Medium-term response of breeding Blue Chaffinch Fringilla teydea teydea to experimental thinning in a Pinus canariensis plantation (Tenerife, Canary Islands)
Fecha
2010Resumen
We studied the medium-term response of the endemic Blue Chaffinch Fringilla teydea
teydea to experimental thinning in a Pinus canariensis plantation on the island of Tenerife
during breeding season. Distance Sampling method was applied to line transects, and
habitat preferences were modelled by means of univariate regression trees. The density
was 1.70 birds/ha (1.09 to 2.68 95%CI) in thinned areas and 0.56 birds/ha (0.33 to 0.97
95%CI) in unthinned areas. The Blue Chaffinch densities peaked in thinned areas where
the density of trees with Diameter at Breast Height of <25 cmwas between 10.5 and 16.5
trees/plot (r = 25 m) and the cover of Adenocarpus shrubs was 82.5%. Thinning had
added heterogeneity into the stand structure at least in terms of lowering the basal area of
small pine trees and increasing the understorey cover of Adenocarpus shrubs, with average
cover being 37.15% in thinned and only 1.40% in unthinned areas.Our results justify
the silvicultural thinning of 2844 hectares of pine plantation on the summit of Gran
Canaria as a means of increasing the density of the endangered Gran Canaria Blue Chaffinch
(Fringilla teydea polatzeki).