EU-wide maps of growing stock and above-ground biomass in forests based on remote sensing and field measurements Heinz Gallaun a, *, Giuliana Zanchi a , Gert-Jan Nabuurs b , Geerten Hengeveld b , Mathias Schardt a , Pieter J. Verkerk c a Joanneum Research, Steyrergasse 17, 8010 Graz, Styria, Austria b Alterra b.v., PO Box 47, 6700 AA Wageningen, Netherlands c European Forest Institute, Torikatu 34, 80100 Joensuu, Finland 1. Introduction The overall objective of this study was to develop EU-wide maps on growing stock and above-ground woody biomass for the two species groups ‘‘broadleaves’’ and ‘‘conifers’’, by combining national forest inventory data and remotely sensed data. Forests cover 44% of land area in Europe and are therefore of major ecological, political and economic importance. Whereas accurate estimations of forest parameters are available at the local level, especially for growing stock, European-wide assessments with high spatial resolution are not common. The recent development of strategies for renewable energy production, the progressive globalisation of the markets, including the market of wood products, and carbon stock estimation for climate change modelling, have increased the demand for spatial explicit information on forest resources. Two important para- meters that well describe the spatial distribution of the forest resources are maps on growing stock and the biomass stock. For the estimation of growing stock and above-ground biomass, different approaches have been developed, based on field measurement, modelling, and remote sensing. A good overview is given by Lu (2006). Field measurements are used for accurate estimation of growing stock and woody biomass from the allometric relationship with measured diameter at breast height and tree height. Mostly, only small areas are measured, as the field measurements are very labour- and cost-intensive. The typical size of plots measured in national forest inventories is between 200 m 2 and 500 m 2 . In general, remote sensing approaches for estimating forest para- meters are based on reference data such as e.g. plot data, for which Forest Ecology and Management 260 (2010) 252–261 ARTICLE INFO Article history: Received 9 July 2009 Received in revised form 1 October 2009 Accepted 13 October 2009 Keywords: Biomass Growing stock Carbon Remote sensing Forest inventory MODIS ABSTRACT The overall objective of this study was to combine national forest inventory data and remotely sensed data to produce pan-European maps on growing stock and above-ground woody biomass for the two species groups ‘‘broadleaves’’ and ‘‘conifers’’. An automatic up-scaling approach making use of satellite remote sensing data and field measurement data was applied for EU-wide mapping of growing stock and above-ground biomass in forests. The approach is based on sampling and allows the direct combination of data with different measurement units such as forest inventory plot data and satellite remote sensing data. For the classification, data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used. Comprehensive field measurement data from national forest inventories for 98,979 locations from 16 countries were used for which tree species and growing stock estimates were available. The classification results were evaluated by comparison with regional estimates derived independently from the classification from national forest inventories. The validation at the regional level shows a high correlation between the classification results and the field based estimates with correlation coefficient r = 0.96 for coniferous, r = 0.94 for broadleaved and r = 0.97 for total growing stock per hectare. The mean absolute error of the estimations is 25 m 3 /ha for coniferous, 20 m 3 /ha for broadleaved and 25 m 3 /ha for total growing stock per hectare. Biomass conversion and expansion factors were applied to convert the growing stock classification results to carbon stock in above-ground biomass. As results of the classification, coniferous and broadleaved growing stock as well as carbon stock of the above-ground biomass is mapped on a wall-to-wall basis with a spatial resolution of 500 m  500 m per grid cell. The mapped area is 5 million km 2 , of which 2 million km 2 are forests, and covers the whole European Union, the EFTA countries, the Balkans, Belarus, the Ukraine, Moldova, Armenia, Azerbaijan, Georgia and Turkey. ß 2009 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +43 3168761757; fax: +43 31687691757. E-mail address: heinz.gallaun@joanneum.at (H. Gallaun). Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco 0378-1127/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2009.10.011