Understanding and managing coupled human and natural systems (CHANS) is a central challenge of the 21st century, but more focus is needed to pursue the most important questions within this vast field given limited research capacity and funding. We present 40 important questions for CHANS research, identified through a two-part crowdsourcing exercise within the CHANS community. We solicited members of the International Network of Research on Coupled Human and Natural Systems (CHANS-Net) to submit up to three questions that they considered transformative, receiving 540 questions from 207 respondents. After editing for clarity and consistency, we asked the network's members to each evaluate a random subset of 20 questions in importance on a scale from 1 (least important) to 7 (extremely important). Questions on land use and agriculture topped the list, with a median importance ranking of 5.7, followed by questions of scale, climate change and energy, sustainability and development, adaptation and resilience, in addition to seven other categories. We identified 40 questions with a median importance of 6.0 or above, which we highlight as the current view of researchers active in the field as research questions to pursue in order to maximize impact on understanding and managing coupled human and natural systems for achieving sustainable development goals and addressing emerging global challenges.

The effects of armed conflict on biodiversity are an emerging concern in conservation due in part to the occurrence of war in biodiversity hotspots, though few studies have addressed it. We investigate this topic by examining changes in forest cover on the Atlantic Coast of Nicaragua from 1978 to 1993, a period covering their civil war. We predict an increase in forest cover between pre-and post-conflict periods as residents abandoned agriculture plots and migrated from conflict areas. We used a remote sensing approach to detect changes in forest cover area and fragmentation at two study sites. Results confirmed that in the first 5-7 years of the conflict, reforestation was greater than deforestation, but in the latter years of the conflict deforested land almost doubled that which was reforested. Although some forest loss was due to Category 4 Hurricane Joan, several conflict-related factors were partially responsible for these results, such as mass human migration and land reform. Understanding how and why forest cover changes during periods of conflict can help conservationists protect resources both during war and in the tumultuous period following the cessation of violence when nascent governments lack the power to effectively govern and community institutions are fractured by war. In areas where the livelihoods of people are directly dependent on local resources, anticipating ecological and social impacts can help improve future conservation efforts.

Tropical forest conversion to pasture, which drives greenhouse gas emissions, soil degradation, and biodiversity loss, remains a pressing socio-ecological challenge. This problem has spurred increased interest in the potential of small-scale agroforestry systems to couple sustainable agriculture with biodiversity conservation, particularly in rapidly developing areas of the tropics. In addition to providing natural resources (i.e. food, medicine, lumber), agroforestry systems have the potential to maintain higher levels of biodiversity and greater biomass than lower diversity crop or pasture systems. Greater plant diversity may also enhance soil quality, further supporting agricultural productivity in nutrient-limited tropical systems. Yet, the nature of these relationships remains equivocal. To better understand how different land use strategies impact ecosystem services, we characterized the relationships between plant diversity (including species richness, phylogenetic diversity, and natural resource diversity), and soil quality within pasture, agroforests, and secondary forests, three common land use types maintained by small-scale farmers in the Pearl Lagoon Basin, Nicaragua. The area is undergoing accelerated globalization following the 2007 completion of the region’s first major road; a change which is expected to increase forest conversion for agriculture. However, farmer agrobiodiversity maintenance in the Basin was previously found to be positively correlated with affiliation to local agricultural NGOs through the maintenance of agroforestry systems, despite these farmers residing in the communities closest to the new road, highlighting the potential for maintaining diverse agroforestry agricultural strategies despite heightened globalization pressures. We found that agroforestry sites tended to have higher surface soil %C, %N, and pH relative to neighboring to secondary forest, while maintaining comparable plant diversity. In contrast, pasture reduced species richness, phylogenetic diversity, and natural resource diversity. No significant relationships were found between plant diversity and the soil properties assessed; however higher species richness and phylodiversity was positively correlated with natural resource diversity. These finding suggest that small, diversified agroforestry systems may be a viable strategy for promoting both social and ecological functions in eastern Nicaragua and other rapidly developing areas of the tropics.

No abstract