Abstract
Afforestation plays an important role in soil protection and ecological restoration. The objective of this study is to understand the effect of afforestation on soil carbon and soil microbial communities in the Loess Plateau of China. We measured two chemically-separated carbon fractions (i.e., humic acid, HA, and fulvic acid, FA) and soil microbial communities within shrublands (18-year-old Caragana korshinskii Kom (shrubland I) and 28-year-old Caragana korshinskii Kom (shrubland II)) and cropland. The size and structure of the soil microbial community was measured by phospholipid fatty acid (PLFA) analysis. The analysis of C-fractions indicated that at a depth of 0–20 cm, FA-C concentration in shrubland I and shrubland II were 1.7 times that of cropland, while HA-C had similar values across all three sites. Total PLFAs, G+ (Gram positive) bacterial, G− (Gram negative) bacterial, and actinobacterial PLFAs were highest in shrubland II, followed by shrubland I and finally cropland. Fungal PLFAs were significantly higher in shrubland II compared to the other sites. Additionally, we found a high degree of synergy between main microbial groups (apart from fungi) with FA-C. We concluded that planting C. korshinskii in abandoned cropland could alter the size and structure of soil microbial community, with these changes being closely related to carbon sequestration and humus formation.
Highlights
Soil organic matter (SOM) is as a critical constituent of the physical, chemical, and biological qualities of soil [1]
We found a higher soil organic carbon (SOC) from shrubland I than shrubland II at a depth of 0–20 cm, while the results were opposite at a depth of 20–40 cm
Changes in carbon fractions and soil microbial community were assessed in the response to afforestation from abandoned cropland on the Loess Plateau of China
Summary
Soil organic matter (SOM) is as a critical constituent of the physical, chemical, and biological qualities of soil [1]. Restoring soil carbon is essential to enhancing soil quality, sustaining and improving food production, maintaining clean water, and reducing increases in atmospheric CO2 [2]. It has been suggested that alteration with different fractions of SOM are more effective in indicating changes in soil use than the total soil organic matter content. Humic substances are stable organic matter compounds which can increase moisture retention, improve soil buffering capacity, and supply plants with available micronutrients [3]. The changes in the proportion of humic substances realistically reflect carbon sequestration in soils. Humic substances (HSs) can be divided into fulvic acids (FAs, alkali-extractable and acid soluble), humic acids
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