Grazing ability of European black pine understorey vegetation by goats

Goats' utilizing ability of spontaneous vegetation, depending on stocking density, grazing season and day period, was studied on a European black pine (Pinus nigra Arnold subsp. nigra) reforested slope of the Pyrenees with direct observation of the animals' grazing behaviour. Goats spent about 59% of their time eating in spring versus 85% in autumn. However, the mean grazing time (8.6 h) was not affected either by stocking density or grazing season. While stocking density showed an effect on the time that goats devoted to consuming different groups of plants, it was much affected by the grazing season. Goats spent 50% of their total grazing time on browse species in spring, but this activity decreased to 32% in autumn. Browsing preferences, however, varied markedly among plant species. Buxus sempervirens L. was never consumed by goats, but Genista scorpius (L.) DC. was frequently browsed both in spring (36%) and autumn (20%). The time devoted to consume thorny species, like Rosa spp., declined significantly from spring to autumn showing an opposite tendency to that observed for aromatic species that were almost exclusively consumed in autumn. Goats spent up to 7.1% of their grazing time eating lower pine branches and up to 1.3% on the litter layer of needles. The high proportion of time devoted to consuming these materials suggests that goats' grazing activity may effectively contribute towards controlling the dead fuel layer build-up in European pine stands. A diurnal pattern of plant utilisation was observed that was characterised by a longer time devoted to browsing species early in the morning than during the rest of the day. The different seasonal and diurnal utilisation ability of the spontaneous vegetation by goats could provide foresters with a useful management tool in sustainable mixed forage systems.