Dendrochronology involves studying tree rings for the dating of tree growth in response to annual environmental conditions. This dating technique is relatively simple and inexpensive; it requires the collection of cores that are acquired using increment borers. Once extracted, these cylindrical cores show annual growth for the tree, with each year being distinguished by a light and dark coloration. The light-colored wood grew during the growing season, and the dark-colored wood was formed during the winter. The beginning of each light-colored line in the wood marks a new year because that is the start of a new growing season.
Because the amount of growth in trees is often a reflection of how optimal the environmental conditions are, the size of these rings may indicate what conditions were like in certain years. For example, drought conditions may cause a tree to have minimal growth for a growing season and as a result that year's ring will be relatively smaller than the others. In addition to precipitation, tree ring growth can indicate other environmental influences on growth such as temperature, competition, and more traumatic events like floods and forest fires. Knowing the age of trees can help determine plant establishment in places like river basins/terraces, landslide-prone areas, and areas of glacial retreat.
Two interesting papers that include the use of dendrochronology:
Chen, D., Zhou, F., Dong, Z., Zeng, A., Ou, T., & Fang, K. (2020). A tree-ring δ18O based reconstruction of East Asia summer monsoon over the past two centuries. PLoS ONE, 15(6), 1–15. https://doi.org/10.1371/journal.pone.0234421
This paper dives into the patterns of the East Asian Summer Monsoon (EASM) from 1815-2014 by studying tree ring growth of Pinus massoniana (Chinese Red Pine). The researchers used oxygen isotope data within the tree rings to determine the "source water isotope compositions and atmospheric vapor pressure deficit", which are correlated with precipitation. For this study, dendrochronology was the ideal method for dating because other methods like palynology, peat deposits, and stalagmites couldn't produce interpretable information on interannual and interdecadal scales.
Caetano-Andrade, V. L., Clement, C. R., Weigel, D., Trumbore, S., Boivin, N., Schöngart, J., & Roberts, P. (2020). Tropical Trees as Time Capsules of Anthropogenic Activity. Trends in Plant Science, 25(4), 369–380. https://doi.org/10.1016/j.tplants.2019.12.010
In this article, the authors discuss how dendrochronology in addition to radiocarbon dating is able to tell the history of human-environment interactions over the past few hundred years in the Amazon. One example: land use change before and after the arrival of Europeans and the effect their arrival had on indigenous populations can be seen in the tree ring data. Another such change was the increase in competition between certain species as fruit-bearing trees became more populous due to the intentional seeding of them by humans. All of the findings that were discussed support their closing claim that trees being "cultural heritage repositories of knowledge" are another ecosystem service that are supplied.