Historical mapping of woodland reveals causes and temporal patterns of contraction in Öræfi, Iceland, from the 12th century AD to present

Background/Question/Methods

Land-cover changes in Iceland over the last millennium encompass birch (Betula pubescens) woodland depletion and extensive soil erosion. Yet few studies have focused on spatial change of birch woodland coverage in Iceland over centuries and why and how the woodland depletion took place.

The main objectives of this study are: (1) to map the woodland distribution today in Öræfi (1066 km²) in southern Iceland; (2) to map woodland holdings over a period of 900 years from the 11^th century AD to the early 20^th century; (3) explain the relative impacts of socio-economic and natural forces on woodland cover over this period. We use a combined approach of historical reconstruction from diverse written archives, GIS techniques and field work.

Results/Conclusions

The woodland in Öræfi now covers 11 km² (1 % of the study area). The woodland holdings, 12 in total, are regularly listed in the church inventories from 1179 to 1570 and most of them were owned by the church. In the first complete register for the district in 1641 the woodland holdings were 5, owned and used by 20 estates.

Of 25 woodlands registered through history 21 remain today and four have disappeared. A woodland disappeared in the AD 1362 eruption from Öræfajökull, one was overrun by an advancing glacier at the end of the 18^th century and two woodlands were exhausted near the end of the 19^th century. The woodlands were used for firewood and charcoal making and grazing during the study period. Crucially, in most cases only one estate had authority over each holding and none were commons. The main driving force behind the development of woodlands was socio-economic, rather than natural, where the form of ownership was fundamental for the fate of the woodland. Harsh climate and volcanism were not directly responsible for woodland depletion. The latter half of the 19^th century was the period of the greatest woodland loss. This period coincides with considerable expansion in livestock numbers, especially sheep and associated all year around grazing, at a time when the Little Ice Age culminated in Iceland.

Keywords: Deforestation. Soil erosion. Land ownership. GIS. Historical mapping.