Nutrient cycling and land use management: an introduction

Abstract

The aim of this short series of papers is to summarize and explore some developments in the study of nutrient cycling in relation to land use management. Traditional discussion of ecosystems in biogeography and ecology has emphasized the balanced or steady state of nutrient cycles in most natural and semi-natural environments (Tivy 1982; Odum 1983; Pears 1985; Thompson et al. 1986). The disruption caused to these cycles by man’s activities through numerous different forms of land use, particularly agriculture and forestry, are now widely documented (e.g. Briggs and Courtney 1985). Until recently, much of this discussion has been largely descriptive in nature. However, present trends indicate that various aspects of the modified and simplified nutrient cycles resulting from land use activity are now receiving close attention and research on the applied aspects of nutrient cycling, and its implications for management practice in agriculture and forestry, is assuming ever-increasing importance (Frissel 1977, 1978; Lee et al. 1983; Lowrance et al. 1984). The concept of the agro-ecosystem is now widely recognized (Odum 1984) and a journal of that title has been published since 1974, with a symposium on Cycling of Mineral Nutrients in Agricultural Ecosystems presented in 1977 (Frissel 1977). The highly modified and simplified nutrient cycles which characterize such ecosystems may now be seen as being of equal, if not greater, significance for research than those of natural and semi-natural systems for which nutrient cycles were quantified under the International Biological Programme in the 1960s and 1970s (Leith and Whittaker 1975). A number of existing research projects into nutrient cycling under various land use regimes in different world biomes is now underway within the Man and the Biosphere programme (Giacomini 1978; Batisse 1980).