Ecological niches and distribution of ground‐dwelling beetles (Coleoptera: Carabidae, Aphodiinae—Scarabaeidae) in a modified wetland landscape

Abstract

Environmental conditions crucially influence species presence, distribution, population dynamics and phenology. Global warming and land use changes exacerbate these conditions, converting wetlands into terrestrial or aquatic ecosystems and altering biotic communities. Ground-dwelling beetles support key ecosystem functions such as nutrient cycling, pest control and seed dispersal. Despite previous studies on beetle diversity under various management practices, research on the ecological niches of beetles in Argentinian wetlands is limited. This study evaluates the influence of microhabitat-scale environmental variables on ground-dwelling beetle niches in modified wetlands in the Lower Delta of the Parana River. Wetland replacement with planted forests alters the natural hydrological regime causing environmental changes. Six habitat types, categorised by tree species, land use and stand age, were studied. Beetles were collected using pitfall traps over 2 years, while environmental variables and vegetation structure were also measured. We recorded 45 beetle species within the Carabidae and Aphodiinae (Scarabaeidae). Hydrophilic species like Meraulax alatus, Loxandrus audouini and Lomanoxoides bitubericolis were primarily found in willow plantations and mature silvopastoral areas, where soil moisture is suitable, while species with greater ecological plasticity, like Paranortes cordicollis and Pachymorphus striatulus, thrived in poplar plantations. We conclude that structural and functional changes in this modified wetland landscape, induced by water management, planted forest species and livestock presence, generate different environmental conditions that act as environmental filters, shaping the occurrence of species according to their specific habitat requirements. Understanding and characterising beetle species niches is therefore crucial in preserving the ecological function and biodiversity of this wetland landscape.