Time-delayed biodiversity feedbacks and the sustainability of social-ecological systems

Abstract

The sustainability of coupled social-ecological systems (SESs) hinges on their long-term ecological dynamics. Land conversion generates extinction and functioning debts, i.e. a time-delayed loss of species and associated ecosystem services. Sustainability theory, however, has not so far considered the long-term consequences of these ecological debts on SESs. We investigate this question using a dynamical model that couples human demography, technological change and biodiversity. Human population growth drives land conversion, which in turn reduces biodiversity-dependent ecosystem services to agricultural production (ecological feedback).Technological change brings about a demographic transition leading to a population equilibrium. When the ecological feedback is delayed in time, some SESs experience population overshoots followed by large reductions in biodiversity, human population size and well-being, which we call environmental crises. Using a sustainability criterion that captures the vulnerability of an SES to such crises, we show that some of the characteristics common to modern SESs (e.g. high production efficiency and labor intensity, concavedown ecological relationships) are detrimental to their long-term sustainability. Maintaining sustainability thus requires strong counteracting forces, such as the demographic transition and land-use management. To this end, we provide integrative sustainability thresholds for land conversion, biodiversity loss and human population size -each threshold being related to the others through the economic, technological, demographic and ecological parameters of the SES. Numerical simulations show that remaining within these sustainable boundaries prevents environmental crises from occurring. By capturing the long-term ecological and socioeconomic drivers of SESs, our theoretical approach proposes a new way to define integrative conservation objectives that ensure the long-term sustainability of our planet.

Understanding extinction debts: spatio–temporal scales, mechanisms and a roadmap for future research

“…these estimates; Isbell et al 2015). Adding to this picture, extinction debts have been shown to decrease the sustainability of socio-ecological systems (Lafuite andLoreau 2017, Lafuite et al 2017), reinforcing the consensus about the importance of biodiversity in providing ecosystem functions and services that benefit humanity (Cardinale et al 2012, Hooper et al 2012.…”

“…Considering the spatio-temporal scales that extinction debts can reach (Fig. 4, Halley et al 2016Halley et al , 2017, further investigation into their consequences, and the extension of those consequences to ecosystem service debts (Isbell et al 2015, Valiente-Banuet et al 2015, Lafuite and Loreau 2017) is essential if we are to understand extinction debt implications for human life (Isbell et al 2017). At the same time, the more mechanistically complex a model is, the harder it is to parameterize (Getz et al 2018) and to interpret emergent patterns.…”

Coupled land use and ecological models reveal emergence and feedbacks in socio‐ecological systems

“…More generally, feedbacks between ecosystem services and elements of biodiversity warrant increased attention, particularly where they relate to soil biodiversity (Vukicevich et al 2016, de Valença et al 2017, Delgado-Baquerizo et al 2017. The timescales of such feedbacks can also have crucial implications for socio-ecological dynamics (Lafuite and Loreau 2017), as can relatively neglected aspects of genetic and functional diversity (De Palma et al 2017). Such effects are also strongly modulated by the knowledge and attitudes of land managers, which we did not consider here, but which can be varied in the model framework we used (Brown et al 2016, Pe'er et al 2017.…”

Foresight is required to enforce sustainability under time-delayed biodiversity loss

“…The accumulation of these extinction debts generates functioning debts [20] that postpone the negative effect of biodiversity loss on ecosystem processes. Since many of the ecosystem services that play a direct or indirect role in agricultural production depend on biodiversity [21,22,23,24], current species extinction rates [25,26,27] do not only threaten the long-term provisioning [28,29] and stability of ecosystem processes [30,31,32], they also generate a time-delayed feedback loop between humans and nature [33]. In the long run, such time-delayed biodiversity feedbacks may result in large environmental crises, i.e.…”

“…In the long run, such time-delayed biodiversity feedbacks may result in large environmental crises, i.e. overshoot-and-collapse population cycles [33], similar to the famine cycles that have been observed in extinct societies [34].…”