosystem thresholds, tipping points, and critical transitions". New Phytologist 218, nr 4 (8.05.2018): 1315–17. http://dx.doi.org/10.1111/nph.15145.
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Start, Denon. "Predator macroevolution drives trophic cascades and ecosystem functioning". Proceedings of the Royal Society B: Biological Sciences 285, nr 1883 (25.07.2018): 20180384. http://dx.doi.org/10.1098/rspb.2018.0384.
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Biologists now recognize that ecology can drive evolution, and that evolution in turn produces ecological patterns. I extend this thinking to include longer time scales, suggesting that macroevolutionary transitions can create phenotypic differences among species, which then have predictable impacts on species interactions, community assembly and ecosystem functioning. Repeated speciation can exacerbate these patterns by creating communities with similar phenotypes and hence ecological impacts. Here, I use several experiments to test these ideas in dragonfly larvae that occupy ponds with fish, ponds without fish, or both. I show that macroevolutionary transitions between habitats cause fishless pond species to be more active relative to fish pond specialists, reducing prey abundance, shifting prey community composition and creating stronger trophic cascades. These effects scale up to the community level with predictable consequences for ecosystem multi-functioning. I suggest that macroevolutionary history can have predictable impacts on phenotypic traits, with consequences for interacting species and ecosystems.
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Duan, Menglei, Connor Bax, Kati Laakso, Nooshin Mashhadi, Nelson Mattie i Arturo Sanchez-Azofeifa. "Characterizing Transitions between Successional Stages in a Tropical Dry Forest Using LiDAR Techniques". Remote Sensing 15, nr 2 (13.01.2023): 479. http://dx.doi.org/10.3390/rs15020479.
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Secondary succession is defined as natural regeneration following complete forest clearance from anthropogenic or natural disturbances. Traditional strategies aimed to map and characterize secondary succession using remote sensing are usually based on deterministic approaches, where transitions between successional stages are not considered. These transitions represent rich environments between successional stages and play a key role in ecosystem regeneration. Here, we evaluate the use of the Full-waveform Airborne LiDAR to characterize changes in forest structure between the transition of early-to-intermediate and intermediate-to-late forest succession at the Santa Rosa National Park Environmental Monitoring Super Site (SRNP-EMSS), Guanacaste, Costa Rica. The vertical forest structure was analyzed on twenty cross-sections selected between forest transitions previously mapped using machine learning; leaf area density (LAD) and waveform metrics were studied based on the waveform profile derived from twenty-seven plots distributed in different successional forest patches. Results suggest that LiDAR techniques can identify forest structure differences between successional stages and their transitions. The significance proves that transitions exist, highlights the unique transitional characteristics between intermediate and late successional stages and contributes to understanding the significance of inter-successional stages (transitions) in secondary dry forests.
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Watson, Lisa, Menno W. Straatsma, Niko Wanders, Judith A. Verstegen, Steven M. de Jong i Derek Karssenberg. "Global ecosystem service values in climate class transitions". Environmental Research Letters 15, nr 2 (28.01.2020): 024008. http://dx.doi.org/10.1088/1748-9326/ab5aab.
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Zhang, Hongxia, Wei Xu, Youming Lei i Yan Qiao. "Noise-induced vegetation transitions in the Grazing Ecosystem". Applied Mathematical Modelling 76 (grudzień 2019): 225–37. http://dx.doi.org/10.1016/j.apm.2019.06.009.
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Viglizzo, Ernesto F., Marcelo D. Nosetto, Esteban G. Jobbágy, M. Florencia Ricard i Federico C. Frank. "The ecohydrology of ecosystem transitions: a meta-analysis". Ecohydrology 8, nr 5 (7.08.2014): 911–21. http://dx.doi.org/10.1002/eco.1540.
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Roser, Thorsten, Ksenija Kuzmina i Mikko Koria. "Enabling Sustainable Adaptation and Transitions: Exploring New Roles of a Tourism Innovation Intermediary in Andalusia, Spain". Tourism and Hospitality 4, nr 3 (30.06.2023): 390–405. http://dx.doi.org/10.3390/tourhosp4030024.
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Tourism is a major global and local industry creating value through services that are enhanced and enabled through intermediaries that support innovation in the sector. This exploratory case study examines the roles and activities of a publicly funded tourism innovation intermediary for small medium-sized enterprises (SMEs) and professionals in Andalucia, Spain. We note the gap in knowledge on how intermediaries may best support stakeholders in achieving resilience and sustainability in transitions in tourism service ecosystems. Building on interviews, reports, and observations, this study finds that the intermediary has successfully supported its stakeholders in enhancing their adaptability in the current service ecosystem. There is less evidence of achieving deliberate transformations towards long-term sustainability and resilience. As the intermediary is uniquely positioned at the meso-level of the regional tourism service ecosystem, this study proposes exploring engagement to cover both macro and micro-level activities to enable moving towards becoming a transition intermediary and a regional sustainability catalyst. This study furthermore proposes an expanded range of roles and activities for the intermediary to enable moving towards resilience and sustainability, while contributing to the understanding of innovation intermediaries supporting sustainability in the tourism sector.
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Hoover, David L., Brandon Bestelmeyer, Nancy B. Grimm, Travis E. Huxman, Sasha C. Reed, Osvaldo Sala, Timothy R. Seastedt, Hailey Wilmer i Scott Ferrenberg. "Traversing the Wasteland: A Framework for Assessing Ecological Threats to Drylands". BioScience 70, nr 1 (18.12.2019): 35–47. http://dx.doi.org/10.1093/biosci/biz126.
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Abstract Drylands cover 41% of the Earth's terrestrial surface, play a critical role in global ecosystem function, and are home to over two billion people. Like other biomes, drylands face increasing pressure from global change, but many of these ecosystems are close to tipping points, which, if crossed, can lead to abrupt transitions and persistent degraded states. Their limited but variable precipitation, low soil fertility, and low productivity have given rise to a perception that drylands are wastelands, needing societal intervention to bring value to them. Negative perceptions of drylands synergistically combine with conflicting sociocultural values regarding what constitutes a threat to these ecosystems. In the present article, we propose a framework for assessing threats to dryland ecosystems and suggest we must also combat the negative perceptions of drylands in order to preserve the ecosystem services that they offer.
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Zhao, Yanjie, Rong Wang, Xiangdong Yang, John A. Dearing, Charles Patrick Doncaster, Peter Langdon i Xuhui Dong. "Reconstruction of Ecological Transitions in a Temperate Shallow Lake of the Middle Yangtze River Basin in the Last Century". Water 14, nr 7 (1.04.2022): 1136. http://dx.doi.org/10.3390/w14071136.
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Exogenous drivers may cause a gradual and reversible change in a lake equilibrium, or they may force it over a threshold to a persistent alternative stable state, described as a regime shift in the ecosystem. In the mid-and-lower Yangtze River Basin (MLYB), major environmental problems in shallow lakes have been eutrophication and abrupt algal blooms under anthropogenic disturbances for the recent century. Much value is therefore placed on understanding the changes in shallow-lake ecosystems that characteristically precede changes in the state of the lake. Here, we describe a case study of the paleolimnological signature in diatom assemblages of various types of regime shifts caused by historically documented anthropogenic drivers in a temperate shallow lake: Taibai Lake. We evaluate the effectiveness of paleolimnological data as a surrogate for long-term monitoring. Algorithms using sequential t and F statistics detected breakpoints in the time series of diatom assemblages, in 1994–1996, 1974–1977, 1952–1956, and 1931–1934, respectively. The regression statistics suggest that the hydrodynamic–ecosystem and aquacultural–ecosystem relationships fit better in the breakpoint regression model, and the relationship between nutrient loading and ecosystem state suits the linear model. Feedback loops help reconstruct dynamic changes in Taibai influenced by major stressors. Our study exemplifies the value of system approaches to identifying regime shifts and their possible causes in shallow lakes from paleolimnological records. The case study of Taibai set an example of reconstructing the ecological regime shifts in shallow lakes in the MLYB and understanding the state changes in lake ecosystems, which will benefit effective lake management.
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Olofsson, Johan, i Eric Post. "Effects of large herbivores on tundra vegetation in a changing climate, and implications for rewilding". Philosophical Transactions of the Royal Society B: Biological Sciences 373, nr 1761 (22.10.2018): 20170437. http://dx.doi.org/10.1098/rstb.2017.0437.
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In contrast to that of the Pleistocene epoch, between approximately 2.6 million and 10 000 years before present, the extant community of large herbivores in Arctic tundra is species-poor predominantly due to human extinctions. We here discuss how this species-poor herbivore guild influences tundra ecosystems, especially in relation to the rapidly changing climate. We show that present herbivore assemblages have large effects on tundra ecosystem composition and function and suggest that the effect on thermophilic species expected to invade the tundra in a warmer climate is especially strong, and that herbivores slow ecosystem responses to climate change. We focus on the ability of herbivores to drive transitions between different vegetation states. One such transition is between tundra and forest. A second vegetation transition discussed is between grasslands and moss- and shrub-dominated tundra. Contemporary studies show that herbivores can drive such state shifts and that a more diverse herbivore assemblage would have even higher potential to do so. We conclude that even though many large herbivores, and especially the megaherbivores, are extinct, there is a potential to reintroduce large herbivores in many arctic locations, and that doing so would potentially reduce some of the unwanted effects of a warmer climate. This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.
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Ghadami, Amin, Shiyang Chen i Bogdan I. Epureanu. "Data-driven identification of reliable sensor species to predict regime shifts in ecological networks". Royal Society Open Science 7, nr 8 (sierpień 2020): 200896. http://dx.doi.org/10.1098/rsos.200896.
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Signals of critical slowing down are useful for predicting impending transitions in ecosystems. However, in a system with complex interacting components not all components provide the same quality of information to detect system-wide transitions. Identifying the best indicator species in complex ecosystems is a challenging task when a model of the system is not available. In this paper, we propose a data-driven approach to rank the elements of a spatially distributed ecosystem based on their reliability in providing early-warning signals of critical transitions. The proposed method is rooted in experimental modal analysis techniques traditionally used to identify structural dynamical systems. We show that one could use natural system fluctuations and the system responses to small perturbations to reveal the slowest direction of the system dynamics and identify indicator regions that are best suited for detecting abrupt transitions in a network of interacting components. The approach is applied to several ecosystems to demonstrate how it successfully ranks regions based on their reliability to provide early-warning signals of regime shifts. The significance of identifying the indicator species and the challenges associated with ranking nodes in networks of interacting components are also discussed.
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Brooks, Marjorie L. "Unlocking the biogeochemical role of beaver in state-transition of landscapes in Yellowstone's northern range". UW National Parks Service Research Station Annual Reports 41 (15.12.2018): 55–64. http://dx.doi.org/10.13001/uwnpsrc.2018.5649.
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Extirpation of wolves from the Greater Yellowstone Ecosystem in the 1920s hypothetically triggered a trophic cascade in which browsers, released from wolf (Canis lupus) predation, over-browsed riparian zones. Eventually, vast meadow-wetland complexes transitioned to grass-lodgepole systems. By 1954, beaver (Castor canadensis) virtually abandoned the Greater Yellowstone Ecosystem. In 2000, Colorado State University established experimental dams with browsing exclosures for Long Term Environmental Research in Biology (LTREB) on three streams in Lamar Valley to compare hydrologic effects of pseudo-beaver dams and browsing on willow (Salix spp.) productivity and state transitions. In 2015, beaver began recolonizing the region. I investigated how the biogeochemical role of beaver versus their hydrologic influence affects the underlying mechanisms of state transition: nutrient cycling, productivity, and stream respiration. Analyses of the 2017 field samples show that beaver streams trend toward higher nutrient levels and higher variances than the LTREB sites. The data tentatively support the role of beaver as keystone species in state transitions, although more data are needed. The unexpected and late May notice from the NPS to obtain an independent research permit—approved late August—curtailed my 2018 research to a brief field bout in September. Analysis of 2018 samples is underway.
Featured photo from Figure 1 in report.
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Brooks, Marjorie L. "Unlocking the biogeochemical role of beaver in state-transition of landscapes in Yellowstone's northern range: Tantalizing insights, initial results, and evolving research design". UW National Parks Service Research Station Annual Reports 42 (15.12.2019): 70–79. http://dx.doi.org/10.13001/uwnpsrc.2019.5741.
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Extirpation of wolves from the Greater Yellowstone Ecosystem in the 1920s hypothetically triggered a trophic cascade in which herbivores over-browsed riparian zones once released from the fear of wolf (Canis lupus) predation. Eventually, vast meadow-wetland complexes transitioned to grass-lodgepole systems. By 1954, beaver (Castor canadensis) virtually abandoned the Greater Yellowstone Ecosystem. In 2000, Colorado State University established experimental dams with browsing exclosures for Long Term Environmental Research in Biology (LTREB) on three streams in Lamar Valley to compare hydrologic effects of pseudo-beaver dams and browsing on willow (Salix spp.) productivity and state transitions. In 2015, beaver began recolonizing the region. I investigate how the biogeochemical role of beaver versus their hydrologic influence affects the underlying mechanisms of state transition: nutrient cycling, productivity, and stream respiration. Analyses of the 2017 field samples showed that beaver streams trend toward higher nutrient levels and higher variances than the LTREB sites. These trends continued in 2018 and 2019. The data tentatively support the role of beaver as keystone species in state transitions. Interannual modeling of nutrient dynamics, comparisons of stream metabolism, and genetic identification of microbial communities are underway. Similarly, analyses of the repeated measures collected across the month of July 2019 are underway.
Featured photo from figure 1 in report.
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Sanchez, Jessica L., Heather D. Bracken-Grissom i Joel C. Trexler. "Freshwater-to-marine transitions may explain the evolution of herbivory in the subgenus Mollienesia (genus Poecilia, mollies and guppies)". Biological Journal of the Linnean Society 127, nr 4 (24.06.2019): 742–61. http://dx.doi.org/10.1093/biolinnean/blz045.
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Abstract The ability of organisms to cross ecosystem boundaries is an important catalyst of evolutionary diversification. The genus Poecilia (mollies and guppies) is an excellent system for studying ecosystem transitions because species display a range of salinity and dietary preferences, with herbivory concentrated in the subgenus Mollienesia. We reconstructed ancestral habitats and diets across a phylogeny of the genus Poecilia, evaluated diversification rates and used phylogenetically independent contrasts to determine whether diet evolved in response to habitat transition in this group. The results suggest that ancestors of subgenus Mollienesia were exclusively herbivorous, whereas ancestral diets of other Poecilia included animals. We found that transitions across euryhaline boundaries occurred at least once in this group, probably after the divergence of the subgenus Mollienesia. Furthermore, increased salinity affiliation explained 24% of the decrease in animals in the gut, and jaw morphology was associated with the percentage of animals in the gut, but not with the percentage of species occupying saline habitats. These findings suggest that in the genus Poecilia, herbivory evolved in association with transitions from fresh to euryhaline habitats, and jaw morphology evolved in response to the appearance of herbivory. These results provide a rare example of increased diet diversification associated with the transition from freshwater to euryhaline habitats.
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Hernández-Almeida, Iván, Martin Grosjean, Juan José Gómez-Navarro, Isabelle Larocque-Tobler, Alicja Bonk, Dirk Enters, Alicja Ustrzycka i in. "Resilience, rapid transitions and regime shifts: Fingerprinting the responses of Lake Żabińskie (NE Poland) to climate variability and human disturbance since AD 1000". Holocene 27, nr 2 (19.08.2016): 258–70. http://dx.doi.org/10.1177/0959683616658529.
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Rapid ecosystem transitions and adverse effects on ecosystem services as responses to combined climate and human impacts are of major concern. Yet few long-term (i.e. >60 years) quantitative observational time series exist, particularly for ecosystems that have a long history of human intervention. Here, we combine three major environmental pressures (land use, nutrients and erosion) with quantitative summer and winter climate reconstructions and climate model simulations to explore the system dynamics, resilience and the role of disturbance regimes in varved eutrophic Lake Żabińskie (NE Poland) since AD 1000. The comparison between these independent sources of information allows us to establish the coherence and points of disagreements between such data sets. We find that climate reconstructions capture noticeably natural forced climate variability, while internal variability is the dominant source of variability during most parts of the last millennium at the regional scale, precisely at which climate models seem to underestimate forced variability. Using different multivariate analyses and change point detection techniques, we identify ecosystem changes through time and shifts between rather stable states and highly variable ones. Prior to AD 1600, the lake ecosystem was characterised by high stability and resilience against observed natural climate variability. During this period, the anthropogenic fingerprint was small; the lake ecosystem was buffered against the combined human and natural disturbance. In contrast, lake–ecosystem conditions started to fluctuate across a broad range of states after AD 1600. The period AD 1745–1886 represents the phase with the strongest human disturbance of the catchment–lake ecosystem. During that time, the range of natural climate variability did not increase. Analyses of the frequency of change points in the multi-proxy data set suggest that the last 400 years were highly variable and increased vulnerability of the ecosystem to the anthropogenic disturbances. This led to significant rapid ecosystem transformations.
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Vidiella, Blai, Josep Sardanyés i Ricard V. Solé. "Synthetic soil crusts against green-desert transitions: a spatial model". Royal Society Open Science 7, nr 8 (sierpień 2020): 200161. http://dx.doi.org/10.1098/rsos.200161.
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Semiarid ecosystems are threatened by global warming due to longer dehydration times and increasing soil degradation. Mounting evidence indicates that, given the current trends, drylands are likely to expand and possibly experience catastrophic shifts from vegetated to desert states. Here, we explore a recent suggestion based on the concept of ecosystem terraformation, where a synthetic organism is used to counterbalance some of the nonlinear effects causing the presence of such tipping points. Using an explicit spatial model incorporating facilitation and considering a simplification of states found in semiarid ecosystems including vegetation, fertile and desert soil, we investigate how engineered microorganisms can shape the fate of these ecosystems. Specifically, two different, but complementary, terraformation strategies are proposed: Cooperation -based: C -terraformation; and Dispersion -based: D -terraformation. The first strategy involves the use of soil synthetic microorganisms to introduce cooperative loops (facilitation) with the vegetation. The second one involves the introduction of engineered microorganisms improving their dispersal capacity, thus facilitating the transition from desert to fertile soil. We show that small modifications enhancing cooperative loops can effectively modify the aridity level of the critical transition found at increasing soil degradation rates, also identifying a stronger protection against soil degradation by using the D -terraformation strategy. The same results are found in a mean-field model providing insights into the transitions and dynamics tied to these terraformation strategies. The potential consequences and extensions of these models are discussed.
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Vidiella, Blai, Josep Sardanyés i Ricard Solé. "Exploiting delayed transitions to sustain semiarid ecosystems after catastrophic shifts". Journal of The Royal Society Interface 15, nr 143 (czerwiec 2018): 20180083. http://dx.doi.org/10.1098/rsif.2018.0083.
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Semiarid ecosystems (including arid, semiarid and dry-subhumid ecosystems) span more than 40% of extant habitats and contain a similar percentage of the human population. Theoretical models and palaeoclimatic data predict a grim future, with rapid shifts towards a desert state, with accelerated diversity losses and ecological collapses. These shifts are a consequence of the special nonlinearities resulting from ecological facilitation. Here, we investigate a simple model of semiarid ecosystems identifying the so-called ghost, which appears after a catastrophic transition from a vegetated to a desert state once a critical rate of soil degradation is overcome. The ghost involves a slowdown of transients towards the desert state, making the ecosystem seem stable even though vegetation extinction is inevitable. We use this model to show how to exploit the ecological ghosts to avoid collapse. Doing so involves the restoration of small fractions of desert areas with vegetation capable of maintaining a stable community once the catastrophic shift condition has been achieved. This intervention method is successfully tested under the presence of demographic stochastic fluctuations.
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Shaughnessy, Haydn. "Recognizing the ecosystem phase-change: a guide to four types". Strategy & Leadership 42, nr 1 (14.01.2014): 17–23. http://dx.doi.org/10.1108/sl-09-2013-0074.
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Purpose – This article introduces the concept of a industry phase change. Phase-changes are historical transitions, ones that create a new industry and consumer ecosystem. They are not merely disruptive technologies. Design/methodology/approach – A phase-change is marked by a complex transformation in human behavior produced by a new way to satisfy consumption needs. The Kodak case is described. Findings – A current phase-change sweeping many business sectors is driven by the growing search for competitive advantage through connected ecosystems of stakeholders that co-create value – customers, innovators, partners and communities. Practical implications – Co-creative ecosystems are a phase-change that requires a new set of executive and management skills, a different culture, a new approach to information, as well as new forms of leadership. Originality/value – Explains the success factors of the four major types of modern ecosystems: scale ecosystems; creative commons/open source ecosystems; customer ecosystems; and systemic ecosystems. Shows how Kodak was disrupted by its lack of understanding of ecosystems management.
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Cumming, Graeme S., Andreas Buerkert, Ellen M. Hoffmann, Eva Schlecht, Stephan von Cramon-Taubadel i Teja Tscharntke. "Implications of agricultural transitions and urbanization for ecosystem services". Nature 515, nr 7525 (listopad 2014): 50–57. http://dx.doi.org/10.1038/nature13945.
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Rietkerk, Max, Victor Brovkin, Peter M. van Bodegom, Martin Claussen, Stefan C. Dekker, Henk A. Dijkstra, Sergey V. Goryachkin i in. "Local ecosystem feedbacks and critical transitions in the climate". Ecological Complexity 8, nr 3 (wrzesień 2011): 223–28. http://dx.doi.org/10.1016/j.ecocom.2011.03.001.
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Melone, Angelica, Leah L. Bremer, Susan E. Crow, Zoe Hastings, Kawika B. Winter, Tamara Ticktin, Yoshimi M. Rii i in. "Assessing Baseline Carbon Stocks for Forest Transitions: A Case Study of Agroforestry Restoration from Hawaiʻi". Agriculture 11, nr 3 (25.02.2021): 189. http://dx.doi.org/10.3390/agriculture11030189.
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As the extent of secondary forests continues to expand throughout the tropics, there is a growing need to better understand the ecosystem services, including carbon (C) storage provided by these ecosystems. Despite their spatial extent, there are limited data on how the ecosystem services provided by secondary forest may be enhanced through the restoration of both ecological and agroecological functions in these systems. This study quantifies the above- and below-ground C stocks in a non-native secondary forest in Hawaiʻi where a community-based non-profit seeks to restore a multi-strata agroforestry system for cultural and ecological benefits. For soil C, we use the equivalent soil mass method both to estimate stocks and examine spatial heterogeneity at high resolution (eg. sub 5 m) to define a method and sampling design that can be replicated to track changes in C stocks on-site and elsewhere. The assessed total ecosystem C was ~388.5 Mg C/ha. Carbon stock was highest in trees (~192.4 Mg C/ha; ~50% of total C); followed by soil (~136.4 Mg C/ha; ~35% of total C); roots (~52.7 Mg C/ha; ~14% of total C); and was lowest in coarse woody debris (~4.7 Mg C/ha; ~1% of total C) and litter (~2.3 Mg C/ha; <1% of total C). This work provides a baseline carbon assessment prior to agroforest restoration that will help to better quantify the contributions of secondary forest transitions and restoration efforts to state climate policy. In addition to the role of C sequestration in climate mitigation, we also highlight soil C as a critical metric of hybrid, people-centered restoration success given the role of soil organic matter in the production of a suite of on- and off-site ecosystem services closely linked to local sustainable development goals.
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Wang, Rong, John A. Dearing i Peter G. Langdon. "Critical Transitions in Lake Ecosystem State May Be Driven by Coupled Feedback Mechanisms: A Case Study from Lake Erhai, China". Water 14, nr 1 (3.01.2022): 85. http://dx.doi.org/10.3390/w14010085.
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Critical transitions between ecosystem states can be triggered by relatively small external forces or internal perturbations and may show time-lagged or hysteretic recovery. Understanding the precise mechanisms of a transition is important for ecosystem management, but it is hampered by a lack of information about the preceding interactions and associated feedback between different components in an ecosystem. This paper employs a range of data, including paleolimnological, environmental monitoring and documentary sources from lake Erhai and its catchment, to investigate the ecosystem structure and dynamics across multiple trophic levels through the process of eutrophication. A long-term perspective shows the growth and decline of two distinct, but coupled, positive feedback loops: a macrophyte-loop and a phosphorus-recycling-loop. The macrophyte-loop became weaker, and the phosphorus-recycling-loop became stronger during the process of lake eutrophication, indicating that the critical transition was propelled by the interaction of two positive feedback loops with different strengths. For lake restoration, future weakening of the phosphorus-recycling loop or a reduction in external pressures is expected to trigger macrophyte growth and eventually produce clear water conditions, but the speed of recovery will probably depend on the rates of feedback loops and the strength of their coupling.
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Chen, Dechao, Xinliang Xu, Huailong Jiang, Zongyao Sun, Luo Liu i Zhi Qiao. "Contribution of Spatial Heterogeneity and Temporal-Spatial Change of Ecosystems to the Thermal Environment of Tourist Destinations: A Case Study of Sichuan-Chongqing Region, China". Advances in Meteorology 2020 (23.06.2020): 1–15. http://dx.doi.org/10.1155/2020/6798958.
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Tourism development activities affect the structure and functions of ecosystems directly triggering changes in the thermal environment of tourism destinations and raising a need for sustainable development of the tourism industry. Using the 2005–2015 moderate resolution imaging spectroradiometer (MODIS) data on the land surface temperature combined with the land use data, the urban thermal environment contribution index (CI) of prefecture-level cities and ecosystem types corresponding to the study area in Sichuan-Chongqing region were quantitatively calculated under various seasonal and diurnal conditions in terms of the scales of administrative divisions and ecosystem types. The characteristics of the roles played by different cities and ecosystem types to contribute to the thermal environment of the metropolitan region were summarized, and the differences and changes in the corresponding contribution intensity of various ecosystem types were measured. The results indicate the following: (1) Different cities play different roles as the sources and sinks with respect to the thermal environment in the daytime and nighttime. Based on the diurnal differences of the contribution indices, cities can be divided into three types: the day-night heat source type, the day-sink and night-source type, and the day-night heat sink type. (2) The farmland and the grassland ecosystems are the most important source and sink landscapes in the thermal environment of the Sichuan-Chongqing Region, respectively. (3) The region is affected by the spatial arrangement of the internal ecosystems and its own development conditions, and, consequently, there are significant temporal-spatial variations and role transitions between heat source and heat sink regarding the contribution of different ecosystem types to the thermal environment of individual cities. It is important to scientifically regulate the thermal environment effect on tourism destinations and maintain the comfort and sustainable development through identifying the source and sink ecosystems of the thermal environment, controlling the quantity and spatial arrangement of the heat source ecosystems, and fully enabling the cooling effect of the heat sink ecosystems.
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Oliveras, Immaculada, i Yadvinder Malhi. "Many shades of green: the dynamic tropical forest–savannah transition zones". Philosophical Transactions of the Royal Society B: Biological Sciences 371, nr 1703 (19.09.2016): 20150308. http://dx.doi.org/10.1098/rstb.2015.0308.
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The forest–savannah transition is the most widespread ecotone in tropical areas, separating two of the most productive terrestrial ecosystems. Here, we review current understanding of the factors that shape this transition, and how it may change under various drivers of local or global change. At broadest scales, the location of the transition is shaped by water availability, mediated strongly at local scales by fire regimes, herbivory pressure and spatial variation in soil properties. The frequently dynamic nature of this transition suggests that forest and savannah can exist as alternative stable states, maintained and separated by fire–grass feedbacks and tree shade–fire suppression feedback. However, this theory is still contested and the relative contributions of the main biotic and abiotic drivers and their interactions are yet not fully understood. These drivers interplay with a wide range of ecological processes and attributes at the global, continental, regional and local scales. The evolutionary history of the biotic and abiotic drivers and processes plays an important role in the current distributions of these transitions as well as in their species composition and ecosystem functioning. This ecotone can be sensitive to shifts in climate and other driving factors, but is also potentially stabilized by negative feedback processes. There is abundant evidence that these transitions are shifting under contemporary global and local changes, but the direction of shift varies according to region. However, it still remains uncertain how these transitions will respond to rapid and multi-faceted ongoing current changes, and how increasing human influence will interact with these shifts. This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.
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Li, Jie, i Matteo Convertino. "Temperature increase drives critical slowing down of fish ecosystems". PLOS ONE 16, nr 10 (20.10.2021): e0246222. http://dx.doi.org/10.1371/journal.pone.0246222.
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Fish ecosystems perform ecological functions that are critically important for the sustainability of marine ecosystems, such as global food security and carbon stock. During the 21st century, significant global warming caused by climate change has created pressing challenges for fish ecosystems that threaten species existence and global ecosystem health. Here, we study a coastal fish community in Maizuru Bay, Japan, and investigate the relationships between fluctuations of ST, abundance-based species interactions and salient fish biodiversity. Observations show that a local 20% increase in temperature from 2002 to 2014 underpins a long-term reduction in fish diversity (∼25%) played out by some native and invasive species (e.g. Chinese wrasse) becoming exceedingly abundant; this causes a large decay in commercially valuable species (e.g. Japanese anchovy) coupled to an increase in ecological productivity. The fish community is analyzed considering five temperature ranges to understand its atemporal seasonal sensitivity to ST changes, and long-term trends. An optimal information flow model is used to reconstruct species interaction networks that emerge as topologically different for distinct temperature ranges and species dynamics. Networks for low temperatures are more scale-free compared to ones for intermediate (15-20°C) temperatures in which the fish ecosystem experiences a first-order phase transition in interactions from locally stable to metastable and globally unstable for high temperatures states as suggested by abundance-spectrum transitions. The dynamic dominant eigenvalue of species interactions shows increasing instability for competitive species (spiking in summer due to intermediate-season critical transitions) leading to enhanced community variability and critical slowing down despite higher time-point resilience. Native competitive species whose abundance is distributed more exponentially have the highest total directed interactions and are keystone species (e.g. Wrasse and Horse mackerel) for the most salient links with cooperative decaying species. Competitive species, with higher eco-climatic memory and synchronization, are the most affected by temperature and play an important role in maintaining fish ecosystem stability via multitrophic cascades (via cooperative-competitive species imbalance), and as bioindicators of change. More climate-fitted species follow temperature increase causing larger divergence divergence between competitive and cooperative species. Decreasing dominant eigenvalues and lower relative network optimality for warmer oceans indicate fishery more attracted toward persistent oscillatory states, yet unpredictable, with lower cooperation, diversity and fish stock despite the increase in community abundance due to non-commercial and venomous species. We emphasize how changes in species interaction organization, primarily affected by temperature fluctuations, are the backbone of biodiversity dynamics and yet for functional diversity in contrast to taxonomic richness. Abundance and richness manifest gradual shifts while interactions show sudden shift. The work provides data-driven tools for analyzing and monitoring fish ecosystems under the pressure of global warming or other stressors. Abundance and interaction patterns derived by network-based analyses proved useful to assess ecosystem susceptibility and effective change, and formulate predictive dynamic information for science-based fishery policy aimed to maintain marine ecosystems stable and sustainable.
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Dakos, Vasilis, Stephen R. Carpenter, Egbert H. van Nes i Marten Scheffer. "Resilience indicators: prospects and limitations for early warnings of regime shifts". Philosophical Transactions of the Royal Society B: Biological Sciences 370, nr 1659 (5.01.2015): 20130263. http://dx.doi.org/10.1098/rstb.2013.0263.
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In the vicinity of tipping points—or more precisely bifurcation points—ecosystems recover slowly from small perturbations. Such slowness may be interpreted as a sign of low resilience in the sense that the ecosystem could easily be tipped through a critical transition into a contrasting state. Indicators of this phenomenon of ‘critical slowing down (CSD)’ include a rise in temporal correlation and variance. Such indicators of CSD can provide an early warning signal of a nearby tipping point. Or, they may offer a possibility to rank reefs, lakes or other ecosystems according to their resilience. The fact that CSD may happen across a wide range of complex ecosystems close to tipping points implies a powerful generality. However, indicators of CSD are not manifested in all cases where regime shifts occur. This is because not all regime shifts are associated with tipping points. Here, we review the exploding literature about this issue to provide guidance on what to expect and what not to expect when it comes to the CSD-based early warning signals for critical transitions.
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Hirvensalo, Antero, Satu Teerikangas, Noelia-Sarah Reynolds, Helka Kalliomäki, Raine Mäntysalo, Hanna Mattila i Kaisa Granqvist. "Agency in Circular City Ecosystems—A Rationalities Perspective". Sustainability 13, nr 5 (26.02.2021): 2544. http://dx.doi.org/10.3390/su13052544.
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The concept of agency is increasingly used in the literature on sustainability transitions. In this paper, we add to that discussion by arguing that the concept of rationality opens new avenues to theorizing relational agency in transitions toward a circular economy. To this end, we compare rationality conceptions from management (e.g., collaboration and competition) with critical theory perspectives on rationality (e.g., instrumental and communicative rationality). This leads us to develop a typology matrix for describing plural rationalities underpinning relational agency. We illustrate this typology using excerpts from an in-depth case study of an ongoing city-coordinated ecosystem that develops a smart technology-enabled urban area based on the principles of circularity. The first contribution of this interdisciplinary paper is to offer a rational perspective on theorizing the antecedents of relational agency in circular economy transitions, where communicatively rational action enables agency and change. Secondly, our paper contributes to the literature on circular cities through conceptualizing circular transition as simultaneous collaboration and competition. Thirdly, our paper introduces a dyadic perspective on rationality to the literature on coopetition and provides an operating space from which professionals can navigate, depending on the type of coopetitive situation.
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Liu, Yongqiang, Shuang Wang, Zipeng Chen i Shuangshuang Tu. "Research on the Response of Ecosystem Service Function to Landscape Pattern Changes Caused by Land Use Transition: A Case Study of the Guangxi Zhuang Autonomous Region, China". Land 11, nr 5 (20.05.2022): 752. http://dx.doi.org/10.3390/land11050752.
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Land use transitions cause reconfigurations of regional landscape patterns which can further change the regional ecosystem service functions and its values, especially in environmentally fragile regions. Firstly, this paper theoretically examines the relationships between land use transitions, landscape pattern evolution and the responses of ecosystem service functions in the Guangxi Zhuang Autonomous Region (Guangxi). Then, it explores the spatio-temporal evolution features of land use transition by using land use change matrices, examines landscape patterns by using the landscape pattern index, and studies ecosystem service value (ESV) by revising the coefficients of ESV per unit area. Finally, focus is placed on the empirical analysis of ESV responses to landscape pattern evolution caused by land use transitions in Guangxi. The results show that: (1) Guangxi has undergone an overall intensity-changing process of land use transition at a moderate rate during 1990–2010 and at a drastic rate during 2010–2018. In general, the area of construction land and waterbodies has increased, while forested land, grassland and farmland have decreased. Landscape fragmentation and heterogeneity are higher in the central area than that in the surrounding areas, while patch aggregation and connectivity show an opposite trend. Forested land patches are highly clustered, while grassland and farmland are fragmented and scattered and construction land patches tend to have aggregated. (2) The total loss of ESV has reached 20.56 billion RMB in Guangxi, and all areas’ single ESVs have decreased to different degrees during the past 28 years. Spatially, the ESV distribution shows a differentiated pattern of low in the central plain and high in the surrounding mountain regions which are mainly dominated by high-value zones. (3) The total ESV has significant positive correlations with the largest patch index (LPI), COHESION and the Aggregation Index (AI), and significant negative correlations with the Number of Patches (NP) and the Shannon Diversity Index (SHDI), while the correlation with the Landscape Shape Index (LSI) is not significant, indicating that the influence on ESV caused by landscape pattern evolution varies greatly. (4) The change of land area and multi-directional shifts among different land use types caused by land use transitions in Guangxi could both lead to the evolution of landscape patterns. Further, ecological service function responded obviously to the landscape pattern evolution in Guangxi, causing significant changes in strengthening or weakening of the ecological service function and its value. This systematic analysis should help coordinate the relationship of regional land use regulation, landscape pattern optimization and ecosystem operation in Guangxi or even China.
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Henkin, Zalmen, No'am G. Seligman i Imanuel Noy-Meir. "Successional Transitions and Management of a Phosphorus-Limited Shrubland Ecosystem". Rangeland Ecology & Management 60, nr 5 (wrzesień 2007): 453–63. http://dx.doi.org/10.2111/1551-5028(2007)60[453:stamoa]2.0.co;2.
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Manies, Kristen L., Jennifer W. Harden, Christopher C. Fuller i Merritt R. Turetsky. "Decadal and long-term boreal soil carbon and nitrogen sequestration rates across a variety of ecosystems". Biogeosciences 13, nr 15 (1.08.2016): 4315–27. http://dx.doi.org/10.5194/bg-13-4315-2016.
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Abstract. Boreal soils play a critical role in the global carbon (C) cycle; therefore, it is important to understand the mechanisms that control soil C accumulation and loss for this region. Examining C & nitrogen (N) accumulation rates over decades to centuries may provide additional understanding of the dominant mechanisms for their storage, which can be masked by seasonal and interannual variability when investigated over the short term. We examined longer-term accumulation rates, using 210Pb and 14C to date soil layers, for a wide variety of boreal ecosystems: a black spruce forest, a shrub ecosystem, a tussock grass ecosystem, a sedge-dominated ecosystem, and a rich fen. All ecosystems had similar decadal C accumulation rates, averaging 84 ± 42 gC m−2 yr−1. Long-term (century) C accumulation rates were slower than decadal rates, averaging 14 ± 5 gC m−2 yr−1 for all ecosystems except the rich fen, for which the long-term C accumulation rates was more similar to decadal rates (44 ± 5 and 76 ± 9 gC m−2 yr−1, respectively). The rich fen also had the highest long-term N accumulation rates (2.7 gN m−2 yr−1). The lowest N accumulation rate, on both a decadal and long-term basis, was found in the black spruce forest (0.2 and 1.4 gN m−2 yr−1, respectively). Our results suggest that the controls on long-term C and N cycling at the rich fen is fundamentally different from the other ecosystems, likely due to differences in the predominant drivers of nutrient cycling (oxygen availability, for C) and reduced amounts of disturbance by fire (for C and N). This result implies that most shifts in ecosystem vegetation across the boreal region, driven by either climate or succession, will not significantly impact regional C or N dynamics over years to decades. However, ecosystem transitions to or from a rich fen will promote significant shifts in soil C and N storage.
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Siegel, Shepherd. "The Career Ladder Program: Implementing Re-ED Principles in Vocational Settings". Behavioral Disorders 14, nr 1 (listopad 1988): 16–26. http://dx.doi.org/10.1177/019874298801400105.
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Youths in transition and in programs which address special needs such as mild handicaps and emotional disturbance are often the defining members of a discordant ecosystem. Employment and employer behavior play a crucial role in any successful transition from school to independent adult life. The Career Ladder Program utilizes principles from Re-ED such as team building, affective education, ecosystematic intervention, and long-range enablement planning to address the issues faced by these young people and to facilitate successful transitions. This article outlines some of the relevant principles, dynamics of the transition experience, and examples of how the principles are actually applied.
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Bury, T. M., C. T. Bauch i M. Anand. "Detecting and distinguishing tipping points using spectral early warning signals". Journal of The Royal Society Interface 17, nr 170 (wrzesień 2020): 20200482. http://dx.doi.org/10.1098/rsif.2020.0482.
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Theory and observation tell us that many complex systems exhibit tipping points—thresholds involving an abrupt and irreversible transition to a contrasting dynamical regime. Such events are commonly referred to as critical transitions. Current research seeks to develop early warning signals (EWS) of critical transitions that could help prevent undesirable events such as ecosystem collapse. However, conventional EWS do not indicate the type of transition, since they are based on the generic phenomena of critical slowing down. For instance, they may fail to distinguish the onset of oscillations (e.g. Hopf bifurcation) from a transition to a distant attractor (e.g. Fold bifurcation). Moreover, conventional EWS are less reliable in systems with density-dependent noise. Other EWS based on the power spectrum (spectral EWS) have been proposed, but they rely upon spectral reddening, which does not occur prior to critical transitions with an oscillatory component. Here, we use Ornstein–Uhlenbeck theory to derive analytic approximations for EWS prior to each type of local bifurcation, thereby creating new spectral EWS that provide greater sensitivity to transition proximity; higher robustness to density-dependent noise and bifurcation type; and clues to the type of approaching transition. We demonstrate the advantage of applying these spectral EWS in concert with conventional EWS using a population model, and show that they provide a characteristic signal prior to two different Hopf bifurcations in data from a predator–prey chemostat experiment. The ability to better infer and differentiate the nature of upcoming transitions in complex systems will help humanity manage critical transitions in the Anthropocene Era.
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Kumar, Dushyant, Mirjam Pfeiffer, Camille Gaillard, Liam Langan i Simon Scheiter. "Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia". Biogeosciences 18, nr 9 (17.05.2021): 2957–79. http://dx.doi.org/10.5194/bg-18-2957-2021.
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Abstract. South Asian vegetation provides essential ecosystem services to the 1.7 billion inhabitants living in the region. However, biodiversity and ecosystem services are threatened by climate and land-use change. Understanding and assessing how ecosystems respond to simultaneous increases in atmospheric CO2 and future climate change is of vital importance to avoid undesired ecosystem change. Failed reaction to increasing CO2 and climate change will likely have severe consequences for biodiversity and humankind. Here, we used the adaptive dynamic global vegetation model version 2 (aDGVM2) to simulate vegetation dynamics in South Asia under RCP4.5 and RCP8.5, and we explored how the presence or absence of CO2 fertilization influences vegetation responses to climate change. Simulated vegetation under both representative concentration pathways (RCPs) without CO2 fertilization effects showed a decrease in tree dominance and biomass, whereas simulations with CO2 fertilization showed an increase in biomass, canopy cover, and tree height and a decrease in biome-specific evapotranspiration by the end of the 21st century. The predicted changes in aboveground biomass and canopy cover triggered transition towards tree-dominated biomes. We found that savanna regions are at high risk of woody encroachment and transitioning into forest. We also found transitions of deciduous forest to evergreen forest in the mountain regions. Vegetation types using C3 photosynthetic pathway were not saturated at current CO2 concentrations, and the model simulated a strong CO2 fertilization effect with the rising CO2. Hence, vegetation in the region has the potential to remain a carbon sink. Projections showed that the bioclimatic envelopes of biomes need adjustments to account for shifts caused by climate change and elevated CO2. The results of our study help to understand the regional climate–vegetation interactions and can support the development of regional strategies to preserve ecosystem services and biodiversity under elevated CO2 and climate change.
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Mascareño, Aldo. "Close to the Edge: From Crisis To Critical Transitions in Social Systems Theory". Soziale Systeme 25, nr 2 (22.11.2022): 251–76. http://dx.doi.org/10.1515/sosys-2020-0026.
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Abstract Niklas Luhmann has considered the concept of crisis as a negative self-description of modern society. However, in different argumentative contexts, he uses the concept to refer to operative processes in and between partial systems that were not further developed, such as interruption of systemic relations, crisis threshold, and rapid transitions. Drawing on theoretical analyses and empirical research, I argue that the theory of critical transitions developed in ecosystem research offers a conceptual horizon from which to obtain insights to understand and explain sudden changes in modern society. To this extent, I propose a mechanism of critical transitions in meaning-based social systems and discuss its components in light of the related literature. I conclude that, while preserving the concept of crisis as a negative self-description, that of critical transition is more adequate to address the factual, temporal, and social operations producing sudden shifts in complex social systems.
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Gallagher, Brian K., i David H. Secor. "Intensified environmental and density-dependent regulation of white perch recruitment after an ecosystem shift in the Hudson River Estuary". Canadian Journal of Fisheries and Aquatic Sciences 75, nr 1 (styczeń 2018): 36–46. http://dx.doi.org/10.1139/cjfas-2016-0455.
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Long-term monitoring data were used to test whether the invasion of zebra mussels (Dreissena polymorpha) in the Hudson River Estuary in 1991 altered the influence of density dependence and environmental conditions on life-stage transitions, growth, and partial migration in white perch (Morone americana). During the post-invasion period (1992–2013), we estimated standing stocks of white perch eggs, yolk-sac larvae (YSL), post-yolk-sac larvae (PYSL), young-of-the-year (YOY), and adults as well as indices of YOY growth and spatial distribution. A series of linear and nonlinear functions were employed to model life-stage transitions, while the effects of six environmental and density-dependent variables on YOY growth and partial migration were quantified. Comparisons to pre-invasion observations (1974–1991) indicated that egg–YSL, PYSL–YOY, and YOY–yearling transitions changed significantly after the invasion, while PYSL abundance developed a stronger negative effect on YOY growth. The PYSL–YOY transition became more sensitive to density dependence and freshwater flow from 1992 to 2013, which is consistent with diminished abundance and increased environmental sensitivity of the forage base in the Hudson River Estuary reported after the zebra mussel invasion.
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Giagnocavo, Cynthia, Miguel de Cara-García, Mónica González, Melchor Juan, José Ignacio Marín-Guirao, Sepide Mehrabi, Estefanía Rodríguez, Jan van der Blom i Eduardo Crisol-Martínez. "Reconnecting Farmers with Nature through Agroecological Transitions: Interacting Niches and Experimentation and the Role of Agricultural Knowledge and Innovation Systems". Agriculture 12, nr 2 (20.01.2022): 137. http://dx.doi.org/10.3390/agriculture12020137.
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Sustainability transitions in agriculture are explored through an analysis of niche initiatives within a common production system, relying on sustainable transitions, multi-level perspectives, and agroecological frameworks, and involving multi-actor, agricultural knowledge, and innovation systems (AKIS). The article focuses on how experimental niches and sustainable activities affect farmers’ relationships with nature, and the reconceptualisation of the production system in which they operate, particularly where this system is embedded in less sustainable conventional or dominant regimes and landscapes. The need for fundamental changes, in the way that humans interact with nature, is widely argued for in order to achieve sustainable development, and farmers occupy a central role through participation in complex networks of agri-food systems. They have also found themselves disconnected from nature through conventional agri-industrial production practices. Four niches (biological control, ecological restoration, soil health, and ecological pond management) within the greenhouse sector of Almeria (SE Spain) are explored in a case study. Our results indicate that a farmer’s interaction with nature is functional, but through agroecological practices, a deeper understanding of the ecosystems in which greenhouse landscapes are embedded may be gained. As they become more connected to nature and benefit from ecosystem services, they can transition to more sustainable agricultural systems.
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Vandermeer, John, i Ivette Perfecto. "Hysteresis and critical transitions in a coffee agroecosystem". Proceedings of the National Academy of Sciences 116, nr 30 (9.07.2019): 15074–79. http://dx.doi.org/10.1073/pnas.1902773116.
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Seeking to employ ecological principles in agricultural management, a classical ecological debate provides a useful framing. Whether ecosystems are controlled from above (predators are the limiting force over herbivores) or from below (overutilization of plant resources is the limiting force over herbivores) is a debate that has motivated much research. The dichotomous nature of the debate (above or below) has been criticized as too limiting, especially in light of contemporary appreciation of ecological complexity—control is more likely from a panoply of direct and indirect interactions. In the context of the agroecosystem, regulation is assumed to be from above and pests are controlled, a way of using ecological insights in service of an essential ecosystem service—pest control. However, this obvious resolution of the old debate does not negate the deeper appreciation of complexity—the natural enemies themselves constitute a complex system. Here we use some key concepts from complexity science to interrogate the natural functioning of pest regulation through spatially explicit dynamics of a predator and a disease operating simultaneously but distributed in space. Using the green coffee scale insect as a focal species, we argue that certain key ideas of complexity science shed light on how that system operates. In particular, a hysteretic pattern associated with distance to a keystone ant is evident.
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Piayda, Arndt, Maren Dubbert, Rolf Siegwolf, Matthias Cuntz i Christiane Werner. "Quantification of dynamic soil–vegetation feedbacks following an isotopically labelled precipitation pulse". Biogeosciences 14, nr 9 (5.05.2017): 2293–306. http://dx.doi.org/10.5194/bg-14-2293-2017.
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Abstract. The presence of vegetation alters hydrological cycles of ecosystems. Complex plant–soil interactions govern the fate of precipitation input and water transitions through ecosystem compartments. Disentangling these interactions is a major challenge in the field of ecohydrology and a pivotal foundation for understanding the carbon cycle of semi-arid ecosystems. Stable water isotopes can be used in this context as tracer to quantify water movement through soil–vegetation–atmosphere interfaces. The aim of this study is to disentangle vegetation effects on soil water infiltration and distribution as well as dynamics of soil evaporation and grassland water use in a Mediterranean cork oak woodland during dry conditions. An irrigation experiment using δ18O labelled water was carried out in order to quantify distinct effects of tree and herbaceous vegetation on the infiltration and distribution of event water in the soil profile. Dynamic responses of soil and herbaceous vegetation fluxes to precipitation regarding event water use, water uptake depth plasticity, and contribution to ecosystem soil evaporation and transpiration were quantified. Total water loss to the atmosphere from bare soil was as high as from vegetated soil, utilizing large amounts of unproductive evaporation for transpiration, but infiltration rates decreased. No adjustments of main root water uptake depth to changes in water availability could be observed during the experiment. This forces understorey plants to compete with adjacent trees for water in deeper soil layers at the onset of summer. Thus, understorey plants are subjected to chronic water deficits faster, leading to premature senescence at the onset of drought. Despite this water competition, the presence of cork oak trees fosters infiltration and reduces evapotranspirative water losses from the understorey and the soil, both due to altered microclimatic conditions under crown shading. This study highlights complex soil–plant–atmosphere and inter-species interactions controlling rain pulse transitions through a typical Mediterranean savannah ecosystem, disentangled by the use of stable water isotopes.
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Richardson, Andrew D., T. Andy Black, Philippe Ciais, Nicolas Delbart, Mark A. Friedl, Nadine Gobron, David Y. Hollinger i in. "Influence of spring and autumn phenological transitions on forest ecosystem productivity". Philosophical Transactions of the Royal Society B: Biological Sciences 365, nr 1555 (12.10.2010): 3227–46. http://dx.doi.org/10.1098/rstb.2010.0102.
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We use eddy covariance measurements of net ecosystem productivity (NEP) from 21 FLUXNET sites (153 site-years of data) to investigate relationships between phenology and productivity (in terms of both NEP and gross ecosystem photosynthesis, GEP) in temperate and boreal forests. Results are used to evaluate the plausibility of four different conceptual models. Phenological indicators were derived from the eddy covariance time series, and from remote sensing and models. We examine spatial patterns (across sites) and temporal patterns (across years); an important conclusion is that it is likely that neither of these accurately represents how productivity will respond to future phenological shifts resulting from ongoing climate change. In spring and autumn, increased GEP resulting from an ‘extra’ day tends to be offset by concurrent, but smaller, increases in ecosystem respiration, and thus the effect on NEP is still positive. Spring productivity anomalies appear to have carry-over effects that translate to productivity anomalies in the following autumn, but it is not clear that these result directly from phenological anomalies. Finally, the productivity of evergreen needleleaf forests is less sensitive to phenology than is productivity of deciduous broadleaf forests. This has implications for how climate change may drive shifts in competition within mixed-species stands.