Shifts in soil nutrient concentrations and C:N:P stoichiometry during long-term natural vegetation restoration

Rentian Ma; Feinan Hu; Jingfang Liu; Chunli Wang; Zilong Wang; Gang Liu; Shiwei Zhao

doi:10.7717/peerj.8382

Shifts in soil nutrient concentrations and C:N:P stoichiometry during long-term natural vegetation restoration

PeerJ. 2020 Jan 22:8:e8382. doi: 10.7717/peerj.8382. eCollection 2020.

Authors

Rentian Ma¹, Feinan Hu^{1

2}, Jingfang Liu¹, Chunli Wang¹, Zilong Wang¹, Gang Liu^{1

2}, Shiwei Zhao^{1

2}

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, China.
² Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi, China.

Abstract

Background: Ecological stoichiometry (C:N:P ratios) in soil is an important indicator of the elemental balance in ecological interactions and processes. Long-term natural vegetation plays an important role in the accumulation and distribution of soil stoichiometry. However, information about the effects of long-term secondary forest succession on soil stoichiometry along a deep soil profile is still limited.

Methods: We selected Ziwuling secondary succession forest developed from farmland as the study area, investigated the concentrations and stoichiometry of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) at a depth of 0-100 cm along a 90-year succession chronosequence, including farmland (control), grassland, shrub, early forest, and climax forest.

Results: SOC and TN concentrations significantly increased with increasing restoration age, whereas soil P concentration remained relatively stable across various successional stages. SOC and TN concentrations decreased with an increase in soil depth, exhibiting distinct soil nutrient "surface-aggregation" (high nutrients concentration in the top soil layer). The soil C:P and N:P ratios increased with an increase in restoration age, whereas the variation of the C:N ratio was small and relatively stable across vegetation succession. The nutrient limitation changed along with vegetation succession, transitioning from limited N in the earlier successional stages to limited P in the later successional stages.

Conclusion: Our results suggest that more nitrogen input should be applied to earlier succession stages, and more phosphorus input should be utilized in later succession stages in order to address limited availability of these elements. In general, natural vegetation restoration was an ecologically beneficial practice for the recovery of degraded soils in this area. The findings of this study strengthen our understanding of the changes of soil nutrient concentration and nutrient limitation after vegetation restoration, and provide a simple guideline for future vegetation restoration and reconstruction efforts on the Loess Plateau.

Keywords: Nitrogen; Phosphorus; Secondary forest; Soil organic carbon; Vegetation restoration.

Grants and funding

This work was supported by the National Key R&D Program of China (2016YFE0202900), the Fundamental Research Funds for the Central Universities (2452019078), and the National Natural Science Foundation of China (41601236 and 41761144060). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.