Ground cover management in organic apple orchards in South Africa: Trade-offs between above- and belowground ecosystem services

The global demand for organically farmed products is increasing, as consumers become aware of the lower environmental impact of organic farming. Organic growers have to rely on the simultaneous provision of multiple ecosystem services as they cannot replace natural regulatory processes (e.g. biological control) by artificial inputs (e.g. synthetic pesticides). The provision of individual ecosystem services in organic production systems can be actively supported by management decisions, but it remains unknown to what extent individual management practices affect the relationships between multiple above- and belowground ecosystem services.
A major constraint for organic production of temperate fruits in South Africa is the limited availability of alternative strategies for pest control and nutrient management in soils. Here we aim to understand the ecological mechanisms that underlie the simultaneous provision of related above- and belowground ecosystem services and how different ground cover management strategies contribute to synergies between these services. We will further assess the drivers that motivate growers to apply certain ground cover management strategies to facilitate the application of recommended strategies and to improve multifunctionality in organic apple production systems.
Field studies in organic apple orchards in the Western Cape will focus on the effect of different ground cover management strategies on above- and belowground communities of microbes, animals and plants and related above- (e.g. biological control) and belowground (e.g. decomposition or nutrient mineralization) services. Multivariate models will be used to analyse relationships between services and to provide information about strategies that foster synergies between services. Interviews with growers and discussions at a dissemination meeting will help understanding decision processes in terms of the application of management strategies. The consortium has excellent experience in organic farming and aboveground biodiversity and ecosystem services research (K. Birkhofer, R. Lindborg) and belowground diversity and processes (K. Birkhofer, W Swart) and the proposed coordinator in South Africa (M. Addison) has well-established contacts to apple growers in the Western Cape area. In addition to a dissemination meeting, a policy letter, contributions to international conferences and open-access publications will contribute to the national and international dissemination of findings and their impact on organic apple production.