Carbon Nitrogen And Phosphorus Cycling In Forest Soils

The majority of carbon stored in the soils of the world is stored in forests. The refractory nature of some portions of forest soil organic matter also provides the slow, gradual release of organic nitrogen and phosphorus to sustain long term forest productivity. Contemporary and future disturbances, such as climatic warming, deforestation, short rotation sylviculture, the invasion of exotic species, and fire, all place strains on the integrity of this homeostatic system of C, N, and P cycling. On the other hand, the CO2 fertilization effect may partially offset losses of soil organic matter, but many have questioned the ability of N and P stocks to sustain the CO2 fertilization effect. Despite many advances in the understanding of C, N, and P cycling in forest soils, many questions remain. For example, no complete inventory of the myriad structural formulae of soil organic N and P has ever been made. The factors that cause the resistance of soil organic matter to mineralization are still hotly debated. Is it possible to “engineer” forest soil organic matter so that it sequesters even more C? The role of microbial species diversity in forest C, N, and P cycling is poorly understood. The difficulty in measuring the contribution of roots to soil organic C, N, and P makes its contribution uncertain. Finally, global differences in climate, soils, and species make the extrapolation of any one important study difficult to extrapolate to forest soils worldwide.

The majority of carbon stored in the soils of the world is stored in forests. The refractory nature of some portions of forest soil organic matter also provides the slow, gradual release of organic nitrogen and phosphorus to sustain long term forest productivity. Contemporary and future disturbances, such as climatic warming, deforestation, short rotation sylviculture, the invasion of exotic species, and fire, all place strains on the integrity of this homeostatic system of C, N, and P cycling. On the other hand, the CO2 fertilization effect may partially offset losses of soil organic matter, but many have questioned the ability of N and P stocks to sustain the CO2 fertilization effect.

The papers published in this volume were presented to that workshop which was held in Canberra on 29-30 April and 1 May 1981.

Phosphorus (P) is a finite resource which is essential for life. It is a limiting nutrient in many ecosystems but also a pollutant which can affect biodiversity in terrestrial ecosystems and change the ecology of water bodies. This book collects the latest information on biological processes in soil P cycling, which to date have remained much less understood than physico-chemical processes. The methods section presents spectroscopic techniques and the characterization of microbial P forms, as well as the use of tracers, molecular approaches and modeling of soil-plant systems. The section on processes deals with mycorrhizal symbioses, microbial P solubilization, soil macrofauna, phosphatase enzymes and rhizosphere processes. On the system level, P cycling is examined for grasslands, arctic and alpine soils, forest plantations, tropical forests, and dryland regions. Further, P management with respect to animal production and cropping, and the interactions between global change and P cycling, are treated.

The long-term productivity of forest ecosystems depends on the cycling of nutrients. The effect of carbon dioxide fertilization on forest productivity may ultimately be limited by the rate of nutrient cycling. Contemporary and future disturbances such as climatic warming, N-deposition, deforestation, short rotation sylviculture, fire (both wild and controlled), and the invasion of exotic species all place strains on the integrity of ecosystem nutrient cycling. Global differences in climate, soils, and species make it difficult to extrapolate even a single important study worldwide. Despite advances in the understanding of nutrient cycling and carbon production in forests, many questions remain. The chapters in this volume reflect many contemporary research priorities. The thirteen studies in this volume are arranged in the following subject groups: • N and P resorption from foliage worldwide, along chronosequences and along elevation gradients; • Litter production and decomposition; • N and P stoichiometry as affected by N deposition, geographic gradients, species changes, and ecosystem restoration; • Effects of N and P addition on understory biomass, litter, and soil; • Effects of burning on soil nutrients; • Effects of N addition on soil fauna.

The availability or lack of nutrients shapes ecosystems in fundamental ways. From forest productivity to soil fertility, from the diversity of animals to the composition of microbial communities, nutrient cycling and limitation are the basic mechanisms underlying ecosystem ecology. In this book, Peter Vitousek builds on over twenty years of research in Hawai'i to evaluate the controls and consequences of variation in nutrient availability and limitation. Integrating research from geochemistry, pedology, atmospheric chemistry, ecophysiology, and ecology, Vitousek addresses fundamental questions: How do the cycles of different elements interact? How do biological processes operating in minutes or hours interact with geochemical processes operating over millions of years? How does biological diversity interact with nutrient cycling and limitation in ecosystems? The Hawaiian Islands provide the author with an excellent model system for answering these questions as he integrates across levels of biological organization. He evaluates the connections between plant nutrient use efficiency, nutrient cycling and limitation within ecosystems, and nutrient input-output budgets of ecosystems. This book makes use of the Hawaiian ecosystems to explore the mechanisms that shape productivity and diversity in ecosystems throughout the world. It will be essential reading for all ecologists and environmental scientists.

This book presents a comprehensive overview of nutrient cycling processes and their importance for plant growth and ecosystem sustainability. The book combines fundamental scientific studies and devised practical approaches. It contains contributions of leading international authorities from various disciplines resulting in multidisciplinary approaches, and all chapters have been carefully reviewed. This volume will support scientists and practitioners alike.