Olav Liest@l 1916-2002

Dendrochronological crossdating was used to expand a pre-existing multi-millennial tree-ring chronology for Finnish Lapland. Twelve tree-ring series from sedimentary archives of five small lakes contributed to the oldest part of the chronology, extending the record to 5634 BC (previously 5520 BC). Today, the chronology is the longest conifer tree-ring chronology in Eurasia. The geologically oldest pine megafossils were found the eastern part of the region, i.e. north-east Finnish Lapland, and this is also where the authors expect that other very old pine megafossils may be found in the future. Cool climatic conditions c.8 ka ago may have prevented pine regeneration in the tundra-forest ecotone. This may explain the practical difficulty of making the chronology longer than its present form in the study region.     

Mid‐ and late Holocene tree population density changes in northern Fennoscandia derived by a new method using megafossil pines and their tree‐ring series

Changes in tree density are estimated for the northern forest‐limit region of Finnish Lapland over the past seven and a half millennia. This is done using dendrochronologically dated Scots pine megafossils and their tree‐ring series. Direct and indirect estimates of past tree density are derived from chronology sample size (CSS) and growth trend modelling (GTM) respectively. The latter is a new method, where the past levels of growth competition (the influence of nearby trees) are extracted from the behaviour of growth trends in cross‐dated tree‐ring series, trends that are expected to be driven by tree‐density control. Two records constructed from the same original data set but by different means (independently) correlate significantly. Both records show a tree‐density maximum around 3000–1750 BC , indicating relative warmth during that time. Another positive tree‐density anomaly occurred in accordance with the ‘Medieval Warm Period’, preceding the thinning at the forest‐limit due to the ‘Little Ice Age’. Copyright © 2005 John Wiley & Sons, Ltd.     

关于维管植物大化石保存方式术语的商榷

本文讨论了维管植物大化石保存方式中使用的术语，发现其中存在一些问题，主要表现在：（1）对化石化作用使用的术语经常与植物大化石保存方式所使用的术语混为一谈；（2）对同一术语不同的作者可能有不同的解释。这种状况很容易造成认识上的混乱。作者回顾了相关的讨论，并运用图解的方式对维管植物大化石的保存类型作了归类和比较的进一步讨论，建议把化石化作用所使用的术语和植物大化石保存方式所使用的术语合理地分开，从而尽可能地避免术语使用上的混乱。     

华北地台东缘新元古代地层对比和宏体化石研究的进展和发展趋势

尽管利用多重地层学方法,对华北地台东缘新元古代地层的划分和对比研究取得了很大的进展,但仍然存在很多争议和问题。今后应在以下几方面展开研究:①寻找新元古代Rodinia超大陆热构造事件和冰川事件的地层学标志,厘定这些标志在地层柱中的位置及其与宏体化石演化阶段的对应关系;②结合碳酸盐岩中C、O和Sr同位素地层学研究,寻找和鉴别新元古代地层中的火山岩和火山碎屑岩,测定其中锆石的U-Pb年龄,解决与华南地区新元古代年代地层的对比问题;③划分“辽南生物群”和“淮南生物群”的不同生物组合,明确各组合的演化历程,深入探讨其谱系归属及与华南地区晚新元古代生物群的关系,完善华北地台东缘新元古代生物地层划分和对比的方案。