Discovery of tree rings dating back to 326 BC have enabled
scientists from the Cold and Arid Regions Environmental and
Engineering Research Institute, the Chinese Academy of Sciences, to
establish a breakthrough annual tree ring study from 326 BC to 2000
AD. It is reported to be the longest sequence of its kind in China.
As
is well known, rings record a tree's growth for a year. Scientific
study shows that the annual ring also reflects the ecological
environment around the tree during its growth. Therefore, the study
of the sequence of annual ring helps scientists analyze the climate
and ecological environment.
However, according to Dr. Zhang Qibing, the leader of the group of
scientists, meteorological and ecological data usually does not
exceed 100 years. In the latter half of 2001, the research group
headed by Zhang went to Qinghai to collect over 240 tree centers of
Qilian sprengeri ferns (S. przewalskii) and 10 disk samples of
ancient trees. By measuring the width between different rings and
comparing the width between rings in living trees, Zhang found that
the earliest annual ring dates back to 326 BC. On this basis, the
research group established the tree annual ring sequence from 326
BC to 2000 AD. By studying the annual ring and meteorological data,
scientists found that spring rainfall had a great influence on the
growth of the rings. Therefore, they concluded the annual ring
sequence could show precipitation conditions from a long time
ago.
Experts also pointed out that at the beginning of the 5th century
when climate was suitable for tree growth, nomadic tribes were
thriving. The study of trees' annual rings provided data to
determine the year of climate changes and social and cultural
evolution. The sequence of annual rings is of great value for
research on the time and space leading to a certain climate or
ecological environment change over the past 2,326 years -- and it
can help predict future environmental evolution.
((新華網 [Xinhua News
Agency], translated by Li Jinhui for China.org.cn, June 14,
2002)