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Woody Weeds activities continue after project end

The Woody Weeds project will finish this year. Nevertheless, new initiatives will continue the work and use the knowledge generated by project activities to support implementation of the Kenyan National Prosopis Strategy (NPS).

The successful Woody Weeds project has generated knowledge about the invasion by Prosopis and Lantana in Eastern Africa, which was in part the result of work done by eight PhD and ten MSc students, who did (and do) their research on social and ecological effects and the management of these species as part of the Woody Weeds project. Throughout the six years of the project, the team members closely cooperated with stakeholders from the local to the national level in each of the three target countries, i.e. Tanzania, Kenya and Ethiopia.

The results and knowledge generated through the Woody Weeds project, which have been published in leading international journals, are being utilised in two follow-up projects and for decision making on the national scale. Moreover, participants in the Woody Weeds project are members of national working groups that develop strategies to deal with invasive alien species (IAS) in all three countries where the project operates.


Schematic view of the overlap of the Woody Weeds projects, follow-up projects and the implementation phase of the Kenyan National Prosopis Strategy.

Last year, a Transformation Acceleration Grant was awarded to the Woody Weeds team in Kenya and Switzerland under the Swiss r4d programme, which aims to participate in the development of the Kenyan NPS and to upscale our currently on-going activities at the local scale to co-design Prosopis management at the County level. This small project will continue until the end of 2021. The main focus of the activities funded by the Grant will be on Baringo County and will be out-scaled to a second County.

A new project, “Woody Weeds +”, brings together Swiss and Kenyan partners of the Woody Weeds project, the University of Nairobi and Farmbetter Ltd. Woody Weeds + will implement the newly established NPS, jointly with relevant stakeholders, in a target area stretching from West to East along the southern edge of Kenya’s northern rangelands, targeting areas in Baringo, Isiolo and Tana River counties. Farmbetter Ltd. will contribute an app which will help boosting information dissemination, awareness raising and decision support within and beyond the target area. The new project is funded by the Swiss Agency for Development and Cooperation (SDC).

The two new projects described above focus on Kenya, but the Woody Weeds partners are also exploring opportunities to continue with our activities in Ethiopia and Tanzania.

Well-coordinated, multi-agency approach to manage Prosopis in Kenya


Simon Choge of the Kenyan Forestry Research Institute, Marigat sub-centre, will lead the National Centre of Excellence on Prosopis.

In 2020, the Kenyan Government has decided to develop a National Prosopis Strategy that aims to implement a well-coordinated, multi-agency approach to manage the highly invasive tree Prosopis juliflora. Native to the Americas., this tree was introduced to Kenya in the early 1970s to provide a source of wood material, fodder and to stabilize degraded ecosystems. However, soon after the introduction Prosopis started to spread and invade grasslands, cropland and biodiversity hotspot areas, particularly in riparian ecosystems. Until recently, Kenya has promoted a ‘management by utilization approach’ to reduce the impacts of this tree on livelihoods and ecosystems. However, as shown by the Woody Weeds project for Baringo County, this approach has not slowed down the spread of Prosopis as intended. The new National Prosopis Strategy, to which partners of the Woody Weeds project contributed through useful data generated by the project as well as expertise, aims to integrate different management approaches, including chemical, physical and biological control in order to reduce invasions followed by reclamation and restoration of the affected areas. The National Strategy also underlines the need to halt further spread of this highly invasive tree by activating prevention, early detection and rapid response mechanisms in newly invaded areas or those with high potential for invasion.

Invasive tree, Prosopis juliflora, seriously reduces water resources in Ethiopia, costing rural livelihoods, new research reveals

(reblogged from https://www.cabi.org/news-article/invasive-tree-prosopis-juliflora-seriously-reduces-water-resources-in-ethiopia-costing-rural-livelihoods-new-research-reveals/)

New research has revealed how an invasion of the alien evergreen tree, Prosopis juliflora seriously diminishes water resources in the Afar Region of Ethiopia, consuming enough of this already scarce resource to irrigate cotton and sugarcane generating some US$ 320 million and US$ 470 million net benefits per year.


Prosopis invasion. Photo: Urs Schaffner.

A team of Ethiopian, South African and Swiss scientists, including lead author Dr Hailu Shiferaw, Dr Tena Alamirew, and Dr Gete Zeleke from the Water and Land Resource Centre of Addis Ababa University, Ethiopia, and Dr Sebinasi Dzikiti from Stellenbosch University, South Africa, and Dr Urs Schaffner, Head Ecosystems Management, CABI, have been assessing water use of prosopis and its impacts on catchment water budget and rural livelihoods in the dry Afar Region of Ethiopia, since 2015 as part of a long-term collaboration in the framework of the CABI-led Woody Weeds project.

Their new study, published in Scientific Reports, provides evidence that this alien tree, which has invaded both the floodplains of the Awash River and the surrounding dryland habitats, uses excessive amounts of water by consuming approximately 3.1-3.3 billion m3/yr of water throughout the year in the Afar Region.

Dr Shiferaw said, “We found that single trees of the evergreen prosopis consume between 1-36 liters of water per day, depending on stem diameter and site conditions. Prosopis trees not only use water throughout the year, but even consume more water during the dry season, when almost all native plants have shed their leaves. The high sap flow of prosopis in the drylands throughout the year may be due to exceptionally deep roots that penetrate up to 50m below the surface, where they tap into groundwater that cannot be used by native trees with shorter roots.”

In the context of climate change and an increasing frequency of drought events in dry regions of Sub-Saharan Africa, the report concludes that this invasive tree is likely to have serious consequences for sustainable livelihoods in the region unless its spread is contained and its density reduced.

Dr Urs Schaffner, senior author and Head Ecosystems Management at CABI in Switzerland, said, “Since its introduction in the Afar Region in the 1980s, prosopis has invaded 1.2 million ha of land. Thus, unless the spread of prosopis is contained and the density reduced in areas where it has become established, this invasive tree is likely to have serious consequences for sustainable livelihoods in the region. The estimated net benefits from water savings alone would strongly justify the implementation of a coordinated control programme.”

The report clearly supports findings from work undertaken in South Africa on water use by invasive tree species. Prof Brian van Wilgen from Stellenbosch University, South Africa, previous scientific advisor to the ‘Working for Water’ programme in South Africa and partner of the Woody Weeds project, said, “In South Africa, invasive alien trees are estimated to reduce surface water runoff by between 1.5 and 2.5 billion m3 per year, and this could increase substantially as the invasions continue to spread. In addition, invasive trees in drier parts of the country have substantially reduced water in groundwater aquifers on which local farmers and towns are totally reliant.”

He further explained that, “These losses have serious consequences for a country where water scarcity limits economic activity and growth. The government in South Africa has responded by creating a multi-million dollar, national-scale programme, dubbed ‘Working for Water’, to control invasive alien trees, and has also passed legislation preventing further propagation of invasive alien trees and requiring landowners to control them.”

Hailu Shiferaw, Tena Alamirew, Sebinasi Dzikiti, Woldeamlak Bewket, Gete Zeleke and Urs Schaffner, ‘Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia,’ Scientific Reports, 29 January 2021, DOI: 10.1038/s41598-021-81776-6

Restoration of degraded grassland can benefit climate change mitigation and key ecosystem services

Reblogged from cabi.org

An animation summarising the results is also available!

New research has demonstrated how, in contrast to encroachment by the invasive alien tree species Prosopis julifora (nationally known as `Mathenge` or `Promi` in Baringo), the restoration of grasslands in tropical semi-arid regions can both mitigate the impacts of climate change and restore key benefits healthy grasslands provide for pastoralists and agro-pastoralist communities.


Prosopis invasion. Photo: Urs Schaffner.

A team of Kenyan and Swiss scientists, including lead author Ms.Purity Rima Mbaabu, affiliated to Kenya Forestry Research Institute, Institute for Climate Change and Adaptation of University of Nairobi and Chuka University and Dr Urs Schaffner from CABI’s Swiss Centre in Delémont, assessed how invasion by P. julifora and the restoration of degraded grasslands affected soil organic carbon (SOC), biodiversity and fodder availability.

The study, published in Scientific Reports, revealed that degradation of grasslands in Baringo County, Kenya, has led to a loss of approximately 40% of SOC, the most important carbon pool in soils. These findings confirm that grassland degradation significantly contributes to the release of greenhouse gases and thus to climate change. The authors also showed that 30 years of grassland restoration replenished SOC to a soil depth of 1 metre at a rate of 1.4% per year and also restored herbaceous biomass to levels of pristine grasslands, while plant biodiversity remained low. Invasion of P. julifora, on the other hand, increased SOC primarily in the upper 30cm and suppressed herbaceous vegetation.

Grasslands comprise 40% of the Earth’s natural vegetation and contain a substantial amount of the world’s SOC. In supporting the livelihoods of over one billion people worldwide, they provide a home to a wide variety of animals and plants and support other ecosystem services such as the regulation and storage of water flows, forage for livestock production and tourism.

However, grasslands are under severe threat from degradation, conversion to other land uses as well as from encroachment by P. julifora which has accounted for the disappearance of over 30% of grasslands in Baringo County.

The scientists say that efforts to reverse land degradation in Baringo County and other parts of Sub-Saharan Africa should consider restoration of historical grasslands and their associated ecosystem services. To meet the needs of wood, the planting of native trees should be promoted on land which historically used to be forested.


A restored grassland in Baringo County (Credit: Ms. Purity Rima Mbaabu)

Ms Mbaabu said, “The importance of managing grasslands to optimise carbon sequestration for climate change mitigation is widely recognised. Soils are the largest terrestrial carbon reservoir containing more carbon than the vegetation and the atmosphere combined.

“Yet, soil organic carbon, which makes up about two thirds of global soil carbon, is sensitive to land degradation with significant negative consequences for soil quality and productivity and an exacerbation of greenhouse gas emissions.”

Prof Olago from the Institute for Climate Change and Adaptation of the University of Nairobi emphasized that: “Halting and reversing land degradation and restoring degraded soils and their associated services in rangelands is essential for climate change mitigation and for ensuring resilient agro-ecological systems that underpin sustainable rural livelihoods and that meet medium to long-term sustainable development objectives such as the 2030 global sustainable development goals (SDGs) and Africa’s Agenda 2063. The choices taken on how to manage our soil resources today will have wide-ranging consequences for human wellbeing for generations to come.”

Dr Schaffner said, “Our results provide evidence that the replenishment of the soil organic carbon stocks through restoration of degraded grasslands can be achieved within 20-30 years and does not lead to multiple trade-offs with fodder for livestock and other ecosystem services.

“The extent to which grassland restoration will increase primary productivity and soil organic carbon, however, will depend on socio-economic factors including land tenure systems and enforcement of land use rights affecting the level and type of grazing management.”

Prosopis was introduced into Baringo County in the early 1980s through the Fuelwood Afforestation Extension Project which aimed to mitigate firewood scarcity and desertification. However, soon after its introduction Prosopis started to escape from the plantations and to invade the surrounding ecosystems. Today, the costs of Prosopis and other invasive trees and shrubs, such as Lantana camara and Chromolaena odorata, in South Africa alone are estimated to cost USD$1 billion a year.

Full paper reference

Purity Rima Mbaabu, Daniel Olago, Maina Gichaba, Sandra Eckert, René Eschen, Silas Oriaso, Simon Kosgei Choge, Theo Edmund Werner Linders, & Urs Schaffner, ‘Restoration of degraded grasslands, but not invasion by Prosopis julifora, avoids trade-offs between climate change mitigation and other ecosystem services,’ Scientific Reports, 24 November 2020, DOI: 10.1038/s41598-020-77126-7
This paper is available to view open access here: http://www.nature.com/articles/s41598-020-77126-7

All Woody Weeds videos together on one page

Over the past years we have made videos that showcase various aspects of the Woody Weeds project, including stakeholder engagement, activities in different countries and sustainable management practices for Lantana and Prosopis.
Below, these are brought together:

  • The Woody Weeds project in Ethiopia
  • The Woody Weeds project in Tanzania
  • Amina talks about being a PhD student in the Woody Weeds
    project
  • Tanzanian new invasive species Task Force
  • Removing Prosopis fosters peace in Ruko Conservancy in Kenya
  • Responding to Invasive Trees – Community Voices
  • (part of the Digital Storytellers project)

  • How can we manage invasive weeds in arable lands? – Community Voices
  • (part of the Digital Storytellers project)

    The-effect-of-management-by-different-landowners

    What factors are associated with long-term Prosopis management success in South Africa?

    Through the Working for Water Programme, the South African government has been clearing plots of Prosopis and other invasive plants since 1995. Some farmers started with management even before 1995 and some still haven’t started with management. Several factors affect the ability of the landowner to manage the invasion, with the main factor being funding. It is extremely expensive to manage Prosopis and often, especially in very dense stands, the cost of management outweighs the cost of the land per hectare.

    Jano Barnard investigates the effect of the management of the invasive Prosopis tree on its abundance as part of his MSc research project with the Centre for Invasion Biology at Stellenbosch University. The study is conducted in the low-lying area between the small towns of Carnarvon and Vanwyksvlei in the Northern Cape province of South Africa. Prosopis heavily invaded this area in the past 100 or more years and the management of Prosopis only recently became a priority for both private landowners and the government.

    Jano shows Prosopis in the landscape where is conducting his MSc reasearch in the video above.

    Trend analysis of a time-series of satellite imagery is used to highlight episodes of Prosopis clearing and regrowth. Comparing these with neighbouring unmanaged sites can increase the chance of correct identifications of clearing and regrowth. Through this research, Jano aims to evaluate what types of management are effective for the long-term reduction of Prosopis abundance on several privately and government-managed sites.

    Scientists suggest global guidelines for sustainable use of non-native trees to protect worldwide biodiversity

    (Reblogged from www.cabi.org)

    A team of international scientists have collaborated to propose a series of global guidelines for the sustainable use of non-native tree species to help protect biodiversity and ecosystems around the world already threatened by climate change.

    The new paper, published in the journal NeoBiota, uses the Council of Europe – Bern Convention Code of Conduct on Invasive Alien Trees as a starting point, to present eight recommendations all aimed at maximising the benefits of non-native trees, while minimising their negative impacts.

    The guidelines include using native trees, or non-invasive non-native trees as opposed to invasive non-native trees, being aware of the risk of invasion and consider global change trends and developing and supporting global networks and collaborative research and information sharing on native and non-native trees.

    The scientists suggest that the guidelines are a first step towards building a global agreement on the precautions that should be taken when introducing and planting non-native trees and serve to complement statutory requirements under international and national legislation.

    Lead author Dr Giuseppe Brundu, from the University of Sassari, Italy, said, “The application of the global guidelines and the achievement of their goals will help to conserve forest biodiversity, ensure sustainable forestry, and contribute to the achievement of several Sustainable Development Goals (SDGs) of the United Nations linked with forest biodiversity.”


    Prosopis juliflora, where in Afar County, Ethiopia, its coverage rapidly increased to 1,2 million ha in just 31 years (Credit: CABI).

    The researchers highlight how non-native species – such as Prosopis juliflora which was introduced in Eastern Africa in the 1970s to provide wood and fodder for livestock and help reduce soil erosion and the effects of dust storms – make up 44% of plantation forests globally.

    They point to major tree planting campaigns, including the 60 Million Trees Initiative from the Madagascar Government, which either do not specify or include non-native species planted – often to balance economic and ecological interests as with the case in Madagascar. Other similar schemes have included 60 million trees planted in Italy – one for each Italian citizen to fight climate change – where a mix of native and non-native tree species were recommended.

    However, the scientists warn that unless their global guidelines are taken seriously the spread of non-native tree species will make the conservation of forest biodiversity and work towards achieving a number of SDGs – linked with forest sustainability – difficult to achieve.

    Professor Dave Richardson, co-author from Stellenbosch University, South Africa, said, “The global guidelines on non-native tree species offer general recommendations and provide a basic framework and suggestions on tools for planning and implementing sustainable use of non-native trees in nationally appropriate and scientifically sound practices that account for national and sub-national needs.”

    Dr Urs Schaffner, co-author and Head Ecosystems Management at CABI Switzerland, is an expert on Prosopis juliflora and believes such invasive trees can also impact severely on rural people’s livelihoods with, for example, 86% losses in grassland experienced in Baringo Country, Kenya.

    Dr Schaffner added, “It is important to bear in mind that national circumstances vary considerably in terms of biophysical conditions, institutional and legal frameworks, economic challenges and possibilities, management, and use, among other factors.

    “Therefore, no ‘one-size-fits-all’ approach can be applied in the implementation of the guidelines. Instead, various technical and organisational options must be combined to achieve efficient implementation of the guidelines.”

    Reference:

    Brundu G, Pauchard A, Pyšek P, Perg J, Bindewald AM, Brunori A, Canavan S, Campagnaro T, Celesti-Grapow L, Dechoum M de S, Dufour-Dror J-M, Essl F, Flory LS, Genovesi P, Guarino F, Guangzhe L, Hulme PE, Jäger H, Kettle CJ, Krumm F, Langdon B, Lapin K, Lozano V, Le Roux JJ, Novoa A, Nuñez MA, Porté AJ, Silva JS, Schaffner U, Sitzia T, Tanner R, Tshidada N, Vítková M, Westergren M, Wilson JRU, Richardson DM, ‘Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts,’ NeoBiota, 2020. DOI: 10.3897/neobiota.61.58380

    National Task Force to Manage Invasive Species in Tanzania

    Tanzania is known for its rich biodiversity, beautiful range lands, for wildlife and fertile plains for agriculture. However, these natural systems are threatened by hundreds of invasive species that affect livelihoods of people. To address the threat and the need to find solutions, the Government of Tanzania formed a National Task Force to Manage Invasive Species. The Task Force was inaugurated by the Vice President of the United Republic of Tanzania Hon. Dr. Samia Suluhu.

    The Woody Weeds project has worked in Amani, Tanga Region, and Kahe, Kilimanjaro Region, since 2015 to manage invasive woody species and mitigate their negative impact on livelihoods, biodiversity and ecosystem services. The project has a significant contribution in providing information necessary for management of invasive species in Tanzania. Three members of the Woody Weeds project (Dr. John R. Mbwambo, Dr. Charles J. Kilawe and Dr. Ezekiel E. Mwakalukwa) are members of the National Task Force which the Government formed. The Woody Weeds project is working with the Government through research and training institutions to generate information necessary for decision making in combating invasive species.

    Removing Prosopis fosters peace in Ruko Conservancy

    Ruko Conservancy in Baringo, Kenya, has removed all Prosopis juliflora from its area with support of the Woody Weeds project. The conservancy was established to foster peace between the Pokot and Ilchamus communities and to conserve the natural resources of the area. Recently P. juliflora has started invading the area, threatening biodiversity and access to land. Since the invasion was still in an early stage, the best option was to remove it from the entire conservancy area. In the video below, members of both communities explain the work and how removing P. juliflora from the conservancy will protect their future.

    Active cultivation

    Drivers of Prosopis juliflora trajectories

    Prosopis juliflora, a highly invasive shrub, is spreading rapidly in Marigat sub-county (Kenya). This indicates that sustainable land management (SLM) practices, which could help controlling this weed, are either not adopted or are discontinued after a short while, thus blazing the trail for Prosopis. However, the absence of invasion in some areas shows that there are land users who have implemented SLM practices successfully.

    Using satellite images covering the period from 1988 to 2016, PhD student Beatrice Adoyo identified three main types of spatial-temporal invasion trajectories that show widely diverging success in managing Prosopis (see map below):

    • Areas that have remained invaded since initial invasion: SLM practices have never been implemented; this is the dominant trajectory
    • Areas that are Prosopis free since initial clearance: SLM practices have been implemented consistently giving no chance to re-invasion
    • Re-invaded areas: SLM practices were implemented for a while but later abandoned

    Prosopis juliflora trajectories in Marigat Sub-County, Baringo County, Kenya.

    Beatrice gathered information from land users on different social, political, environmental and economic drivers associated with these trajectories. Preliminary findings show that continuous clearance of Prosopis is primarily linked to active land use, for example through continuous cultivation. Constant invasion is associated with ineffective SLM practices such as the above-ground cutting of Prosopis for charcoal production, which facilitates coppicing and the formation of dense thickets. Further analysis of drivers will be useful to determine strategies to support the uptake and continuous use of SLM practices aimed at controlling the spread of Prosopis.