# Structural and Functional Responses of Small Mammal Communities to Land Abandonment in a Region of High Biodiversity

## TL;DR

This study shows that land abandonment in Transylvania boosts small mammal diversity and suggests maintaining habitat mosaics to support biodiversity.

## Contribution

The study reveals that land abandonment increases small mammal abundance and diversity in a high biodiversity region, offering new insights into agricultural landscape management.

## Key findings

- Land abandonment increases small mammal abundance, diversity, and functional trait composition.
- Abandonment effects are stronger in pastures, where grazing limits small mammals.
- Abandoned landscapes support more diverse communities than central and western Europe.

## Abstract

Our study conducted in southeastern Transylvania (central Romania) is aimed at assessing the effect of farming abandonment on the diversity, abundance, and community composition of small mammals, a functional group of animals having important ecological functions in terrestrial ecosystems. The research area features a mosaic agricultural landscape characterised by a variety of small-sized arable fields and extensive pastures. This mosaic allows the coexistence of numerous species, thus enriching the regional diversity of small mammal communities, which is higher than in agricultural landscapes in western and central Europe. The abandonment of agricultural land, a result of the depopulation of villages and the economic inefficiency of small-scale farming, was associated with an increase in small mammal abundance and diversity, as well as a change in the functional trait composition. Our results show that local temporary abandonment of arable land and pastures may help preserve and boost small mammal diversity and suggest that agricultural management strategies that conserve the mosaic of habitats are essential for maintaining biodiversity in agricultural landscapes.

Small mammals are common in farmland, where their communities are affected by agricultural management. However, so far, no clear patterns have emerged, its effect varying in accordance with the ecological context, spatial scale, and geographic area. We aimed to assess whether the discontinuation of land cultivation and pasture grazing leads to significant changes in the abundance, diversity, and composition of small mammal communities. These were surveyed in transects of live traps set in used and abandoned arable fields and pastures in highly patched agricultural landscapes in Transylvania (Romania). Farmland abandonment was positively related to species richness, taxonomic and functional diversity, and abundance. Its effect was stronger in pastures, where intensive grazing is a limiting factor for small mammals. Functional trait composition was also sensitive to fallowing and abandonment of grazing, which promote diurnal activity, broader niches, and lower fertility. In conclusion, small mammals benefit from the maintenance of uncultivated plots and low numbers of grazing livestock, which we recommend as management strategy in traditional mosaic landscapes, to support taxonomic and functional biodiversity with implications in ecosystem service functionality. Our results also revealed more diverse communities than those showcased by similar studies in central and western Europe, with similar overall abundances.