Multi-scale vulnerability of natural capital in a panarchy of social–ecological landscapes

Environmental security, as the opposite of environmental vulnerability (fragility), is multi-layered, multi-scale and complex, existing in both the objective physical, biological, and social realm, and the subjective realm of individual human perception. In this paper, we detect and quantify the scales and spatial patterns of human land use as ecosystem disturbances at different hierarchical levels in a panarchy of social–ecological landscapes (SELs) by using a conceptual framework that characterizes multi-scale disturbance patterns exhibited on satellite imagery over a four-year time period in Apulia (South Italy). In this paper we advance the measure of the functional importance of ESPs provided by natural areas and permanent cultivations based on their effectiveness at performing the services. Any landscape element contributes to the overall proportion of disturbance in the region, through its composition of disturbed locations (pixels), and to the overall disturbance connectivity through its configuration. Such landscape elements represent, in turn, functional units for assessing functional contributions of ES providers at different scale(s) of operation of the service. We assume that such effectiveness at performing the services will result directly affected by how much disturbance surrounds ESP locations at different neighborhoods. Multi-scale measurements of the composition and spatial configuration of disturbance are the basis for evaluating vulnerability of ecosystem services through multi-scale disturbance profiles concerning land-use locations where most of ecosystem service providers reside. Vulnerability estimates are derived from the identification of scale range couplings or mismatches among land-use disturbances related to different land uses and revealed by trajectories from the global profile to local spatial patterns. Scale mismatches of disturbances in space and time determine the role of land use as a disturbance source or sink, and may govern the triggering of landscape changes affecting ecosystem service providers at the scale(s) of operation of the service. The role of natural areas and permanent cultivations (olive groves and vineyards) in providing disturbance regulation across scales in South Italy has consequences for regional SELs since it may govern if and how disturbances associated with land-use intensification (sources) will affect the functional contribution of ES providers.     

From chaos to chaos. An analysis of a discrete age-structured prey–predator model

Discrete age-structured density-dependent one-population models and discrete age-structured density-dependent prey–predator models are considered. Regarding the former, we present formal proofs of the nature of bifurcations involved as well as presenting some new results about the dynamics in unstable and chaotic parameter regions. Regarding the latter, we show that increased predation may act both as a stabilizing and a destabilizing effect. Moreover, we find that possible periodic dynamics of low period, either exact or approximate, may not be generated by the predator, but it may be generated by the prey. Finally, what is most interesting from the biological point of view, is that given that the prey, in absence of the predator, exhibits periodic or almost periodic oscillations of low period, then the introduction of the predator does not alter this periodicity in any substantial way until the stabilizing effect of increased predation becomes so strong that a stable equilibrium is achieved. Received: 16 June 2000 / Revised version: 18 January 2001 / Published online: 12 October 2001     

Emergy analysis of regional water ecological–economic system

The theoretical framework and methodology of a water ecological–economic system (WEES) assessment based on emergy synthesis are proposed in this paper. Through calculating ecological and economic inputs and outputs within and outside the complex system, this paper discusses the system's economic situation, water resources development and system sustainability based on a series of emergy indicators. Besides traditional indices, following the principle of system assessment, four new indices, water emergy ratio (WER), water emergy utilization ratio (WEUR), water emergy self-support ratio (WESR), and water emergy density (WED) are formulated to assess the state of water resources development quantitatively. Taking the Zhengzhou water ecological–economic system as a study area, through the comparison of the systematic indicators of Zhengzhou with those of the selected Chinese cities, the general status of the Zhengzhou water ecological–economic system in China is identified. The results also show that most indicators of Beijing are located at middle levels among the selected Chinese cities. In particular, the sustainability, expressed by the indicators emergy-based sustainability index (ESI) and water resources population carrying capacity (WPC) were 1.34 and 1.94 million, respectively, in Zhengzhou in 2005, which indicates that the Zhengzhou WEES is in heavy pressure of water resources and is located at low levels of sustainability.     

Modeling responses of coupled social–ecological systems of the Gulf of California to anthropogenic and natural perturbations

Key elements of the rapidly expanding field of ecosystem-based management include: (a) understanding connections among social and ecological systems and (b) developing analytical approaches to inform the necessary trade-offs among ecosystem services and human activities in coastal and marine areas. To address these needs, we investigate the impacts of multiple economic sectors on the marine ecosystem and dependent human community in the Gulf of California with an ecological-economic model. We focus on the spotted rose snapper (Lutjanus guttatus), an economically important species targeted concurrently by the nearshore artisanal fleet, the sportfishing fleet, and by the industrial shrimp fleet as bycatch. Economic returns to the local community are driven by the artisanal fishery catch and the number of tourists who engage in the sportsfishery, and these variables are in turn impacted by fish abundance. We find that the coexistence of the two sectors (and production of both seafood and tourism services) creates stability in key elements of the coupled systems. When the coupled systems are perturbed by changes in exploitation and climate variability, the artisanal fishery responds more rapidly and to a greater degree than the sportsfishery to shifts in the fish population. Our results suggest that vital components of coupled systems may well respond differently to climate variability or other perturbations, and that management strategies should be developed with this in mind. Models like ours can facilitate the development and testing of hypotheses about the form and strength of interactions between ecosystems, services, and the human communities that rely on them. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. H. M. Leslie and M. Schlüter contributed equally to this paper.     

Self-organised spatial patterns and chaos in a ratio-dependent predator–prey system

Mechanisms and scenarios of pattern formation in predator–prey systems have been a focus of many studies recently as they are thought to mimic the processes of ecological patterning in real-world ecosystems. Considerable work has been done with regards to both Turing and non-Turing patterns where the latter often appears to be chaotic. In particular, spatiotemporal chaos remains a controversial issue as it can have important implications for population dynamics. Most of the results, however, were obtained in terms of ‘traditional’ predator–prey models where the per capita predation rate depends on the prey density only. A relatively new family of ratio-dependent predator–prey models remains less studied and still poorly understood, especially when space is taken into account explicitly, in spite of their apparent ecological relevance. In this paper, we consider spatiotemporal pattern formation in a ratio-dependent predator–prey system. We show that the system can develop patterns both inside and outside of the Turing parameter domain. Contrary to widespread opinion, we show that the interaction between two different type of instability, such as the Turing–Hopf bifurcation, does not necessarily lead to the onset of chaos; on the contrary, the emerging patterns remain stationary and almost regular. Spatiotemporal chaos can only be observed for parameters well inside the Turing–Hopf domain. We then investigate the relative importance of these two instability types on the onset of chaos and show that, in a ratio-dependent predator–prey system, the Hopf bifurcation is indeed essential for the onset of chaos whilst the Turing instability is not.     

A predator–prey refuge system: Evolutionary stability in ecological systems

A refuge model is developed for a single predator species and either one or two prey species where no predators are present in the prey refuge. An individual’s fitness depends on its strategy choice or ecotype (predators decide which prey species to pursue and prey decide what proportion of their time to spend in the refuge) as well as on the population sizes of all three species. It is shown that, when there is a single prey species with a refuge or two prey species with no refuge compete only indirectly (i.e. there is only apparent competition between prey species), that stable resident systems where all individuals in each species have the same ecotype cannot be destabilized by the introduction of mutant ecotypes that are initially selectively neutral. In game-theoretic terms, this means that stable monomorphic resident systems, with ecotypes given by a Nash equilibrium, are both ecologically and evolutionarily stable. However, we show that this is no longer the case when the two indirectly-competing prey species have a refuge. This illustrates theoretically that two ecological factors, that are separately stabilizing (apparent competition and refuge use), may have a combined destabilizing effect from the evolutionary perspective. These results generalize the concept of an evolutionarily stable strategy (ESS) to models in evolutionary ecology. Several biological examples of predator–prey systems are discussed from this perspective.     

Aggregate index of social–environmental sustainability to evaluate the social–environmental quality in a watershed in the Southern Amazon

The purpose of this study was to build an aggregate index of social–environmental sustainability derived from incorporation of indicators of the quality of soil, water, and vegetation, and social organization and socioeconomic variables, in order to assess the overall social–environmental quality in a micro watershed in the Southern Amazon. From a population of 105 family production units 56 were randomly selected for evaluation of indicators of the quality of soil and water as well as for conducting interviews to evaluate the farmers’ perception of soil, water, and vegetation quality and also of socioeconomic aspects of agroecosystems. The aggregate index built from social–environmental sustainability indicators shows that the selected indicators were adequate for describing social–environmental quality and confirms the hypothesis that the studied micro-watershed in the southern edge of the Amazon is in a state of collapse, and is socially and environmentally degraded.     

The root–soil system of Norway spruce subjected to turning moment: resistance as a function of rotation

The reactions of trees to wind, rockfall, and snow and debris flow depend largely on how strong and deformable their anchorage in the soil is. Here, the resistive turning moment M of the root–soil system as a function of the rotation ϕ at the stem base plays the major role. M(ϕ) describes the behavior of the root–soil system when subject to rotational moment, with the maximum M(ϕ) indicating the anchorage strength M _a of the tree. We assessed M(ϕ) of 66 Norway spruce (Picea abies L. Karst) by pulling them over with a winch. These 45- to 170-year-old trees grew at sites of low and high elevation, with a diameter at breast height DBH = 14–69 cm and a height H = 9–42 m. M(ϕ) displayed a strong nonlinear behavior. M _a was reached at a lower ϕ for large trees than for small trees. Thus overhanging tree weight contributed less to M _a for the large trees. Overturning also occurred at a lower ϕ for the large trees. These observations show that the rotational ductility of the root–soil system is higher for small trees. M _a could be described by four monovariate linear regression equations of tree weight, stem weight, stem volume and DBH ² ·H (0.80 < R ² < 0.95), and ϕ at M _a, ϕ _a, by a power law of DBH²·H (R ² = 0.85). We found significantly higher M _a for the low-elevation spruces than for the high-elevation spruces, which were more shallowly anchored, but no significant difference in ϕ _a. The 66 curves of M(ϕ), normalized (_n) by M _a in M-direction and by ϕ _a in ϕ-direction, yielded one characteristic average curve: . Using and the predictions of M _a and ϕ _a, it is shown that M(ϕ) and the curves associated with M(ϕ) can be predicted with a relative standard error ≤25%. The parameterization of M(ϕ) by tree size and weight is novel and provides useful information for predicting with finite-element computer models how trees will react to natural hazards.     

Navigating challenges and opportunities of land degradation and sustainable livelihood development in dryland social–ecological systems: a case study from Mexico

Drylands are one of the most diverse yet highly vulnerable social–ecological systems on Earth. Water scarcity has contributed to high levels of heterogeneity, variability and unpredictability, which together have shaped the long coadaptative process of coupling humans and nature. Land degradation and desertification in drylands are some of the largest and most far-reaching global environmental and social change problems, and thus are a daunting challenge for science and society. In this study, we merged the Drylands Development Paradigm, Holling''s adaptive cycle metaphor and resilience theory to assess the challenges and opportunities for livelihood development in the Amapola dryland social–ecological system (DSES), a small isolated village in the semi-arid region of Mexico. After 450 years of local social–ecological evolution, external drivers (neoliberal policies, change in land reform legislation) have become the most dominant force in livelihood development, at the cost of loss of natural and cultural capital and an increasingly dysfunctional landscape. Local DSESs have become increasingly coupled to dynamic larger-scale drivers. Hence, cross-scale connectedness feeds back on and transforms local self-sustaining subsistence farming conditions, causing loss of livelihood resilience and diversification in a globally changing world. Effective efforts to combat desertification and improve livelihood security in DSESs need to consider their cyclical rhythms. Hence, we advocate novel dryland stewardship strategies, which foster adaptive capacity, and continuous evaluation and social learning at all levels. Finally, we call for an effective, flexible and viable policy framework that enhances local biotic and cultural diversity of drylands to transform global drylands into a resilient biome in the context of global environmental and social change.     

On a predator–prey system of Gause type

In this paper a Gause type model of interactions between predator and prey population is considered. We deal with the sufficient condition due to Kuang and Freedman in the generalized form including a kind of weight function. In a previous paper we proved that the existence of such weight function implies the uniqueness of limit cycle. In the present paper we give a new condition equivalent to the existence of a weight function (Theorem 4.4). As a consequence of our result, it is shown that some simple qualitative properties of the trophic function and the prey isocline ensure the uniqueness of limit cycle.     

The cichlid–Cichlidogyrus network: a blueprint for a model system of parasite evolution

Hydrobiologia - Species interactions are a key aspect of evolutionary biology. Parasites, specifically, are drivers of the evolution of species communities and impact biosecurity and public health....     

Dissemination of spores in a glasshouse: Pattern or chaos?

The dissemination of particles in a glasshouse with three united compartments was observed from experiments withLycopodium sp. The experiments were performed in a glasshouse with open and closed ventilation openings, spore sources on two heights above soil surface, and in two consecutive time intervals. The spores were caught with self constructed spore traps placed at regular distances from each other. Air circulation was observed using smoke-puffs. High ventilation caused a rapid cleaning of the air while in a closed glasshouse spores remained suspended for quite a long time. Though the three compartments of the glasshouse were not separated by walls, a so-called cell structure of the individual compartments could be indicated.     

Coevolution of dispersal in a parasitoid–host system

Interspecific interactions and the evolution of dispersal are both of interest when considering the potential impact of habitat fragmentation on community ecology, but the interaction between these processes is not well studied. We address this by considering the coevolution of dispersal strategies in a host–parasitoid system. An individual-based host–parasitoid metapopulation model was constructed for a patchy environment, allowing for evolution in dispersal rates of both species. Highly rarefied environments with few suitable patches selected against dispersal in both species, as did relatively static environments. Provided that parasitoids persist, all the variables studied led to stable equilibria in dispersal rates for both species. There was a tendency toward higher dispersal rates in parasitoids because of the asymmetric relationships of the two species to the patches: vacant patches are most valuable for hosts, but unsuitable for parasitoids, which require an established host population to reproduce. High host dispersal rate was favoured by high host population growth rate, and in the parasitoid by high growth rates in both species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Stasipatric speciation: resurrecting a system to bury a hypothesis?

The process of speciation remains a fundamental topic in evolutionary biology. Numerous models of speciation have been proposed and they are as diverse and colourful as the scientists who conceived them ( Coyne & Orr 2004 ). One of the more controversial theories has been the ‘stasipatric speciation’ model, proposed by the pioneering and influential cytogeneticist Michael White and his co‐workers ( White 1968 ; White et al. 1967 ). This is one of a number of speciation models whereby chromosomal rearrangements drive the speciation process. The inspiration for the theory of stasipatric speciation came from White’s karyotypic analyses of a group of Australian grasshoppers of the genus Vandiemenella ( White et al. 1967 ) ( Fig. 1 ). It has been exactly three decades since the last scientific publication on this group of grasshoppers, over which time the molecular revolution dramatically altered the landscape of evolutionary genetics. Kawakami and colleagues have successfully resurrected the Vandiemenella system ( Kawakami et al. 2009a, 2007 ) and in this issue they have applied modern molecular‐based techniques to reassess the validity of the stasipatric speciation model for this historically important group ( Kawakami et al. 2009b ).

Figure 1 Open in figure viewer PowerPoint The grasshopper (Vandiemenella viatica) that inspired Michael White to develop the stasipatric speciation model (photograph by Remko Leijs).     

Optimizing size thresholds in a plant–pollinator interaction web: towards a mechanistic understanding of ecological networks

Using functional traits together with abundance effects strengthens the prediction of interactions between pairs of species in ecological networks. Insights into the way species interact as well as prediction accuracy can be gained when thresholds for trait value combinations that make interactions possible are optimized through model selection. I present novel data of two subalpine plant–pollinator communities and build several stochastic models integrating flower abundance and morphological threshold rules that allow or restrict interactions between species. The number of correctly predicted interactions was highest when thresholds were set so that the insect’s proboscis was not shorter than the nectar-holder depth minus 1–1.6 mm, and not wider than the nectar-holder width minus 0.5 mm. In comparison with models based solely on plant abundance effects, the model incorporating optimized size thresholds better predicted the distribution of the trait differences between plants and insects. This indicates that a mechanistic approach of interaction webs based on optimized size thresholds provides valuable information on community structure. The possible implications for community functioning are discussed.