Forest recovery after intense disturbance by volcanic activity

我们研究了北海道岛Komagatake火山上自然再生的日本落叶松林分的分布和林分结构。在此基础上，研究了山杉树和部分阔叶树幼树的生物量分配、枝条动态和水势的季节变化。山上的林分主要由山林分、桦树、白杨和其他各种林分组成。在东经500米。林分优势高度为2.0 ~ 6.1m，地面基底面积为0.1 ~ 7.8 m^2/ha。这些值表明林分严重限制生长。高海拔林分的优势高度和基面积发育程度低于低海拔林分。在西元前500 ~ 700m之间逐渐形成了现在的山蕨。在1929年火山爆发后的20到50年间。此后，建立的山柰菌数量显著增加。我们认为，火山爆发后20年以来种植的山柰人工林和早期入侵的个体的种子传播对山柰树的生长有促进作用。山杉树的生物量分配给叶片的生物量比阔叶树多，分配给根系的生物量比阔叶树少，而细根的生物量比阔叶树多。虽然樟子树的芽在生长季节几乎全部成活，但阔叶树的芽死亡率相当高。这些特性使山柰幼苗能够顺利建立和生长。我们认为阔叶树可以通过发芽来维持种群。从树木水势的测定结果来看，我们认为山杉树是耐旱树种，即使在低水势条件下也能保持生理能力，而马氏木则是避旱树种，往往保持较高的水势以维持良好的生理活性

We studied distribution and stand structure of a naturally regenerated Larix kaempferi stand on Mt. Komagatake, a volcano on the island of Hokkaido. Further, biomass allocation, dynamics of shoots, and seasonal changes of water potential were examined in saplings of L.kaempferi and some broadleaved trees. The stands on the mountain were composed of L.kaempferi, Betula spp. and Populus maximowiczii, and assortments of others. At 500m a. s. 1., the stand dominant height was 2.0 to 6.1m and basal area at ground level was 0.1 to 7.8 m^2/ha. These values indicate that the stand intensively restricted growth. The stands at higher altitudes were less developed than at lower altitudes in dominant height and basal area. The present L.kaempferi gradually started being established in the area between 500 and 700m a. s. 1. during 20 to 50 years after the eruption in 1929. Thereafter the number of the established L.kaempferi increased remarkably. We believed that seed dispersal from artificial forests of L.kaempferi that have been planted since 20 years after the eruption, and from the individuals that had invaded in the very early period, contributed to the increase of L.kaempferi trees. L.kaempferi allocated more biomass to leaves than broadleaved trees and less to roots which, however, had a larger ratio of fine roots. Although almost all of the shoots of L.kaempferi survived the growing season, broadleaved trees showed considerably high mortality ratios of shoots. These traits enable L.kaempferi seedlings to establish and to growth favorably. We considered that broadleaved trees could have persisted their population by sprouting. From the results of examining water potential of trees, we regarded L.kaempferi as a drought-tolerant tree, which can maintain physiological ability even under the low water potential, however, P.maximowiczii can be regarded as a drought-avoiding tree which tend to retain high water potential to sustain favorable physiological activity