ACCLIMATE Plant Litter Decomposition Data

Graphs

Extensive, Moderate, and Minimal indicate locations at the site with corresponding permafrost thaw states.

Summary Points

• What is it: Litter decomposition is the measurement of the rate at which microbes in the soil decompose plant matter.
• Non-Scientific name: Plant material breakdown
• Why do we measure it: We measure decomposition to indicate how carbon and nutrients are cycling through the environment. This also contributes to our understanding of ecosystem health.
• How was it measured: The breakdown of cellulose paper is used to measure decomposition. First, we weigh the cellulose paper and record this weight before placing the cellulose paper into a mesh screen bag divided into 4 sections. Two sections are placed at a lower depth (10-20 cm) within the soil while the other two are placed higher (0-10 cm). These mesh screen bags are left in the ground until the following year when they are collected and reweighed for that following year’s overall decomposition.
• Long term trends:
• High and low trends: Over the years, the extensive permafrost thaw plots had higher decomposition rates when compared to the moderate and minimal plots. Overall, the moderate and minimal plots are not significantly different in decomposition rates. 2023 had the highest decomposition rate at the Gradient site in both layers. Across the years, the control plots at the Warming Experiment had a trend of lower decomposition rates in the 0-10cm. However, in 2020, the Warming Experiment control plots began to match and then exceed air warming plots. The highest rates of decomposition are within the warming plots.
• What happened in 2024: In 2024, at the Warming experiment, the Air and Soil warming plots had a higher overall decomposition rate when compared to other plots in both soil layers. 2024 also showed the same pattern with the extensive plots at Gradient having a higher decomposition rate compared to the moderate and minimal plots.
• Where is this science going?: Depending on further variability in conditions, decomposition rates could increase as they greatly did in 2023. With warming conditions, plant material will be further accessible to microbes within the soil, leading to higher decomposition rates. Continuing to measure decomposition will help to record ecosystem health and functionality.

Images

Ariella Thompson in the lab at UAF weighs out each piece of cellulose paper which will be placed in the decomposition mesh bags at both the Warming Experiment and Thaw Gradient sites.