DendrOS, an open-source dendrochronology software

Hi everyone,

Together with Mauro Bernabei (CNR-IBE, the Institute of BioEconomy of the Italian National Research Council), I have been developing a new piece of open-source software for our field: DendrOS.

DendrOS is a cross-platform application for dendrochronological analysis and cross-dating of tree-ring width series. It is written in Python with a PyQt6 interface and released under the GNU General Public License v3, so it runs on Linux and Windows and can be read, modified and redistributed like the rest of our Arc-Team tools.

The project started from a practical need. Many dendrochronologists still rely on PAST4 or PAST5. They are solid reference software, but closed-source and Windows-only, and they no longer fit the open workflow we built around our other projects. DendrOS aims to bring the same working method into the open-source world.

DendrOS can import the most common formats used in dendrochronology (.rwl, .txt and .fh, i.e. the CATRAS/Holmes format) and display them in an interactive time-series plot with pan, zoom and a movable year cursor. Series are managed in a tree with View/Edit/Ref/Info columns, and two separate vertical and horizontal zoom tools, inspired by PAST4, let you stretch the plot on a single axis.

The core of the application is cross-dating: DendrOS slides one or more samples against a reference series (or against a master chronology built on the fly) and ranks every possible position with the Baillie-Pilcher t-value (tBP), together with its p-value, the Pearson correlation coefficient and the Gleichläufigkeit percentage. The best offset can then be applied to the series with a click. Beyond cross-dating, DendrOS can build a master chronology by averaging the overlapping series, highlight concordance bands and pointer years (Weiserjahre), and detrend/index the series through the dplPy library (spline, modified negative exponential, Hugershoff, linear, horizontal). The whole session is saved in a readable .dendro project file.

Below, you can see the main window of DendrOS.

The main window of DendrOS, with the series tree on the left and the time-series plot on the right.

DendrOS is already part of the ArcheOS software list, the GitHub project that marks the first step of the ArcheOS revival, in the dendrochronology section. You can find the source code and the user guide on GitHub, while a pre-built Windows executable is generated automatically from the latest commit and published under Releases, so no Python installation is required to try it.

The project is still under active development, so any feedback from colleagues working with dendrochronology is more than welcome.

I hope you find this useful. Have a nice day!