Farmer knowledge of the relationships among soil macrofauna, soil quality and tree species in a smallholder agroforestry system of western Honduras

Efforts to increase above- and below-ground biodiversity in farming systems require greater understanding of how farmers develop and use their knowledge of biodiversity, ecological processes and soil quality. The goal of this research was to assess the extent to which farmers have incorporated their observations of native species and ecological processes into farm management practices in a hillside agroforestry system of western Honduras. The system incorporates slash-and-mulch of native vegetation (rather than slash-and-burn cultivation, which was widely practiced in the area before 1990), and the retention of trees within cropping fields. Information on farmer knowledge was elicited primarily through semi-structured interviews with 20 farmers. Farmers interviewed distinguish several local soil types on the basis of soil texture, colour, structure and stone content, with each soil type having varying suitability for the major crops grown in the district (maize, beans, sorghum and pasture). The most highly valued tree species are those that fulfil multiple economic and agricultural functions, including having a positive influence on soil quality through decomposition, nutrient cycling, and provision of soil cover. In particular, species with small, fine leaves that gave dappled shade (rather than solid shade) and decomposed rapidly were preferred. Farmers named 16 commonly recognised, distinct soil macrofauna taxa. The most detailed knowledge on the relationship between soil fauna and soil quality was held on taxa considered to have either beneficial or harmful effects on farming activities, such as earthworms and beetle larvae. Farmers had complex understanding of the influence of fire on soils, vegetation, crop yield and soil biota over various lengths of time, which may have been gained through a combination of first-hand experience, interaction with agricultural extension workers, and information gained from other farmers. It is likely that local ecological knowledge of the effect of different species on soil quality, the interactions among species, and the role of vegetation in maintaining agricultural productivity and landscape integrity, is an important component of the adoption and success of the agroforestry system.