Trees in agricultural landscapes provides valuable ecosystem services in Africa

When agriculture expands and is intensified it often results in a decline of biodiversity and ecosystem services. In order to restore important ecosystem services, multi-functional landscapes are often argued for. Besides food and fibre, the aim of multifunctional landscapes is to benefit various beneficial organisms, including insects that can pollinate crops, natural enemies that combat pests and organisms in the soil that affect nutrient and water flow.

A litterature study of ecosystem services from trees on farms

In a new study, researchers from SLU has, together with colleagues from JKUAT (Jomo Kenyatta University of Agriculture and Technology) and ICRAF (World Agroforestry Centre) in Kenya studied what role trees play in multi-functional landscapes of Africa. In total, 350 journal articles published between 1995-2014 were assessed.

The literature review showed that trees on farms and in agricultural landscapes in most cases result in improved food security via, e.g., reduced pest problems, improved soil fertility and water regulation. The positive effects were most consistent in semi-arid areas. In general, trees in the agricultural landscape were positive, but in some cases a decline in production of particular crops was noted as a trade-off.

Many important values have been overlooked

– Very few of the available studies had investigated the production of wood, medicinal products, fruits and nuts, and no studies had looked at cultural ecosystem services such as recreation and spiritual values. This makes it difficult to establish all the synergies and trade-offs associated with trees in the landscape. In addition, most studies on ecosystem services are carried out at a field scale although the potential benefits of the ecosystem services are at farm or landscape scales, says Mattias Jonsson, one of the researchers behind the study.

Promoting ecosystem services leads to better crop production in the long run

In the study, the researchers also stress that longer-term trends and benefits can be missed when focusing on short-term gains. By promoting ecosystem services, soil fertility is increased and therefore also, in the long run, crop production.