QUANTIFICATION OF LAND-USE DYNAMICS - AN ILLUSTRATION FROM COSTA-RICA

In many cases, studies dealing with land degradation require the quant ification of land-use dynamics. Although research has been carried out to describe land-use dynamics and its driving forces, very little has been done on the recognition of indicators for the quantification of land use dynamics. This article presents and discusses three different indicators recognised during a Costa Rican case-study: (1) a single-t ime analysis of spatial patterns; (2) standard Markov chains with a so il-type modifier; (3) gee-referenced Markov chains with indices for si ze, shape and land cover in neighbouring polygons. The first indicator is applied to a study area of 2942 km(2) in the northeast of Costa Ri ca for which 1992 aerial photographs are available. Spatial patterns o f land cover can only be related to land cover modifications when good insight into the colonization history exists. For the study area, cle ar land-use sequences have been found. Both standard and gee-reference d Markov chains have been calculated for a smaller pilot area of 151 k m(2) for which aerial photographs taken on five different dates area a vailable. Clear differences in probabilities are found for soil type a nd polygon size. For the shape and boundary index, no clear relations were found in the pilot area. The quantification of land-use dynamics using these kinds of indicators is necessary for the comparison of reg ions and for land degradation modelling.