WINETECH Technical Yearbook 2021

et al ., 2011). But these studies were mostly done in Western European and North American systems (Batáry et al ., 2015; Winter et al ., 2018) and the effectiveness of these methods are site-specific, meaning tailored strategies are needed for farms in different settings (Cunningham et al ., 2013; Tscharntke et al ., 2012). Thus, identifying local practices that promote biodiversity will provide valuable guidance to farmland conservation efforts. These practices should be relevant to both small- and large-scale farmers and should be easy to apply in order to be an attractive option (Sattler & Nagel, 2010; Sutherland, 2010). On the other hand, a holistic approach, such as organic farming, has also been shown to benefit biodiversity (Bengtsson et al ., 2005; Hole et al ., 2005; Letourneau & Bothwell, 2008). Organic farms use a combination of environmental-friendly practices, i.e. avoiding insecticides and synthetic fertilisers, and use a range of regenerative practices that aim to improve resilience in the agroecosystem. Using a combination of complementary practices generates the greatest positive effect for the environment, and may even have synergistic effects (Hole et al ., 2005; Rigby & Cáceres, 2001). However, it has not really been tested whether a carefully selected individual practice or a holistic approach

holds the greatest benefit for biodiversity (Hole et al ., 2005). STUDY AREA The Cape Floristic Region (CFR) of South Africa is a Mediterranean-type ecosystem and a global biodiversity hotspot (Mittermeier et al ., 2004). The CFR supports an exceptional diversity of endemic plants (Goldblatt & Manning, 2000; Manning & Goldblatt, 2012), with a similar trend in the diversity of arthropods (Janion- Scheepers et al ., 2020; Kemp & Ellis, 2017; Procheş & Cowling, 2006). However, a large area of the CFR has been transformed to agriculture (Cowling et al ., 2003), with vineyards alone covering around 88 366 ha (SAWIS, 2019). Globally, there is a trend for vineyard intensification and vineyards have the potential to support high levels of biodiversity (Isaia et al ., 2006; Paiola et al ., 2020). It is therefore important to understand which factors create favourable conditions for biodiversity in vineyards, as it will contribute to conservation in vineyard- dominated landscapes. We assessed the ef fect of var ious management practices, i.e. application intensity of agrochemicals, tillage, cover crop characteristics, soil compaction, and the volume of plant litter on arthropod diversity in vineyards across the CFR, and

whether there is added benefit of a holistic approach compared to an integrated approach. In particular, we tested these effects for spiders, beetles, and true bugs that live on the ground, on the cover crop, and on the vine foliage. Additionally, we tested these effects on predators, herbivores, and detritivores. FINDINGS Effect of management practices We expected different arthropods to respond differently due to their wide range of resource requirements, sensitivity to agricultural disturbances (Birkhofer et al ., 2014; Fuller et al ., 2005), and microhabitat preference (Shapira et al ., 2018). However, there was a consistent, strong positive effect of vegetation- related variables on arthropods. Increased herbaceous vegetation in the cover crops positively influenced the species richness of arthropods in each of the taxonomic, microhabitat, and feeding guild groups. Additionally, the volume of plant litter, number of plant species, and vegetation height in vineyard inter-rows positively influenced arthropod species richness, whereas grass cover promoted arthropod richness on the vines. Our findings are in line with results from recent global reviews showing that extensive

vegetation management can significantly enhance biodiversity in vineyards (Paiola et al . 2020; Winter et al ., 2018) and in other crops (Isbell et al ., 2017; Lichtenberg et al ., 2017). The effect is possibly due to a greater diversity of resources that a more diverse and dense cover crop provides, i.e. food and hosts, as well as greater structural complexity, refuge, and moderated microclimate in the crop fields (Danne et al ., 2010; Landis et al ., 2000), being provided by both the live plants and plant litter. Increasing vineyard cover crop diversity can promote important services provided by arthropods in vineyards, such as natural pest control (Shapira et al ., 2018; Sanguankeo & León, 2011; Sommaggio et al ., 2018). It can also promote the conservation of wild bees (Kratschmer et al ., 2019) and specialist butterflies (James et al ., 2015). An important advantage that perennial crops have over annual crops is the permanence of the crop. This allows the establishment of more diverse and longer lasting cover crops that can provide alternative microhabitats (Simon et al ., 2010) and resources for longer periods of the year (Pfiffner et al ., 2019). Effect of overall farming approach Globally, organic farming has been shown to mitigate the ongoing loss of biodiversity (Bengtsson et al ., 2005), but the effects vary for different taxa and systems (Birkhofer

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