State-and-Transition models: Operationalizing ecosystem condition and the capacity to generate ecosystem services

RUSCH, GRACIELA; RUSCH, VERÓNICA; GOIJMAN, ANDREA; VARELA, SANTIAGO; LÓPEZ, DARDO R.; CAVALLERO, LAURA; PERI, PABLO; CARDOZO, ANDREA

Conferencia; European Ecosystem Services Conference; 2016

University of Antwerp

We propose a methodology to model the dynamics of Ñire forest as a response of levels of critical natural and management processes, and that explicitly links these processes to ecosystem condition and its capacity to provide important ES. We developed a State-and-Transition model (STM) for Ñire forests in northern Patagonia under silvopastoral use, that helped gather the existing ecological knowledge of the system, using multiple sources, including historical maps and essays, vegetation surveys and field data. We adjusted the model in a workshop of experts and subsequent field and literature checks. Seven states and 13 negative transitions were described, as well the factors that trigger transitions and their associated levels of grazing and fuel-wood extraction. Most transitions are irreversible, which means that there is a need of specific interventions to revert ecological degradation. States were characterized by state variables indicating structural and functional features such as cover of dominant plant species, vegetation cover and tree recruitment, which were in turn linked to ecological processes and structures underpinning the provision of services such as herbaceous primary productivity, stand basal area, habitat quality, soil erosion control, and recreation opportunities. We implemented 3 transitions as a Bayesian Belief Network (BBNs), providing a graphical and easily accessible representation of the model, to explore how levels of ecosystem service flows are related to thresholds in ecosystem condition, while incorporating uncertainty. We propose STMs implemented as BBNs as a robust tool to inform the implementation of the Forest Law and the management of Ñire forest that incorporates knowledge about multiple benefits generated by these systems at the same time that integrates the best available biodiversity and ecological knowledge.