Gayana Bot. 62(2): 61-61, 2005 ISSN 0016-5301

ARTÍCULOS REGULARES

PREFACE

RISK ASSESSMENT OF AGRICULTURAL INTENSIFICATION ON N DEPOSITION ON PRISTINE FORESTS AND PLANTATIONS IN SOUTHERN CHILE

P. Boeckx, L. Paulino & R. Godoy

The 2^nd international workshop in the framework of a bilateral scientific and technological cooperation between Flanders and Chile was held on January 11, 2005 in Valdivia, Chile. The title of the workshop and the project is: "Risk assessment of agricultural intensification on N deposition on pristine forests and plantations in southern Chile". The Chilean promoters were Universidad Austral and INIA-Remehue. The Flemish promoters were Ghent University and Catholic University Leuven. We would like to thank the Ministry of the Flemish Community, for financially supporting this collaboration (BIL/01/04). We are also grateful for the scientific and financial support of Universidad Austral de Chile, Chilean National Commission for Science and Technology (CONICYT), FONDECYT grants 1020989 and 1030344, International Cooperation Agency (AGCI) and Scientific Initiative Millennium (ICM MIDEPLAN). Finally we thank Dr. Chris Lusk as editor of Gayana Botanica for providing us a space in this special issue.

During the 2^nd international workshop 13 scientific presentations were given. Seven contributors agreed to produce a full paper for this special issue of Gayana Botanica. The highlights of these papers are summarized below, covering various aspects of biogeochemical cycles and processes in forests, hydrology in forested ecosystems and the environmental effects of agricultural practices.

The first set of contributions deals with biogeochemical cycles and process studies of N in forest ecosystems. Godoy et al. point out that dry inorganic N deposition could be underestimated in Chilean terrestrial ecosystems. Based on a monthly monitoring campaign, using a method with passive samplers, dry N deposition was estimated at 12 kg ha^-1. Dry N deposition increased in the following order: Pinus plantation < grassland < Nothofagus forest. Staelens et al. reported on N inputs to semi-

pristine Nothofagus stands in the central depression and the Andean mountains. These authors suggested that dry deposition could be in the order of 4-8 kg N ha^-1, exceeding wet deposition. They also showed that internal N return is larger than external atmospheric N inputs. Boeckx et al. highlighted the lack of scientific data on trace gas N fluxes (N₂O and NO) from forest soils and the potential importance of these fluxes.

Two papers tackle hydrological subjects. Peters et al. introduce the concept of ecohydrology and discuss monitoring and modelling aspects of this topic. Oyarzún et al. compare N losses from native forest and exotic plantations in the coastal range of south-central Chile, finding substantially higher inorganic N export from the latter. .

The last two contributions present an overview and a case study of the impact of agriculture on the environment. Van Cleemput & Boeckx give a summary of the potential impact of agricultural practices on the environment. They discuss items such as nitrate leaching and the health risk of nitrate in drinking water, eutrophication, emission of greenhouse gases and the greenhouse effect, ozone formation y acidification. A case study from southern Chile on nitrate leaching is presented by Alfaro et al. They showed that nitrate loss form grassland soils varied between 16-18 kg N ha^-1. These relatively low nitrate losses could be explained via the low N input and the buffering capacity of the Andisols. However, the risk for runoff losses and intensification of livestock production is stressed as well.

This volume of Gayana Botanica depicts current biogeochemical research in southern Chile. This kind of research is needed to establish a deeper knowledge of the ecological functioning of forest ecosystems and hopefully contributes to its protection or sustainable management.