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The effect of tropical deforestation on heat exposure and subsequent human health outcomes remains understudied, especially among an increasingly vulnerable population—healthy, adult subsistence workers in rural industrializing tropical countries. We report on a field experiment that estimated the short-term effects of heat exposure from deforestation on cognitive performance. We randomly assigned rural, adult subsistence workers in East Kalimantan, Indonesia to deforested or forested settings, and standard or high incentive piece rate payments. Participants worked in forested or deforested settings for up to 90 min, where ambient and black globe temperatures in deforested areas were, on average, 2.1 °C and 10 °C higher. After completing the experimental task, participants were asked to take a validated general cognitive assessment test (CAT) and episodic memory test (EMT). We found participants in deforested settings had statistically significant lower scores on both CAT and EMT. Effects were largely driven by heat effects on male participants and those working after noon. Our results highlight how heat exposure from tropical deforestation may lead to declines in cognitive performance even in favorable work settings. Policymakers should consider how land use planning that takes into account the cooling services of trees can play a significant role in increasing resilience to heat from climate and land use change in the tropics.

Background. With climate change, adverse human health effects caused by heat exposure are of increasing public health concern. Forests provide beneficial ecosystem services for human health, including local cooling. Few studies have assessed the relationship between deforestation and heat-related health effects in tropical, rural populations. We sought to determine whether deforested compared to forested landscapes are associated with increased physiological heat strain in a rural, tropical environment. Methods. We analyzed data from 363 healthy adult participants from ten villages who participated in a two-by-two factorial, randomized study in East Kalimantan, Indonesia from 10/1/17 to 11/6/17. Using simple randomization, field staff allocated participants equally to different conditions to conduct a 90 min outdoor activity, representative of typical work. Core body temperature (CBT) was estimated at each minute during the activity using a validated algorithm from baseline oral temperatures and sequential heart rate data, measured using chest band monitors. We used linear regression models, clustered by village and with a sandwich variance estimator, to assess the association between deforested versus forested conditions and the number of minutes each participant spent above an estimated CBT threshold of 38.5 °C. Results. Compared to those in the forested condition ( n = 172), participants in the deforested condition ( n = 159) spent an average of 3.08 (95% confidence interval (CI) 0.57, 5.60) additional minutes with an estimated CBT exceeding 38.5 °C, after adjustment for age, sex, body mass index, and experiment start time, with a larger difference among those who began the experiment after 12 noon (5.17 [95% CI 2.20, 8.15]). Conclusions . In this experimental study in a tropical, rural setting, activity in a deforested versus a forested setting was associated with increased objectively measured heat strain. Longer durations of hyperthermia can increase the risk of serious health outcomes. Land use decisions should consider the implications of deforestation on local heat exposure and health as well as on forest services, including carbon storage functions that impact climate change mitigation.

Growing threats and limited resources have always been the financial realities of biodiversity conservation. As the conservation sector has matured, however, the accountability of conservation investments has become an increasingly debated topic, with two key topics being driven to the forefront of the discourse: understanding how to manage the risks associated with our conservation investments and demonstrating that our investments are making a difference through evidence-based analyses. A better understanding of the uncertainties associated with conservation decisions is a central component of managing risks to investments that is often neglected. This focus issue presents both theoretical and applied approaches to quantifying and managing risks. Furthermore, transparent and replicable approaches to measuring impacts of conservation investments are noticeably absent in many conservation programs globally. This focus issue contains state of the art conservation program impact evaluations that both demonstrate how these methods can be used to measure outcomes as well as directing future investments. This focus issue thus brings together current thinking and case studies that can provide a valuable resource for directing future conservation investments.

Conservation projects occur under many types of uncertainty. Where this uncertainty can affect achievement of a project’s objectives, there is risk. Understanding risks to project success should influence a range of strategic and tactical decisions in conservation, and yet, formal risk assessment rarely features in the guidance or practice of conservation planning. We describe how subjective risk analysis tools can be framed to facilitate the rapid identification and assessment of risks to conservation projects, and how this information should influence conservation planning. Our approach is illustrated with an assessment of risks to conservation success as part of a conservation plan for the work of The Nature Conservancy in northern Australia. Risks can be both internal and external to a project, and occur across environmental, social, economic and political systems. Based on the relative importance of a risk and the level of certainty in its assessment we propose a series of appropriate, project level responses including research, monitoring, and active amelioration. Explicit identification, prioritization, and where possible, management of risks are important elements of using conservation resources in an informed and accountable manner.