Peer-reviewed publications

Large-scale reforestation, afforestation, and forest restoration schemes have gained global support as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of forestation from a biophysical perspective. In the Community Earth System Model version 2 (CESM2), we apply a global forestation scenario, within a Paris Agreement-compatible warming scenario, to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is up to 2 °C cooler at low latitudes by 2100, driven by a 10 % increase in evaporative cooling in forested areas. However, afforested areas where grassland or shrubland are replaced lead to a doubling of plant water demand in some tropical regions, causing significant decreases in soil moisture (∼ 5 % globally, 5 %–10 % regionally) and water availability (∼ 10 % globally, 10 %–15 % regionally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over the expanded tropical forests, with enhanced negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the precipitation response to simulated large-scale deforestation found in previous studies. The forestation scenario demonstrates local cooling benefits without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive forestation, especially afforestation, have implications for its viability, given the uncertainty in future precipitation changes.

Rangers play a crucial role on the frontline of conservation; however, they often face difficult and sometimes dangerous working conditions, along with inadequate pay, equipment, training, and recognition. This study aims to determine the influence of rangers’ working conditions on their vulnerability to corruption using correlation analysis. The research utilized the Global Ranger Perception Survey 2019 dataset, a global-scale survey that collected responses from 6,101 rangers across 25 countries on various aspects of their working conditions. We further analyzed the results by gender and geographic region. Key findings indicate that women have a lower propensity to engage in corrupt activities. Conversely, at the regional level, Latin America demonstrates a heightened susceptibility to corruption compared to other regions. Additionally, there is a strong correlation between corruption and certain aspects of rangers’ working conditions in Latin America. Future assessments, such as the State of the Ranger Report, could provide a monitoring mechanism to evaluate the long-term effects of improvements in rangers' working conditions and their potential vulnerability to corruption worldwide. Country-specific or even landscape-specific in-depth studies would be valuable for developing targeted strategies to address corruption within the workforce while also improving rangers’ working conditions.

Integrated assessment models that incorporate biodiversity and ecosystem services could be an important tool for improving our understanding of interconnected social-economic-ecological systems, and for analyzing how policy alternatives could shift future trajectories towards more sustainable development. Despite recent scientific and technological advances, key gaps remain in the scientific community’s ability to deliver information to decision-makers at the pace and scale needed to address sustainability challenges. We identify five research frontiers for integrated social-economic-ecological modeling that incorporate biodiversity and ecosystem services: 1) downscaling impacts of direct and indirect drivers on ecosystems; 2) incorporating long-term feedbacks in ecosystems; 3) linking ecological impacts to social and economic impacts, 4) disaggregating outcomes for distributional equity considerations, 5) incorporating ecological feedbacks within the social-economic system. We discuss challenges and progress along each of these five frontiers, and the science-policy linkages needed to move new research and information into action.

In birds, patterns of development of the adrenocortical response to stressors vary among individuals, types of stressors, and species. Since there are benefits and costs of exposure to elevated glucocorticoids, this variation is presumably a product of selection such that animals modulate glucocorticoid secretion in contexts where doing so increases their fitness. In this study, we evaluated hypothalamo–pituitary–adrenal (HPA) activity in first-hatched free-living seabird nestlings that engage in intense sibling competition and facultative siblicide (black-legged kittiwakes, Rissa tridactyla). We sampled 5 day old chicks (of the ∼45 day nestling period), a critical early age when food availability drives establishment of important parent-offspring and intra-brood dynamics. We experimentally supplemented parents with food (“supplemented”) and measured chick baseline corticosterone secretion and capacity to rapidly increase corticosterone in response to an acute challenge (handling and 15 min of restraint in a bag). We also used topical administration of corticosterone to evaluate the ability of chicks to downregulate physiologically relevant corticosterone levels on a short time scale (minutes). We found that 5 day old chicks are not hypo-responsive but release corticosterone in proportion to the magnitude of the challenge, showing differences in baseline between parental feeding treatments (supplemented vs non-supplemented), moderate increases in response to handling, and a larger response to restraint (comparable to adults) that also differed between chicks from supplemented and control nests. Topical application of exogenous corticosterone increased circulating levels nearly to restraint-induced levels and induced downregulation of HPA responsiveness to the acute challenge of handling. Parental supplemental feeding did not affect absorbance/clearance or negative feedback. Thus, while endogenous secretion of corticosterone in young chicks is sensitive to environmental context, other aspects of the HPA function, such as rapid negative feedback and/or the ability to clear acute elevations in corticosterone, are not. We conclude that 5 day old kittiwake chicks are capable of robust adrenocortical responses to novel challenges, and are sensitive to parental food availability, which may be transduced behaviorally, nutritionally, or via maternal effects. Questions remain about the function of such rapid, large acute stress-induced increases in corticosterone in very young chicks.

The tropical dry regions in the Neotropics face significant anthropogenic pressures, impacting local communities’ life patterns and wellbeing. In a study of the Gulf of Mexico’s tropical dry region, we evaluated traditional uses of tree species in vegetation patches. Notably, Acacia cochliacantha, Cedrela odorata, Enterolobium cyclocarpum, Gliricidia sepium, and Guazuma ulmifolia were the most commonly used species. Firewood and pasture management were widespread uses, while reforestation was less common. Proximity to human settlements influenced inhabitants’ use and recognition of plant species. Despite reduced forest cover, local communities still recognize multiple uses for vegetation patches. This research provides essential baseline information for conservation efforts.

Community-based natural resource management (CBNRM) is common in most types of ecosystems that are characterized by common property practices. However, the emergence and spread of CBNRM has varied across geographies and contexts. This study explores factors that have enabled the modern emergence, persistence, and spread of marine CBNRM in four coastal districts in Tanzania. It also investigates how CBNRM—particularly local ownership and management of marine resources —is implemented and developed. It draws on a document review of the grey and scientific literature, and in-depth qualitative field work carried out in four coastal districts on mainland Tanzania. The field work involved 15 key informant interviews, 12 focus groups discussion, and participant observation, documenting the perceptions of resource users. The findings indicate that marine CBNRM – operationalized largely through local organizations called Beach Management Units (BMUs) – have strong support from local communities, but emerged, persist, and scaled largely through government and donor led initiatives. The local communities' strong desire to safeguard fisheries resources and reduce overexploitation, caused by illegal harvesting practices, promoted the quick expansion of BMUs, which in turn ensured the continuation of CBNRM. The positive experience and lessons learned from BMUs established early in the process encouraged the spread and ultimately scaling out of CBNRM. Expanding and sustaining marine CBNRM beyond its current form, which relies heavily on external support, will require innovative approaches that foster collective action, identify sustainable financing mechanisms, provide clarity in roles and responsibilities, and identify cost-effective and scalable CBNRM approaches.

Populations on the periphery of a species range generally occupy marginal or less continuous habitat and can have greater extinction risk than populations in the range-center. For climate-sensitive populations on the trailing edge of a species' distribution (i.e. low latitude or low elevation), the effects of climate change are expected to compound these threats, increasing the vulnerability of these populations. The spruce grouse Canachites canadensis is a boreal forest specialist that is expected to experience range contraction at the trailing edge of its range due to climate change. In this study, we investigated the genetic structure, genetic diversity, and connectivity of spruce grouse in Minnesota, along the southeastern range limit in the United States. Clustering algorithms and genetic diversity indices suggested a single continuous population occurred throughout northern Minnesota. We detected no signatures of recent inbreeding or population bottlenecks. We used maximum likelihood population effects modeling and identified coniferous forest land cover and lower average spring temperatures as predictors of gene flow. We used two approaches based on circuit theory to map the potential for gene flow and identified regions of consistently high gene flow in the northwest and northeast of the study area. Omniscape, which incorporated additional parameters representing the likely origins of dispersers and the maximum dispersal distance, suggested a more continuous gene flow landscape than did Circuitscape. Our work highlights the current genetic integrity of one of the largest populations of the eastern subspecies of spruce grouse C. c. canadensis in the United States, identifies key landscape attributes for functional connectivity, and demonstrates complementary approaches of Circuitscape and Omniscape for gene flow mapping.

Nature-based solutions (NBS) can deliver many benefits to human wellbeing, including some crucial to climate adaptation. We quantitatively assess the global potential of NBS strategies of protection, restoration, and agroforestry by modeling global climate change mitigation and local ecosystem services (water availability, sediment retention, runoff, pollination, nitrogen retention, green water storage, and coastal protection). The strategies with the most potential to help people do not necessarily deliver the most climate change mitigation: per area of conservation action, agroforestry provides substantial benefits (>20% increase in at least one local ecosystem service) to three times more people on average than reforestation while providing less than one tenth the carbon sequestration per unit area. Each strategy delivers a different suite of ecosystem service benefits; for instance, avoided forest conversion provides a strong increase in nitrogen retention (100% increase to 72 million people if fully implemented globally) while agroforestry increases pollination services (100% increase to 3.0 billion people if fully implemented globally). One common disservice shared by all the NBS strategies modeled here is that increased woody biomass increases transpiration, reducing annual runoff and in some watersheds negatively impacting local water availability. In addition, the places with the greatest potential for climate change mitigation are not necessarily the ones with the most people. For instance, reforestation in Latin America has the greatest climate change mitigation potential, but the greatest ecosystem service benefits are in Africa. Focusing on nations with high climate mitigation potential as well as high local ecosystem service potential, such as Nigeria in the case of reforestation, India for agroforestry, and the Republic of Congo for avoided forest conversion, can help identify win-win sites for implementation. We find that concentrating implementation of these three conservation strategies in critical places, covering 5.8 million km2, could benefit 2.0 billion people with increased local ecosystem services provision. These critical places cover only 35% of the possible area of implementation but would provide 80% of the benefits that are possible globally for the selected set of ecosystem services under the NBS scenarios examined here. We conclude that targeting these critical places for protection, restoration, and agroforestry interventions will be key to achieving adaptation and human wellbeing goals while also increasing nature-based carbon mitigation.

Nature-based climate solutions (NbCSs) could play an important role in meeting the goals of the Paris Agreement. The contribution approach offers an alternative model to carbon offsetting for funding NbCSs. This paper presents three crucial design principles to help ensure the contribution approach results in high-quality climate and other benefits and avoids harms.

For many decades, food-based dietary guidelines (FBDGs) were only health-oriented. This changed post-2009 when gradually, an increasing number of countries began to include environmental sustainability considerations in their guidelines. International organisations such as the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have stated that governments should include environmental sustainability in future FBDGs. However, methodologies on how this should be done are lacking. Therefore, through workshops and discussions with experts, we analysed a selection of methodologies and classified them into six groups: (1) health first; (2) additional advice; (3) demonstrating synergies; (4) modelling impact; (5) combining strategies; (6) systems first. We then assessed how innovative each approach was and their potential for transformative impact. Of the 6 approaches investigated, only approaches 5 and 6 could be considered as disruptive innovations and leading to major changes. Adding environmental sustainability into FBDGs is a policy innovation and has become a debate between old and new multi-criteria guidelines for eating. With the addition of environmental sustainability in FBDGS, a new or emerging set of multi-criteria guidelines for judging food are being proposed that challenges past norms and governance. Today, there is growing scientific consensus that diets that are good for human health are also good for the environment. There is also a growing recognition that food system change is inevitable and desirable. We see this as a positive opportunity to collaborate on FBDGs that are more appropriate for the 21st century and ambitious enough to meet the environmental challenges at hand.