Animals and plants form the foundation for a bio-based economy. Agriculture and forestry additionally represent an essential economic factor: more than 300,000 companies are active in this field in Germany. The significance of agriculture and forestry for added value in rural areas is great. Those at work on farms and in forests husband more than three-fourths of the area of Germany. After the Second World War, one farmer could feed ten people: today, the number is 147. During recent years, many farmers have expanded their area of activity. They produce, for example, bio-based raw materials for industry as well as biomass for renewable energy. This includes industry and energy crops such as rapeseed and maize, in addition to by-products such as liquid manure and straw. From agricultural biomass, fermenters produce source materials for bio-based plastics and other sustainable chemicals (see section “Chemistry”). Biogas plants and CHP stations likewise supply heat, power and fuels (see section “Energy”). Around half the German farmers also own forests. Wood as raw material goes into many and various products: lumber, plywood, engineered wood, wood-synthetic composites, paper, cardboard, bio-energy pellets and briquettes.