Short rotation crops
Willows and poplars are fast-growing tree species that can be cultivated on arable land. They have their highest biomass growth in the first few years after planting or harvesting and can therefore be harvested in "short rotation", i.e. repeatedly every 3 - 6 years. During harvesting, the entire tree is cut off about 15 cm above the ground and the trunks and branches are either laid out to dry or processed directly into chippings. The harvested biomass contains around 45% cellulose and 15% lignin. This makes it particularly suitable for paper production or for generating heat through combustion.