Tree species differ in their effects on soil properties and biogeochemical cycles. The supply of nitrogen typically differs by two-fold under the influence of different species on the same soil types, and rates of trace gas fluxes (including NO, N20 and CH4) may differ even more. The influence of global changes on soils (and feedback between soils and the atmosphere) will depend more strongly on changes in the distributions of tree species across landscapes, than on direct effects of climate on soils. This book examines the state of knowledge of the effects of tree species on soils, considering evidence from broad natural gradients in species distributions, and from "common garden" experiments where several species have been planted on the same site. Topics include the influence of the chemistry of forest litter on soil biogeochemistry, the dependence of soil biotic communities on tree species, and the interactions of physical, chemical and biological factors in determining the overall effects of different species. Case studies from across North America, Europe, Russia, South America and Australia illustrate the key role played by tree species in determining long-term development and sustainability of soils.

These proceedings fonn the outcome of an International Conference on "Impacts of Global change on Tree Physiology and Forest Ecosystems ", held from 26-29 November 1996, at Wageningen, The Netherlands. The conference brought together biologists, ecologists, and forest scientist working in the field of impacts of elevated CO and air pollution on tree physiology and forest ecosystems, and marked the 2 completion of a European COST action on "Impacts of Elevated C02 levels and Air Pollutants on Tree Physiology" (ICAT / COST-614), as well as the conclusion of the frrst phase of an EU-funded project entitled "Long-Term Effects of C02 and Climate Change on European Forests (LTEEF) ", that was carried out under the Environment and Climate Programme of the 4th Framework Programme (contract no's EV5V-CT94-0468 and PECOINIS-CT94-0112). The conference aimed to present an overview of current knowledge of effects of air pollution and climate change, at the biophysical, biochemical and physiological level of trees, against the background of climatic conditions and natural stresses. For the proceedings, we have asked the authors to provide an overview of their recent work, providing an entrance to a particular field of research rather than presenting unpublished material. The meeting took place at the International Agricultural Centre (lAC) with fmancial support provided by the COST-614 secretariat in Brussels. We like to thank mrs. A. van der Bunte of lAC for her support in organising the meeting, mr. A. J. H.

Global Change and Forest Soils: Cultivating Stewardship of a Finite Natural Resource, Volume 36, provides a state-of-the-science summary and synthesis of global forest soils that identifies concerns, issues and opportunities for soil adaptation and mitigation as external pressures from global changes arise. Where, how and why some soils are resilient to global change while others are at risk is explored, as are upcoming train wrecks and success stories across boreal, temperate, and tropical forests. Each chapter offers multiple sections written by leading soil scientists who comment on wildfires, climate change and forest harvesting effects, while also introducing examples of current global issues. Readers will find this book to be an integrated, up-to-date assessment on global forest soils.

Trees are among the longest-living organisms. They are sensitive to extreme climatic events and document the effects of environmental changes in form of structural modifications of their tissues. These modifications represent an integrated signal of complex biological responses enforced by the environment. For example, temporal change in stem increment integrates multiple information of tree performance, and wood anatomical traits may be altered by climatic extremes or environmental stress. Recent developments in preparative tools and computational image analysis enable to quantify changes in wood anatomical features, like vessel density or vessel size. Thus, impacts on their functioning can be related to climatic forcing factors. Similarly, new developments in monitoring (cambial) phenology and mechanistic modelling are enlightening the interrelationships between environmental factors, wood formation and tree performance and mortality. Quantitative wood anatomy is a reliable indicator of drought occurrence during the growing season, and therefore has been studied intensively in recent years. The variability in wood anatomy not only alters the biological and hydraulic functioning of a tree, but may also influence the technological properties of wood, with substantial impacts in forestry. On a larger scale, alterations of sapwood and phloem area and their ratios to other functional traits provide measures to detect changes in a tree’s life functions, and increasing risk of drought-induced mortality with possible impacts on hydrological processes and species composition of plant communities. Genetic variability within and across populations is assumed to be crucial for species survival in an unpredictable future world. The magnitude of genetic variation and heritability of adaptive traits might define the ability to adapt to climate change. Is there a relation between genetic variability and resilience to climate change? Is it possible to link genetic expression and climate change to obtain deeper knowledge of functional genetics? To derive precise estimates of genetic determinism it is important to define adaptive traits in wood properties and on a whole-tree scale. Understanding the mechanisms ruling these processes is fundamental to assess the impact of extreme climate events on forest ecosystems, and to provide realistic scenarios of tree responses to changing climates. Wood is also a major carbon sink with a long-term residence, impacting the global carbon cycle. How well do we understand the link between wood growth dynamics, wood carbon allocation and the global carbon cycle? Papers contribution to this Research Topic will cover a wide range of ecosystems. However, special relevance will be given to Mediterranean-type areas. These involve coastal regions of four continents, making Mediterranean-type ecosystems extremely interesting for investigating the potential impacts of global change on growth and for studying responses of woody plants under extreme environmental conditions. For example, the ongoing trend towards warmer temperatures and reduced precipitation can increase the susceptibility to fire and pests. The EU-funded COST Action STREeSS (Studying Tree Responses to extreme Events: a SynthesiS) addresses such crucial tree biological and forest ecological issues by providing a collection of important methodological and scientific insights, about the current state of knowledge, and by opinions for future research needs.

Much attention has been given to above ground biomass and its potential as a carbon sink, but in a mature forest ecosystem 40 to 60 percent of the stored carbon is below ground. As increasing numbers of forests are managed in a wide diversity of climates and soils, the importance of forest soils as a potential carbon sink grows. The Potenti