The concept of “weed” is partly related to the natural occupation by plant species of milieus that have been opened for cultivation. These species, which represent the natural flora of agroecosystems, can be perceived as a hindrance to the cultivated species and to the realization of certain agricultural operations. Their presence in the field can induce a loss of income for the farmer, as it reduces the quantity and quality of the crop or slows down work. Conversely, weeds can provide benefits that have recently been redefined in terms of ecosystem services. The services attributed to weed species are widely varied and include soil protection, the sheltering of auxiliary crops, but they also play a role of trophic resources by providing vertebrate and invertebrate species with nectar, leaves and seeds.

Within the context of the development of agroecology, many research prospects are presently opening up in ecology and in the management of weed flora of cultivated fields. Among these prospects, the improved evaluation of the ecosystem services associated with the presence of weed species will require a deeper knowledge of their autoecology, but also of the biotic relationships they are involved in. In the same way, the setting up of landscape structures and the development of new cropping systems with very low levels of soil disturbance might greatly facilitate biological interactions and thus lead to a better regulation of weeds in agroecosystems.