Accumulated Degree Days (ADD)
Definition
The sum of daily mean temperatures above a threshold (usually 0 °C) over a period of interest. Used as a measure of the biological decomposition work done during burial, because microbial and enzymatic activity scales with temperature.
- Unit
- Degree-day (DD). Temperature difference multiplied by duration.
- Application domains
- Decomposition rate estimation, insect development timing, root growth dating in buried remains.
- Temperature dependency
- Microbial and enzymatic activity scale with temperature, making ADD a direct proxy for biological work done.
Common questions
How is Accumulated Degree Days (ADD) calculated?+
ADD is the sum of (mean daily temperature minus a base temperature) for each day since the event (death, oviposition, or burial). For example, if the base temperature is 0°C and the mean daily temperature is 15°C, that day contributes 15 degree-days. You keep adding these values across all days.
Why does ADD matter in forensic science?+
ADD measures cumulative thermal energy, which controls how fast biological processes happen. Decomposition rate, insect larval development, and root growth all speed up with warmth and slow down in cold. By knowing the ADD required to reach a particular decomposition stage or insect development milestone, forensic examiners can back-calculate time since death.
Is the base temperature always the same?+
No. Different biological processes have different base temperatures. In entomology, the threshold depends on the insect species and which larval stage you're tracking. In decomposition studies using Body Farm data, researchers use the formula specific to their dataset. In burial work, 0°C is common, but the threshold shifts based on microbial activity rates.
Related terms
- Burial Interval
- The elapsed time between placement of the body in the ground and the time of recovery. Distinct from the post-mortem interval (time...
- Cadaver Decomposition Island (CDI)
- The localised area of soil and vegetation altered by the decomposition fluids and gases released from a body. A CDI has a...
- Accumulated Degree Hours (ADH)
- A temperature-corrected measure of developmental time. Calculated by summing (hourly ambient temperature minus the species-specific base temperature threshold) across the period of...
- AFTER
- Australian Facility for Taphonomic Experimental Research, University of Technology Sydney (2016). First body farm outside the United States; subtropical eastern Australian decomposition...
- Annual Growth Ring
- A layer of secondary xylem produced during one growing season, visible in cross-section as alternating early-wood (large-celled, pale) and late-wood (dense, dark)...
- Anthropology Research Facility (ARF)
- The first outdoor human decomposition research facility, established by William M. Bass at the University of Tennessee Knoxville in 1981. The foundational...
- Autolysis
- Self-digestion of cells after death caused by the release of lysosomal enzymes. No microbial involvement is required. Autolysis begins within minutes of...
- Base (Lower Developmental) Threshold
- The temperature below which an insect species does not develop. For forensically important blow flies in temperate regions this typically ranges from...
- Behrensmeyer Weathering Stages
- A six-stage (0-5) macroscopic scale for characterising the degree of environmental weathering on bone, published by Anna Kay Behrensmeyer in Paleobiology (1978)....
- Blowfly
- Common name for Calliphoridae. The female lays eggs in moist orifices (mouth, nose, eyes, wounds); eggs hatch in 8 to 24 hours...
- Calliphoridae
- The blowfly family: metallic-coloured flies that are typically the earliest colonisers of exposed remains. Forensically important genera include Calliphora, Lucilia, Chrysomya, and...
- Carrion Succession
- The predictable, roughly sequential replacement of insect communities on a decomposing body, driven by changing chemical substrate. Not a strict relay with...
Explained in these topics
- Temperature, Accumulated Degree Days and Degree HoursThe cumulative sum of (mean daily temperature minus base temperature) for each day since oviposition. The unit is degree-day (DD). Development completes when A...
- Burial Interval EstimationThe sum of daily mean temperatures above a threshold (usually 0 °C) over a period of interest. Used as a measure of the biological decomposition work done duri...
- Decomposition Stages and the Megyesi Total Body ScoreCumulative thermal energy experienced by a body since death, computed as the sum of (mean daily temperature minus base temperature) across each day of the PMI....
- Forensic Entomology: Insects of Forensic Importance and ApplicationsSum over time of (mean daily temperature minus species-specific base temperature). Larval development requires a fixed ADD to reach each stage, allowing back-c...
- Root Growth and Grave DatingA thermal-accumulation measure used in forensic entomology and occasionally in botanical PMI work to correlate temperature-dependent biological processes (inse...
- The Body Farm Research Stack: ARF Tennessee, STAFS Texas, AFTER Australia and BeyondCumulative thermal energy (sum of mean daily temperature minus base temperature across all days of the PMI). The unit in which decomposition rate is expressed...