Soil Organic Carbon Stocks in Afforested Agricultural Land in Lithuanian Hemiboreal Forest Zone

Abstract

In the context of the specificity of soil organic carbon (SOC) storage in afforested land, nutrient-poor Arenosols and nutrient-rich Luvisols after afforestation with coniferous and deciduous tree species were studied in comparison to the same soils of croplands and grasslands. This study analysed the changes in SOC stock up to 30 years after afforestation of agricultural land in Lithuania, representing the cool temperate moist climate region of Europe. The SOC stocks were evaluated by applying the paired-site design. The mean mass and SOC stocks of the forest floor in afforested Arenosols increased more than in Luvisols. Almost twice as much forest floor mass was observed in coniferous than in deciduous stands 2–3 decades after afforestation. The mean bulk density of fine (<2 mm) soil in the 0–30 cm mineral topsoil layer of croplands was higher than in afforested sites and grasslands. The clear decreasing trend in mean bulk density due to forest stand age with the lowest values in the 21–30-year-old stands was found in afforested Luvisols. In contrast, the SOC concentrations in the 0–30 cm mineral topsoil layer, especially in Luvisols afforested with coniferous species, showed an increasing trend due to the influence of stand age. The mean SOC values in the 0–30 cm mineral topsoil layer of Arenosols and Luvisols during the 30 years after afforestation did not significantly differ from the adjacent croplands or grasslands. The mean SOC stock slightly increased with the forest stand age in Luvisols; however, the highest mean SOC stock was detected in the grasslands. In the Arenosols, there was higher SOC accumulation in the forest floor with increasing stand age than in the Luvisols, while the proportion of SOC stocks in mineral topsoil layers was similar and more comparable to grasslands. These findings suggest encouragement of afforestation of former agricultural land under the current climate and soil characteristics in the region, but the conversion of perennial grasslands to forest land should be done with caution.

Changes in Organic Carbon Stock in Soil and Whole Tree Biomass in Afforested Areas in Latvia

“…In addition, in this case the effect of former land use had been long lasting. In a study carried out in Lithuania the average bulk density of fine (<2 mm) soil in the 0–30 cm layer was found to be higher in croplands compared to afforested areas (20–30 years after afforestation) and grasslands [ 17 ].…”

“…However, after several years, the accumulation of SOC reaches a level comparable to non-forested soils, and eventually, several decades after the afforestation process the SOC stock begins to increase more rapidly. Nevertheless, studies indicate that achieving the SOC levels found in natural forests requires a significant amount of time [ 15 , 16 , 17 ]. Furthermore, frequently significant translocation of SOC was observed within the soil profile, with a decrease in SOC and nitrogen (N) in deeper soil layer compensated by an increase in upper soil layer [ 18 ].…”

Spatial Distribution and Regulating Factors of Soil Nutrient Stocks in Afforested Dump of Pingshuo Opencast Coalmine, China

“…Moreover, most areas were characterized by low APD (<0.051 Mg ha −1 ) and AKD values (<0.82 Mg ha −1 ), while several high-APD or high-AKD "points" were sporadically scattered across the South Dump (Figure 4). Numerous studies have explored the effects of afforestation on soil nutrient stocks in natural ecosystems [14,18,20,54,55]. It has remained controversial about the specific influence of afforestation on the evolution of soil nutrient stocks and different studies might draw different conclusions due to the comprehensive influence of climate, topography, and geological background [20].…”

Changes in Soil Properties and Scots Pine Tree Growth Induced by Different Soil Ploughing Prior to Afforestation: A Case Study

“…Over a different period, the afforestation of arable land impacts higher C stocks via C sequestration in tree biomass; input of litterfall and subsequent development of forest floor result in higher soil organic carbon (SOC) reserves in forests compared to croplands. In the afforested sites, soil organic matter tends to accumulate more intensively, and the C sequestration in the forest floor is determined [1,7,8]. In the longer term, C sequestration is associated with the C content in the mineral topsoil layers.…”

“…However, C content in mineral soils does not change in the first decades or even decreases following afforestation [13]. Recent studies on afforestation conducted in the region indicated that the new forest plantations established on agricultural land did not cause a significant increase in SOC stocks in the mineral 0-30 cm topsoil during the first 30 years period [8,14]. Analysis of the relationship between soil tillage technologies and changes in SOC showed that C stocks increase below the plough layer [15].…”