Nutrient Cycling and Limitation: Hawaii as a Model System

Nutrient Cycling and Limitation has its roots in the long-neglected and currently unfashionable field of plant succession. Almost no mention is made of those topics – such as conservation biology, competition, rarity, species diversity and the link with ecosystem properties – that constitute the core of contemporary plant ecology. Rather, the book is about the dynamics of plant nutrients in terrestrial ecosystems: where nutrients come from, how long they persist in soils, and how nutrient flows through terrestrial ecosystems are regulated by feedback systems involving soil microbes, plant physiology and plant litter. The study of model systems and the utilization of environmental gradients is given concise exposition in chapters 2 and 3. Vitousek clearly regards this meth-odological theme as being of central importance, for it provides the subtext to almost every page. He argues the case for model systems in general, and environmental gradients in particular, as being the field ecologist's most parsimonious route to scientific enlightenment. He enthusiastically concludes that Hawaii is the best place in the world to study terrestrial plant nutrient dynamics, and presents a body of research findings that comprise a quite profound understanding of many of the fundamental biotic and abiotic processes that shape the world. One of the most impressive aspects of Nutrient Cycling and Limitation is the scope of the material it covers, and the extent to which the material is integrated to provide a truly ecosystem-level overview, that is itself placed neatly within a global context. I am aware of few scientific writers since Darwin who have shown such facility. Vitousek's gift for synthesis is exemplified by chapters 2 and 3, in which plate tec-tonics, geomorphology, atmospheric circulation, evolution , topographic effects on climate, and their consequences for weathering and soil chemistry, are all seamlessly interlinked to provide a very complete background to his research. Starting from Walker and Syers' (1976) model of phosphorus and nitrogen availability through long-term soil development, Vitousek considers the implications of nutrient dynamics for biological processes. He discusses the various parameters that could be measured, outlining their individual merits and drawbacks, and detailing potential confounding factors and his strategies for circumventing them. Assumptions are explicitly enunciated – an all too rare thing in ecology – and evidence is carefully weighted according to its reliance on assumption. Also notable is the emphasis on the widely differing time scales across which strong interactions occur. Whereas some of the processes …