To discard or not to discard: On cross-dating ecological tree-ring collections
Tree-ring research has given generations of scientists a long memory of what is acceptable for a tree to be included for data analysis. The established criteria, however, were set through purposeful goals to maximize the response for climatic reconstructions. Ecology is different. Tree-rings are increasingly being used to study a wide swath of ecology, including the carbon cycle or the response of ecosystems to global changes. A fundamental aspect of ecology is to understand the range of response within a population. The fundamental process of crossdating for climatic reconstructions, however, brings the decision to discard or not to discard “problematic” samples. This approach is limiting likely highly limiting to broadening our understanding of ecology. Ergo, all cores provide useful information when trying to understand the ecology of a forest It is tempting to dismiss the samples that do not appear to crossdate according to common standards, but we discourage this practice. These individuals, often slow-growing suppressed trees, are sometimes the most ecologically interesting and represent a significant portion of aboveground carbon and offer information on competition and disturbance dynamics. As such, they contain an important, but often overlooked signal for the ecology of a population from a tree-ring perspective. We present case studies where more than a few trees appear better “crossdated” via COFECHA at different calendar dates than what see as crossdated using maker rings and other visual features. We will then offer a synthesis of how we solved these almost intractable samples and make recommendations on how to present/justify these samples for publishing.