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Root distribution of the wild jack tree (Artocarpus hirsutus) was determined by selective placement of 32p at various depths and lateral distances from the tree, in Kerala, India. In eight-and-a-half-year-old trees growing on a lateritic site, absorption of 32p from a lateral distance of 75 cm and 30 cm depth was much greater than from 150 and 225 cm lateral distance and 60 and 90 cm depth. Root activity declined with increasing depth and lateral distance. Most of the physiologically active roots were concentrated within a radius of 75 cm and 30 cm depth, although the tap root might reach even deeper. Possibly, surface accumulation of feeder roots may cause considerable overlap of the tree and crop root zones in intercropping situations. However, as the tree roots seldom extend beyond 2.25 m laterally from the trunk, the effect of overlapping root zones and the associated competitive effects may not be a serious problem for intercropping during the first few years (< 10 years after planting) of tree growth.

Livestock forms an integral component of humid tropical cropping systems, providing food and financial security, employment, and insurance against crop failure for small scale farmers. However, livestock sector is seriously constrained by the drastic decline in fodder base and high cost of feeds, incurring huge economic loss to farmers. Hence fodder production should be intensified in cropping system by including alternate feeds like nutrient rich fodder trees and shrubs to supplement conventional fodder. Fodder trees serve as a potential source of quality green fodder to livestock especially during lean periods. Moreover, tree leaves can be cheaper feed supplements than the commercial concentrates and can easily be grown by the small-holder farmers. Leucaena, mulberry, kadamba, calliandra, agathi, moringa and gliricidia are promising fodder tress by virtue of their nutritive foliage, fast growing nature with higher biomass production, amenable to heavy pruning, good coppicing ability and easy management. Moreover, these trees can be grown in close hedgerows as fodder banks in integration with existing crops to maximize productivity in land crunch humid tropical areas. Enhancing tree cover in cropping systems also offers ecosystem services like enhanced carbon storage and associated global warming issues. Forage and nutrient yields, and carbon accretion can be substantially elevated and crop–tree competition can be minimized by appropriate stand management practices and proper regulation of overstorey and understorey components. Extensive studies conducted on tree fodder bank establishment, management and their productive and protective functions in humid tropical cropping systems of South India are reviewed in this paper.