Evaluation of Soil Organic Layers Thickness and Soil Organic Carbon Stock in Hemiboreal Forests in Latvia

Abstract

In the forest land of many European countries, including hemiboreal Latvia, organic soils are considered to be large sources of greenhouse gas (GHG) emissions. At the same time, growing efforts are expected in the near future to decrease emissions from the Land Use, Land Use Change and Forestry sector, including lands with organic soils to achieve enhanced contributions to the emissions and removals balance target set by the Paris Agreement. This paper aims to describe the distribution of organic soil layer thickness in forest land based on national forest inventory data and to evaluate soil organic carbon stock in Latvian forests classified as land with organic soil. The average thickness of the forest floor (organic material consisting of undecomposed or partially decomposed litter, O horizon) was greatest in coniferous forests with wet mineral soil, and decreased with increasing soil fertility. However, forest stand characteristics, including basal area and age, were weak predictors of O horizon thickness. In forests with organic soil, a lower proportion of soil organic matter layer (H horizon) in the top 70 cm soil layer, but a higher soil organic carbon stock both in the 0–30 cm layer and in the 0–100 cm layer was found in drained organic soils than in wet organic soils. Furthermore, the distribution of the soil H horizon thickness across different forest site types highlighted the potential overestimation of area of drained organic soils in Latvian forest land reported within the National GHG Inventory.

Soil Fungi and Soil Organic Carbon Stocks in the Profile of a Forest Arenosol

“…where EC = the difference between the carbon fumigated and unfumigated soil samples, and MBN = FN/0.54 (2) where FN = the difference between the nitrogen fumigated and unfumigated soil samples.…”

“…To better understand, and potentially mitigate, future climate change, studies assessing soil organic carbon (SOC), soil fungi, and other parameters of soil are very important. Forest soils have a high potential for significant carbon sequestration [1][2][3][4]. Organic matter from aboveground and belowground vegetation is the main source of organic matter significantly affecting SOC stocks in mineral soil layers [5][6][7][8].…”

Role of Andean tropical montane soil organic carbon in the deglacial carbon budget

“…Within this pedologic pool, SOC accounts for a carbon reservoir of about 1550 Pg, this mass is more than the global atmospheric pool (780 Pg), biotic pool (650 Pg) pool, or the surface ocean pool (900 Pg) (Janzen, 2004; Lal, 2004, 2008). In general, SOC consists primarily of carbon that was taken out of the atmosphere via photosynthesis and deposited as decayed or decaying organic components including dead plant material, bacteria, fungus, peat, litter, humus, cellulose, and lignin (Bārdule et al, 2021; Mayer et al, 2020; Schils et al, 2008). The carbon that is fixed by plants is transferred to the soil via dead plant matter and this dead organic matter creates a substrate, which decomposes and respires back to the atmosphere as carbon dioxide or methane depending on the availability of oxygen in the soil (Schils et al, 2008).…”

Old-Growth Coniferous Stands on Fertile Drained Organic Soil: First Results of Tree Biomass and Deadwood Carbon Stocks in Hemiboreal Latvia

“…Forests are expected to increase carbon removal from the atmosphere and decrease greenhouse gas emissions to achieve global climate change mitigation goals. Organic soils store a large amount of carbon stock [1], but drained areas are an especially large source of greenhouse gas emissions in the forest land of many European countries [2,3]. However, some authors have found that soil carbon stock can remain stable or even increase after drainage, especially in the boreal vegetation zone [4][5][6].…”

“…Few studies have dealt with carbon storage in drained hemiboreal organic soils, where tree biomass and soil carbon were assessed [1,6]. In an earlier study of forests with organic soils (both naturally wet and drained sites), it was concluded that forest age is an important factor affecting carbon stock in dynamics, demonstrating that carbon stocks subsequently decrease in decaying forests [3,6]. Under unmanaged conditions, stands on drained organic soils may also reach the old-growth stage as, in general, management intensity in European forests is decreasing [7].…”