Avifauna and landscape in northern Spain: effects of reafforestations with exotic trees
Published: Volume 37(2), December 1990. Pages 229-245.
Original Title: Avifauna y paisaje en el norte de España: efecto de las repoblaciones con Árboles exóticos
The entry of Spain into the European Community may produce the ruin of most farms in the North of the Country because of the low commercial competitiviness of their dairy products. The use of these farmlands to produce cheap wood by means of pine and eucalyptus reafforestations has been suggested as an alternative use of this area. In spite of the importance of this potential landscape remodelation, few studies have been devoted to predict its impact on wildlife. This work studies the breeding and wintering bird communities in farmlands, Pinus radiata and Eucalyptus globulus plantations of the Basque Country and Cantabria in order to predict the impact on birds of this future economical policy. Broadleaved natural forests (a mixture of Fagus sylvatica and Quercus spp.) are also studied to compare their bird communities with those occupying the exotic tree plantations. Results show that farmlands are the habitat with the highest richness of breeding birds, the broadleaved forests being the second one in this ranking. Farmlands are also the habitat with highest densities of summer migrants. Eucalyptus globulus plantations are the poorest habitat for birds. 36 % and 6 % of the bird species recorded are concentrated in farmlands and broadleaved forests. However, none species use pine or eucalyptus plantations as their exclusive breeding habitat. During winter, farmlands continue to be the exclusive habitat for 38 % of species, with the highest densities of wintering birds. Broadleaved forests and pine plantations show intermediate scores whilst eucalyptus plantations are again the. poorest habitat. We conclude that the avifauna of these pine an eucalyptus plantations is a poor and biased sample of the primitive forest bird fauna. A sharp increase of surface occupied by these tree plantations, and the related decrease of farmlands, will suppose an important impoverishment of the breeding and wintering avifauna of this region. According to the importance of farmlands as breeding and wintering grounds of many foreing birds, this landscape modification could also affect the avifauna of other countries.