Shaded perennial agroforestry systems

Abstract

The shaded perennial systems, also called plantation-crop combinations, include managed multistrata tree-crop associations predominantly in the tropics, in which the main crops are perennials that are harvested periodically like arable crops. These tree crops are economically and socially very important to the countries where they are cultivated because of the large number of people involved in the cultivation and processing of the products. The major tropical tree crops in agroforestry systems (AFS) include coconut (Cocos nucifera), coffee (Coffea spp.), and cacao (Theobroma cacao); oil palm (Elaeis guineensis), and rubber (Hevea brasiliensis) are also components of AFS to a limited scale. There are also several other types of shaded perennial systems that are less widely distributed, including black pepper (Piper nigrum) vines trailed onto the trunks of trees, and palms such as Bactris gasipaes (peach palm) and Euterpe oleracea (açaí or assai). The harvested products of almost all these tree crops need to be processed immediately after harvesting under exacting conditions to get the high-value end-products. Contrary to the popular image of largescale plantations associated with these crops, sizeable areas of most of them, particularly coconut, coffee, and several of the localized tree crops are cultivated in mixed (agroforestry) stands with other species on smallholder farms. Research on the high-value tree crops such as coffee, cacao, rubber, and oil palm has traditionally been well-organized but focused on maximizing the productivity of the harvested product of the crop raised in monocultural stands. Research on integrated smallholder crop combinations involving coconut palm, shaded coffee, and cacao has also progressed substantially since the late 1900s. Agroforestry systems involving these tree crops are receiving heightened attention nowadays in the context of the ecosystem services they provide and their potential role in climate change mitigation and biodiversity conservation.