The effect of human‐modified landscape structure on forest grouse broods in two landscape types

Abstract

Citation: Huhta, E., P. Helle, V. Nivala, and A. Nikula. 2017. The effect of human-modified landscape structure on forest grouse broods in two landscape types. Ecosphere 8(9):e01950. 10. 1002/ecs2.1950 Abstract. The population sizes and the breeding success of Finnish tetraonids have been decreasing for decades. In this study, the presence of a grouse hen with a brood in a landscape was used to indicate habitat-related breeding success. We combined the locations of 938 black grouse (Tetrao tetrix), 388 capercaillie (T. urogallus), and 917 hazel grouse (Tetrastes bonasia) broods after the breeding season in midAugust with landscape data by employing Geographic Information System and grouse data derived from the Finnish wildlife triangle censuses conducted during [1997][1998][1999][2000][2001][2002][2003][2004]. Two large study areas with different landscape structures, northern forest-mire area and southern cultivated area, were selected for the investigation. The presence of grouse broods was positively related to the amount of old coniferous mixed forest. Grouse broods may prefer this forest habitat because of a rich understorey cover and a rich bilberry field layer offering a diversity of insects as food. Broods had a strong positive response to the amount of forest habitat. The effect of forest fragmentation on the broods' distribution did not increase even with decreasing forest habitat. We suggest that there are several ecological causes for the observed spatial correlations. Predation on nests and broods by generalist predators is presumably high in human-modified open and semi-open landscapes. Against our expectations, the effect of landscape composition on grouse broods was more marked in the northern than in the southern study area, most likely because predator populations are more food-regulated in the north. This finding supports the alternative prey hypothesis. Further, large drained and reforested peatland mire areas had a negative impact on grouse broods in the north. In the drainage areas, decreased availability of vegetation cover and insect food, increased predation risk, and drowning of chicks in ditches may increase brood mortality.

Trade-offs between wood production and forest grouse habitats in two regions with distinctive landscapes

“…In southern agricultural landscapes, forests are more permanently fragmented than in northern managed forest landscapes. In a previous study it has been shown that forest habitat loss is more important than habitat fragmentation for grouse broods (Huhta et al 2017). However, forest fragmentation might not be totally meaningless since grouse broods were less numerous in the areas with high densities of forest-open land edges (Huhta et al 2017).…”

“…Changes to the landscape and forest structure due to forest management (habitat loss, habitat degradation, forest fragmentation), increased predator densities, excessive hunting, and adverse climatic changes have been implicated in this decline (e.g., Storaas et al 1999;Kurki et al 2000;Ludwig et al 2006). Several studies on the structural features of landscapes and forest stands for grouse habitats indicate how forest felling may negatively affect their populations (e.g., Rolstad 1989;Klaus 1991;Storch 1993;Åberg et al 2003;Miettinen et al 2008Miettinen et al , 2010Sirkiä et al 2010;Wegge and Rolstad 2011;Huhta et al 2017). The safeguarding of grouse habitats is urgently needed to ensure the survival of forest grouse populations in boreal forest landscapes over the long term.…”

Decomposing the Spatial and Temporal Effects of Climate and Habitat on a Hazel Grouse (Tetrastes bonasia) Population in Northeastern Chinese Mountains

“…Moreover, the complex vegetation structure can help hazel grouse hide themselves from predators. However, many studies in other areas have shown that coniferous forest is also an indispensable habitat [ 50 , 51 , 52 ] that can help hazel grouse avoid predators in winter when the vegetation structure of deciduous forest is reduced, especially when snow cover is not enough for hiding. Because the winter is a critical period for hazel grouse, factors affecting the winter distribution of the hazel grouse need further research.…”

Potential of Carbon Offsets to Promote the Management of Capercaillie Lekking Sites in Finnish Forests

“…These studies also indicate that our results might apply not only to Finland, but also to other regions. From the viewpoint of grouse species, the maintenance of forest cover could be beneficial in many ways; for example, it could decrease the need for ditch cleaning [49], which in turn, could decrease chick mortality rates [50,51]. In addition, the avoidance of clear cutting could enhance the growth of blueberry shrubs [31], which are vital for grouse species [52][53][54][55].…”