Smart Orchards aid the messy business of pollination

One of the common threats to biodiversity listed is agriculture. Mina Anders and colleagues have examined whether biodiversity and agriculture have to have an antagonistic relationship. In a new paper in the Journal of Applied Ecology, the authors propose smart orchard design and ecological intensification to enhance pollination services for Macadamia integrifolia. The research offers the possibility of cutting the environmental impacts of agricultural production while still obtaining high yields.

Macadamia is a pollen-limited plant, meaning that the factor that makes most difference to nut set is pollen delivery. Get more pollen to the flowers, and you get more nuts. A macadamia tree can have hundreds of thousands of flowers to pollinate, so that’s a lot of pollen that needs to be delivered.

Anders and colleagues studied three factors – agronomic input, orchard design, and landscape composition – in ten South African macadamia orchards. As expected, insect pollination was important, increasing the initial and final nut set. Hand pollination further improved nut set, confirming earlier research. One of the interesting results was that flower visitation rates increased with the cover of semi-natural habitats in the surrounding landscape. This outperformed the effect of managed honeybee colonies onsite.

Perhaps unsurprisingly, the biologists found that the orchard design significantly influenced initial nut set. Planting macadamia rows perpendicular to semi-natural habitats increased initial nut set more than three times as much as parallel row orientation. Initial nut set was 80% higher at the edge of semi-natural habitats than at the orchard centre. In contrast, agronomic practices like irrigation did not affect initial nut set. The final nut set depended on the preconditions of the initial nut set.

The authors are keen to emphasise the value of using ecosystem services to assist agriculture. In their article, they write.

Our pollination experiment corroborated the high reliance of macadamia on cross-pollination for nut production, as shown by enhanced nut set in the open (23%) and hand pollination treatments (367%). Moreover, the flower visitation rate of insect pollinators was one of the most important variables explaining the initial nut set of open-pollinated racemes. Interestingly, flower visitation rates were mainly driven by landscape composition (i.e. the cover of semi-natural habitats) and orchard design (row orientation) and less related to agronomic practices (supplementary honeybee colonies). These findings indicate that ecological intensification by promotion of pollination services based on landscape and orchard design could represent one element for sustainable macadamia production, despite farmers’ high investments in conventional intensification practices, such as irrigation or managed honeybee colonies.

Anders et al. 2023.

READ THE ARTICLE

Anders, M., Grass, I., Linden, V.M.G., Taylor, P.J. and Westphal, C. (2023) “Smart orchard design improves crop pollination,” The Journal of Applied Ecology. Available at: https://doi.org/10.1111/1365-2664.14363.