Tjädern och skogsbruket : effekter av skogsbruket på tjäderlekplatser i norra Skaraborgs län
Abstract (Summary)The capercaillie (Tetrao urogallus) is one of the species of wood fowls with distribution in Europe and Russia. It is well adapted to a life in the northern coniferous forest area. The population of capercaillies has diminished considerably during the postwar period in the whole distribution area outside Russia, where it on the contrary has increased in number. Because of this increase the BirdLife International states the population as stable. The reasons for the decrease in the northern part of Europe are believed to emanate from different sources of which the changing methods in forestry during the second half of the 20th century seem to be one of the most important ones. Climate conditions and changed predacious pressure are other possible causes.In an attempt to observe the effects of the measures in forestry taken within the distribution areas of the mating grounds of the capercailzies, twelve sites in the northern county of Skaraborg, registered during the years 1990-1995, were again registered in spring 2005. The number of male birds today on these grounds has been compared to the number of earlier registrations. No mating ground shows an increase in the number of male birds and in five places the mating ground has been totally abandoned. Within the mating ground consisting of 300 hectares the acreage of different kinds of land has been measured. The analysis of the correlation between the use of the different kinds of land and the number of male birds has not given any significant results (p> 0,05). There is one significant correlation between lost numbers of male birds and the alter of the share of plantation (p<0,05). The reason why the male birds have disappeared and in other places have diminished in number could be the result of the increased effect of both the forestry measures taken and other factors. The size of the cutting area as well as the location in relation to the centre of the mating ground seems to be of importance in influencing the capercaillie. The knowledge of the mating grounds is therefore essential to the concerned parties in planning forestry measures in a considerate way. The capercaillie has high demands upon its environment with several different biotopes within its territory; its preference for old forests with a long continuity favors several other species, which thereby makes the capercaillie useful as a general covering species in the nature conservation work.
School:Högskolan i Skövde
Source Type:Master's Thesis
Date of Publication:09/19/2006