This is a great project spotted over on the Public Lab stream of notes – Kina Smith made these dendrometers to measure the constantly fluctuating diameter of trees, especially as effected by water intake (explained below). We think of trees as growing, sure, but almost magically over time, when in fact they are continually growing and shrinking, even throughout the course of the day, influenced by environmental factors – amazing!
I’ve been doing work for the University of Alaska Fairbanks for the past few months working on new sensor and datalogger systems for a tree physiology and ground water project. I’m developing a system of Dendrometers, which are sensors that measure tree diameter. I’m not as eloquent about what exactly this measurement tells us as the science scientists are, but it has to do with finding correlations in water content and water movement within the tree. As a tree (especially Birch) takes in water and moves it through its body, it expands. This can happen across a 12 hour period in small, but measureable amounts. The tree will also expand as it puts on biomass, obviously, but the day to day expansions and contractions are what we’re trying to understand in combination with sap flux, water content, and meteorological data. We’re trying to understand how Birch trees use water across the growing season and trying to predict how changes in snowpack will affect them. The Birch take it most of the water they use during the spring from the snowmelt.