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 School of Geography and the Environment

Villagers in Ghana

Framework for monitoring invasive tree species in Ghana

This project used participatory methods to explore the impact of invasive species on local communities and farmers in Ghana. The species (Neem and Leucaena) were introduced as 'useful' plants, but have since become over-abundant and problematic for some people due to unchecked growth. A manual is being written with guidelines on how to identify invasive species, how to prevent species invading and how to deal with them once they are present. It will discuss community perceptions of invasiveness, whether benefits outweigh the negative impacts of invasion, and the impact of invasive species on biodiversity.

Project Outline

The project responds to concern over the invasiveness of exotic tree species, in particular neem (Azadirachta indica) and Leucaena leucocephala, in fallow agricultural land, dry forest and game reserves in Ghana. This is in the context of worldwide concern about invasive species (e.g. Global Invasive Species Programme supported by the Scientific Committee on Problems of the Environment (SCOPE), IUCN and UNEP; FAO global survey).

The project uses a multidisciplinary approach to develop a framework for the monitoring and evaluation of the impact of invasive tree species. Different stakeholders have different perceptions of invasiveness: for some it is a problem, for others the benefits outweigh the disadvantages. Because of this, a participatory approach is needed. This is the first known use of participatory approaches to problem-solving with respect to invasive species.

Negative impacts identified include: disrupting the natural succession of savannah and dry forest, reducing the availability of agricultural land for farmers, contributing to the loss of rare tree species, and reducing mammal biodiversity. Positive impacts identified include: provision of fuelwood, fodder, herbal medicines and pesticides, habitat for small bushmeat, and (depending on the species) restoration of soil fertility. Clearly we cannot generalise but instead need to understand stakeholder perspectives and look at the way the whole system works together.

The project is relevant to the conservation priorities of Ghana as outlined in its Environmental Action Plan (1991), highlights community-based approaches to conservation. The priority of the Darwin Initiative (funded by the UK Department for the Environment Food and Rural Affairs) is to assist countries in implementing the Biodiversity Convention; this project supports in particular articles 8j, 12 and 14. It is also relevant to the sustainability of agricultural activities in some parts of Ghana.


  • Develop a participatory process (based on local and scientific knowledge) to monitor the impacts of 'invasive' species.
  • Develop approaches to addressing problems identified as a result of the participatory monitoring.
  • Raise awareness of the causes and consequences of invasiveness.

Main findings

Results of using a participatory approach:

  • Different stakeholders exchange perceptions: neem or Leucaena are not problems in themselves, but only to some people in some situations.
  • Technical testing of farmers' knowledge supports local observations.
  • Women increase confidence in contributing to group discussions.
  • Management options shared (repeated pruning; grow tall and use seeds as fodder, eliminate in selected areas only).
  • Awareness of values (foreign species often considered better than local species).
  • Suggests trends into the future: changes in values, beliefs, interests & priorities, in management, markets and impacts, potential conflicts between stakeholders, etc.

Connections between issues:

  • Neem, organic agriculture, markets for its products.
  • Neem, charcoal and deforestation in the north.
  • Leucaena, soil fertility and burning.
  • Leucaena, changing social and cultural values, and burning.
  • New species, new winners, new losers.


  • Extension system: be wary of research which brings in species or technologies from outside, without local testing, consultation and rigorous thinking through of knock-on effects (systemic, holistic analysis).
  • Joint problem-solving must take account of different stakeholder needs if effectiveness is to be optimized in the long-term; traditional land tenure can help.
  • Biophysical research shows shade is the best weapon against neem; and a hot burn destroys more than an early burn so changing management regimes may reduce it.
  • Integrated approach to problem-solving: build in market strengthening for natural pesticides, and alternatives to charcoal burning in the north.
  • Support for traditional decision-making: there is traditional ecological knowledge but people are abandoning traditional authority and feel helpless in the face of change.
  • Addressing the values that give more importance to the foreign and new above the indigenous and traditional.

Project Partners

  • Dr Anna Lawrence, participatory forestry research. Environmental Change Institute.
  • Dr Joanne Chamberlain, forest biologist, project leader. Email
  • Mr Bright Kankam, forest biologist. Forest Research Institute of Ghana, Kumasi. Email
  • Mr Jonas Kpierekoh, Suntaa Nuntaa, Wa - agroforestry development worker. Environmental Protection Agency, Ghana.
  • Ms Felicity Childs, agroforestry extension.
  • Mr Paul Maiteny, collaborative learning and systems approaches. Email:
  • With the support of Dr Joe Cobbinah (FORIG), Mr Bob Loggah, Diana and Beatrice (Suntaa Nuntaa), GOAN staff.