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Sustainable agriculture for forest conservation

Kew is involved in new projects to promote tree-based systems as alternatives to ‘slash and burn’ agriculture to reduce the pressure on tropical forests.

Photo of farmed hillside
Alley-cropping of Inga on a farm in Honduras (Photo: G. Hernandez/Inga Foundation)

Conversion of natural habitat to unsustainable agricultural land, especially shifting or slash-and-burn agriculture in tropical forests, is seen as one of the greatest threats to the survival of rare plant species and a major global contributor of climate-change gases.

In the Neotropics a system of alley-cropping that permits good yields, permanently, has been developed using the legume Inga by Terry Pennington (Kew) and Mike Hands (Inga Foundation) over the last 20 years. In the past year, Kew has initiated several projects seeking to replicate this success, in the Neotropics with Inga and in the palaeotropics using native species with similar attributes.

The results of a project on the sustainable management of the caatinga vegetation of north-eastern Brazil for firewood production have also been published recently in an illustrated booklet.

Inga agroforests in Bolivia

A project funded by the UK Darwin Initiative is developing Inga agroforests as tools for the rehabilitation of degraded cattle pastures in the Bolivian Amazon. The aim is to reduce pressure on forests from ‘slash and burn’ agriculture through the establishment of tree-based systems to ‘capture’ degraded pasture and then plant crops between rows of specially selected Inga trees.

Inga trees increase soil fertility, suppress weeds and attract natural biological control agents, enabling degraded pastures to be transformed into productive forested land within two years. They do so through microbial association with their roots, the production of a copious, dense and rapidly decomposing leaf-litter and the presence of special insect-attracting nectaries on their leaves.

This three-year project began in October 2013 and is a collaboration between Bolivian NGO Herencia, four forest communities, Kew Associate and Inga specialist Terry Pennington and the Kew Tropical America Team.

Alley-cropping in Congo

The Inga Foundation and Kew, with support from MPD Congo S.A., a prospective mining company, have begun a trial to evaluate native legume tree species for alley-cropping potential in the Republic of Congo. Candidate species were screened for Inga-like attributes and are now growing well, despite extremely impoverished and acid (pH 4) soils. Funding is being sought to continue the project beyond 2014.

The objective is an Inga-like system that can be taken up by local communities to address the slash-and-burn agriculture prevalent throughout the CEMAC (Congo Basin) countries, and beyond. Previous agroforestry trials in Tropical Africa have used exotic Neotropical species which are invasive risks. This seems to have been the first time that native African forest trees have been employed for this purpose.

Madagascar Agroforestry Livelihoods Project

The Kew Madagascar Conservation Centre (KMCC) has started the Madagascar Agroforestry Livelihoods Project with funding from the UK Darwin Initiative. The project is working with 30 communities in the Itremo Massif and Ambositra-Vondrozo Humid Forest Corridor protected areas to establish alley-cropping, forest gardens and tree plantations as well as restoring forest along the margins. The main objective is to provide communities with an alternative to slash and burn cultivation, by restoring agricultural productivity and biodiversity on the deforested slopes near to the villages.

Kew’s project partners are Feedback Madagascar, local NGO Ny Tanintsika, Silo National des Graines Forestières and the Inga Foundation. The project is very similar to Kew’s Bolivian agroforestry project, but it will be using native Madagascan tree species with similar properties to Inga.

Photo of three people collecting Inga fruits

Collecting Inga fruits for the Madagascar Agroforestry Livelihoods Project

Caatinga fuelwood

The results of the project ‘Sustainable Management of the Caatinga Vegetation for Firewood production', funded by CNPq (Brazil) and the Clothworkers’ Foundation (UK), have been published in a 24-page booklet in Portuguese, Cuidando da Caatinga (Caring for the Caatinga), aimed at local smallholders, NGOs, decision makers, environmentalists and scientists in northeast Brazil.

The booklet explains what the caatinga is and highlights its biodiversity, stating why it needs protection and sustainable management. In particular, it concentrates on how to manage caatinga by coppicing, pollarding and crown-thinning four species of tree utilised for fuelwood and charcoal production: Croton sonderianus, Mimosa ophthalmocentra, M. tenuiflora, and Poincianella pyramidalis (often known as Caesalpinia pyramidalis).

Photo of a man spraying a tree

Conducting research on the sustainable management of caatinga vegetation (Photo: P. Gasson)

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