Succession as Model – findings

OVERVIEW                      DESIGN                      PUBLICATIONS

NATURAL SUCCESSION AS A MODEL FOR THE DESIGN OF SUSTAINABLE AGROECOSYSTEMS

Five examples of findings from the project at CATIE are listed below. More detail on these and other results are found in PROJECT PUBLICATIONS.

1. Indeed it proved possible to imitate the structure of the natural ecosystem and thereby gain many of its functional attributes: high productivity, modest losses to herbivores, and nutrient retentiveness.

2. Further augmentation of species richness in the already-rich natural vegetation led to only modest  changes in ecosystem functioning. Productivity increased slightly, for example, but herbivory neither increased (because of palatable introductions) nor decreased (due to increased resistance), and nutrient retention, already very high in the natural successional vegetation, was equally high in the enriched succession.

3. The tree monoculture surprised my colleagues and me not only by its high productivity (almost equal to that of equal-aged successional vegetation), but also by its ability to prevent leaching losses of nutrients. Monocultures of shorter life span species (maize and cassava) did not share this functional attribute. 

4. The predilection of leaf cutting ants for cassava revealed the newly observed concept of associational susceptibility. Just as herbivore resistance is sometimes conferred through plant association with unpalatable species, we found the corollary:  plants intermixed with a plant species that is particularly attractive to an herbivore suffered more leaf tissue loss than they did when the target plant species was absent.

5. A satellite plot maintained vegetation-free for five years declined markedly in many aspects of soil fertility, but surprised us by not declining in total organic matter. The green-hell-to-red-desert myth persists, but our work showed that it is not relevant to young volcanic soils in the humid tropics.