| 26 Jan 2026
Cold winters, warm summers, no dry season: greenhouse gas emissions from forest organic soils in the Köppen–Geiger Dfb climate zone
Abstract. Greenhouse gas (GHG) emissions from organic soils are a key component of land-use-related emissions, particularly in countries with large areas of organic soils. Temperate-zone forest soils remain less studied in GHG research than boreal soils. However, recent work has expanded coverage in the northeastern temperate region, which, under the Köppen–Geiger climate classification, shares key climatic characteristics with the southern boreal region (Dfb). This study synthesised updated GHG flux data to evaluate carbon balance and emissions from forest organic soils in the Dfb zone, stratified by drainage status, nutrient availability, and dominant tree species. Such stratification revealed CO2 source-sink patterns, which encourage the ecological relevance of using these categories for data aggregation. The dominant tree species reflected nutrient status: drained coniferous and deciduous stands have been reported as CO2 sources, emitting 0.03 ± 0.55 and 0.47 ± 0.29 t CO2‑C ha−1 year−1, respectively, though soils tended to shift toward CO2 sinks in stands older than 25 years. In contrast, undrained soils have generally been observed to function as CO2 sinks, although not necessarily in all sites. However, this stratification was less informative for CH4 and N2O. CH4 fluxes were primarily determined by water table level rather than by other site variables, whereas N2O showed a tendency toward elevated emissions in deciduous stands, irrespective of drainage status.
The manuscript from Butlers et al. describes ghg-emission measurements from forests in the temperate climate zone especially for Latvia and surrounding countries. With the help from this collected data, the authors derived emission factors for organic soils under forests for Latvia. This emission factors are of high relevance of ghg reporting since these factors are missing for many countries. Of course, emission factors presented in this paper have to be improved, but it is a first step. Therefore, the topic of that paper is of high relevance for the readers of the journal. The authors also conclude correctly, that measurements and emissions factors for organic soils under forest for the temperate climate zone are missing.
The title of the manuscript does not describe the content well. It should contain that the manuscript is about to derive emission factors for organic soils under forest from ghg emission measurements. By reading the current title, readers may think it is about differences of ghg emissions in winter and summer or under changing climate.
Further the quality control of the used studies should be described in more detail. In line 60 the authors mention, that some of the studies have not described vegetation. The question is, if such studies can be used to derive emission factors for organic soils under forest. Many studies did not give soil properties. How do deal with that? Where are the borders the authors decided not to take a study into calculation for emission factors? What quality requirements were applied to the measurement systems? Studies differ in length and frequency of measurements. The authors should explain, which standards were applied to the different studies. Which flux type was considered for the CO2 fluxes? NEE or Reco? In line 220 the authors mention that varying study design of the different studies lead to biases within the results. The question which has to be answered is, is it better to include all studies or use only the few studies which meets all quality criteria?
In units’ year should be abbreviated with a. In line 133 hyphen is used instead of small - at -4,55. Line 318 there is an error with formatting.
In the reference list gases should be subscripted (e.g., N2O, CO2…). The reference Latvia’s National Inventory Document in line 449 is not mentioned in the text.