Pinus contorta colonization and biomass accumulation in lands adjacent to plantations in Iceland
摘要
Pinus contorta readily colonizes suitable lands adjacent to plantations in many parts of the world. It is considered an invasive problem in some regions, but it can also provide afforestation benefits, especially in restoration of degraded lands. After settlement, Iceland suffered a millennium of deforestation and overgrazing by sheep, which resulted in vast eroded areas. Much reduced were woodlands of Betula pubescens, the only substantial native tree species. In the last several decades, Icelandic foresters have established plantations of nonnative trees. Of the exotic species, P. contorta is most successful in spreading by natural regeneration. We mapped and collected allometric data on P. contorta individuals in five permanent plots along plantation edges during 2015–2017 and repeated the assessment during 2021–2022. P. contorta spread readily into open cover but was limited by dense moss-heath or grass. We calculated the rate of aboveground biomass accumulation and carbon sequestration by the colonizing P. contorta. Determination of these rates are lacking in previous studies of P. contorta expansion. Sequestration rates were > 1 Mg C ha−1 y−1 in the most-developed subplots. We derived an equation of biomass accumulation in early colonization that may be a practical reference for forest managers elsewhere. We conclude that P. contorta has considerable potential to sequester carbon and afforest desertified areas by natural regeneration.