Abstract
Afforestation plays an important role in soil carbon storage and water balance. However, there is a lack of information on deep soil carbon and water storage. The study investigates the effect of returning farmland to the forest on soil carbon accumulation and soil water consumption in 20-m deep soil profile in the hilly and gully region of the Chinese Loess Plateau. Four sampling sites were selected: Platycladus orientalis (Linn.) Franco forest (PO: oriental arborvitae), Pinus tabulaeformis Carr. Forest (PT: southern Chinese pine), apple orchard (AO) and farmland (FL, as a control). Soil organic carbon (SOC) and soil inorganic carbon (SIC) content were measured in 50-cm sampling intervals of 20-m soil profiles, as well as the associated factors (e.g. soil water content). The mean SOC content of PT was the highest in the 1–5 m layer and that of FL was the lowest (p < 0.05). Compared with FL, the SOC storages of PO, PT and AO increased by 2.20, 6.33 and 0.90 kg m−2 (p > 0.05), respectively, in the whole profile. The SIC content was relatively uniform throughout the profile at all land-use types and SIC storage was 9–10 times higher than SOC storage. The soil water storage of PO, PT and AO was significantly different from that of FL with a decrease of 1169.32, 1161.60 and 1139.63 mm, respectively. After the 36-yrs implementation of the “Grain for Green” Project, SOC in 20 m soil profiles increased as a water depletion cost compared with FL. Further investigation is still needed to understand the deep soil water and carbon interactions regarding ecological restoration sustainability in the Northern Loess Plateau.
Highlights
Afforestation plays an important role in soil carbon storage and water balance
There were no significant differences between FL, PO, Pinus tabulaeformis Carr. Forest (PT), and apple orchard (AO) in the 0–1 m layer (Fig. 3a)
The mean Soil organic carbon (SOC) content of PT was higher than other land uses in the 1–5 m layer, SOC content of FL was lower than PT and AO in the 5–10 m layer, and SOC content of PT was significantly different from AO in the 10–20 m layer (Fig. 3a)
Summary
Afforestation plays an important role in soil carbon storage and water balance. there is a lack of information on deep soil carbon and water storage. The study investigates the effect of returning farmland to the forest on soil carbon accumulation and soil water consumption in 20-m deep soil profile in the hilly and gully region of the Chinese Loess Plateau. Environmental problems, such as soil degradation and global climate change, have received increasing attention in the last few decades[1,2,3]. Previous studies have unanimously reported that ecological restoration increased SOC storage in the top layer (0–1 m) and decreased S WS10,14; similar investigation concerning SIC has been lacking[15,16]. It is not clear how much SOC and SIC storage in a deep soil and the relationship of SOC and SIC storage with SWS expense below 1 m in the Chinese Loess Plateau[22]
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