Soil carbon stock changes in transitional mire drained for forestry in Latvia: a case study

Abstract

The aim of the study is to evaluate the impact of drainage on soil carbon stock in a transitional mire drained for forestry. The study site is located in the central part of Latvia representing hemiboreal vegetation zone. Site was drained in 1960. It is located in a catchment area of the river Veseta. An undrained site at the same catchment area was chosen for control (ca. 2.5 km between sites). In both sites, the depth of peat is 4 -4.5 m. Drained site is dominated by coniferous trees. Soil samples collected in 2014 were used to determine bulk density and carbon content, and to calculate soil carbon stock. Samples were collected down to 80 cm depth. Ground surface elevation was measured before and several times after the drainage to determine peat subsidence. Carbon stock has increased by 0.3 tons ha -1 yr 1 after drainage, although peat has subsided on average by 26 cm (13 -48 cm). Subsidence was mainly caused by physical shrinkage of peat not by organic matter oxidation. Drainage was followed by compaction of aerated soil layer, which has caused most of the subsidence, especially during the first years after drainage. Soil bulk density has increased almost twice at soil surface layer 0 -10 cm (from 75 kg m 3 to 141 kg m 3 ). Differences decrease at deeper sampling depths. It is concluded that drainage is not always followed by reduction of carbon stock in soil. Increased above and below ground litter production rates may offset accelerated decomposition of organic matter after drainage.

Improved activity data for accounting greenhouse gas emissions due to management of wetlands

“…The share of rewetted areas is insignificant; therefore, this land use category can be merged with flooded lands and emissions can be calculated using the methodology for flooded lands. Peat extraction and abandoned fields (13,8,10,12) Rewetted land excl. forest (6) Flooded land (4,5) Settlements (3) Forest land (1,7,9,11) Farmland (2) Figure 3.…”

“…Peat extraction and abandoned fields (13,8,10,12) Rewetted land excl. forest (6) Flooded land (4,5) Settlements (3) Forest land (1,7,9,11) Farmland (2) Figure 3.…”

“…Managed organic soil is one of the largest key sources of GHG emissions in boreal and cool temperate moist climate regions in Europe (Salm et al, 2009). However, scientifically based accounting methods for GHG emissions have been developed and activity data are available mainly for organic soils in boreal climate region (Laiho, 2006;Lupikis et al, 2017;Lupiķis & Lazdins, 2017;von Arnold et al, 2005). For instance, the default emission factors in the 2013 Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Wetlands for forest land on drained nutrient-rich organic soils in the boreal zone are based on data from 62 sites, while for the temperate zone, there are data from only 8 sites and both nutrient-rich and poor soils are lumped together (Blain et al, 2013).…”

“…Flooded land (4,5) Rewetted land excl. forest (6) Peat extraction and abandont fields (13,8,10,12) Area , kha Figure 4. Area which should be reported under wetlands category of the GHG inventory.…”

Reviews and syntheses: Greenhouse gas exchange data from drained organic forest soils – a review of current approaches and recommendations for future research

“…Inventory methods were applied in five studies (Minkkinen and Laine, 1998;Minkkinen et al, 1999;Simola et al, 2012;Pitkänen et al, 2013;Lupikis and Lazdins, 2017). On average, studies using inventory methods included a higher number of sites monitored compared to studies using flux methods (Table 1).…”