Abstract
In tropical soil the organic matter content decreases and the soil structure deteriorates faster than in temperate areas when the land is transferred to agriculture. At the same time the biodiversity of soil organismsl decreases. Knowledge of these structural and functitonal changes in tropical soil and their importance for soil processes is far from complete. In this project we ask the following questions: How are the communities of soil fauna in tropical agriculture affected by amounts and quantity of of soil organic matter and different crops and different intesity of soil cultivation? - Is the soil food web more stable and recilient in soil with high organic matter content and high biodiversity than in degraded soils? - To what extent are different taxonomic and functional groups of soil animals feeding on the growing crop and on microorganisms that derive their nutriment from the growing crop, and to what extent do they use the dead organic matter as their basic food source? The structure of the soil fauna community will be studied by sampling in allready existing field experiments. Feeding ecological relationships will be studied by mass spectronomy analysis of the ratios of the stable isotops 13C/12C and 15N/14N, which reflect the animals trophic possitions. In one field experiment the crop will be labelled with 13C-enriched CO2 and the increased concentration of the 13C isotop will be followed through the food web.
Sweden