I urval från Stockholms universitets publikationsdatabas

• Amplitude and timescale of metacommunity trait-lag response to climate change

  Jon Norberg, Helen Moor.

  Climate change is altering the structure and functioning of communities. Trait-based approaches are powerful predictive tools that allow consideration of changes in structure and functioning simultaneously. The realised biomass-weighted trait distribution of a community rests on the ecophysiology of individuals, but integrates local species interactions and spatial dynamics that feed back to ecosystem functioning. Consider a response trait that determines species performance (e.g. growth rate) as a function of an environmental variable (e.g. temperature). The change in this response trait's distribution following directional environmental change integrates all factors contributing to the community's response and directly reflects the community's response capacity.

  Here we introduce the average regional community trait-lag (TL_MC) as a novel measure of whole-metacommunity response to warming. We show that functional compensation (shifts in resident species relative abundances) confers initial response capacity to communities by reducing and delaying the initial development of a trait-lag. Metacommunity adaptive capacity in the long-term, however, was dependent on dispersal and species tracking of their climate niche by incremental traversal of the landscape. With increasing inter-patch distances, network properties of the functional connectivity network became increasingly more important, and may guide prioritisation of habitat for conservation.

  Läs mer om Amplitude and timescale of metacommunity trait-lag response to climate change

• Towards a trait-based ecology of wetland vegetation

  Helen Moor (et al.).

  1. Functional traits mechanistically capture plant responses to environmental gradients as well as plant effects on ecosystem functioning. Yet most trait-based theory stems from terrestrial systems and extension to other habitats can provide new insights.

  2. Wetlands differ from terrestrial systems in conditions (e.g. soil water saturation, anoxia, pH extremes), plant adaptations (e.g. aerenchyma, clonality, ubiquity of bryophytes) and important processes (e.g. denitrification, peat accumulation, methane emission). Wetland plant adaptations and trait (co-)variation can be situated along major plant trait trade-off axes (e.g. the resource economics spectrum), but soil saturation represents a complex stress gradient beyond a simple extension of commonly studied water availability gradients.

  3. Traits that affect ecosystem functioning overlap with patterns in terrestrial systems. But wetland-specific traits that mediate plant effects on soil redox conditions, microbial communities and on water flow, as well as trait spectra of mosses, vary among wetland types.

  4. Synthesis: With increasing availability of quantitative plant traits a trait-based ecology of wetlands is emerging, with the potential to advance process-based understanding and prediction. We provide an interactive cause-and-effect framework that may guide research efforts to disentangle the multiple interacting processes involved in scaling from environmental conditions to ecosystem functioning via plant communities. 

  Läs mer om Towards a trait-based ecology of wetland vegetation

• Ecological Memory of Historical Contamination Influences the Response of Phytoplankton Communities

  2021. Didier L. Baho (et al.). Ecosystems (New York. Print) 24 (7), 1591-1607

  Artikel

  Ecological memory (EM) recognizes the importance of previous stress encounters in promoting community tolerance and thereby enhances ecosystem stability, provided that gained tolerances are preserved during non-stress periods. Drawing from this concept, we hypothesized that the recruitment of tolerant species can be facilitated by imposing an initial sorting process (conditioning) during the early stages of community assembly, which should result in higher production (biomass development and photosynthetic efficiency) and stable community composition. To test this, phytoplankton resting stages were germinated from lake sediments originating from two catchments that differed in contamination history: one impacted by long-term herbicides and pesticides exposures (historically contaminated lake) from an agricultural catchment compared to a low-impacted one (near-pristine lake) from a forested catchment. Conditioning was achieved by adding an herbicide (Isoproturon, which was commonly used in the catchment of the historically contaminated lake) during germination. Afterward, the communities obtained from germination were exposed to an increasing gradient of Isoproturon. As hypothesized, upon conditioning, the phytoplankton assemblages from the historically contaminated lake were able to rapidly restore photosynthetic efficiency (p > 0.01) and became structurally (community composition) more resistant to Isoproturon. The communities of the near-pristine lake did not yield these positive effects regardless of conditioning, supporting that EM was a unique attribute of the historically stressed ecosystem. Moreover, assemblages that displayed higher structural resistance concurrently yielded lower biomass, indicating that benefits of EM in increasing structural stability may trade-off with production. Our results clearly indicate that EM can foster ecosystem stability to a recurring stressor.

  Läs mer om Ecological Memory of Historical Contamination Influences the Response of Phytoplankton Communities

• The importance of species interactions in eco-evolutionary community dynamics under climate change

  2021. Anna Åkesson (et al.). Nature Communications 12 (1)

  Artikel

  Eco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species' interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes. Understanding the dynamics of species interactions can help predict community responses to climate change. A spatially explicit model finds that species interactions and competition mitigate the harmful impacts of climate change, and that temperature-dependent competition makes communities more variable and responsive to changing climates.

  Läs mer om The importance of species interactions in eco-evolutionary community dynamics under climate change

• A more dynamic understanding of human behaviour for the Anthropocene

  2019. Caroline Schill (et al.). Nature Sustainability 2 (12), 1075-1082

  Artikel

  Human behaviour is of profound significance in shaping pathways towards sustainability. Yet, the approach to understanding human behaviour in many fields remains reliant on overly simplistic models. For a better understanding of the interface between human behaviour and sustainability, we take work in behavioural economics and cognitive psychology as a starting point, but argue for an expansion of this work by adopting a more dynamic and systemic understanding of human behaviour, that is, as part of complex adaptive systems. A complex adaptive systems approach allows us to capture behaviour as ''enculturated' and 'enearthed', co-evolving with socio-cultural and biophysical contexts. Connecting human behaviour and context through a complex adaptive systems lens is critical to inform environmental governance and management for sustainability, and ultimately to better understand the dynamics of the Anthropocene itself.

  Läs mer om A more dynamic understanding of human behaviour for the Anthropocene

• A single pulse of diffuse contaminants alters the size distribution of natural phytoplankton communities

  2019. Didier L. Baho (et al.). Science of the Total Environment 683, 578-588

  Artikel

  The presence of a multitude of bioactive organic pollutants collectively classified as pharmaceuticals and personal care products (PPCPs) in freshwaters is of concern, considering that ecological assessments of their potential impacts on natural systems are still scarce. In this field experiment we tested whether a single pulse exposure to a mixture of 12 pharmaceuticals and personal care products, which are commonly found in European inland waters, can influence the size distributions of natural lake phytoplankton communities. Size is one of the most influential determinants of community structure and functioning, particularly in planktonic communities and food webs. Using an in-situ microcosm approach, phytoplankton communities in two lakes with different nutrient levels (mesotrophic and eutrophic) were exposed to a concentration gradient of the PPCPs mixture at five levels. We tested whether sub-lethal PPCPs doses affect the scaling of organisms' abundances with their size, and the slope of these size spectra, which describe changes in the abundances of small relative to large phytoplankton. Our results showed that a large proportion (approximately 80%) of the dataset followed a power-law distribution, thus suggesting evidence of scale invariance of abundances, as expected in steady state ecosystems. PPCPs were however found to induce significant changes in the size spectra and community structure of natural phytoplankton assemblages. The two highest treatment levels of PPCPs were associated with decreased abundance of the most dominant size class (nano-phytoplankton: 2-5 mu m), leading to a flattening of the size spectra slope. These results suggest that a pulse exposure to PPCPs induce changes that potentially lead to unsteady ecosystem states and cascading effects in the aquatic food webs, by favoring larger non-edible algae at the expense of small edible species. We propose higher susceptibility due to higher surface to volume ratio in small species as the likely cause of these structural changes.

  Läs mer om A single pulse of diffuse contaminants alters the size distribution of natural phytoplankton communities

• Ecosystem tipping points in an evolving world

  2019. Vasilis Dakos (et al.). Nature Ecology & Evolution 3 (3), 355-362

  Artikel

  There is growing concern over tipping points arising in ecosystems because of the crossing of environmental thresholds. Tipping points lead to abrupt and possibly irreversible shifts between alternative ecosystem states, potentially incurring high societal costs. Trait variation in populations is central to the biotic feedbacks that maintain alternative ecosystem states, as they govern the responses of populations to environmental change that could stabilize or destabilize ecosystem states. However, we know little about how evolutionary changes in trait distributions over time affect the occurrence of tipping points and even less about how big-scale ecological shifts reciprocally interact with trait dynamics. We argue that interactions between ecological and evolutionary processes should be taken into account in order to understand the balance of feedbacks governing tipping points in nature.

  Läs mer om Ecosystem tipping points in an evolving world

• Resilience of Natural Phytoplankton Communities to Pulse Disturbances from Micropollutant Exposure and Vertical Mixing

  2019. Didier L. Baho (et al.). Environmental Toxicology and Chemistry 38 (10), 2197-2208

  Artikel

  Freshwaters are increasingly exposed to complex mixtures of pharmaceutical and personal care products (PPCPs) from municipal wastewater, which are known to alter freshwater communities' structure and functioning. However, their interaction with other disturbances and whether their combined effects can impact ecological resilience (i.e., the ability of a system to tolerate disturbances without altering the system's original structure and processes) remain unexplored. Using in situ mesocosms in 2 lakes with different nutrient levels (mesotrophic and eutrophic), we assessed whether a pulse exposure to sublethal concentrations of 12 PPCPs affects the ecological resilience of natural phytoplankton communities that experienced an abrupt environmental change involving the destabilization of the water column through mixing. Such mixing events are predicted to increase as the effects of climate change unfold, leading to more frequent storms, which disrupt stratification in lakes and force communities to restructure. We assessed their combined effects on community metrics (biomass, species richness, and composition) and their relative resilience using 4 indicators (cross-scale, within-scale, aggregation length, and gap length), inferred from phytoplankton communities by discontinuity analysis. The mixing disturbance alone had negligible effects on the community metrics, but when combined with chemical contaminants significant changes were measured: reducing total biomass, species richness, and altered community composition of phytoplankton. Once these changes occurred, they persisted until the end of the experiment (day 20), when the communities' structures from the 2 highest exposure levels diverged from the controls. The resilience indicators were not affected by PPCPs but differed significantly between lakes, with lower resilience found in the eutrophic lake. Thus, PPCPs can significantly alter community structures and reinforce mechanisms that maintain ecosystems in a degraded state.

  Läs mer om Resilience of Natural Phytoplankton Communities to Pulse Disturbances from Micropollutant Exposure and Vertical Mixing

• Scaling functional traits to ecosystem processes

  2019. Adriano Mazziotta (et al.). Journal of Ecology 107 (2), 843-859

  Artikel

  The role of trait trade-offs and environmental filtering in explaining the variability in functional traits and ecosystem processes has received considerable attention for vascular plants but less so for bryophytes. Thus, we do not know whether the same forces also shape the phenotypic variability of bryophytes. Here, we assess how environmental gradients and trade-offs shape functional traits and subsequently ecosystem processes for peat mosses (Sphagnum), a globally important plant genus for carbon accumulation. We used piecewise Structural Equation Modeling (SEM) to understand how environmental gradients influence vital processes across levels of biological organization. We gathered data on functional traits for 15 globally important Sphagnum species covering a wide range of ecological preferences. Phenotypes lie along well-established axes of the plant economic spectrum characterizing trade-offs between vital physiological functions. Using SEM, we clarified the mechanisms of trait covariation and scaling to ecosystem processes. We tested whether peat mosses, like vascular plants, constrain trait variability between a fast turnover strategy based on resource acquisition via fast traits and processes, and a strategy of resource conservation, via slow traits and processes. We parameterized a process-based model estimating ecosystem processes linking environmental drivers with architectural and functional traits. In our SEM approach the amount of variance explained varied substantially (0.29 <= R-2 <= 0.82) among traits and processes in Sphagnum, and the model could predict some of them with high to intermediate accuracy for an independent dataset. R-2 variability was mainly explained by traits and species identity, and poorly by environmental filtering. Some Sphagnum species avoid the stress caused by periodic desiccation in hollows via resource acquisition based on fast photosynthesis and growth, while other species are adapted to grow high above the water-table on hummocks by slow physiological traits and processes to conserve resources. Synthesis.We contribute to a unified theory generating individual fitness, canopy dynamics and ecosystem processes from trait variation. As for vascular plants, the functional traits in the Sphagnum economic spectrum are linked into an integrated phenotypic network partly filtered by the environment and shaped by trade-offs in resource acquisition and conservation.

  Läs mer om Scaling functional traits to ecosystem processes

• Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

  2018. Steven J. Lade (et al.). Earth System Dynamics 9 (2), 507-523

  Artikel

  Changes to climate-carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate-carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate-carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate-carbon feedback; and concentration-carbon feedbacks may be more sensitive to future climate change than climate-carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

  Läs mer om Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

• Strategies for sustainable management of renewable resources during environmental change

  2017. Emilie Lindkvist, Örjan Ekeberg, Jon Norberg. Proceedings of the Royal Society of London. Biological Sciences 284 (1850)

  Artikel

  As a consequence of global environmental change, management strategies that can deal with unexpected change in resource dynamics are becoming increasingly important. In this paper we undertake a novel approach to studying resource growth problems using a computational form of adaptive management to find optimal strategies for prevalent natural resource management dilemmas. We scrutinize adaptive management, or learning-by-doing, to better understand how to simultaneously manage and learn about a system when its dynamics are unknown. We study important trade-offs in decision-making with respect to choosing optimal actions (harvest efforts) for sustainable management during change. This is operationalized through an artificially intelligent model where we analyze how different trends and fluctuations in growth rates of a renewable resource affect the performance of different management strategies. Our results show that the optimal strategy for managing resources with declining growth is capable of managing resources with fluctuating or increasing growth at a negligible cost, creating in a management strategy that is both efficient and robust towards future unknown changes. To obtain this strategy, adaptive management should strive for: high learning rates to new knowledge, high valuation of future outcomes and modest exploration around what is perceived as the optimal action.

  Läs mer om Strategies for sustainable management of renewable resources during environmental change

• Towards a trait-based ecology of wetland vegetation

  2017. Helen Moor (et al.). Journal of Ecology 105 (6), 1623-1635

  Artikel

  1. Functional traits mechanistically capture plant responses to environmental gradients as well as plant effects on ecosystem functioning. Yet most trait-based theory stems from terrestrial systems and extension to other habitats can provide new insights. 2. Wetlands differ from terrestrial systems in conditions (e.g. soil water saturation, anoxia, pH extremes), plant adaptations (e.g. aerenchyma, clonality, ubiquity of bryophytes) and important processes (e.g. denitrification, peat accumulation, methane emission). Wetland plant adaptations and trait (co-)variation can be situated along major plant trait trade-off axes (e.g. the resource economics spectrum), but soil saturation represents a complex stress gradient beyond a simple extension of commonly studied water availability gradients. 3. Traits that affect ecosystem functioning overlap with patterns in terrestrial systems. But wetland-specific traits that mediate plant effects on soil redox conditions, microbial communities and on water flow, as well as trait spectra of mosses, vary among wetland types. 4. Synthesis. With increasing availability of quantitative plant traits a trait-based ecology of wetlands is emerging, with the potential to advance process-based understanding and prediction. We provide an interactive cause-and-effect framework that may guide research efforts to disentangle the multiple interacting processes involved in scaling from environmental conditions to ecosystem functioning via plant communities.

  Läs mer om Towards a trait-based ecology of wetland vegetation

• Mapping bundles of ecosystem services reveals distinct types of multifunctionality within a Swedish landscape

  2015. Cibele Queiroz (et al.). Ambio 44, s89-S101

  Artikel

  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 Norrstrom 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.

  Läs mer om Mapping bundles of ecosystem services reveals distinct types of multifunctionality within a Swedish landscape

• Predicting climate change effects on wetland ecosystem services using species distribution modeling and plant functional traits

  2015. Helen Moor, Kristoffer Hylander, Jon Norberg. Ambio 44, 113-126

  Artikel

  Wetlands provide multiple ecosystem services, the sustainable use of which requires knowledge of the underlying ecological mechanisms. Functional traits, particularly the community-weighted mean trait (CWMT), provide a strong link between species communities and ecosystem functioning. We here combine species distribution modeling and plant functional traits to estimate the direction of change of ecosystem processes under climate change. We model changes in CWMT values for traits relevant to three key services, focusing on the regional species pool in the Norrstrom area (central Sweden) and three main wetland types. Our method predicts proportional shifts toward faster growing, more productive and taller species, which tend to increase CWMT values of specific leaf area and canopy height, whereas changes in root depth vary. The predicted changes in CWMT values suggest a potential increase in flood attenuation services, a potential increase in short (but not long)-term nutrient retention, and ambiguous outcomes for carbon sequestration.

  Läs mer om Predicting climate change effects on wetland ecosystem services using species distribution modeling and plant functional traits

• Diatom Cell Size, Coloniality and Motility

  2014. Filip Svensson, Jon Norberg, Pauline Snoeijs. PLOS ONE 9 (10)

  Artikel

  Reduction in body size has been proposed as a universal response of organisms, both to warming and to decreased salinity. However, it is still controversial if size reduction is caused by temperature or salinity on their own, or if other factors interfere as well. We used natural benthic diatom communities to explore how body size'' (cells and colonies) and motility change along temperature (2-26 degrees C) and salinity (0.5-7.8) gradients in the brackish Baltic Sea. Fourth-corner analysis confirmed that small cell and colony sizes were associated with high temperature in summer. Average community cell volume decreased linearly with 2.2% per degrees C. However, cells were larger with artificial warming when nutrient concentrations were high in the cold season. Average community cell volume increased by 5.2% per degrees C of artificial warming from 0 to 8.5 degrees C and simultaneously there was a selection for motility, which probably helped to optimize growth rates by trade-offs between nutrient supply and irradiation. Along the Baltic Sea salinity gradient cell size decreased with decreasing salinity, apparently mediated by nutrient stoichiometry. Altogether, our results suggest that climate change in this century may polarize seasonality by creating two new niches, with elevated temperature at high nutrient concentrations in the cold season (increasing cell size) and elevated temperature at low nutrient concentrations in the warm season (decreasing cell size). Higher temperature in summer and lower salinity by increased land-runoff are expected to decrease the average cell size of primary producers, which is likely to affect the transfer of energy to higher trophic levels.

  Läs mer om Diatom Cell Size, Coloniality and Motility

• Modeling experiential learning

  2014. Emilie Lindkvist, Jon Norberg. Ecological Economics 104, 107-118

  Artikel

  Adaptive management incorporates learning-by-doing (LBD) in order to capture learning and knowledge generation processes, crucial for sustainable resource use in the presence of uncertainty and environmental change. By contrast, an optimization approach to management identifies the most efficient exploitation strategy by postulating an absolute understanding of the resource dynamics and its inherent uncertainties. Here, we study the potential and limitations of LBD in achieving optimal management by undertaking an analysis using a simple growth model as a benchmark for evaluating the performance of an agent equipped with a 'state-of-the-art' learning algorithm. The agent possesses no a priori knowledge about the resource dynamics, and learns management solely by resource interaction. We show that for a logistic growth function the agent can achieve 90% efficiency compared to the optimal control solution, whereas when a threshold (tipping point) is introduced, efficiency drops to 65%. Thus, our study supports the effectiveness of the LED approach. However, when a threshold is introduced efficiency decreases as experimentation may cause resource collapse. Further, the study proposes that: an appropriate amount of experimentation, high valuation of future stocks (discounting) and, a modest rate of adapting to new knowledge, will likely enhance the effectiveness of LBD as a management strategy.

  Läs mer om Modeling experiential learning

• Social-ecological systems as complex adaptive systems

  2013. Ann-Sophie Crépin (et al.). Environment and Development Economics 18 (2), 111-132

  Artikel

  Systems linking people and nature, known as social-ecological systems, are increasingly understood as complex adaptive systems. Essential features of these complex adaptive systems – such as nonlinear feedbacks, strategic interactions, individual and spatial heterogeneity, and varying time scales – pose substantial challenges for modeling. However, ignoring these characteristics can distort our picture of how these systems work, causing policies to be less effective or even counterproductive. In this paper we present recent developments in modeling social-ecological systems, illustrate some of these challenges with examples related to coral reefs and grasslands, and identify the implications for economic and policy analysis.

  Läs mer om Social-ecological systems as complex adaptive systems

• Eco-evolutionary responses of biodiversity to climate change

  2012. Jon Norberg (et al.). Nature Climate Change 2 (10), 747-751

  Artikel

  Climate change is predicted to alter global species diversity(1), the distribution of human pathogens' and ecosystem services(3). Forecasting these changes and designing adequate management of future ecosystem services will require predictive models encompassing the most fundamental biotic responses. However, most present models omit important processes such as evolution and competition(4,5). Here we develop a spatially explicit eco-evolutionary model of multi-species responses to climate change. We demonstrate that both dispersal and evolution differentially mediate extinction risks and biodiversity alterations through time and across climate gradients. Together, high genetic variance and low dispersal best minimized extinction risks. Surprisingly, high dispersal did not reduce extinctions, because the shifting ranges of some species hastened the decline of others. Evolutionary responses dominated during the later stages of climatic changes and in hot regions. No extinctions occurred without competition, which highlights the importance of including species interactions in global biodiversity models. Most notably, climate change created extinction and evolutionary debts, with changes in species richness and traits occuring long after climate stabilization. Therefore, even if we halt anthropogenic climate change today, transient eco-evolutionary dynamics would ensure centuries of additional alterations in global biodiversity.

  Läs mer om Eco-evolutionary responses of biodiversity to climate change

• Coupled economic-ecological systems with slow and fast dynamics - Modelling and analysis method

  2011. Anne-Sophie Crépin, Jon Norberg, Karl-Göran Maler. Ecological Economics 70 (8), 1448-1458

  Artikel

  The purpose of this article is to contribute to the exploration of non-convex dynamics in coupled human-nature systems. We study welfare issues associated with the management of a human-nature complex adaptive system with a threshold and a stochastic driver. We exemplify with a specific system where we link changes in the number and diversity of birds to the abundance of a pest (insects) that causes damages to goods and services valuable to human beings. We present a method that simplifies the analysis and helps us discuss different management models that combine direct and indirect controls of the pest. This allows us to show that 1) the choice of control method depends in a highly non-linear way on biodiversity characteristics and 2) the socially optimal outcome may not be reachable using price instruments. Hence the price vs. quantity debate needs to be revisited using a complex adaptive system lens.

  Läs mer om Coupled economic-ecological systems with slow and fast dynamics - Modelling and analysis method

• A general mulit-trait-based framework for studying the effects of biodiversity on ecosystem functioning

  2007. VM Savage, CT Webb, Jon Norberg. Journal of theoretical biology 247 (2), 213-229

  Artikel

  Läs mer om A general mulit-trait-based framework for studying the effects of biodiversity on ecosystem functioning

• A network approach for analyzing spatially structured populations in fragmented landscape

  2007. Örjan Bodin, Jon Norberg. Landscape Ecology 22 (1), 31-44

  Artikel

  Läs mer om A network approach for analyzing spatially structured populations in fragmented landscape

• Adaptive management of the Great Barrier Reef and the Grand Canyon world heritage areas

  2007. TP Hughes (et al.). Ambio 36 (7), 586-592

  Artikel

  Läs mer om Adaptive management of the Great Barrier Reef and the Grand Canyon world heritage areas

• Ecosystem processes and biodiversity

  1998. Jon Norberg.

  Avhandling (Dok)

  Today, human enterprise has implications for all of nature, from the well being of the smallest organism, to the alteration of global biogeochemical cycles. To understand how major ecosystem processes are affected by environmental changes and decreasing biodiversity is crucial as many of natures services depend of such processes. In this thesis I have investigated two aspects thereof: 1) the effect of changing temperature on ecosystem structure and community metabolism, and 2) the importance of species composition and species richness for ecosystem processes. I found that different sensitivity of photosynthesis and metabolic rates based on internal energy sources to temperature will have important consequences for herbivores causing decreased herbivore biomass with increasing temperature. I also showed that the response of phytoplankton biomass to temperature might be very difficult to predict >from knowledge of species physiology since indirect effect and trophic interactions in ecosystems determine which limiting factor, e.g. predation, nutrient limitation or growth efficiency is most crucial. A result from an experiment where four different zooplankton species where grown in single culture as well as in polyculture indicated that species-specific interactions are important for ecosystem processes even within a guild of species that is assumed to be one well-defined functional group. Partial similarity between species in resource utilization explains moderated response to trophic regulation and also has implications for the relation between species richness and ecosystem functioning. The last paper makes the point that the magnitude and reliability of ecosystem process rates are closely linked to species richness and mechanisms of species invasions and extinction. A mathematical model explores the mechanisms thereof in detail.

  Läs mer om Ecosystem processes and biodiversity

Visa alla publikationer av Jon Norberg vid Stockholms universitet