The Agriculture and Forestry Ontology AFO (ca. 6 000 concepts) is based on the Agriforest thesaurus maintained by the Viikki Campus Library, University of Helsinki. The combination of AFO and the Finnish General Upper Ontology YSO has been created in the FinnONTO project by the Viikki Science Library in cooperation with the Semantic Computing Research Group. The ontology was created by aligning the Agriculture and Forestry Ontology AFO with the Finnish General Upper Ontology YSO using the top ontology and other modelling principles of YSO. This way the equivalent and differing concepts and their links to more general concepts could be explicitly described. This combination of ontologies can be used for describing resources especially in domain of agriculture, forestry, veterinary medicine, food science, environmental science and biology.