remote sensing Article Potential of Different Optical and SAR Data in Forest and Land Cover Classification to Support REDD+ MRV Laura Sirro 1, *, Tuomas Häme 1 , Yrjö Rauste 1 , Jorma Kilpi 1 ID , Jarno Hämäläinen 2 , Katja Gunia 2 , Bernardus de Jong 3 and Fernando Paz Pellat 4 1 VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT FI-02044, Finland; tuomas.hame@vtt.fi (T.H.); yrjo.rauste@vtt.fi (Y.R.); jorma.kilpi@vtt.fi (J.K.) 2 Arbonaut Ltd., Kaislakatu 2, Joensuu FI-80130, Finland; jarno.hamalainen@arbonaut.com (J.H.); katja.gunia@arbonaut.com (K.G.) 3 El Colegio de la Frontera Sur, Av. Rancho Polígono 2-A, Parque Industrial Lerma, Campeche, Campeche CP 24500, Mexico; bjong@ecosur.mx 4 Colegio de Postgraduados, Km 36.5 Carretera México-Texcoco, Texcoco 56230, Mexico; pellat@colpos.mx * Correspondence: laura.sirro@vtt.fi; Tel.: +358-40-538-7769 Received: 9 May 2018; Accepted: 11 June 2018; Published: 14 June 2018   Abstract: The applicability of optical and synthetic aperture radar (SAR) data for land cover classification to support REDD+ (Reducing Emissions from Deforestation and Forest Degradation) MRV (measuring, reporting and verification) services was tested on a tropical to sub-tropical test site. The 100 km by 100 km test site was situated in the State of Chiapas in Mexico. Land cover classifications were computed using RapidEye and Landsat TM optical satellite images and ALOS PALSAR L-band and Envisat ASAR C-band images. Identical sample plot data from Kompsat-2 imagery of one-metre spatial resolution were used for the accuracy assessment. The overall accuracy for forest and non-forest classification varied between 95% for the RapidEye classification and 74% for the Envisat ASAR classification. For more detailed land cover classification, the accuracies varied between 89% and 70%, respectively. A combination of Landsat TM and ALOS PALSAR data sets provided only 1% improvement in the overall accuracy. The biases were small in most classifications, varying from practically zero for the Landsat TM based classification to a 7% overestimation of forest area in the Envisat ASAR classification. Considering the pros and cons of the data types, we recommend optical data of 10 m spatial resolution as the primary data source for REDD MRV purposes. The results with L-band SAR data were nearly as accurate as the optical data but considering the present maturity of the imaging systems and image analysis methods, the L-band SAR is recommended as a secondary data source. The C-band SAR clearly has poorer potential than the L-band but it is applicable in stratification for a statistical sampling when other image types are unavailable. Keywords: REDD; land cover classification; Landsat; RapidEye; ALOS PALSAR; Envisat ASAR 1. Introduction The global yearly deforestation rate during 2000–2010 was 13 million hectares [1]. Although the rate has recently been decreasing in several countries such as Brazil, it is still high in the tropical zone [2]. The carbon densities of tropical and boreal forests are similar but the differences in the speed of nutrient recycling result in a situation where over 50% of tropical forest carbon is stored in the living biomass, whereas the corresponding figure is 20% in boreal forest [3,4]. In the tropical forest, a large Remote Sens. 2018, 10, 942; doi:10.3390/rs10060942 www.mdpi.com/journal/remotesensing