Abstract
BackgroundEcological 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.MethodsWe 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.ResultsSOC 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.ConclusionOur 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.
Highlights
Natural vegetation restoration has been widely used to prevent soil degradation, improve the ecological environment, and rehabilitate degraded environments (Mcgroddy, Daufresne & Hedin, 2004; Grünzweig et al, 2007; Wang et al, 2014)
The soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) concentrations decreased with an increase in soil depth in the study site
The SOC and TN concentrations had the highest variability at 0–10 cm with coefficient variation (CV) of 0.41 and 0.40, respectively
Summary
Natural vegetation restoration has been widely used to prevent soil degradation, improve the ecological environment, and rehabilitate degraded environments (Mcgroddy, Daufresne & Hedin, 2004; Grünzweig et al, 2007; Wang et al, 2014). To some extent, these elements’ synergistic effects control ecological processes such as the biological elemental cycle and energy transfer (Agren, 2008; Ladanai, Agren & Olsson, 2010; Laik et al, 2009). C:N:P stoichiometry mainly focuses on the interaction and balance of chemical elements in ecological processes (Agren, 2008; Mcgroddy, Daufresne & Hedin, 2004; Ren et al, 2016; Wardle et al, 2004), and provides a useful and effective way to study the distribution, nutrient limitation, and regulatory mechanism of nutrient composition in the ecosystem (Wang et al, 2014). 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
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