Paper Abstracts

Tree-ring chronology shortening via disturbances

J. Woodmorappe

Discipline: Geology

Abstract: The Disturbance-Clustering hypothesis, first introduced here, posits that geographically-demarcated subtly-perturbed tree rings had induced the affected trees to crossmatch not in accordance with climatic signals, as is assumed in conventional dendrochronology. They instead crossmatch only within a geographic cluster of like-perturbed trees, and not with those of other clusters or with any of the remaining unaffected climatically-governed trees. During chronology-building, these clusters became connected with each other, into an artificially-long chronology, by means of rarely-occurring fortuitously-crossmatching "bridge" series. An experiment involving fifteen ostensibly heterochronous ancient trees graphically supports this hypothesis. Merely one-per-decade individual-ring perturbations induce all fifteen series to form a self-clustering, robust false master chronology (common variance), moreover to which each series crossmatches to an almost-entirely-convincing degree (nearly all satisfying all the important statistics, and including segment-by-segment correspondence of the curves). Significantly, and as experimentally demonstrated in this paper, at least 3 of every 10 disturbances can be omitted in some series, and a robust master chronology still develops. What's more, the construction of the master chronology is not dependent upon the presence of any series that has the full complement of disturbances. Clearly, modestly-disturbed series could adequately have served as the "core" of a cluster of disturbed trees, just as required by the Disturbance-Clustering hypothesis.
Furthermore, the previously-introduced now-called Migrating-Disturbance hypothesis does not require a literal repetition of events in time. A lateral movement of disturbances over centuries is sufficient, as is illustrated.
The Swedish and Finnish (Lapland) long Scots pine chronologies have a number of internal discontinuities. While not invalidating the chronologies, these discontinuities provide possible clues to their deconstruction.