Functional composition of ant assemblages in habitat islands is driven by habitat factors and landscape composition

Szabolcs Mizser,Gábor Lőrinczi,Orsolya Valkó,Dávid D. Nagy,Balázs Deák,Attila Torma,Béla Tóthmérész,Zsolt Végvári,Ferenc Báthori

doi:10.1038/s41598-021-00385-5

Abstract

Fragmented natural habitats within human-transformed landscapes play a key role in preserving biodiversity. Ants as keystone species are essential elements of terrestrial ecosystems; thus, it is important to understand the factors influencing their presence. In a large-scale multi-site study, we surveyed ant assemblages using sweep netting and D-vac sampling on 158 ancient burial mounds preserving grassland habitats in agricultural landscapes in East-Hungary. We asked the following questions: (1) How do habitat factors and landscape composition affect species richness and functional diversity of ants? (2) Which ant traits are affected by habitat factors and landscape composition? Despite their small sizes, mounds as permanent and relatively undisturbed landscape elements could provide safe havens for diverse ant assemblages even in transformed agricultural landscapes. The complex habitat structure of wooded mounds supported high species and functional diversity of ant assemblages. Ant species on wooded mounds had small or medium-sized colonies, enabling the co-existence of more species. The effect of landscape composition on ant assemblages was mediated by habitat factors: steep slopes buffered the negative effect of the cropland matrix and enabled higher ant diversity.

Highlights

Fragmented natural habitats within human-transformed landscapes play a key role in preserving biodiversity
We explored the effects of habitat factors and landscape composition on ant assemblages in a large-scale multi-site study, involving 158 grassland islands
We asked the following questions: (1) What are the effects of habitat factors and landscape composition on the species richness, functional diversity and abundance of ant assemblages maintained in habitat islands that are embedded in transformed agricultural landscapes? (2) Which ant traits are affected by habitat factors and landscape composition?

Summary

Introduction

Fragmented natural habitats within human-transformed landscapes play a key role in preserving biodiversity. Due to the intensified anthropogenic land transformation activities (e.g., ploughing, forestation and the spread of urban infrastructure), in intensively used landscapes, several natural and semi-natural grassland habitats survived only in small fragments, acting as habitat islands[2] Despite their small size, these terrestrial islands can considerably contribute to the maintenance of grassland b iodiversity[3,4]. In small habitat islands the reduction of intact core areas and increased edge effect can lead to considerable changes in the abiotic environment of the fragments (such as increased temperature, decreased air humidity and soil moisture)[14] These changes can lead to the extinction of area-sensitive habitat specialist species and may promote the encroachment of g eneralists[15]. Such processes have been documented in various taxa including plants, vertebrates and arthropods[12,21,22]

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Conclusion