Abstract

A synthesis of progress achieved thus far is provided for a 10-year research and development program aimed at the ecological and economic rehabilitation of agroecosystems in the unirrigated portions of the central valley of Chile's Mediterranean climate region. We review our data on (1) revised management techniques aimed at restoring the gross superstructure and former levels of diversity and productivity of a mixed espinales formation; (2) selection and utilization of ecotypes of the naturalized annual Medicago polymorpha L. and the N2-fixing microsymbiont Rhizobium meliloti, for gradual improvement of espinal soil fertility; and (3) studies of the outstandingly well adapted and fast growing Canary Island tree Chamaecytisus proliferus (L. fil.) Link ssp. palmensis (Christ) Kunkel (Tagasaste), which along with about three dozen other woody nitrogen-fixing legume and several nonlegume multipurpose trees, was considered to be of potential value for deep soil layer rehabilitation combined with economic improvements. In all these subprograms, efforts were made to identify techniques or organisms that could provide short-term benefits to landowners, especially in the form of wood, fuelwood, or forage for livestock. We also consider various approaches to be added to the program over the next decade, especially in view of the overarching goal of reintegrating fragmented landscapes and combining restoration with rehabilitation and reallocation at this spatial scale.