Forest soils in south-west Germany show rising methane uptake
The story at a glance
A study of 13 forest soils in south-west Germany found that methane uptake increased by an average of about 3% a year. The records span up to 24 years, and the trend varied substantially between sites.1
The regional result contrasts with earlier reports of falling uptake at US research sites. A 2026 reanalysis confirmed those declines but questioned whether rainfall explains them. The findings do not establish a global trend.134
The story in brief
What you need to know
- The German study estimated an average methane-uptake increase of approximately 3% per year across its 13 sites. Individual sites differed substantially, so the average does not describe every forest in the region equally.1
- Researchers associated the increase with lower annual precipitation and soil moisture, alongside rising soil temperatures. These relationships are proposed explanations for the observed local trend, not proof that warming or drying will increase uptake elsewhere.12
- An earlier study reported methane-uptake declines of 53% to 89% at two long-term research sites in the north-eastern United States. Its review of published measurements also estimated a global decline, though those records cover different places and periods from the German study.31
- The earlier US study linked declining uptake partly to increased precipitation. A 2026 reanalysis found that precipitation and measured soil moisture did not adequately explain the declines in those records, while confirming that the declines occurred.34
- Together, the studies show that long-term methane-uptake trends differ between the monitored regions. They do not establish a single explanation for those differences or show that forest soils worldwide are becoming stronger methane sinks.134
Conservation context
Why this matters
Forest soils absorb atmospheric methane, and their uptake is relevant to understanding climate feedbacks. The regional differences in these studies underline why local measurements should not be treated as a global pattern when assessing methane budgets.134
The developing story
What happens next
Further evidence is needed to establish how representative the German sites are, whether their trend will persist, and what drives the US declines. The research also identifies a need to account for regional variation and measurement uncertainty in global methane-budget estimates.14
Established evidence
What we know
- The German analysis covered 13 forest soils in south-west Germany, with measurements spanning up to 24 years.1
- Researchers estimated methane fluxes using soil gas profiles and checked these estimates against chamber measurements. The paper reports site-to-site variation and measurement limitations.1
- The German study reports increasing uptake, while the earlier US study reports declines at its two research sites.13
- The 2026 reanalysis challenges rainfall as an adequate explanation for the US declines and says further evidence is needed to identify the mechanisms.4
Open questions
What we don't know
- It remains unclear how representative the 13 south-west German sites are of other forest types and climate regions.1
- The available findings do not establish whether the German uptake trend will continue as precipitation, soil moisture and temperature change.1
- The mechanism behind the long-term US declines remains unresolved because precipitation and measured soil moisture did not adequately explain them.4
- How regional differences and uncertainty in long-term measurements should be represented in global methane-budget estimates remains an open question.14
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