Facilitating Strategy and Action Plans to Address Woody Weeds in Tanzania’s Lake Natron Basin
23 July 2024, Africa: Prosopis juliflora is considered one of the world’s most threatening non-native tree species. Though it was introduced to Eastern Africa in the 1970s to provide wood and fodder and reduce erosion on degraded land, it has since spread rapidly with a range of severe impacts.
In part one of a two-part blog, we look at how CABI scientists are busy working in partnership to support the implementation of the Tanzanian National Invasive Species Strategy and Action Plan (NISSAP) with a focus on Prosopis juliflora in the Lake Natron Basin, a biodiversity hotspot.
The project, co-led by CABI and the Tanzania Forestry Research Institute (TAFORI), has raised awareness about the starting invasion by Prosopis among many stakeholders in the Lake Natron Basin and the project has supported co-development of a management plan for this species.
Now, communities have recognised the threat and organised themselves to manage the species before widespread impacts on biodiversity and livelihoods occur.
So far, communities have removed around 20 hectares of Prosopis in Wosiwosi village – which is home to around 4,000 people – as part of a management plan to prevent, detect, and contain/control the invasive weed.
The problem of invasive tree species and the need to manage them before impacts are felt and have become irreversible
Invasive alien tree species are a major threat to Eastern-African biodiversity and livelihoods. For example, Prosopis juliflora, a spiny shrub or tree introduced into many countries worldwide, blocks access to land, reduces water availability and increases habitat for predators and vectors of disease.
As a result of these direct impacts on the environment, Prosopis can turn grasslands into shrubland and change the predominant basis of the economy from livestock into wood.
Seeds of the trees are spread by animals feeding on the pods and water. The far-reaching impacts change people’s livelihoods and is difficult, if not impossible, to reverse these impacts once the species has become established.
With funding from the Darwin Initiative, this project worked with representatives of diverse stakeholder groups from communities in the Lake Natron basin and subnational and national institutions to co-design a landscape scale management plan for Prosopis.
The Lake Natron basin, a landscape characterised by grassland and lakes that are home to people as well as iconic wildlife, stretches roughly from the Kenyan border to the southern end of Lake Manyara in Tanzania.
The distribution of Prosopis is currently very limited in the area, but most of the landscape is suitable for the species, suggesting that impacts will become widespread. Hence, management of the species is urgently needed to ensure impacts are either prevented or minimised.
IAS management strategies and prioritising management aims
Invasions are dynamic in space and time. It is important to consider the presence and abundance of the invasive plants in a landscape when deciding on management strategies.
This is because different management aims are appropriate for parts of a landscape where a species does not occur (but that are suitable for the plants), areas where the plants occur sparsely, and areas where the species is either widespread or dense.
Management of invasive species becomes increasingly difficult and expensive when the plants establish and spread in an area. Priority should therefore be given to prevention of establishment and removal of sparse trees.
Acting at the early stages of plant invasions is most likely to be successful and, although the cost may seem high, it is far less costly than suffering the impacts of and managing widespread invasions.
Once a species has become established and is spreading locally, it is very difficult to remove from the area and reverse its impacts on livelihoods and the environment.
When this situation arises, it is important to prioritise containment of the invasion and to protect assets with environmental, economic, or cultural importance by removing the trees and preventing re-establishment in the cleared area.
Together with partners and stakeholders, we use an inclusive Integrated Land Management approach to co-design landscape management plan
Effective management of invasive species on a landscape scale requires coordinated action, to ensure that management goals correspond to the level of invasion and management actions are implemented accordingly.
It is equally important that all relevant stakeholders, both those living in the landscape and those that depend on resources derived from the landscape, are aware of the problem, agree on management goals and participate in management of the species.
Design of landscape management plans should be done by people with knowledge of the landscape and biological invasion by Prosopis, and decision makers should include people living in the area, government agencies, as well as managers of protected areas.
An important hindrance for the coordination of action in landscapes of northern Tanzania (and likely elsewhere) is the lack of structures or institutions where all actors meet, as the management of the protected and non-protected areas falls under different government departments at the national level.
This project created a Local Implementation Group with representatives of, among others, communities, pastoralists, protected areas, local and district administrations to reflect on impacts of Prosopis in the landscape and strategies for managing this threat.
Support for national invasive species policies
The members of the Local Implementation Group developed the Prosopis Management Plan for the Lake Natron Basin that was presented to the Regional Administrative Secretary of Arusha Region.
It was also presented to the Vice-President’s Office in Dodoma, which is coordinating implementation of Tanzania’s National Invasive Species Strategy and Action Plan (NISSAP).
Through its activities, the project team is helping to implement the NISSAP, developing and improving measures for controlling the species, which will be built into ‘Sustainable Land Management’ strategies that will help Tanzania mitigate the impacts of Prosopis.
(For Latest Agriculture News & Updates, follow Krishak Jagat on Google News)
(+80 Million Farming Audience Visits Krishak Jagat’s Hindi Website – Click Here for Website)
