Agriculture is one of the most vulnerable and adaptation-prone sources of livelihood facing climate change. Joint adaptation planning by farmers and researchers can help develop practically feasible and environmentally and economically sound adaptation actions as well as encourage the proactive building of farm adaptive capacity. Here, the perceptions of Finnish farmers and rural stakeholders regarding intercropping, the cultivation of two or more crop genotypes together in time and space, as a means to prepare for climate change, were collected in an open workshop. Our aim was to identify the potentials and challenges associated with intercropping, its role as an adaptation strategy, and in farm adaptive capacity. Qualitative analysis revealed better yield security, increased nutrient and protein self-sufficiency, soil conservation and maintenance, reduced pathogen pressure and regulation of water dynamics as the main perceived potentials of intercropping. Potentials relating to the farm economy and environment were also recognized. The main challenges associated with intercropping were related to the lack of information on crop variety performance and optimal yielding in mixtures, industry and policy requirements for seed purity, more complicated crop management and harvesting, and the economic risks associated with experimenting with novel mixtures. Nitrogen-fixing legumes; deep-rooted species, such as lucerne (Medicago sativa L.); special crops, such as herbs in forage mixtures; and autumn-sown winter oilseeds and cereals were highlighted as the most promising intercrops. Because the recognized potentials relate to the safeguarding of field cropping from anticipated climate change and the associated weather variability, we conclude that intercropping can serve as one adaptation strategy to strengthen the adaptive capacity of Finnish farms. However, assuring markets and policies that allow the development of intercropping, performing experiments to assess the benefits and implement options in practice, and providing farmers and farm advisors with more knowledge on the method represent the critical prerequisites for the broader adoption of intercropping.

Himanen, S. J., P. Rikkonen, and H. Kahiluoto. 2016. Codesigning a resilient food system. Ecology and Society 21(4):41. https://doi.org/10.5751/ES-08878-210441

Associational herbivore resistance is potentiated by neighbouring heterogenic plant species that impact a focal plant’s attraction to herbivores or the damage that they cause. One mechanism to confer associational resistance is believed to be exposure to neighbour-emitted volatiles, the receivers of which range from intra- and interspecific neighbour plants to higher-trophic-level insects. In previous studies the passive adsorption of neighbour-emitted semivolatiles has been reported, but little is known regarding the mechanisms and ecological consequences on the receiver plant and its associated biota. To utilize volatile-based associational resistance for agricultural applications, it is imperative to know its effectiveness under varying diurnal temperatures and whether herbivore natural enemies, providing biological control, are impacted. Mimicking varying diurnal temperatures in a laboratory set-up, we assessed how the tritrophic model system Brassica oleracea var. italica (broccoli)–Plutella xylostella (crucifer specialist herbivore)–Cotesia vestalis (endoparasitoid of P. xylostella) is influenced by exposure to the natural semivolatile emitter plant Rhododendron tomentosum Harmaja. Rhododendron tomentosum-exposed B. oleracea was less susceptible to P. xylostella oviposition at both night-time (12°C) and day-time (22°C) temperatures and less favoured and damaged by P. xylostella larvae at 12°C. Exposure did not interfere with indirect defence, i.e. attraction of the natural enemy C. vestalis on host-damaged, R. tomentosum-exposed B. oleracea under 22°C, while there was a reduction in attraction (marginal preference towards host-damaged B. oleracea) under 12°C. The ability of R. tomentosum exposure to render associational resistance against an agriculturally important Brassica herbivore P. xylostella without severely compromising the specialist parasitoid C. vestalis host location encourages further studies on the potential of using this naturally abundant plant for biocontrol. The generality of our finding on temperature as a potential regulating mechanism for the efficacy of semivolatile emitter-based associational resistance towards specialist pest larval damage should be further studied in natural and agricultural associations. Our study emphasizes the need to develop techniques to compare volatiles at the leaf versus air interface and associate their appearance and ecological role with times of activity and level of specialisation of herbivores and their natural enemies.