WINETECH Technical Yearbook 2021

broader benefits, such as biological pest control, recycling of nutrients, regulating microclimate and hydrological processes, and reducing soil erosion (Garcia et al ., 2018). Managing a diverse cover crop can therefore be an effective multi-functional practice in vineyards. It is a low-cost practice, easy to implement, and is already implemented in many vineyards worldwide. The findings of this study are vital for ensuring the sustainability of viticulture in a global biodiversity hotspot, and for gaining the continued support and approval from the general public. This is important as there is a growing demand for sustainably produced products in South Africa (Kelly & Metelerkamp, 2015). Over time the increased demand for sustainably sourced products should motivate more and more farmers to adopt an environmental-friendly approach which will hold benefits to biodiversity and wine production within the CFR. SUMMARY Intensive agriculture threatens our global biodiversity and requires a shift to environmental-friendly farming. Identifying farm management practices that can also enhance biodiversity, will help guide future conservation efforts in farmlands. We therefore assessed how individual

management practices affect arthropod diversity in vineyards. We also looked at whether these effects were different on arthropods that occur on integrated vs. organic vineyards. Increased herbaceous vegetation in vineyard cover crops consistently had a strong positive effect on arthropod diversity. Additionally, plant litter on the vineyard floor, the number of plant species and the height of plants in the cover crop positively influenced arthropod diversity. We did not find major differences in the effects of organic vs. integrated management practices on the studied arthropods. Our results show that managing a dense and diverse cover crop in vineyards is a strategic and cost- effective way to enhance arthropod diversity, through minimal adjustment to current management practices, regardless of the farming approach. ACKNOWLEDGEMENTS This study was conducted by Stellenbosch University and funded by the Mapula Trust and The Lewis Foundation. We would like to thank the Cape Winelands Biosphere Reserve and all landowners, farmmanagers and viticulturalists that made their vineyards and management information available to us. The sampling of arthropods was approved by Cape Nature, permit number AAA007-00144-0056.

Suction sampling of arthropods in the vine foliage layer. (Photo: Susan Geldenhuys).

et al ., 2014; Fuller et al ., 2005). Studies on organic farming in the CFR have also shown mixed results for different taxa (Gaigher & Samways, 2010; Gaigher & Samways, 2014; Kehinde & Samways, 2012). Here, organic vineyards did not have a significantly positive effect compared to integrated vineyards. This may be due to most wine farms already complying with international wine industry sustainability through the Integrated Production of Wine Scheme of South Africa (IPW) (http://www.ipw. co.za). Although the use of conventional agrochemicals is permitted under IPW guidelines, farmers use it cautiously, i.e. for spot treatments only, and usually in combination with non-chemical plant protection measures e.g., biological releases of beneficial insects. Another reason for the

lack of positive effects may be due to the proportion of organic farms in the landscape being too low. It has been shown that higher proportions of organic farms in a landscape can enhance field-scale arthropod diversity, and that an organic farming approach works best as an area-wide management strategy (Holzschuh et al ., 2008; Inclán et al ., 2015). Thus, increasing the number of organic farms in agricultural landscapes will have greater benefits to arthropod biodiversity. CONCLUSION We demonstrated clear benefits of vineyard cover crops on arthropod diversity in the CFR, which corresponds with global recommendations for improving vineyard sustainability (Paiola et al . 2020; Winter et al ., 2018). Furthermore, diversifying cover crops in vineyards may have

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