Aboveground woody biomass of natural birch woodland in Iceland – Comparison of two inventories 1987-1988 and 2005-2011

The only native tree species in Iceland forming woodland is the mountain birch. Since human settlement in the 9th century AD, natural birch woodlands have decreased from around 28% to 1.5% of the terrestrial area. In this paper we estimated and compared aboveground woody biomass stocks of two sample inventories from 1987-1988 and 2005-2011. Total above- ground woody biomass stocks in 1987-1988 and 2005-2011 were 1503 Gg (SE = 175, n= 272) and 1455 Gg (SE = 180, n= 181), respectively, for the woodland already existing in 1987-1988. The biomass estimates in 2005-2011were not significantly different from the 1987-1988 estimates in the < 2 m height class (P = 0.282) nor in the 2 - 4 m height class (P = 0.673). We concluded that the aboveground woody biomass of the natural birch woodland already existing in 1987-1991 had not changed between the two inventories. Additionally, we estimated an aboveground woody biomass increment of 37 Gg for the woodland expansion occurring between these two inventories.