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Guiding the conservation of food tree species in Burkina Faso with a threat-mapping approach

Shea tree (Vitellaria paradoxa) in agroforestry parkland. Photo by H. Gaisberger/Bioversity International
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A shea tree in agroforestry parkland. Photo by H. Gaisberger/Bioversity International

Agroforestry parklands are among the most widespread traditional land-use systems in sub-Saharan Africa, where scattered individual trees occur on cultivated fields. Over the last decades, agroforestry parklands in Burkina Faso have come under increasing demographic and climatic pressures, which are threatening indigenous tree species that contribute to rural households’ income and nutrition.

In a paper published in PLOS ONE, FTA researchers from Bioversity International and the World Agroforestry Centre analyzed 16 important food tree species in Burkina Faso and six key threats to them: overexploitation, overgrazing, fire, cotton production, mining and climate change. This analysis is crucial to plan for timely and more selective and efficient conservation actions.

Figure 2: Combined threat magnitude levels ‘high’ and ‘very high’ for all species across all threats and protected areas. Photo by H. Gaisberger/Bioversity International

Our species-specific threat model, developed with national and international partners, combines freely accessible datasets, species distribution models (SDMs), climate models and expert survey results. The model is able to predict, at a fine-scale, where multiple threats are likely to have a negative impact on the availability of suitable habitat in the present and near future. This approach helps to determine which threat contributes most to high-threat levels in certain areas of the country. This is fundamental to guide specific conservation actions such as ex situ conservation, active regeneration and tree planting.

We have found that all 16 species face serious threats throughout much of their distribution in Burkina Faso, and that climate change is predicted to be the most prevalent threat in the long term, whereas overexploitation and cotton production are the most important in the short term.

More than 55% of the distribution of ten of the species is under high or very high threat (Figure 2). Conservation plans – prioritizing the species and if possible, the populations, that are most important to local people – should be urgently developed.

For example, Vitellaria paradoxa, a multipurpose tree with a wide range of food and medicinal uses, is very highly threatened by climate change along its northern margin (Figure 3). Valuable seed sources in this area may be lost unless seed is collected for planting in more suitable climate and/or for ex situ conservation. Populations highly threatened by overexploitation in the central part of Burkina Faso should be prioritized for assisted regeneration as they grow in areas where predicted future climate would produce suitable habitat.

Figure 3: Threat magnitude levels of ‘Climate change’ for shea tree. Photo by H. Gaisberger/Bioversity International

Knowing the regions where threats are most serious allows decision-makers to plan actions at the population level to maintain the genetic diversity across the species’ distribution range. High genetic diversity is important to ensure growth and resilience to site conditions now and in the future.

In the same way, recommendations can be derived from threat maps of the other selected food tree species such as Parkia biglobosa, Adansonia digitata, Boscia senegalensis and Detarium microcarpum.

This approach can be easily used with other species and in other countries, and applied at different scales, from local to continental level, as long as appropriate spatial data and knowledgeable experts are available.

Using maps to visualize threats and their predicted impact is very powerful – it makes results easily accessible and understandable to decision-makers from private and public agencies, who can take action to conserve vulnerable species.

The GIS threat layers to create the threat maps are accessible on Dataverse.

Read the paper: Spatially explicit multi-threat assessment of food tree species in Burkina Faso: A fine-scale approach.

By Hannes Gaisberger, originally published by Bioversity International.


This study was carried out within the framework of the project ‘Threats to priority food tree species in Burkina Faso: Drivers of resource losses and mitigation measures’, financed by the Austrian Development Agency (ADA) and through contributions from the CGIAR Research Program on Forests, Trees and Agroforestry (FTA), which is supported by CGIAR Fund Donors.

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  • Spatially explicit multi-threat assessment of food tree species in Burkina Faso: A fine-scale approach

Spatially explicit multi-threat assessment of food tree species in Burkina Faso: A fine-scale approach

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Abstract

Over the last decades agroforestry parklands in Burkina Faso have come under increasing demographic as well as climatic pressures, which are threatening indigenous tree species that contribute substantially to income generation and nutrition in rural households. Analyzing the threats as well as the species vulnerability to them is fundamental for priority setting in conservation planning.

Guided by literature and local experts we selected 16 important food tree species (Acacia macrostachya, Acacia senegal, Adansonia digitata, Annona senegalensis, Balanites aegyptiaca, Bombax costatum, Boscia senegalensis, Detarium microcarpum, Lannea microcarpa, Parkia biglobosa, Sclerocarya birrea, Strychnos spinosa, Tamarindus indica, Vitellaria paradoxa, Ximenia americana, Ziziphus mauritiana) and six key threats to them (overexploitation, overgrazing, fire, cotton production, mining and climate change).

We developed a species-specific and spatially explicit approach combining freely accessible datasets, species distribution models (SDMs), climate models and expert survey results to predict, at fine scale, where these threats are likely to have the greatest impact. We find that all species face serious threats throughout much of their distribution in Burkina Faso and that climate change is predicted to be the most prevalent threat in the long term, whereas overexploitation and cotton production are the most important short-term threats. Tree populations growing in areas designated as ‘highly threatened’ due to climate change should be used as seed sources for ex situ conservation and planting in areas where future climate is predicting suitable habitats. Assisted regeneration is suggested for populations in areas where suitable habitat under future climate conditions coincides with high threat levels due to short-term threats.

In the case of Vitellaria paradoxa, we suggest collecting seed along the northern margins of its distribution and considering assisted regeneration in the central part where the current threat level is high due to overexploitation. In the same way, population-specific recommendations can be derived from the individual and combined threat maps of the other 15 food tree species. The approach can be easily transferred to other countries and can be used to analyze general and species specific threats at finer and more local as well as at broader (continental) scales in order to plan more selective and efficient conservation actions in time. The concept can be applied anywhere as long as appropriate spatial data are available as well as knowledgeable experts.

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  • Finding a way in for better landscape governance

Finding a way in for better landscape governance

A water porter makes his way to a gold panning area in Sindri village, Burkina Faso. Photo by O. Girard/CIFOR
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A dry landscape is seen in Burkina Faso. Photo by D. Tiveau/CIFOR

Study in Ghana and Burkina Faso finds an entry point for landscape approaches in natural resource management schemes.

Landscape approaches provide a framework to find solutions to social, environmental and economic challenges in Africa. In the past, sectoral approaches were often used to manage land, but more and more experts agree that integrated approaches are needed to ensure that landscapes are managed sustainably.

With this kind of approach, a landscape would be managed in such a way that it provides environmental services for more than one group or sector. For example, a single landscape could be managed in an integrated way to become a source of water for local communities and agriculture, provide trees for timber, support local biodiversity and give shade for cocoa farming. In this way, integrated landscape approaches can also contribute to solving global environmental challenges such as biodiversity loss, food insecurity and climate change.

Read also: Stepping up to the challenge to end poverty and hunger without trashing the planet

Scientists from the University of Amsterdam (UvA) and Center for International Forestry Research (CIFOR) explored three established natural resource management schemes in the West African nations of Burkina Faso and Ghana to see if they could identify locally embedded entry points for implementing integrated landscape approaches.

“All three have interacting land uses, whether through agroforestry systems common throughout Burkina Faso, or a mosaic of wildlife reserves, food production and timber tree planting in Ghana,” said researcher Mirjam Ros-Tonen from the University of Amsterdam.

“But they all face deforestation, biodiversity loss, climate change and persistent poverty,” added Samson Foli, also from UvA.

A water porter makes his way to a gold panning area in Sindri village, Burkina Faso. Photo by O. Girard/CIFOR

THREE SCHEMES, THREE RESULTS

All three schemes target landscape degradation and involve local communities. The Chantier d’Aménagement Forestier (CAF) scheme encompasses forest management sites across Burkina Faso.

In Ghana, the Modified Taungya System (MTS) aims to restore degraded forest reserves while allowing farmers to interplant food crops, and the Community Resource Management Areas (CREMAs) target wildlife conservation and livelihood diversification at the fringes of protected areas and wildlife reserves, through participatory natural resource management.

The team scored each scheme on five design principles for integrated landscape approaches derived from a previous study. These include extent of integration, adaptive management and continual learning, polycentric governance, multi-stakeholder involvement and capacity-building. The degree of alignment with these principles help identify the strengths and weaknesses of the schemes as entry points for landscape approaches.

“We found challenges in all areas to varying degrees. For example, we found that farmers in Ghana’s MTS had a share in the timber revenues but little say in the design, implementation and running of the MTS,” says Ros-Tonen.

“Secondly, farmers are unable to produce food on MTS lands after about three years when food crops do no longer survive under the shade of the canopy.”

Read also: Forests as food: New report highlights important relationship between forest landscapes and healthy diets

The study shows that a lack of long-term funding and economic incentives threaten the program, while top-down governance arrangements stifle a genuine move toward more collaborative decision-making, power-sharing and institutional diversity.

In Burkina Faso, it was a similar story.

Trees dot the scenery in the Kongoussi area, Burkina Faso. Photo by O. Girard/CIFOR

“In Burkina, the CAF scheme called for co-ops to be involved in decision-making, but a lot of the time local people don’t have the resources to go or prepare for the meetings, so they don’t attend,” Foli says.

ONE SCHEME RISES TO THE TOP

Although these two schemes could succeed if improvements are made, Ghana’s CREMA approach showed more potential.

“The CREMA does a better job at various levels by allowing people to be directly involved in conservation and natural resource use because they have total autonomy,” Foli says.

“They have the liberty to do establish ecotourism initiatives, or game sanctuaries, or other income-generating and local capacity-building projects. Because they are empowered, they have a progressive trajectory, and with government assistance, they receive periodic training from the Forestry Commission or NGOs,” he adds.

The study shows that the CREMA is the only scheme that explicitly deals with trade-offs between conservation and development aims. The CREMA was also found to take a more flexible approach compared to the other two schemes that have a more rigid decision-making structure.

The researchers found that government forestry and land-use planning institutions conduct conservation programs with little consideration for existing norms used by local people in conserving natural resources. Only the CREMA initiative takes local knowledge and practices for the conservation and sustainable use explicitly into account.

“But the CREMA isn’t perfect. We found that all three schemes needed to have a monitoring and evaluation component. This is especially needed here, as all three have been established as a response to failure of past conservation strategies. So we need to know if they are fulfilling their set goals or not,” Foli says.

MORE WORK AHEAD

The study also points to the need for continual learning and a management structure that can adapt to change. The researchers concluded that the CREMA can be improved by building platforms for the exchange and co-creation of knowledge and experimental learning at all levels. In other words, working toward a holistic landscape approach guided by an advanced set of the principles.

“We are also seeing more and more stakeholders becoming involved — NGOs, government, researchers, communities — and that’s a good thing. But for any scheme to be successful, the community and local groups need a bigger voice,” Foli says.

The researchers stress that a realistic perspective is needed to ensure integrated landscape approaches succeed, and that means being flexible in translating the guiding principles based on local context and conservation objectives.

By Suzanna Dayne, originally published at CIFOR’s Forests News


This research forms part of the CGIAR Research Program on Forests, Trees and Agroforestry, which is supported by CGIAR Fund Donors.

This research was supported by the Conservation and Sustainable use of Tropical Forest Biodiversity program financed by the United States Agency for International Development (USAID) and WOTRO Science for Global Development/Food and Business Applied Research Fund through the TREEFARMS project.

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  • Tree cover is good for ground-water too

Tree cover is good for ground-water too

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Photo: Eric Montfort/CIFOR
New study shows that a trade-off between water and tree cover doesn’t always exist. Eric Montfort /CIFOR

By Deanna Ramsay, originally published at CIFOR’s Forests News

It is not often that a study completely upends a prevailing view, and, in doing so, offers hope of improving the lives of hundreds of millions of people.

But that is exactly what research under the CGIAR Program on Forests, Trees and Agroforestry, recently published in Scientific Reports, has done for the understanding of trees and water in dry regions.

In arid places where water is scarce, the planting of trees is often discouraged out of the belief that trees always reduce the availability of much-needed water.

Yet scientists working in Burkina Faso found that when a certain number of trees are present, the amount of groundwater recharge is actually maximized.

The study is a “game changer”, according to one of the study’s authors, Douglas Sheil, professor at the Norwegian University of Life Sciences and a senior research associate with the Center for International Forestry Research (CIFOR).

“We don’t get so many scientific studies in our lives where we see such a potential shift in how we do something,” Sheil said.

“It is very dramatic in the sense that it totally overturns the way we had looked at trees and water availability.”

WET WET WET

Previously, few studies had examined tree cover in the tropics or what effect scattered, or intermediate, tree cover might have on water yields.

Drawing on the idea that trees can improve the movement of water in soil, the scientists worked with an ‘optimum tree cover theory’ that would provide for the maximum amount of groundwater recharge.

The research bridges two contrasting views on forests and water: the ‘trade-off theory’ and the ‘sponge theory’, explained Aida Bargués Tobella of the Swedish University of Agricultural Sciences, one of the study’s lead authors.

The ‘sponge theory’ holds that forests soak up water during the rainy season and slowly release it during the dry season, thereby sustaining stream flow during dry periods, whereas the ‘trade-off theory’—which has become the dominant paradigm—holds that more trees equals less water.

“Both perceptions are true to some extent, but what we show is that the net effect of trees on groundwater recharge depends on the degree of tree cover,” Bargués Tobella said.

“So trees can improve groundwater recharge to a point.”

By testing groundwater levels both near and far from trees in a typical semi-arid landscape over several years, the researchers found that an intermediate amount of tree cover created conditions in which more water was available than if there were no trees or a large number of them.

“Without trees, these sensitive tropical soils lose their large pores, which are responsible for leading water down into the ground quickly,” said Ulrik Ilstedt of the Swedish University of Agricultural Sciences (SLU), the study’s other lead author.

“Without these pores, the water flows away on the soil surface or is trapped in the compact soil surface and evaporates.”

“With that said, if there are too many trees, they will still consume more water than what is gained by their soil improvement.”

Other factors that also affect water availability include tree species, soil quality and type, and climate.

This study was done on a type of soil that is widespread in the tropics, but there are other types of less sensitive soils that would not have produced the same positive effects, according to Ilstedt.

However, some 70 percent of the semi-arid tropics have soils similar to those used for this research, he added.

“The most important point of our study is to show that a trade-off between water and tree cover doesn’t always exist, and that more trees can actually improve groundwater recharge,” Bargués Tobella said.

“This means that people could benefit from the many goods and services that trees provide while also seeing improved water availability.”

And with 340 million people in Africa lacking access to adequate and hygienic sources of water, that’s a lot of benefits.

GIVING TREES

The benefits of trees in the seasonally dry tropics for people in their daily lives are myriad and varied.

In particular, in the study area of Saponé in Burkina Faso, Shea trees dominate: the more Shea trees there are, the more nuts local people can sell.

Trees also support erosion control and climate change mitigation.

“With greater tree cover, there are also benefits like biodiversity, carbon and wood fuel that were being denied before,” Sheil said.

“Large areas of the arid tropics actually have no tree cover, and having more trees would be advantageous, as it would give people more access to fuelwood, fruit and many other benefits.”

The findings from the study enable people to control and manage such conditions by planting more trees, Sheil added, noting that it presented an opportunity for donor organizations to start working to support land management that facilitated the planting of trees in water-deprived areas.

For instance, this research is extremely relevant for ongoing tree-based restoration efforts in the Sahel region, such as the Great Green Wall Initiative or the African Forest Landscape Restoration Initiative (AFR100).

SUSTAINABLE DEVELOPMENT GOALS

Goal Number Six of the recently agreed upon Sustainable Development Goals (SDGs) is to increase access to clean water, with the recognition that water is a basic human requirement.

Landscapes such as those studied in Burkina Faso house some of the world’s poorest people, where, as the study notes, limited water not only constrains food production, nutrition and health, but also reduces opportunities for education, work and improved livelihoods.

The finding that increased tree cover in tropical dry regions could increase people’s access to water could therefore have a major impact on their lives, the researchers believe.

“The study needs to repeated in other sites as the optimal tree cover will vary with conditions, and with the species involved, but there is no good reason not to expect similar results in other parts of the tropics,” Sheil said. “I think this will have global significance.”

 

This research forms part of the CGIAR Research Program on Forests, Trees and Agroforestry.

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