• Energy Research

Managers need to trace social impacts and vulnerability caused by environmental change all the way to its driving forces to target key system components for intervention. However, most available scientific evidence deals with either the ecological impacts of direct drivers or the value of ecosystem benefits to people. Our matrix-based tool combines these types of evidence to make environmental management problems traceable through a structured yet flexible procedure. The tool consists of a series of matrices that sequentially link direct drivers of environmental change, landscapes, ecological conditions, benefits to people, and stakeholder types. Qualitative matrices result from the integration and synthesis of available evidence from literature reviews, and where data is scarce, these are used to elicit quantitative scores from expert opinion. Expert scoring of links and multiplication of matrices allow for estimating the impacts of each driver of environmental change on each stakeholder type and using this information as input to assess stakeholders' vulnerability through impact-influence diagrams. Applying the tool to the Argentine Gran Chaco, a globally threatened ecoregion, yielded a transparent and reliable picture of this data-scarce place, with important management implications. Tracing stakeholder impacts back to direct drivers confirmed that further encroachment of cleared areas around indigenous lands will increase the vulnerability of this social group. Also, assessing confidence levels for every social-ecological link suggested that incentivizing peasant farmers to restore natural forage supply represents a management opportunity to reverse degradation. Our tool makes interdisciplinary frameworks of linked ecological and social systems operational so managers can use the best available knowledge of a place and account for uncertainty to make environmental management decisions.

Regional and global assessments periodically update what we know, and highlight what remains to be known, about the linkages between people and nature that both define and depend upon the state of the environment. To guide research that better informs policy and practice, we systematically synthesize knowledge gaps from recent assessments of four regions of the globe and three key themes by the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services. We assess their relevance to global sustainability goals and trace their evolution relative to those identified in the Millennium Ecosystem Assessment. We found that global sustainability goals cannot be achieved without improved knowledge on feedbacks between social and ecological systems, effectiveness of governance systems and the influence of institutions on the social distribution of ecosystem services. These top research priorities have persisted for the 14 years since the Millennium Ecosystem Assessment. Our analysis also reveals limited understanding of the role of indigenous and local knowledge in sustaining nature’s benefits to people. Our findings contribute to a policy-relevant and solution-oriented agenda for global, long-term social-ecological research.

Millennial-scale biogeographic changes are well understood in many parts of the world, but little is known about long-term vegetation dynamics in subtropical regions. Here we investigate shifts in C3/C4 plant abundance occurred in central Argentina during the past few millennia We determined present day soil organic matter δ13C signatures of grasslands, shrublands and woodlands, containing different mixtures of C3 and C4 plants. We measured past changes in the relative cover of C3/C4 plants by comparing δ13C values in soil profiles with present day δ13C signatures. We analyzed 14C activity in soil depths that showed major changes in vegetation. Present day relative cover of C3/C4 plants determines whole ecosystem δ13C signatures integrated as litter and superficial soil organic matter (R2 = 0.78; p < 0.01). Deeper soils show a consistent shift in δ13C, indicating a continuous replacement of C4 by C3 plants since 3,870 (±210) YBP. During this period, the relative abundance of C3 plants increased 32% (average across sites) with significant changes being observed in all studied ecosystems. Our results show that C4 species were more abundant in the past, but C3 species became dominant during the late Holocene. We identified increases in the relative C3/C4 cover in grasslands, shrublands and woodlands, suggesting a physiological basis for changes in vegetation. The replacement of C4 by C3 plants coincided with changes in climate towards colder and wetter conditions and could represent a climatically driven shift in the C4 species optimum range.