Deciduous forest and resident birds: the problem of fragmentation within a coniferous forest landscape

Abstract

Six species of resident birds were censused in patches of deciduous forest within a coniferous forest landscape in south central Sweden. Here, the forests have been subjected to active forestry for a long time, but with recently increased intensity. Although the forest cover is more or less continuous in this landscape, mature deciduous forest is now a rare element compared with the untouched forest.All censused patches were similar with regards to size, proportion and amount of deciduous trees, but were either isolated in the coniferous forest ('isolated patches') or near to other deciduous patches ('aggregated patches'). We concentrated on six species of resident birds, with moderate area requirements, that are tied to deciduous forest and whose ecology is well-known. The Nuthatch and the Marsh tit, which both show strict year-round territoriality and have a restricted dispersal phase, were significantly more likely to be found in aggregated than in isolated patches. No effect was found for the Great tit and the Blue tit, which are less territorial outside the breeding season and have a longer dispersal phase. Moreover, the Great tit is less specialized on deciduous forest than the other species. Also, the Long-tailed tit was negatively affected by isolation, which may be due to restricted dispersal and to larger area requirements of this flock-territorial species. The Hazel grouse, finally, was not affected, but this larger bird probably uses the forest in a different way from the smaller species.Our study clearly shows that fragmentation of one type of forest (deciduous) within another can have serious detrimental effects on forest-living species and raises important issues for forest management practices and conservation within a forest landscape.

Influences of forest type and habitat structure on bird assemblages of oak (Quercus spp.) and pine (Pinus spp.) stands in southwestern Turkey

“…Stand size and connectivity to surrounding forest stands are known to be important determinants of forest bird assemblages in both native forests and plantations (e.g. van Dorp and Opdam, 1987;Enoksson et al, 1995;Díaz et al, 1998), implying that smaller isolated patches of forests may have a lower species richness than larger patches of the same habitat. In a Spanish study, Santos et al, (2002) found that native stands of holm oak (Q. ilex) had to be of significantly larger size than similar stands located in central Europe in order to support equal numbers of bird territories and species.…”

Dispersal, ranging and settling behaviour of Marsh TitsPoecile palustrisin a fragmented landscape in lowland England

“…The British population fell by 66% between 196966% between and 200666% between (Eaton et al 2009, although the reasons for this decline are unknown (Fuller et al 2005). One contributory factor may be habitat fragmentation (Fuller et al 2005) Marsh Tits showing a negative response to declining patch size and increasing isolation (Enoksson et al 1995, Hinsley et al 1996. A limited tendency or ability of birds to move between habitat fragments would support the hypothesis of habitat fragmentation being a factor in the species' decline, although information on dispersal capabilities is scarce.…”

Sustaining forest landscape connectivity under different land cover change scenarios

“…Its median dispersal distance is 3 km (van Langevelde, 2000;van Langevelde et al, 2000). Among others, it is affected by forest fires, by intensive cuttings deriving from non-sustainable management and especially by forest fragmentation (Verboom et al, 1991;Enoksson et al, 1995;Bellamy et al, 1998;Santos et al, 2002). The nuthatch has been defined as an umbrella species .…”