From diverse to simple: butterfly communities erode from extensive grasslands to intensively used farmland and urban areas

Abstract

The severe biodiversity decline in European agricultural landscapes demands a specific evaluation of the various land-use practices. Many butterflies in Europe, as an important ecological indicator and pollinator taxon, require human interventions to sustain their populations in cultivated landscapes. However, land-use changes and management intensification are currently responsible for their decline. In this study, we compare butterfly communities occurring on 93 sites in seven widely distributed land-use types, viz. extensive meadows and pastures, semi-intensive meadows, vineyards, arable land, settlements and apple orchards. We recorded a high butterfly diversity in supposedly high nature-conservation value (HNV) grasslands (extensive meadows and pastures). All other land-use types showed significantly lower diversity, with decreasing diversity from semi-intensive meadows to apple orchards. Moreover, functional traits uncovered a general trend: extensive grasslands supported communities of more specialized and sedentary species whilst all other non-HNV land-use types showed communities characterized by mobile generalists. Community composition was driven by the land-use type and explained by plant-based indicator values for nutrients and light and temperature variables. Important life-history traits further correlated with site variables confirming the shift from specialists to generalists along increasing land-use intensity gradients and the effect of the thermal environment on phenological traits. We found supporting evidence for the effectiveness of regional Agri-Environmental Measures for butterfly conservation in European cultural landscapes and for the European conservation schemes to focus at least partly on the preservation of HNV grasslands with extensive management. Furthermore, we clearly show the poor ecological state of butterfly communities in more disturbed land-use types (including urban areas) and propose adopting measures to improve butterflies’ conservation in these environments.

Recent increasing homogenisation in Austrian butterfly communities over the past decades

“…2, 4). At the first glance, these results were surprising as species specific lower abundances (before extinction thresholds are passed) should force butterfly communities to internal changes in species composition and dominance orders (Habel et al 2016, 2019b, Bonelli et al 2021, Crossley et al 2021, Guariento et al 2022). Our findings were particularly unexpected as, at the more local scale, such higher compositional variability was already reported for insect communities in anthropogenic habitats with increasing landscape fragmentation (Didham et al 1996), agricultural intensification (Raven and Wagner 2021), isolated calcareous grasslands (Wenzel et al 2006), and urban mosaic landscapes (Banaszak‐Cibicka and Żmihorski 2012).…”

“…In addition, loss of natural habitats at larger geographic scales has frequently caused compositional shifts towards dominance of mobile, widespread, and open landscape species with wide ecological niches, while habitat specialist species decreased (Börschig et al 2013, Habel et al 2019b, 2022, Bonelli et al 2021, Guariento et al 2022). These latter trends act towards faunal and functional homogenisation of regional faunas with a relatively small number of widespread, ubiquist butterfly species becoming constantly dominant (Bonelli et al 2021, Habel et al 2022, Gossner et al 2023).…”

“…An increasing number of studies has demonstrated the decline in abundance and biomass (Hallmann et al 2017, 2020, Seibold et al 2019, Didham et al 2020, van Klink et al 2020) and of species richness (Ollerton et al 2014, Sánchez‐Bayo and Wyckhuys 2019, Raven and Wagner 2021, Warren et al 2021) of many insect taxa during the last decades. Important drivers of this decline are changing land use, particularly due to agricultural intensification, increased urbanisation, landscape homogenisation, tourism, and, more recently and still debated, climate change (Guariento et al 2022). These environmental changes have resulted in the degradation of many natural and semi‐natural habitats and the deterioration of habitat quality due to e.g.…”

Understanding the Dynamics of Sex-Specific Responses Driven by Grassland Management: Using Syrphids as a Model Insect Group

“…Both have led to a reduction in the number of plant species [16]. Alternatively, low-intensity mowing has been utilized to preserve biodiversity, mainly insects, in semi-natural grasslands [17].…”