STABILITY OF WOOD ANATOMY OF LIVING AND HOLOCENE THUJA-OCCIDENTALIS LDERIVED FROM EXPOSED AND SUBMERGED PORTIONS OF THE NIAGARA ESCARPMENT

Millennium-long tree-ring chronologies have recently been derived from Thuja occidentalis L. growing on the exposed cliffs of the Niagara Es carpment, Canada. Lengthening of these chronologies may be possible by incorporating tree-ring series from subaerially exposed and submerged subfossil wood, provided that its anatomy is not significantly influe nced by time or treatment. In order to determine if Holocene-age sampl es would be suitable for incorporation into very long tree-ring chrono logies, a study was undertaken comparing wood structure of living tree s, dead trees exposed to the air during the late Holocene, and dead tr ees submerged since the early Holocene. The results show that the impa ct of time and environment on wood anatomy is considerably lass than e xpected, The anatomy of annual rings in Holocene trees is similar to t hat found in modem specimens. High magnification scanning electron mic rographs show that tracheid walls lose their rectangular appearance af ter 8000 yr, but few other signs of deterioration are present. The res ults mean that Holocene wood can be used to add to the long dendrochro nological record that has already been produced from the Niagara Escar pment. (C) 1995 University of Washington.