Introduction

Forests provide a range of goods and services upon which humanity depends, from local (e.g. flood prevention) to global (e.g. carbon sequestration). Yet some 13 Mha of forest is lost each year, mostly in the tropics (Canadell & Raupach 2008). Considerable political, media and scientific attention has focused on this forest destruction and fragmentation and its implications for livelihoods, biodiversity and ecosystem services. However, human influences on forests now go beyond deforestation and degradation, to changing the states of atmosphere and climates and altering biogeochemical cycles, which in turn bear heavily on the functioning and composition of forest ecosystems. A range of disciplines are required to chart such change, understand how it works and predict where it is going. They span a broad range of scales from photosynthetic machinery in leaves, to the dynamics of forests across wide regions, to global atmospheric circulation. Integration of these multiple strands and scales of investigation has only recently begun, and this volume makes an important contribution to weaving them together into a more cohesive, albeit still incomplete, picture.

The story is told in three parts, beginning with a collection of perspectives on the global environmental drivers of forest change, the complexity of their interaction and effects, and important feedbacks. The second section concentrates on species-level traits and trade-offs, and how these explain the composition and dynamics of forests in a changing world. Finally, a number of approaches and tools are presented for measuring forest change and forecasting its future direction.

Preface

Forests house a significant proportion of global biodiversity and terrestrial carbon, as well as providing livelihoods for millions of people, yet they are changing at an unprecedented rate. They are disappearing rapidly in many parts of the tropics, but are increasing in cover and biomass in many higher-latitude regions. They are responding to industrial pollution and introduced organisms. The dynamics and distribution of forest vegetation are important because they determine the amount of habitat for numerous other organisms, and regulate the delivery of ecosystem services such as carbon storage, and water and soil quality. It is increasingly recognised that forests influence the energy budget of the planet, making an understanding of forest dynamics an essential aspect of climate change modelling.

Despite the importance of forests to biodiversity conservation and the provision of ecosystem services such as erosion control and carbon storage, the community of forest ecologists is strongly differentiated by biome, which constrains conceptual integration at a global scale. In the tropics, there is a concentration of effort and expertise around the networks of large plots coordinated by the Center for Tropical Forest Science on the one hand, and the alliance of smaller plots forming the RAINFOR, AfriTRON and GEM networks on the other, with many others working outside these networks. In temperate and boreal forest regions, there are long-term ecological monitoring sites (e.g. the Long-Term Ecological Research Network, LTER) and impressive national inventory systems that were originally established for monitoring timber stocks but increasingly available to ecologists. In this volume we draw together perspectives from across these diverse communities of forest ecologists to attempt a global synthesis of forest responses to global change.