Delayed behavioural shifts undermine the sustainability of social-ecological systems

Integrating evolutionary theory and social-ecological systems research to address the sustainability challenges of the Anthropocene

The rapid, human-induced changes in the Earth system during the Anthropocene present humanity with critical sustainability challenges. Social-ecological systems (SES) research provides multiple approaches for understanding the complex interactions between humans, social systems, and environments and how we might direct them towards healthier and more resilient futures. However, general theories of SES change have yet to be fully developed. Formal evolutionary theory has been applied as a dynamic theory of change of complex phenomena in biology and the social sciences, but rarely in SES research. In this paper, we explore the connections between both fields, hoping to foster collaboration. After sketching out the distinct intellectual traditions of SES research and evolutionary theory, we map some of their terminological and theoretical connections. We then provide examples of how evolutionary theory might be incorporated into SES research through the use of systems mapping to identify evolutionary processes in SES, the application of concepts from evolutionary developmental biology to understand the connections between systems changes and evolutionary changes, and how evolutionary thinking may help design interventions for beneficial change. Integrating evolutionary theory and SES research can lead to a better understanding of SES changes and positive interventions for a more sustainable Anthropocene. This article is part of the theme issue 'Evolution and sustainability: gathering the strands for an Anthropocene synthesis'.

Habitat percolation transition undermines sustainability in social-ecological agricultural systems

Steady increases in human population size and resource consumption are driving rampant agricultural expansion and intensification. Habitat loss caused by agriculture puts the integrity of ecosystems at risk and threatens the persistence of human societies that rely on ecosystem services. We develop a spatially explicit model describing the coupled dynamics of an agricultural landscape and human population size to assess the effect of different land-use management strategies, defined by agricultural clustering and intensification, on the sustainability of the social-ecological system. We show how agricultural expansion can cause natural habitats to undergo a percolation transition leading to abrupt habitat fragmentation that feedbacks on human's decision making, aggravating landscape degradation. We found that agricultural intensification to spare land from conversion is a successful strategy only in highly natural landscapes, and that clustering agricultural land is the most effective measure to preserve large connected natural fragments, prevent severe fragmentation and thus, enhance sustainability.

Universal scaling of robustness of ecosystem services to species loss

Ensuring reliable supply of services from nature is key to the sustainable development and well-being of human societies. Varied and frequently complex relationships between biodiversity and ecosystem services have, however, frustrated our capacity to quantify and predict the vulnerability of those services to species extinctions. Here, we use a qualitative Boolean modelling framework to identify universal drivers of the robustness of ecosystem service supply to species loss. These drivers comprise simple features of the networks that link species to the functions they perform that, in turn, underpin a service. Together, they define what we call network fragility. Using data from >250 real ecological networks representing services such as pollination and seed-dispersal, we demonstrate that network fragility predicts remarkably well the robustness of empirical ecosystem services. We then show how to quantify contributions of individual species to ecosystem service robustness, enabling quantification of how vulnerability scales from species to services. Our findings provide general insights into the way species, functional traits, and the links between them together determine the vulnerability of ecosystem service supply to biodiversity loss.

A Twitter-Lived Red Tide Crisis on Chiloé Island, Chile: What Can Be Obtained for Social-Ecological Research through Social Media Analysis?

Considering traditional research on social-ecological crises, new social media analysis, particularly Twitter data, contributes with supplementary exploration techniques. In this article, we argue that a social media approach to social-ecological crises can offer an actor-centered meaningful perspective on social facts, a depiction of the general dynamics of meaning making that takes place among actors, and a systemic view of actors’ communication before, during and after the crisis. On the basis of a multi-technique approach to Twitter data (TF-IDF, hierarchical clustering, egocentric networks and principal component analysis) applied to a red tide crisis on Chiloé Island, Chile, in 2016, the most significant red tide in South America ever, we offer a view on the boundaries and dynamics of meaning making in a social-ecological crisis. We conclude that this dynamics shows a permanent reflexive work on elucidating the causes and effects of the crisis that develops according to actors’ commitments, the sequence of events, and political conveniences. In this vein, social media analysis does not replace good qualitative research, it rather opens up supplementary possibilities for capturing meanings from the past that cannot be retrieved otherwise. This is particularly relevant for studying social-ecological crises and supporting collective learning processes that point towards increased resilience capacities and more sustainable trajectories in affected communities.

Agricultural land use and the sustainability of social-ecological systems

Agricultural land expansion and intensification, driven by human consumption of agricultural goods, are among the major threats to environmental degradation and biodiversity conservation. Land degradation can ultimately hamper agricultural production through a decrease in ecosystem services. Thus, designing viable land use policies is a key sustainability challenge. We develop a model describing the coupled dynamics of human demography and landscape composition, while imposing a trade-off between agricultural expansion and in-tensification. We model land use strategies spanning from low-intensity agriculture and high land conversion rates per person to high-intensity agriculture and low land conversion rates per person; and explore their consequences on the long-term dynamics of the coupled human-land system. We seek to characterise the strategies' viability in the long run; and understand the mechanisms that potentially lead to large-scale land degradation and population collapse due to resource scarcity. We show that the viability of land use strategies strongly depends on the land's intrinsic recovery rate. We also find that socio-ecological collapses occur when agricultural intensification is not accompanied by a sufficient decrease in land conversion. Based on these findings we stress the dangers of uninformed land use planning and the importance of precautionary behaviour for land use management and land use policy design.

Sustainable Land-use Management Under Biodiversity Lag Effects

The destruction of natural habitats for agricultural production results in local biodiversity loss. Biodiversity loss in turn affects agricultural production indirectly through a range of biodiversity-dependent ecosystem services. Land conversion thus results in a negative externality, mediated by changes in biodiversity. When the consequences of this externality are delayed in time, lack of internalization results in overshoot-and-collapse dynamics, which are undesirable from a sustainability perspective. Here, we emphasize the importance of forward-looking policies for the long-term sustainability of human-nature interactions. We show that the internalization of this externality through a land tax can result in several win-win effects in the long run. First, more biodiversity is preserved at equilibrium, which increases the carrying capacity and total well-being of the human population. Second, a taxation path that maximizes the discounted sum of human utilities prevents or greatly alleviates overshoot-and-collapse crises, thus increasing the sustainability of the system. In particular, this result holds in the case of imperfect information regarding the precise temporal dynamics of biodiversity loss, suggesting that the design of efficient land-use management policies is possible despite incomplete ecological data. This study highlights the need to internalize biodiversity-dependent externalities through economic incentives, especially under uncertainty regarding long-term ecological dynamics.

Do we have to choose between feeding the human population and conserving nature? Modelling the global dependence of people on ecosystem services

The ability of the human population to continue growing depends strongly on the ecosystem services provided by nature. Nature, however, is becoming more and more degraded as the number of individuals increases, which could potentially threaten the future well-being of the human population. We use a dynamic model to conceptualise links between the global proportion of natural habitats and human demography, through four categories of ecosystem services (provisioning, regulating, cultural recreational and informational) to investigate the common future of nature and humanity in terms of size and well-being. Our model shows that there is generally a trade-off between the quality of life and human population size and identifies four short-term scenarios, corresponding to three long-term steady states of the model. First, human population could experience declines if nature becomes too degraded and regulating services diminish; second the majority of the population could be in a famine state, where the population continues to grow with minimal food provision. Between these scenarios, a desirable future scenario emerges from the model. It occurs if humans convert enough land to feed all the population, while maintaining biodiversity and ecosystem services. Finally, we find a fourth scenario, which combines famine and a decline in the population because of an overexploitation of land leading to a decrease in food production. Human demography is embedded in natural dynamics; the two factors should be considered together if we are to identify a desirable future for both nature and humans.