So far in this botany series, we have gained a reasonable understanding of the world of plants.
To achieve this, we examined plant cells, tissues, organs, organ systems, mechanisms of growth,
evolution, plant classification, and much more. In doing so, we have built upon our pre-existing
knowledge of biomolecules and cellular processes in a way that is specific to the plant kingdom.
However, there’s a lot more to discuss than the basic information we have covered thus far,
so now we are going to dive into some more detailed information that will be of use to
those who intend to go a little deeper with their study of plants. The first topic we
will cover in this endeavor, over the next handful of tutorials, is dendrochronology.
Dendrochronology is a term derived from the Greek words for tree, or “déndron”, time, or “khronos”,
and the suffix “-logia” which translates in English to mean “the science of, or study of.”
So as the study of trees over time, dendrochronology is truly the science of tree
rings, which are visible rings of outward growth that can be examined by looking at a cross section
of a tree, with each ring representing one year of growth, proceeding forwards in time from the
center outwards. It is a diverse field that has applications in archaeology, chemistry, climate
science, geology, history, forestry, and natural resource management. Essentially, it is a form
of environmental monitoring that uses trees as long-term bioindicators, because trees can record
any factor, whether caused by nature or by humans, that impacts the process of ring formation.
Dendrochronologists can study very old trees to learn about past temperatures, rainfall,
insect outbreaks, fires, and other environmental disasters. They can also study large numbers of
relatively young trees to reveal information about localized or global climatic shifts.
In addition, wood from long dead trees, whether in houses, barns, roads, or ships,
can be used to expand existing chronologies further back in time and date archeological finds.
Tree rings, along with ice cores, corals, and sub-fossil pollen in lake sediment,
provide a type of climatological proxy data. This means that they can be used instead of direct
meteorological measurements to reveal past climate information, and we’ll cover exactly how this is
done a bit later. Compared to these other forms of proxy data, tree rings provide a relatively
short record in that most chronologies date from 400 to 1,000 years, with only a handful reaching
over 10,000 years. However, they are considered to be a very reliable form of proxy data, especially
for tracking recent climatic shifts, since trees record this data within their very bodies.
Forests are living libraries that catalog the natural world. Trees are like books,
or journals. They store information about their past. Using dendrochronology we can reveal some
of the mysteries trees hide and learn about their past in order to better predict their future.
Did a single tree have an insect infestation, or did an entire forest suffer? Are some tree
species more sensitive to climatic shifts than others? What did the forest that lived in an
area long ago really look like, and what might the forests of the future look like?
The goal of the next few tutorials in this series will be to provide you with a solid
background in dendrochronology rather than just a brief overview. In order to do this,
we will need to first go over the foundational principles and concepts of dendrochronology.
Then we can get into more detail on the growth and structure of wood using some of the vocabulary
from earlier in the botany series. Then we can examine the field, lab, and computational
procedures necessary to successfully analyze a tree core and build a chronology. Finally, we will
go over some of the subfields of dendrochronology and wrap up the miniseries. Once we are finished,
you may start looking at trees just a bit differently, hopefully with an enhanced awareness
of their complexity and utility. So without further delay, let’s learn about dendrochronology.