The strategy of ecosystem development by Odum emphasizes that:
Odum’s classic strategy of ecosystem development proposes that nutrient cycles become increasingly closed, or “tighter,” as succession proceeds. Early communities have small nutrient pools in biomass, weak retention, and relatively large losses through runoff or leaching. As vegetation, roots, decomposers, and soil organic matter develop, nutrients released by decomposition are captured more efficiently and reused within the community. Longer food chains and greater biological regulation can further slow their escape. Mature systems therefore tend to conserve limiting elements, although distur
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 20