Endangered lowland oak forest steppe remnants keep unique bird species richness in Central Hungary

Abstract

The biodiversity of natural or semi-natural native, old oak woodlands have high conservation importance, especially in landscapes of monocultural forest plantations and arable fields. With a wider variety of microhabitats and foraging sources, such old oak forests can provide essential habitat for native forest bird communities. We conducted a study using bird point counts to compare the forest bird communities of old pedunculate oak (Quercus robur) remnants with native and non-native plantations in central Hungary in a landscape of mostly arable fields, settlements, and monocultural plantations. Avian surveys were carried out in old oak forest remnants, middle-aged oak, white poplar (Populus alba), hybrid poplar (Populus × euramericana), black locust (Robinia pseudoacacia), and pine (Pinus spp.) plantations. Fieldwork has been carried out in nine study sites, where all six habitat types were represented (with a few exceptions), to determine total abundance, species richness, Shannon–Wiener diversity, species evenness, dominant and indicator species, and guild abundances. We found that old oak forest remnants were the most diverse habitats among the studied forest types, while hybrid poplar and pine plantations exhibited the lowest avian biodiversity. The avian guilds most sensitive to the loss of old oak forest remnants were ground foragers, bark foragers, cavity-nesters, residents, and Mediterranean migratory birds. Native habitats were more diverse than non-native plantations. Our results suggest that it is important to conserve all remaining high biodiversity old oak stands and to avoid clear-cutting of monocultural plantations in favour of practices such as mixed-species plantations, longer rotation lengths, or retention forestry.