新西兰霍克湾普卡瓦湖岩芯植硅体分析所揭示的火山喷发事件后的植被变化

含火山灰层沉积的植硅体分析为了解植被对从空中下降的火山灰的反应提供新的信息。新西兰霍克湾的一个深197m钻孔的上部50m样品，提供了距今约50ka以来连续的植被记录。植硅体组合在4个主要的火山灰层都发生了明显的变化，表现在树木和灌木的急剧下降及禾草类和莎草科的繁盛。在每次火山灰降落后，都会有一系宁继后变化，木本类最早死亡，禾草类和莎草科取而代之，并很快占据裸露的地表。经过一个相当长的滞后时间，树木和／或灌木重新替代草本和莎草科。

VEGETATIONAL CHANGES FOLLOWING VOLCANIC ERUPTIVE EVENTS FROM PHYTOLITH ANALYSIS FROM LAKE POUKAWA CORE, HAWKES BAY, NEW ZEALAND

New information on the response of vegetation to air-fall volcanic ash is provided by analysis of phytolithsfrom sediments containing major tephra beds. The top 50 m of a 197-m core in Hawkes Bay, New Zealand provide a continuousvegetation record spanning the time period from approximately 50 ka BP to the present. Significant changes in phytolithassemblages occur at the same depth as four major tephra, indicating a sharp decline in trees and shrubs and a surge in grassand Cyperaceae. A series of successional changes follow each major tephra fall. Initially the woody taxa are killed off andreplaced by grass and Cyperaceae that rapidly colonise the fresh surface. Trees and or shrubs succeed the grass and Cyperaceaeafter a significant lag.