Rhizosphere element circling, multifunctionality, aboveground productivity and trade-offs are better predicted by rhizosphere rare taxa

Abstract

Microbes, especially abundant microbes in bulk soils, form multiple ecosystem functions, which is relatively well studied. However, the role of rhizosphere microbes, especially rhizosphere rare taxa vs. rhizosphere abundant taxa in regulating the element circling, multifunctionality, aboveground net primary productivity (ANPP) and the trade-offs of multiple functions remains largely unknown. Here, we compared the multiple ecosystem functions, the structure and function of rhizosphere soil bacterial and fungal subcommunities (locally rare, locally abundant, regionally rare, regionally abundant, and entire), and the role of subcommunities in the Zea mays and Sophora davidii sole and Z. mays/S. davidii intercropping ecosystems in subtropical China. Results showed that intercropping altered multiple ecosystem functions individually and simultaneously. Intercropped Z. mays significantly decreased the trade-off intensity compared to sole Z. mays, the trade-off intensity under intercropped S. davidii was significantly higher than under intercropped Z. mays. The beta diversities of bacterial and fungal communities, and fungal functions in each subcommunity significantly differed among groups. Network analysis showed intercropping increased the complexity and positive links of rare bacteria in Z. mays rhizosphere, but decreased the complexity and positive links of rare bacteria in S. davidii rhizosphere and the complexity and positive links of fungi in both intercropped plants rhizosphere. Mantel test showed significant changes in species of locally rare bacteria were most strongly related to nitrogen-cycling multifunctionality, ANPP and trade-offs intensity, significant changes in species of locally rare fungus were most strongly related to carbon-cycling multifunctionality, phosphorus-cycling multifunctionality, and average ecosystem multifunctionality. This research highlights the potential and role of rare rhizosphere microorganisms in predicting and regulating system functions, productivity, and trade-offs.

Grazing lowers soil multifunctionality but boosts soil microbial network complexity and stability in a subtropical grassland of China

“…Methods for determining soil physicochemical attributes and extracellular enzyme activity have been described in detail in our recent studies ( Ding et al, 2020 ; Ding and Wang, 2021 ). Briefly, pH was assayed with 1:2.5 suspension (w/v) ( Wang P. et al, 2022 ). Water content and bulk density were measured oven-dried at 105°C.…”

“…SH was determined using a portable penetrometer ( Zhang et al, 2019 ) and reflected the degree of difficulty of root and water penetration ( Ono et al, 2020 ). In addition, other soil properties are often included in soil multifunctionality ( Byrnes et al, 2014 ; Ding and Wang, 2021 ; Du et al, 2022 ; Wang P. et al, 2022 ). Before calculating soil multifunctionality, the C limitation, SH, and BD were reflected using r(f) = –f + max(f), and the vector angle was reflected using f(x) = x−45 when the value of the vector angle was <45 (indicating N limitation) and was reflected using f(x) = −x + 45 when the value of vector angle was >45 (indicating P limitation).…”

Shrub expansion raises both aboveground and underground multifunctionality on a subtropical plateau grassland: coupling multitrophic community assembly to multifunctionality and functional trade-off

“…Multivariate cut-off level analysis (MultiCoLA.1.4) was to determine the specific cut-off of rarities in relative abundance ( Gobet et al, 2010 ). By doing so, the cut-offs of 0.1, 0.05, 0.1, 0.1, and 0.2% were used to partition the abundant and rare archaea, bacteria, fungi, nematodes, and protists in a sample (locally) and across samples (regionally) ( Wang et al, 2022b ), respectively.…”

“…Recent studies have begun to demonstrate the changes in the trade-offs among functions ( Wang et al, 2022b ). Trade-off is defined as a state in which one ecosystem function increases while another decreases ( Lu et al, 2014 ) in a narrow sense.…”

Crucial role of rare taxa in preserving bacterial community stability

“…The construction of ecological networks provided insights into the interactions between different taxa (Faust & Raes, 2012;Ye et al, 2022). Similar to Jiang et al (2019), abundant species exhibited more internal associations and higher node topological characteristics than rare taxa in the total bacterial network (Tables 2 and S3), likely due to the relatively bountiful nutrient resources in fertilized soils and the better resource acquisition capacity of abundant species promoting soil nutrient cycling through close internal associations (Wang et al, 2022). Despite abundant and rare species accounting for more than 80% of the total ASVs, fewer associations occurred between these two groups, partly because rare taxa only occurred in a small sample, making them less likely to interact statistically with abundant taxa (Li, Wu, et al, 2021).…”