 Phytogeographically, Iceland belongs to the Arctic province of the Circumboreal Region within the Boreal Kingdom.Around three-quarters of the island is barren of vegetation; plant life consists mainly of grassland, which is regularly grazed by livestock.The most common tree native to Iceland is the northern birch ("Betula pubescens"), which formerly formed forests over much of Iceland, along with aspens ("Populus tremula"), rowans ("Sorbus aucuparia"), common junipers ("Juniperus communis"), and other smaller trees, mainly willows.