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The fate of wood

Dead wood and the carbon cycle

a grassy field with logs standing vertically
Some logs are suspended above the soil to emulate standing-dead wood, while others are on the soil surface. USDA Forest Service photo by Carl Trettin.

Trees are part of the carbon cycle. When they die, they go on storing carbon for a while. But as the fallen trunks and large branches decompose, that carbon moves into the soil and the atmosphere.

USDA Forest Service researcher Carl Trettin and his colleagues have designed a new study to show how wood-carbon moves into the soil.

The researchers are monitoring one-of-a-kind logs as they decompose. These logs have a unique isotopic signature that allows researchers to follow individual carbon atoms as they move from the wood to soil. The logs are from Free Air Carbon Dioxide Enrichment sites, as a new General Technical Report discusses.

Trettin also contributed to the Coarse Woody Debris Decomposition Assessment Tool, which was led by Zhaohua Dai of Michigan Technological University. The model shows how climate, soil, characteristics of the wood itself, and many other factors – including bacteria, beetles, fungi, and termites – affect decomposition.

Models of the carbon cycle are complex. However, they provide important insights into carbon budgets and carbon storage in forests. This research expands on previous modeling efforts by including termite activity. Termites and other insects break down almost 30% of dead wood.

The study is taking place on nine experimental forests across the U.S.

Read the full text of the General Technical Report. Read the full text of the study in PLOS ONE.