Croplands are intensively managed agricultural ecosystems maintained by supplementation of nutrients and water, sowing and harvesting, soil cultivation and control of non-target plants and animals (weeds and pests). They currently cover 11% of the world’s land surface. Some systems of management include domestic herbivores introduced on harvested stubble or in ‘fallow’ years. These are structurally simple, very low-diversity, high-productivity systems, dominated by one or few non-woody, shallow-rooted annual plant species such as grains (mostly C₃ grasses), vegetables, ‘cut flowers’, legumes, or fibre plants harvested annually by humans for commercial or subsistence production of food, materials, or ornamental displays.