Monitoring is often seen as the poor relative to research. However, the Integrated Monitoring programme has all the demands of a research project but with the added challenge of running it over many years; this requires a great deal of effort and commitment by those involved. Besides providing data to assess the effectiveness of emission reductions, the acquisition of long-term quality controlled and harmonised data are of immense value to those looking at cause–effect relationships, calibrating models and climate change impacts. The data and knowledge are also of great value for the international and national authorities deciding on acid emission reductions and in teaching.
In this special volume of AMBIO some of the results from the Swedish Integrated Monitoring programme, which is carried out in four headwater forested catchments, are presented in seven papers. The preface and foreword present the Integrated Monitoring programme from Swedish and international perspectives. The first four papers deal with the empirical data and the impact of long-term trends in acid deposition on the abiotic and biotic components of the ecosystem (ground vegetation, algae and lichens), while the last three are model applications. The first of the modelling applications deals with catchment acidification while the last two papers deal with dissolved organic carbon in stream water and riparian zone.
As the invited guest editor I wish to thank the authors of all the manuscripts submitted to this special volume of AMBIO and to the reviewers who graciously agreed to review them. I also wish to thank the local editorial group: Stefan Löfgren, Lars Lundin and, in particular, Lars Högbom who greatly assisted in the technical aspects of the work. I would also like to acknowledge the hard work done by all those persons who have been involved in the collection of the data used in preparing these papers.