USDA LTAR Common Experiment measurement: Non-crop plant biodiversity v1

Non-crop plant diversity, implemented by producers to manage environmental quality or biodiversity-based ecosystem services within croplands, is important because it is strongly related to other biodiversity-based ecosystem services and ecosystem function. Diversity is often correlated with primary production and thus associated with numerous ecosystem services, including food, fuel, and fiber provisioning; water management and erosion control; nutrient cycling; carbon storage; and habitat for wildlife and pollinators. Moreover, plant diversity is an ecosystem characteristic amenable to manipulation and predictively responsive to climate change, thus providing a mechanism whereby ecosystem services may be sustainably managed now and into the changing future. In the LTAR croplands common experiment, non-crop plant diversity is measured using a multi-scale plot known as a Whittaker plot. The presence and percent cover of species and ancillary data is observed in eight 1 m2 subplots. The presence of species is observed in eight 10 m2 subplots and four 100 m2 subplots, which can be combined for a list of species at the 400 m2 plot scale. The multi‐scale plot design is consistent with the methods of NEON (Barnett et al. 2019) and the Carolina Vegetation Project (Peet et al. 1998), similar to other multi-scale methods (Stohlgren 2007), and is based on Robert Whittaker’s approach to sampling vegetation. It is possible to modify the size of a Whittaker plot as necessary to fit within experimental constraints. Because the effectiveness of floral strips or hedgerows may depend on landscape context, we also recommend assessing the proportional cover of arable crops as a proxy for landscape simplification (e.g., Tscharntke et al., 2005; Dainese et al., 2019). Calculate the proportional cover of arable crops in circular sectors of a 1 km radius around focal crops or a 750 m or 500 m radius (Albrecht et al. 2020). To assess the impact of non-crop plant diversity on other aspects of biodiversity and ecosystem services, co-locate measurements of beneficial insects (e.g., butterflies and pollinators), soil health attributes, and soil microbial diversity with Whittaker plots.