APPLICATION OF AGROECOLOGICAL CONCEPTS AND HIERARCHY THEORY IN THE DESIGN OF DATABASES FOR SPATIAL AND TEMPORAL CHARACTERIZATION OF LAND AND SOIL

A hierarchial system for integrating information on soil, climate, lan dscape and land use at various scales, is discussed. A series of neste d data bases at various scales (1:5 million and larger) are prepared, according to the concepts of agro-ecological stratification in combina tion with the tenets of Hierarchy Theory. Each polygon at each scale i s treated as a unique area with its own environmental envelope of inte grated information. Transposition between scales and the scientific in tegrity of the data is accomplished through the nested databases, and by carefully matching the ''grain'' of the data to the scale of each d atabase. The nested databases are ''matched'' with a collection of cro p growth models and other procedures of data analyses, each of which i s specific to a general scale of application, and compatible to one of the available databases. The crop growth models are arranged in incre asing detail, as reflected in the structure of the subroutines and tim e steps, and describe a variety of purposes from estimating yield pote ntial to defining yield variability and production risk. The system is supported by a geographic information system.