This book has been compiled as a result of collaboration within the International Energy Agency Bioenergy Agreement. The aim of the book is to review the state of the art with respect to research and practical implications in order to aid the development of the technology for short rotation forestry production.

The aim of this book is to improve the understanding of forest dynamics and the sustainable management of forest ecosystems. How do tree crowns, trees or entire forest stands respond to thinning in the long term? What effect do tree species mixtures and multi-layering have on the productivity and stability of trees, stands or forest enterprises? How do tree and stand growth respond to stress factors such as climate change or air pollution? Furthermore, in the event that one has acquired knowledge about the effects of thinning, mixture and stress, how can one make that knowledge applicable to decision-making in forestry practice? The experimental designs, analytical methods, general relationships and models for answering questions of this kind are the focus of this book. Given the structures dealt with, which range from plant organs to the tree, stand and enterprise levels, and the processes analysed in a time frame of days or months to decades or even centuries, this book is directed at all readers interested in trees, forest stands and forest ecosystems. This work has been compiled for students, scientists, lecturers, forest planners, forest managers, and consultants.

Forest Growth and Yield Modeling synthesizes current scientific literature and provides insights in how models are constructed. Giving suggestions for future developments, and outlining keys for successful implementation of models the book provides a thorough and up-to-date, single source reference for students, researchers and practitioners requiring a current digest of research and methods in the field. The book describes current modelling approaches for predicting forest growth and yield and explores the components that comprise the various modelling approaches. It provides the reader with the tools for evaluating and calibrating growth and yield models and outlines the steps necessary for developing a forest growth and yield model. Single source reference providing an evaluation and synthesis of current scientific literature Detailed descriptions of example models Covers statistical techniques used in forest model construction Accessible, reader-friendly style

In the Netherlands the Institute for Soil Fertility Research plays a major role in soil biological, soil physical and plant nutritional research on the availability of nitrogen to crops. Main subjects of research are nitrogen turnover in the crop-soil ecosystem through biological transformations, nitrogen transport through the soil and nitrogen losses by leaching, denitrification and volatilization, and nitrogen use efficiency of various crops and cropping systems. The current knowledge in the different fields of research is integrated in simulation models. Simulation models not only make it possible to summarize and structure knowledge, but also, after verification, to extra- late the knowledge to situations different from the situations that have actually been studied. Such research is also carried out in other European and non-European countries. To compare the various simulation models currently in use, a workshop was organized by the Institute for Soil Fertility Research on 5-6 June 1990 on the occasion of its centennial. The title of the workshop was 'Nitrogen turnover in the soil-crop ::cosystem: modelling of biological transformations, transport of nitrogen and nitrogen use efficiency'. The 40 Jarticipants, who came from Canada and various European countries, were requested to run their model with data Jrovided by the Institute prior to the workshop. Data from 18 cases were made available to the participants: three ocations, three treatments, and two seasons.

This thesis describes the development and subsequent use of a computer simulation model, FENDS (Forest Ecosystem Nitrogen Dynamics Simulator), designed to investigate growth and nitrogen dynamics in managed stands of Pinus nigra var. maritima (Ait.) Melville. The literature is reviewed as three subject areas. First is the production of biomass, its partition within trees and changes which occur during stand development. Second is the cycling of nitrogen within forest ecosystems including inputs to, and losses from the system. The review ends with a description of the types of model that have been developed in relation to forestry, with emphasis placed upon the computer simulation models. An overview of the model is provided together with an account of its development. The current version is described in detail and assumptions upon which it has been based are discussed. A number of key areas for which information is lacking have been identified including: 1) allocation of growth to tree and ground vegetation components, particularly root systems; 2) turnover rates of root systems; 3) mechanisms controlling storage and remobilisation of nitrogen in trees; 4) changes in opitimum nitrogen concentrations which occur during stand development; and 5) breakdown of recalcitrant organic matter and associated nitrogen dynamics. The model has been used to simulate weeding, fertiliser applications and thinning operations and to examine potential interactions. Results from these simulations are discussed.