Natural and Managed Forest Recovery after a Volcanic Eruption

Abstract

The natural vegetation process and the effect of afforestation work were studied on the pumice plain of Komagatake volcano, southern Hokkaido, Japan. The barren land, newly formed after a huge eruption in 1929, was mainly revegetated naturally by willows (Salix reinii and Salix integra), birches (Betula platyphylla), poplars (Populus sieboldii and Populus maximowiczii), and larch (Larix leptolepis). All the trees had extremely low growthrates attaining less than 3 m in height over 60 years ; low water and nutrient availability probably limited growth.Tree ring analysis demonstrated that willow, poplar and birch have steadily invaded over the first 40 years, butthat the non-native larch has remarkably increased within the past ten years. The forests have been changingfrom early successional deciduous trees to larch. The tree plantation work to promote earlier forest establishmentwas also carried out for the past 30 years. Four species were planted: larch, alder, pine and birch. The plantedlarch had the highest growth rate, followed by alder and pine. These planted trees reached 5 m to 8 m in heightwith the exception of birch. Soil condition on the understory of the plantations were remarkably improvedcompared to natural sites with a well-developed A-horizon and high nitrogen content. Plantations are successfulfor rapidly establishing forest and accelerating succession process on land devastated by volcanic activity.