Impact of climate change mitigation strategies in rice farming on agroecosystem multifunctionality

Abstract

1. Rice agroecosystems are important contributors to climate change through methane (CH4) emissions, while also representing biodiversity hotspots and providing agroecosystem services (ES). Non-continuous flooding irrigation strategies have been globally implemented as climate change mitigation and adaptation practices in rice paddy fields as they decrease CH4 emissions and water use. Although such effects have been widely studied, there is a knowledge gap regarding outcomes in terms of biodiversity and overall agroecosystem multifunctionality. 2. Here, we implemented a field-scale experiment to assess the effects of different irrigation strategies across a water use gradient (CON: continuous flooding; MSD: mid-season drainage; and AWD: alternate wetting and drying) on (i) the provision of ES (i.e. biodiversity conservation, regulating and provisioning services), (ii) overall agroecosystem multifunctionality and (iii) synergies or trade-offs among ES. 3. None of the irrigation strategies benefited most taxa or improve most regulating services. For instance, AWD generally benefited invertebrate diversity while reducing vertebrate abundances and grain yields. Both AWD and MSD decreased CH4 emissions by approximately 80 kg C-CH4 ha−1 but decreased soil carbon storage by 8.8%, when compared to continuously flooded fields. Consequently, all irrigation strategies exhibited a similar level of multifunctionality, although providing different services. Lastly, we did not find trade-offs or synergies between biodiversity conservation, regulating services and provisioning services. 4. Synthesis and applications. These results suggest that, from a landscape management perspective, implementing a single irrigation strategy at large spatial scales should be discouraged due to potential negative effects on particular sets of ES components. Conversely, a mosaic of irrigation strategies should be implemented, promoting ES components aligned with site-specific landscape management objectives.