Scott Johnson

Multi-Trophic Interactions

Photograph of a beetle on chicory flowerMulti-trophic Interactions is a new major research topic in Agroecology that combines existing lines of study at both SCRI and the University of Dundee. Trophic (or feeding) interactions drive the cycling of energy and nutrients in farmland. Insects and other invertebrates feed on plants and in turn are fed on by other insects, spiders, various symbionts, pathogens and vertebrates. A very small proportion of the total species in trophic interactions are pests of agriculture. Most mediate processes that are essential to the cropping cycle, such as the breakdown of dead organisms (crops, weeds, wood, animals), the regulation of pests and the pollination of flowers. These trophic interactions are exceedingly complex and are studied using advanced concepts and methods in organism biology, molecular biology and mathematical modelling.  Through gaining basic knowledge, the topic aims to provide a scientific basis for future management of invertebrate populations in farmland.

Agroecology News Archive

Ecological roles of weeds In an invited plenary talk, Geoff Squire represented the group's ideas on the roles of weeds at the XIII Colloque International sur la Biologie des Mauvaises Herbes held at Dijon, France 8-10 September 2009. The main points of the talk were: weeds have been with us in northern Europe for more than 5000 years - we haven't got rid of them; so we need to understand them better, spend less trying to remove them and make use of their positive roles in the ecosystem. Arable cropping in Scotland is already some way towards coexisting with weeds: its cereal yields and weed seedbanks are both among the highest in the UK!  (Added 14 September 2009)

Publications archive

Refereed publications and major reports from the Agroecology group

Newton, A.C., Begg, G.S., Swanston, J.S. 2008. Deployment of diversity for enhanced crop function. Annals of Applied Biology (doi:10.1111/j.1744-7348.2008.00303.x).

Monocultures are used in high-input systems to maximise short term profitability, but over time yield and quality can become unstable. This paper considers how diversity can be reintroduced to cropping systems to confer stability without compromising quality. It combines expertise between three of SCRI's programmes: Pathology (ACN), Genetics (JSS) and Environment (GSB).

Squire, G.R., Hawes, C., Begg, G.S., Young, M.W. 2009. Cumulative impact of GM herbicide-tolerant cropping on arable plants assessed through species-based and functional taxonomies. Environmental Science and Pollution Research 16(1), 85-94. Published online 2 December 2008 (doi: 10.1007/s11356-008-0072-6).

Above-ground - below-ground trophic interactions

There is now emerging consensus that above-ground and below-ground compartments are intimately linked, with many examples of spatially separated organisms interacting to shape community dynamics via plant-mediated mechanisms. Research at SCRI aims to gain a mechanistic understanding of the genetic and chemical plant-mediated processes which underpin interactions between organisms that exploit different parts of the plant. By understanding these key processes, we aim to exploit natural resistance mechanisms to herbivore attack and manipulate trophic interactions to manage crop pests and maintain system stability.

We work on several systems including barley, raspberry and brassicas, focusing on how soil-dwelling herbivores (predominantly root-feeding insects) affect above-ground herbivores, their antagonists (for example, parasitoids) and plant pathogens. At present our experimental and modelling research is funded by the Scottish Government, the Natural Environmental Research Council and the Engineering and Physical Sciences Research Council. Examples of our current research include the following.Image of aphids

Environment Plant Interactions

Image of the SCRI site looking towards the River TaySCRI's environmental science research spans across disciplines to gain a holistic understanding of how plants respond to and modify environmental processes. Scottish Government commissioned research is gaining an in-depth understanding of the environment in arable farming systems and this is being used to advise on policy development in Scotland. These skills have also been applied to emerging issues relevant to the UK and Europe, including the UK’s Farm Scale Evaluations, international working groups, IPDM-based alternatives to pesicides and EU-wide studies on the ecological impacts of GM plants.

The environment and the ecology of plants and pests are our key research areas, investigated by a strong multidisciplinary team of scientists in entomology, pathology, plant sciences, vegetation ecology, phytochemistry, mathematical modelling and soil sciences. A major area of interest is integrating processes that occur above ground and in the soil. Research conducted on plant interactions with soil has extended from the understanding of sustainable arable systems to ‘green’ engineering solutions for slope stabilisation with vegetation.

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