Dataset Information

Assessing soil degradation under land-use change: insight from soil erosion and soil aggregate stability in a small karst catchment in southwest China.

ABSTRACT:

Background

Soil erodibility (K factor) and soil aggregate stability are often used to assess soil degradation in an erodible environment. However, their applicability under land-use change is uncertain, especially agricultural abandonment.

Methods

Different land-use types, including cropland, abandoned cropland, and native vegetation land, were converted into the successive stages following agricultural abandonment by space-for-time substitution approach in a small karst catchment, Southwest China. The indexes of soil aggregate stability and K factor of the Erosion Productivity Impact Calculator (EPIC) model in soil profiles were calculated to identify which method is suitable to indicate soil degradation under land-use change.

Results

The indexes of soil aggregate stability in the soils at 0∼30 cm depth under native vegetation land were significantly larger than those under cropland and slightly larger than those under abandoned cropland. The K factor was not significantly different among the three land use examples because the EPIC model does not consider soil permeability. In the soil organic carbon (SOC)-rich soils (>2%), the K factor was significantly correlated with silt and clay content ranging within a narrow scope of near 0.010 t hm² h/hm²/MJ/mm. While in the SOC-poor soils, the K factor was significantly increased with decreasing SOC content and was significantly correlated with soil aggregate stability.

Conclusions

Soil aggregate stability is more suitable to indicate soil degradation under land-use change. Sufficient SOC in erodible soils would restrain soil degradation, while SOC loss can significantly increase soil erosion risk.

SUBMITTER: Liu M

PROVIDER: S-EPMC7144589 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Assessing soil degradation under land-use change: insight from soil erosion and soil aggregate stability in a small karst catchment in southwest China.

Liu Man M Han Guilin G

PeerJ 20200406

<h4>Background</h4>Soil erodibility (K factor) and soil aggregate stability are often used to assess soil degradation in an erodible environment. However, their applicability under land-use change is uncertain, especially agricultural abandonment.<h4>Methods</h4>Different land-use types, including cropland, abandoned cropland, and native vegetation land, were converted into the successive stages following agricultural abandonment by space-for-time substitution approach in a small karst catchment ...[more]

PMID: 32292656

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Project description:Soil microbes regulate the carbon cycle and affect the formation and stabilization of soil aggregates. However, the interactions between the soil microbial community and soil organic carbon (SOC) fractions, organic carbon (OC) content in aggregates, and soil aggregate stability after afforestation are remain poorly understood. In our study, we investigated SOC fractions in bulk soil, aggregate-associated OC content, soil aggregate stability, and soil bacterial community with high-throughput 16S rRNA sequencing at sites representing natural secondary forest (NF) and managed forest (MF), with cropland (CL) as reference in a degraded karst region of Southwest China. Our results showed that afforestation remarkably increased the SOC fraction and OC content in aggregates, the mean weight diameter (MWD), and the mean geometric diameter (GMD). The most dominant bacterial phyla detected were Acidobacteriota, Actinobacteriota, Proteobacteria, and Chloroflexi across all soils. Afforestation remarkably altered the relative abundances of most of the dominant soil bacteria at the phylum, class, and order levels. Interestingly, such changes in the abundance of soil bacteria taxa had significantly effects on SOC fraction, aggregate-associated OC content, MWD, and MGD. The abundance of dominant bacterial taxa such as Methylomirabilota, Latescibacterota, Methylomirabilia, MB-A2-108, norank_Latescibacterota; Dehalococcoidia, Rokubacteriales, Gaiellales, Microtrichales, norank_c__MB-A2-108, norank_c__norank_p__Latescibacterota, Rhizobiales, and S085 not only remarkably increased but also had significant positive effects on SOC fractions and aggregate-associated OC content after afforestation. Moreover, MWD and MGD were positively correlated with the relative abundance of Methylomirabilota, Methylomirabilia, Rokubacteriales, Latescibacterota, and Rhizobiales. Results indicated the importance of certain soil bacteria for regulating SOC storage and soil aggregate stability. We concluded that afforestation on cropland could alter the abundance of soil bacteria, and these changes modulate the stability of soil aggregates and SOC fractions.

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Project description:Soil quality assessment is important for karst ecosystems where soil erosion is significant. A large amount of vegetation restoration has been implemented since the early 21st century in degraded karst areas across southwestern China. However, the impacts on soil quality of different restoration types rarely have been compared systematically. In the current study, we investigated the soil quality after a number of vegetation restoration projects as well as their adjacent cropland by analyzing soil samples. Six vegetation restoration types were evaluated, including one natural restoration (natural shrubland, protected for 13 years), three economic forests (4 years Eucalyptus robusta, 4 years Prunus salicina and 6 years Zenia insignis) and two mixed forests (1 year Juglans regia-crop and 13 years Toona sinensis-Pennisetum purpureum ). We evaluated the benefits of different restoration types more accurately by setting each adjacent cropland as the control and setting the variation between the corresponding restored and control site as the evaluation object so that the background differences of six sites could be eliminated. The results indicated that natural shrubland, Toona sinensis-Pennisetum purpureum and Zenia insignis were effective in improving soil quality index (SQI) in degraded karst cropland largely due to their higher SOC and TN content. The variation of SQI (VSQI) of natural shrubland was significantly higher than that in Eucalyptus robusta, Prunus salicina and Juglans regia-crop in total soil layer (0-30 cm) (P < 0.05), indicating natural shrubland had better capacity to improve soil quality. The boosting regression tree model revealed that vegetation restoration type explained 73.49% and restoration time explained 10.30% of the variation in VSQI, which confirmed that vegetation restoration type and restoration time are critical for achieving soil reserves. Therefore, it is vital to select appropriate vegetation type in restoration projects and recovery for a long time in order to achieve better soil quality. The current study provides a theoretical basis on which to assess the effects of different vegetation restoration types on the heterogeneous degraded karst areas.

Dataset Information

Assessing soil degradation under land-use change: insight from soil erosion and soil aggregate stability in a small karst catchment in southwest China.

Background

Methods

Results

Conclusions

Publications

Assessing soil degradation under land-use change: insight from soil erosion and soil aggregate stability in a small karst catchment in southwest China.

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