Ecology and environments of past forests reconstructed by tree ring analysis of buried forests in volcanic deposits

生态试验发现在年轮宽度patternsTree年轮模式的埋葬山毛榉（栗crenata）木材表明不寻常的零星单年强劲的增长减少。这种趋势在青森县大矢泽-野田的Towada-Chuseritephra（约5000 ybo）下方的掩埋树林和福岛县沼泽火山碎屑流存款（约5000 ybp）中发现的烧焦树林中很常见。现代山毛榉林的年轮分析表明，在大多数结实年份，年轮宽度都发生了缩减，但埋藏林的年轮宽度缩减强度比现代山毛榉林的年轮宽度缩减强度大得多。这表明过去的山毛榉树分配了更多的资源比现在的trees.Regeneration regimesGrowth模式下Towada八户火山碎屑流存款（约13，000 ybp）埋藏的针叶林表现出较高的初始增长率表明，森林的再生发生在开放的环境。白头山火山碎屑存款（约1000 ybp）中的埋藏针叶树的生长也表现出较高的初始增长率。这些木材被切割成一年一对，进行14 C摆动匹配分析，以估计高精度的测年。青田遗址栎柱林的年轮揭示了该地区房屋的相对年代。

Ecological trials found in annual ring width patternsTree ring patterns of buried beech (Castanea crenata) woods indicated unusual sporadic single-year strong growth reductions. This tendency was common in burried woods below Towada-Chuseritephra (ca 5000 ybo) at Oyazawa-Noda, Aomori Prefecture and charred woods found in Numazawa pyroclastic flow deposit (ca 5000 ybp) at Fukushima Prefecture. Although tree ring analysis of present beech woods showed occurrence of ring width reduction at most fruiting years, intensties of this reduction for the buried woods are much stronger than that of present ones. This suggested past beech trees had allocated more resources to reproduction than present trees.Regeneration regimesGrowth patterns of buried conifer woods under Towada-Hachinohe pyroclastic flow deposit (ca 13,000 ybp) showed high initial growth rates suggesting that regeneration of the forest have occurred in open environments. Growth of buried confers in pyroclastic deposit (ca 1000 ybp) at Baitoushan in China also showed high initial growth rates.DatingEach of buried confer woods obtained at Baitoushan, Oyazawa-Noda and Numezawa were estimated to be killed in single year (eruption year) by using tree ring analysis. The woods were cut in single year pairs for 14C wiggle matching analysis to estimate high precision dating. Tree rings of Quercus post woods at Aota archaeological site revealed relative dates of houses in the area.