What’s With the Bands on BBG’s Trees?

By BBG Staff | June 7, 2023

In consultation with Andrew Reinmann, an ecologist and biogeochemist at CUNY, Brooklyn Botanic Garden has installed dendrometers—which measure tree growth—around the grounds in a demonstration for visitors.

There’s so much we still don’t know about trees and how they’re reacting to our rapidly changing world. But we can learn a lot through their growth patterns, which shift depending on environmental conditions like temperature, rainfall, and light exposure. Scientists use dendrometers to better understand how trees are responding to stress, how much carbon dioxide they’re pulling out of the atmosphere, and more.

A band dendrometer, a device used to measure tree growth, on a Ginkgo biloba (maidenhair tree) in the Garden. Photo by Michael Stewart.

Garden staff installed two different types of dendrometers on trees. The first, band dendrometers, are simple measuring tape-like instruments that have been used by scientists for decades. As the tree sequesters carbon and builds biomass, expanding its trunk over time, the tape expands, too. The second is called a point dendrometer, a tool that’s newer to science. Point dendrometers can log new data every 15 minutes or so, and are able to record the tiny, imperceptible swells and contractions that reshape a tree’s trunk throughout the day as water flows through it.

These tools can provide scientists with complementary bits of information about trees. By analyzing these measurements over time, researchers can start to determine how trees are responding to environmental changes.

A point dendrometer installed on a beech tree (Fagus sp.) in the Garden. Point dendrometers are sensitive electronic devices that can detect tiny changes in a tree’s diameter over the course of a single day. Photo by Michael Stewart.

The thing is, although they may appear sedentary, “trees aren’t static organisms,” says Reinmann. A flurry of dynamic processes are going on inside of them all the time, at various timescales.

Reinmann’s own research focuses on plant ecophysiology and the terrestrial carbon cycle. In 2022, he received a five-year National Science Foundation CAREER grant to study how climate change and forest fragmentation affect carbon sequestration in temperate forests.

By installing dendrometers at Brooklyn Botanic Garden, “I hope that visitors will start to look at trees as organisms that are active and engaged in the world, much like people are,” he says.

Though we aren’t conducting a formal scientific experiment, our Horticulture team and volunteers will be recording data regularly over a period of several years. We hope to better understand how much carbon the trees at Brooklyn Botanic Garden might be sequestering, and how they’re responding to our changing climate. We also want to get to know our trees as individuals—how they shift, grow, and react to their environment over time.

We’ll update this post as we learn more, so be sure to check back!