Total nitrogen is the main soil property associated with soil fungal community in karst rocky desertification regions in southwest China

Abstract

Karst rocky desertification (KRD) is a type of land deterioration, resulting in the degraded soil and a delicate ecosystem. Previous studies focused on the influence of KRD on the animals and plants, the impact of KRD on microorganisms, especially soil fungi remains to be discovered. This study reveals the change in the soil fungal community in response to KRD progression in southwest China. Illumina HiSeq was used to survey the soil fungal community. Results showed that the soil fungal community in the severe KRD (SKRD) was noticeably different from that in other KRD areas. Statistical analyses suggested that soil TN was the primary factor associated with the fungal community, followed by pH. Phylum Ascomycota was significantly abundant in non-degraded soils; whereas Basidiomycota predominated in SKRD. The ratio of Ascomycota/Basidiomycota significantly decreased along with KRD progression, which might be used as an indicator of KRD severity. Phylum Basidiomycota was sensitive to changes in all the soil properties but AP. Genus Sebacina might have the potential to promote vegetation and land restoration in KRD areas. This study fills a gap of knowledge on changes in soil fungal communities in accordance with KRD progression.

Figure 1

Relative abundance of fungi at phylum level (A), ascomycota/basidiomycota ratio (B), and core genera (C). The Tukey's honest significant difference (HSD) test was used to determine the significance, *P < 0.05. No KRD (NKRD), latent KRD (LKRD), moderate KRD (MKRD), and severe KRD (SKRD).

Figure 2

The Linear discriminant analysis (LDA) Effect Size (LEfSe) analysis was used to identify phylum (A) and genus (B) that respond significantly to karst rocky desertification progression. Relative abundance is significant when P < 0.05, logarithmic LDA score ≥ 2.0. No KRD (NKRD), Latent KRD (LKRD), Medium KRD (MKRD), and severe KRD (SKRD).

Figure 3

The distance-based redundancy analysis (db-RDA) diagram was used to show distribution of soil fungal communities in karst rocky desertification areas. Study sites are labeled in black No KRD (NKRD), latent KRD (LKRD), moderate KRD (MKRD), and severe KRD (SKRD). Soil properties are labeled in blue. Soil organic matter (SOM), total and available nitrogen (TN and AN), total and available phosphorus (TP and AP), and total and available potassium (TK and AK). Phylum is labeled in red.

Figure 4

The multivariate regression tree (MRT) was used to reveal the relationship of relative abundance of core phyla with change in soil properties caused by KRD progression. Soil organic matter (SOM) and total phosphorus (TP).

Figure 5

Study sites overview. Geographic features, soil type, bedrock exposure rate, and vegetation coverage are summarized in the figure. Classification of KRD is based on vegetation coverage, soil depth, and bedrock exposure rates. No KRD (NKRD), latent KRD (LKRD), moderate KRD (MKRD), and severe KRD (SKRD). Figure 1 was generated by the authors using mapinfo (v. 12.0.2) and Adobe Photoshop (v.13.0).