The importance of different forest management systems for people's dietary quality in Tanzania

Context

A large body of literature has shown that forests provide nutritious foods in many low- and middle-income countries. Yet, there is limited evidence on the contributions from different types of forest and tree systems.

Objectives

Here, we focus on individual trees and smaller forest patches outside established forest reserves as well as different forest management systems.

Methods

We do so by combining novel high-resolution data on tree cover with 24-h dietary recall surveys from 465 women in Tanzania.

Results

We show that people with more unclassified tree cover (i.e., individual trees and small forest patches) in their nearby surroundings have more adequate protein, iron, zinc, and vitamin A intakes. We also find that having a nearby forest under Participatory Forest Management (PFM) system is associated with higher adequacy levels of energy, iron, zinc and vitamin A. By contrast, tree cover within other types of forest (e.g., Government Forest Reserves and Government Forest Plantations) is not positively associated with people's dietary quality.

Conclusions

Our key finding is that having individual trees, smaller forest patches and/or forest under PFM in close proximity is more beneficial for people's diets than other types of established forests. Our results highlight the nutritional importance of trees outside established forests and question the often-assumed benefits of forests if these are made inaccessible by social barriers (e.g., legislation). Finally, our results emphasize the need to distinguish between different forest management systems when studying forest-diet linkages.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10980-024-01961-6.

Human behaviors driving disease emergence

Interactions between humans, animals, and the environment facilitate zoonotic spillover-the transmission of pathogens from animals to humans. Narratives that cast modern humans as exogenous and disruptive forces that encroach upon "natural" disease systems limit our understanding of human drivers of disease. This review leverages theory from evolutionary anthropology that situates humans as functional components of disease ecologies, to argue that human adaptive strategies to resource acquisition shape predictable patterns of high-risk human-animal interactions, (2) humans construct ecological processes that facilitate spillover, and (3) contemporary patterns of epidemiological risk are emergent properties of interactions between human foraging ecology and niche construction. In turn, disease ecology serves as an important vehicle to link what some cast as opposing bodies of theory in human ecology. Disease control measures should consider human drivers of disease as rational, adaptive, and dynamic and capitalize on our capacity to influence ecological processes to mitigate risk.

Even low levels of tree cover improve dietary quality in West Africa

Forests are attracting attention as a promising avenue to provide nutritious and "free" food without damaging the environment. Yet, we lack knowledge on the extent to which this holds in areas with sparse tree cover, such as in West Africa. This is largely due to the fact that existing methods are poorly designed to quantify tree cover in drylands. In this study, we estimate how various levels of tree cover across West Africa affect children's (aged 12-59 months) consumption of vitamin A-rich foods. We do so by combining detailed tree cover estimates based on PlanetScope imagery (3 m resolution) with Demographic Health Survey data from >15,000 households. We find that the probability of consuming vitamin A-rich foods increases from 0.45 to 0.53 with an increase in tree cover from the median value of 8.8 to 16.8% (which is the tree cover level at which the predicted probability of consuming vitamin A-rich foods is the highest). Moreover, we observe that the effects of tree cover vary across poverty levels and ecoregions. The poor are more likely than the non-poor to consume vitamin A-rich foods at low levels of tree cover in the lowland forest-savanna ecoregions, whereas the difference between poor and non-poor is less pronounced in the Sahel-Sudan. These results highlight the importance of trees and forests in sustainable food system transformation, even in areas with sparse tree cover.

Typical intracranial myiasis in Nigerian red river hogs (Potamochoerus porcus) caused by an unknown bot fly (Diptera: Oestridae)

We report an unknown taxon of bot fly (Diptera: Oestridae: Oestrinae) in red river hogs (Potamochoerus porcus Linnaeus, 1758) in Cross River State, Nigeria. From direct observation and interviews with local hunters, we document that, remarkably, the parasite typically occurs within the intracranial supra-meningeal space - i.e., between the inner wall of the skull and the brain - but without causing visible inflammation or clinical signs. The parasite is most similar (up to 87.9%) to Rhinoestrus usbekistanicus based on cytochrome oxidase subunit 1 DNA sequencing but is sufficiently divergent phylogenetically to represent a new or previously un-sequenced taxon. Morphologically, the parasite shares some, but not all, features with R. nivarleti. Local cultural belief systems attribute aspects of red river hog behavior (e.g. intelligence, elusiveness) to the parasite, suggesting a prolonged presence in the red river hog population. The parasite's unusual anatomic location may be aberrant, or it may be a protective adaptation to life in red river hogs, which forage vigorously with their snouts.

Deforestation reduces fruit and vegetable consumption in rural Tanzania

Two billion people across the planet suffer from nutrient deficiencies. Dietary diversification is key to solving this problem, yet many food and nutrition security policies, especially in low- and middle-income countries, still focus on increasing agricultural production and access to sufficient calories as the main solution. But calories are not all equal. Here, we show how deforestation in Tanzania caused a reduction in fruit and vegetable consumption (of 14 g per person per day) and thus vitamin A adequacy of diets. Using a combination of regression and weighting analyses to generate quasi-experimental quantitative estimates of the impacts of deforestation on people’s food intake, our study establishes a causal link between deforestation and people’s dietary quality.

Strategies to improve food and nutrition security continue to promote increasing food via agricultural intensification. Little (if any) consideration is given to the role of natural landscapes such as forests in meeting nutrition goals, despite a growing body of literature that shows that having access to these landscapes can improve people’s diets, particularly in rural areas of low- and middle-income countries. In this study, we tested whether deforestation over a 5-y period (2008–2013) affected people’s dietary quality in rural Tanzania using a modeling approach that combined two-way fixed-effects regression analysis with covariate balancing generalized propensity score (CBGPS) weighting which allowed for causal inferences to be made. We found that, over the 5 y, deforestation caused a reduction in household fruit and vegetable consumption and thus vitamin A adequacy of diets. The average household member experienced a reduction in fruit and vegetable consumption of 14 g⋅d⁻¹, which represented a substantial proportion (11%) of average daily intake. Conversely, we found that forest fragmentation over the survey period led to an increase in consumption of these foods and dietary vitamin A adequacy. This study finds a causal link between deforestation and people’s dietary quality, and the results have important implications for policy makers given that forests are largely overlooked in strategies to improve nutrition, but offer potential “win–wins” in terms of meeting nutrition goals as well as conservation and environmental goals.

Zootherapy as a potential pathway for zoonotic spillover: a mixed-methods study of the use of animal products in medicinal and cultural practices in Nigeria

BACKGROUND

Understanding how and why people interact with animals is important for the prevention and control of zoonoses. To date, studies have primarily focused on the most visible forms of human-animal contact (e.g., hunting and consumption), thereby blinding One Health researchers and practitioners to the broader range of human-animal interactions that can serve as cryptic sources of zoonotic diseases. Zootherapy, the use of animal products for traditional medicine and cultural practices, is widespread and can generate opportunities for human exposure to zoonoses. Existing research examining zootherapies omits details necessary to adequately assess potential zoonotic risks.

METHODS

We used a mixed-methods approach, combining quantitative and qualitative data from questionnaires, key informant interviews, and field notes to examine the use of zootherapy in nine villages engaged in wildlife hunting, consumption, and trade in Cross River State, Nigeria. We analyzed medicinal and cultural practices involving animals from a zoonotic disease perspective, by including details of animal use that may generate pathways for zoonotic transmission. We also examined the sociodemographic, cultural, and environmental contexts of zootherapeutic practices that can further shape the nature and frequency of human-animal interactions.

RESULTS

Within our study population, people reported using 44 different animal species for zootherapeutic practices, including taxonomic groups considered to be "high risk" for zoonoses and threatened with extinction. Variation in use of animal parts, preparation norms, and administration practices generated a highly diverse set of zootherapeutic practices (n = 292) and potential zoonotic exposure risks. Use of zootherapy was patterned by demographic and environmental contexts, with zootherapy more commonly practiced by hunting households (OR = 2.47, p < 0.01), and prescriptions that were gender and age specific (e.g., maternal and pediatric care) or highly seasonal (e.g., associated with annual festivals and seasonal illnesses). Specific practices were informed by species availability and theories of healing (i.e., "like cures like" and sympathetic healing and magic) that further shaped the nature of human-animal interactions via zootherapy.

CONCLUSIONS

Epidemiological investigations of zoonoses and public health interventions that aim to reduce zoonotic exposures should explicitly consider zootherapy as a potential pathway for disease transmission and consider the sociocultural and environmental contexts of their use in health messaging and interventions.

The forest restoration frontier

Forest restoration has resulted in approximately 300 million ha of restored forests until today. During the second decade of the twenty-first century several international initiatives have sprung up which aim to add 350 million ha of restored forest by 2030. The paper reviews the development of the forest restoration frontier. It tracks trends of the increase of restored forests, emphasizing developments since the second half of the last century. It equally reviews past and ongoing policies, programs, and projects to restore forests. Available data show how the area of restored forests has progressively increased since the 1960s. There are three major objectives to restoring forest: (1) to produce forest products (timber and other products) or spaces for recreation, (2) to produce regulatory ecosystem services (sequestered carbon, erosion control) and (3) to achieve improvement of rural livelihoods. The emphasis on each of these objectives has changed over time and each objective implied different policies and arrangements, involvement of actors and use of technology and know-how. The large international programs and projects since the beginning of the twenty-first century promote forest restoration for biodiversity conservation, regulatory ecosystem services and improving wellbeing of resident populations. Some of the findings related to the development of the forest restoration frontier since the mid-twentieth century suggest that some of the ambitious goals may be unrealistic and result in unwanted outcomes.

The importance of choosing appropriate methods for assessing wild food plant knowledge and use: A case study among the Baka in Cameroon

In tropical rainforests, access to and availability of natural resources are vital for the dietary diversity and food security of forest-dwelling societies. In the Congo Basin, these are challenged by the increasing exploitation of forests for bushmeat, commercial hardwood, mining, and large-scale agriculture. In this context, a balanced approach is needed between the pressures from forest exploitation, non-timber forest product trade and the livelihood and dietary behavior of rural communities. While there is a general positive association between tree cover and dietary diversity, the complex biocultural interactions between tropical forest food resources and the communities they sustain are still understudied. This research focuses on the knowledge and use of wild food plants by the forest-dwelling Baka people in southeast Cameroon. By using two different sets of methods, namely ex-situ interviews and in-situ surveys, we collected ethnographic and ethnobotanical data in two Baka settlements and explored the diversity of wild edible plants known, the frequency of their consumption, and potential conflicts between local diet and commercial trade in forest resources. Within a single Baka population, we showed that the in-situ walk-in-the-woods method resulted in more detailed information on wild food plant knowledge and use frequency than the ex-situ methods of freelisting and dietary recalls. Our in-situ method yielded 91 wild edible species, much more than the ex-situ freelisting interviews (38 spp.) and dietary recalls (12 spp.). Our results suggest that studies that are based only on ex-situ interviews may underestimate the importance of wild food plants for local communities. We discuss the limitations and strengths of these different methods for investigating the diversity of wild food plant knowledge and uses. Our analysis shows that future studies on wild food plants would profit from a mixed approach that combines in-situ and ex-situ methods.

Eating Bushmeat Improves Food Security in a Biodiversity and Infectious Disease "Hotspot"

Hunting and consumption of wild animals, colloquially known as "bushmeat," is associated with health trade-offs. Contact with wildlife increases exposure to wildlife-origin zoonotic diseases yet bushmeat is an important nutritional resource in many rural communities. In this study, we test the hypothesis that bushmeat improves food security in communities that hunt and trade bushmeat regularly. We conducted 478 interviews with men and women in six communities near Cross River National Park in Nigeria. We used interview responses to relate prevalence and diversity of bushmeat consumption to household food security status. Animal-based foods were the most commonly obtained items from the forest, and 48 types of wild vertebrate animals were consumed within the past 30 days. Seventy-five percent of households experienced some degree of food insecurity related to food access. Bushmeat consumption was significantly associated with relatively higher household food security status. Rodents were more important predictors of food security than other animal taxa. Despite increased bushmeat consumption in food-secure households, food-insecure households consumed a higher diversity of bushmeat species. Results show that consumption of bushmeat, especially rodents, is uniquely related to improved food security. Reliance on a wider diversity of species in food-insecure households may in turn affect their nutrition, exposures to reservoirs of zoonotic infections, and impact on wildlife conservation. Our results indicate that food security should be addressed in conservation and public health strategies aimed at reducing human-wildlife contact, and that improved wildlife protection, when combined with alternative animal-based foods, would positively affect food security in the long term.