Benefits linked to ecosystem provisioning services were the most discussed outcomes (Figure 1), these are depicted by terms like crops, firewood and water. Regulation of ecosystem processes was also frequently discussed depicted by terms such shade, erosion air and dust. Soil was the most reported term in relation to supporting services.
Figure 2 is a conceptual map of pathways from ecosystem services to health outcomes and socio-economic mediators that emerged from the discussions. The Millennium Ecosystem Assessment (MEA) Framework4 was applied to group these outcomes as ‘supporting’, ‘provisioning’, ‘regulating’ and ‘cultural’ services. This framework is widely applied for its simplicity, for example Figure 2 summarises complex interlinkages between the different outcomes, however, this framework is inadequate for informing decisions on interventions in terms of landscape management or policy strategies18,19. MEA has also been criticised for defining ‘ecosystem services’ and ‘ecosystem benefits’ interchangeably18 and for omitting intermediary components along the pathway to well-being.
An ecosystem cascade model19 provides a better framework for handling the multi-dimensional and context dependency of the impacts based on diverging respondents’ viewpoints; perceived benefits and values are subjective, for example, what may be considered a provisioning service by a given community, may play a regulating role in another community19, or even generate disbenefits. Figure 3 demonstrates application of the cascade model to draw out details across some of the complex intermediary steps and show how these relate to measurable health outcomes. There are numerous pathways to consider but the following four were apparent from the analysis i) simple pathways between the ecosystem service and health outcome ii) complex pathways to health with at least one intermediary ecosystem service iii) complex pathways to health with several intermediary ecosystem service and iv) complex pathways to health with socio-economic mediators.
i) Simple pathways to health:
Direct provisioning services such as increase in availability of wild fruits was frequently discussed and linked to health and well-being. The respondents noted a return in native tree species that were previously thought extinct, and commented on their nutritious aspects as well as a means of alleviating hunger. This is demonstrated in Figure 3(i) as a simple pathway to health.
Village 4: ‘there is one specific tree called Mkwata (Strychnos innocua) which bears fruits that are locally known as wild mangoes. People eat them when they are hungry. You will often find people coming back from the hills [presumably the community owned forests] with bags of mangoes’
Village 3: the native fruits are very nutritious when I eat Ukwata (Strychnos innocua) I feel as if I have eaten an avocado.
Wild fruits were eaten directly, converted to juices which were directly consumed or added to porridge in place of sugar.
Village 3: ‘There are plenty of native fruits at the moment, children go and pick them when we have no fruits that we buy from the market. Mdawi tree (Cordia sinensis) produces fruits that the children like, the juice is added to porridge instead of sugar.’
Some native trees were also used as traditional medicine.
Village 4: ‘One of the trees species we actively restore known as Mfuku (Acacia nilotica) can be used as medicine, if you have a cough you chew it some of the tree bark and it treats the cough’
Village 1: ‘Mfuku (Acacia Nilotica) tree is mixed with juice from the Mbuyu (Baobab) tree to treat chest pain’
ii) Complex pathways to health with one intermediary ecosystem service
This pathway highlights services generated by the regulation of ecosystem processes, such as air and water quality, climate, disease, pest and natural hazard regulation4. Figure 3 (ii) shows increased tree shading was associated with improved thermal comfort during outdoor work and reduction in adverse health effects from heat exposure.
Village 2: We had bad agricultural practices, as we use to cut trees down to the point there was no shade for resting.
Village 2: ‘The air is a lot cleaner. I recall in the past during dry and hot seasons at this time of the year, people used to be taken to hospitals with cases of dehydration…since, FMNR this condition has reduced’
Village 3: “During afternoon hours the weather is terrible due to heat…during the time of the year when we are preparing seeds for farming you find people seating under the tree shade preparing their seeds”
Previous work at the study sites showed that areas with high tree-cover were markedly cooler than those with low tree-cover20, confirming what the respondents’ experienced.
Other pathways to health that fit within this framework are linked to air and water quality and flood mitigation. Restored trees acted as wind breakers, reducing the frequency and magnitude of dust storms and resulting to improved respiratory and eye health. Increased tree cover was also associated with better accessibility to cleaner water and in one village this was linked to a reduction in water-borne diseases.
Village 4: ‘the dust used to give us sore eyes every few months…nowadays we get some eye disease but less frequently… for a period of two years since the trees matured, the dust has reduced…’
Village 1: ‘…before we were introduced to FMNR people cut down the trees…the land was barren and the severe dust storms made people cough and have chest infections’
Village 1: ‘In the past we would leave home at 4am to fetch water...it was a very long journey and we would return at 8am. It is amazing how much water we have now...children from schools in neighbouring villages come to our village to drink water...’
Village 1: ‘because of the availability of water we have seen a decrease in cholera incidences which was previously caused by consuming unsafe water’
Respondents in all the villages associated tree cover with prevention of natural hazards, specifically citing flood mitigation, and a reduction in severe winds which were responsible for destruction of property. Associated health benefits would include prevention of injuries1 although this link was not explicitly made during the group discussions.
iii) Complex pathways to health with several intermediary ecosystem services
This pathway has complex interlinkages between multiple functions and services and is well demonstrated by the impact of the restoration on soil quality (Figure 3iii). Increased tree cover enabled the functioning of other ecosystem services by promoting plant biodiversity, which generated compost and enhanced soil moisture and soil nutrients.
Village 2: In the past, we use to clear our farmlands completely but now the trees we have help nourish our farms, when the leaves fall and decompose, soil nutrient improves resulting in quality yield.
Village 2: ‘in a 2 to 3 acre farm you can have about 50 trees, once those trees have some vegetation and the rains come, underneath them the soil becomes very fertile as a result of the compost from the trees’
Improvements in soil quality was linked to nutritional security, with frequent comparisons of crops grown in the vicinity of trees and those in open fields. Tree cover and improved soil quality also increased provision of pastures, this diversified diets by increasing meat and dairy products to supplement plant based diets.
Village 4: You will find there is a difference in crops between areas practicing FMNR and the fields without trees. The crop yields are higher where farmers practice FMNR, because the soils are more fertile, and during the sunny periods the levels of humidity are higher because these areas are never overwhelmed by the sun, the soil stays moist until the rains returns.
Village 1: ‘I have noticed the crops that grow nearer the trees look very different from crops that grow on open fields. The crops growing nearer the trees are healthier…they grow differently’
Village 3: ‘ in the past manure was minimal in the soil and the vegetables had a yellow colour and were bitter in taste. But now the vegetables are greener and tastier’
Village 4: for sure if you go there now (the community forest), the grass is very tall, it is as if someone has given it manure…FMNR has helped restore the grass and the livestock have benefited.
Village 1: …where no other places have grass, our communal fields will still have grass…we feed these to cows and the milk production truly increases, a lot more than when the cattle are left to graze randomly on their own’
Restoring trees was discussed as an effective means of not only reversing degradation, but of also reducing soil erosion and surface runoff.
Village 1: One benefit of the trees is that the roots break up the ground so when the rain falls the roots leave miniscule gaps that capture the rain water into the ground. Without trees that water is carried into the gullies and is wasted
Village 4: ‘you will find that the villagers who live in the hillsides only cut their trees very sparingly because cutting down trees is not profitable, the soil will be eroded by rainwater. Trees help us prevent erosion in a similar way to those who live in the hillsides’
iv) Complex pathways to health with socio-economic mediators
Income generation was the most frequently discussed socio-economic factor, particularly in relation to income diversification through the sale of tree resources such as timber, bee keeping or selling surplus produce. Income mediated the ecological-health outcomes pathway by; improving access to previously inaccessible goods and services (education, healthcare, nutritious food) and by decreased psychological distress associated with poverty.
Village 2: “We used to hide our children because we did not have money to send them to school; but now we have surplus crops that we can sell and get money for school fees…’
Village 2: “things have improved…we have money to buy rice…the children used to have rice only during Christmas and Easter. My older children born before 2015 were accustomed to eating vegetables without peanut flour [highly nutritious and adds flavour to vegetables]. But the younger one who was born after 2015 did not experience this, they were born in time of plenty… we have enough groundnuts to make peanut flour, and we have enough sunflower to make sunflower oil"
Village 1: “One thing that has been an advantage for us as a group members [refers to members of a bee keeping group] is that we have a lot of honey, which is something that we did not have before. We did not have anywhere to put a beehive before [the restoration]”
Gender equality was another important mediator. Female respondents who did most of the labour around the house were the biggest beneficiaries of improved access to firewood and water. The benefits included improved school attendance amongst the younger girls, for adult women there was a reduction in chronic back pain, an increase in time for rest and opportunities to engage in other income generating activities.
Village 2: ‘in the past we suffered from terrible back pains from carrying firewood over long distances, practicing FMNR has reduced the journey’
Witnessing these benefits was a driver for restoration and an important means of countering the initial challenges in implementation.
Village 4: ‘initially, it was only a few of us working in a communal plot, but later even those who were mocking us and opposing the idea, began to realize the benefits and they wanted to learn about FMNR’
Village 3: ‘we are determined to continue with this practice not because we have a project but even if the project ends… because we now know the advantage and will continue regenerating trees’