The present study analyses the energy-budget of ‘village ecosystems’ in a dry tropical environment. These systems depend to a great extent on the surrounding natural forest/savanna ecosystems. Accordingly the objectives of the study were to quantify (i) the energy efficiency of rain-fed agriculture at the ecosystem level, and (ii) the indirect impact of agricultural activity on the surrounding forest/savanna ecosystems.Agronomic output from farming is not sufficient to meet the food-energy requirements of the villagers, hence 27.0 to 51.0% of the requirement is met from outside markets. Operation of the agro-ecosystems involved requires a considerable amount of subsidy from the surrounding forest/savanna ecosystems in terms of fodder and fuel-wood. About 81 to 100% of the fuel needs, and 80–87% of the fodder needs, are met from the natural forest/savanna ecosystems. Thus, for each unit of energy obtained in agronomic yield (including milk), 3.1 units of energy are expended from the surrounding natural ecosystems in the form of fodder and fuel-wood.The erratic and ill-distributed nature of monsoon rains results in moisture deficit which affects the crop production in dry-land farming, causing partial or total failure of the crops. For achieving increased and stable agronomic production under rain-fed conditions, improved dry-land farming techniques have to be applied. Some of these techniques are: (1) introduction of crops and varieties that would be capable of maturing in a period of 90–100 days, and adequate use of appropriate fertilizers; (2) planned rain-water management including storage of surface runoff; and (3) practices of intercropping with crops of longer duration than those currently grown, having slow growth-rates in the early part of their life-cycles.
The Ambangulu Forest, West Usambara Mountains, Tanzania: a threatened Eastern Arc forest
