Abstract
Artificial vegetation restoration can induce variations in accumulation and distribution of soil carbon (C), nitrogen (N) and phosphorus (P). However, little is known about variations in soil C, N and P nutrient fraction stratification following artificial vegetation in Loess Plateau China. Based on the hypothesis that re-vegetated can improve soil quality and stratification ratios (SR) can be used as an indicator to evaluate soil quality. This study measured contents and storages of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and their SRs in topsoil (0–20 cm) and subsoil (20–60 cm) in three 30-year re-vegetated lands that had been converted from arable land (Robinia pseudoacacia L., Caragana Korshinskii Kom. and abandoned cropland with low interferences and few management measures) and one slope cropland (SC) as a control for three soil profiles(0–20 cm, 20–40 cm and 40–60 cm) from June 2009 to June 2013. The results showed that the contents and storages of SOC, TN and TP in re-vegetated land were significantly higher than those in the SC in both topsoil and subsoil. The storages of SOC, TN and TP in the topsoil (0–20 cm) of the re-vegetated lands increased by 16.2%-26.4%, 12.7%-28.4% and 16.5%-20.9%, respectively, and increased by smaller but significant amounts in subsoil from 2009 to 2013. The SRs for SOC, TN and TP in the re-vegetated lands were mostly >2 (either for 0–20:20–40 cm or 0–20:40–60 cm) and greater than that in the SC. The SRs showed an increasing trend with increasing restoration age. The results also showed that the land use type and soil depth were the most influential factors for the SRs and storages, and the SRs of SOC and TN had significantly positive correlations with their storages. The SRs were concluded to be a good indicator for evaluating the soil quality, which can be significantly enhanced through vegetation restoration. Moreover, vegetation restoration can significantly enhance SOC, TN and TP accumulation in both topsoil and subsoil.
Highlights
Artificial vegetation restoration, the conversion of non-vegetated or arable land to a plant covered land, has attracted increasing social attention and has become one of the hottest topics of ecological study as an efficient measure to repair destroyed natural ecosystems [1,2]
Zhao et al [4] and Fu et al [5] illustrated that both large-scale artificial forestry and grasslands that were based on cropland significantly increased soil organic carbon (SOC), soil total nitrogen (TN) and soil total phosphorus (TP) sequestration
The SOC, TN and TP contents decreased by 60.9%-71.4%, 45.7%-61.0%, 49.2%-66.3% when the soil depth changed from 0–20 cm to 40–60 cm among the different re-vegetated lands (P
Summary
Artificial vegetation restoration, the conversion of non-vegetated or arable land to a plant covered land, has attracted increasing social attention and has become one of the hottest topics of ecological study as an efficient measure to repair destroyed natural ecosystems [1,2]. In addition to altering the understory diversity of species[3], artificial vegetation has substantial effects on the accumulation and distribution of soil nutrient components, i.e., soil carbon (C), nitrogen (N) and phosphorus (P) [3]. Compared to the long history of surface soil studies (0–20 cm or shallower), subsoil (sub-surface soil at 20–60 cm) has only been the subject of intensive research in recent years because subsoil has since been recognized to contribute greatly to C, N and P accumulation. Guo and Gifford’s [10] results showed that at least 61% of the total soil C was stored below 30 cm in the northern circumpolar permafrost region, and other research has shown subsoil plays an even more important role as a CO2 sink than top soil [11,12]. Understanding the effect of long-term vegetation recovery on changes in SOC, TN and TP in subsoil, which is not well documented, is important
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