New study in Science: Joint environmental and social benefits from diversified agriculture

Together with Prof. Ingo Grass from the University of Hohenheim in Germany – and 57 co-authors, we examined the effects of agricultural diversification strategies on both environmental and social outcomes. We did so by harmonizing data from 24 studies across 11 countries. We found that farmers who implemented multiple diversification strategies in tandem had more win-win outcomes.

New study in PNAS Nexus

We examine the empirical relationship between having forests and trees in the surroundings and the probability of children consuming nutritious 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 even low levels of tree cover improve the likelihood of children aged 12–59 months consuming vitamin A–rich foods. 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.

New study in Nature – Sustainable Agriculture

We show how forest regrowth in Nigeria has affected people’s dietary quality. We do so by combining a new map on forest regrowth with food consumption panel data from over 1100 households.

We use a a combination of regression and weighting analyses to generate quasi-experimental quantitative estimates of the impacts of forest regrowth on people’s food intake. We find that people living in areas where forest regrowth has occurred have a higher intake of fruits and vegetables and thus higher dietary diversity.

New study in Nature Food

We examined monthly variation in women’s wild food consumption in two districts in India. After identifying that women most frequently consumed foods from forests and common lands in June and July, we estimated the contribution of wild food consumption to dietary diversity (a measure of diet quality), in these months. We used matching — a rigorous, quasi-experimental method — and regression analysis to isolate the causal relationship between wild food consumption and dietary diversity. Women who consumed wild foods were matched to women who did not consume wild foods on key socioeconomic, dietary and forest-level covariates – to ensure that differences in dietary diversity could be attributed to wild food consumption.

We found that women who consumed wild foods had higher average dietary diversity. In June, those women consumed an extra 0.34 food groups and, in July, they consumed an extra 0.30 food groups compared to women who did not consume wild foods.

My little guide to wild foods

Research on how to improve food and nutrition security has the potential to make real-life contributions for local communities suffering from nutrient deficiencies. Yet, most research remains inaccessible to people who could benefit from it. To elevate the impacts of research beyond a scientific paper, we developed and distributed a children’s book on wild foods in Malawi and Tanzania.

The book contents are based on results obtained from data on wild food consumption in Malawi and Tanzania, collected by PhD students Emilie Vansant and Rasmus Skov Olesen. Together they surveyed more than 1000 households across 16 sites in the two countries. The book is designed to educate young children in rural Africa about how wild foods from the forest can contribute to healthy diets. The illustrations were developed in collaboration with graphic facilitator Mette Jeppesen and highlight the importance of consuming foods rich in micronutrients, such as Vitamin A. To better acquaint children with their surrounding landscape, it features common tree species (e.g. wild custard apple, wild java plum) and green leafy plants (e.g. wild cow peas, black jack) and their various functions, including providing nutrient-rich fruits and vegetables.

We traveled to Tanzania and Malawi in March 2023 and distributed the book to ~1500 children across 16 schools through interactive workshops designed to engage students with the book’s contents. When distributing the book to school children, the book was first read out loud to the children with the help of local research assistants. Graphic Facilitator Mette sketched a human body and explained how eating nutritious fruits and vegetables can be good for your eyesight, strength and health. The workshops finished with a drawing activity, where the children were invited to pick certain leaves and fruits to draw together on large sheets of paper. These collective ‘nutritious landscape drawings’ were then left to decorate the classrooms.

New study published in One Earth

Achieving food and nutrition security for the world’s population while at the same time reversing and minimizing damage to the natural environment is a grand societal challenge. A growing body of evidence has shown that access to forests can support food security in some settings, but the linkages between forests and people’s diets are not well understood. The goal of this review is to provide an overview of the explanations behind observed associations between forests and food and nutrition security. We found that 77% of publications show that forests contribute positively to food and nutrition security. The two main explanations are (1) the direct provision of forest foods and (2) indirect effects from forest-based ecosystem services on surrounding agriculture. Our findings suggest that it is pertinent to rethink the dichotomy between agriculture and nature and move toward more integrated nutrition-sensitive landscapes.

Systematic Literature Review: Tree-based farming systems can be a win-win for people and nature

Fruit and timber trees scattered within maize fields in Mulanje District, Malawi (photo credit: Emilie Vansant)

A new paper was published in People & Nature by Emilie Vansant in collaboration with a team of scientists at CIFOR-ICRAF. The study reviews literature linking tree-based farming systems and dietary quality in low- and middle-income countries (LMICs). The synthesis of 36 studies finds:

  1. Maintaining trees in and around farmland – and using these trees for both the direct provision of foods and as a source of income – can serve as a key strategy for households to diversify food consumption and improve dietary quality.
  2. How much a tree-based farming system can influence diets is dependent on policies and institutions at the national scale, bioclimatic and geographical factors at the landscape scale, as well as socioeconomic factors at both the landscape and household levels.
  3. Indigenous populations practicing traditional forms of tree-based farming (which are often diverse systems integrated with wild landscapes) seem to maintain high levels of dietary quality through sourcing food from both wild and cultivated areas

The existing evidence, though limited, points at important knowledge gaps – namely the lack of a typology of tree-based farming systems to facilitate objective comparisons across cultural and geographical contexts. Additionally, there is a paucity of research that explicitly examines the role of non-forest trees in influencing dietary quality. By recognizing the potential of trees to contribute to positive nutritional outcomes in rural communities, this study supports the development of nutritionally-sensitive landscapes in LMICs.

Promotion of the article in CIFOR’s Forest News blog:

Read the full article here.

New study published in PNAS – “deforestation reduces fruit and vegetable consumption in rural Tanzania”

Using a novel modelling technique which combined two-way fixed effects modelling with covariate balancing generalised propensity score (CBGPS) weighting analyses, we were able to isolate deforestation as a causal factor in the decline in household dietary quality over the study period. Specifically, for the average household who experienced a loss of 171 hectares of forest, fruit and vegetable intake decreased by 14 grams per person per day. Given the very low intake of fruit and vegetables in these communities (130 grams per person per day on average, relative to the recommended intake of 400 grams per day), this represented a substantial proportion (11%) of daily intake. Exploration into the potential causal mechanisms of this reduction pointed towards the ‘direct consumption pathway’, indicating that deforestation reduced people’s ability to directly source wild fruits and vegetables from the forest. Given the high vitamin A content of these types of foods, deforestation was also responsible for a reduction in micronutrient adequacy of people’s diets. The results of this study have important implications for policy makers. Strategies to achieve food security very rarely attend to the role of forests, and often promote agricultural intensification and expansion which often comes at the expense of forest landscapes. This study, showing that deforestation caused a decline in dietary quality, highlights the need to better understand the importance of forests for nutrition in certain settings. Indeed, conserving forests potentially offer win-wins in terms of meeting both nutrition goals as well as conservation and environmental goals.  

This new study, published in PNAS, is the first of its kind to establish a causal link between deforestation and people’s dietary quality. While many studies in recent years have found positive associations between living in/near forests and people’s diets in low- and middle-income countries, none to date have established a causal relationship. We used food consumption data from the World Bank’s Living Standards Measurement Study (LSMS) which was collected as part of a panel study from 2008 to 2013 across Tanzania. We examined 1256 rural households that were part of the panel study and used the food consumption data to assess their dietary diversity, dietary adequacy (in terms of calorie and nutrient intakes), and consumption of nutritionally important food groups (i.e. fruits and vegetables). Over the five-year study period, there was a general decline in dietary quality across the sample households. We used the Hansen et al. (2013) tree cover dataset to calculate the extent of forest loss over the study period, measuring forest loss in a ten kilometre radius around clusters of households. The average household experienced a loss of 171 hectares of forest in the surrounding area over the five years.