Impact of soil microbial community diversity loss on carbon and nitrogen cycling

Authors: Hale, Lauren; ZHOU, XISHA - Central South University; GUO, XUE - Tsinghua University; BATES, COLIN - University Of Oklahoma; CURTIS, DANIEL - University Of Oklahoma; WU, LINWEI - University Of Oklahoma; NING, DALIANG - University Of Oklahoma; WANG, GANGSHENG - University Of Oklahoma; ZHOU, JIZHONG - University Of Oklahoma

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/18/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil microorganisms are critical drivers of soil organic matter turnover and nitrogen cycling and community diversity is a common metric used to profile soil biological health. This research explores fundamental relationships between soil microbial biodiversity and carbon and nitrogen cycling. Results revealed the reliance of ecosystem functions on bacterial and fungal community diversity to be context dependent, with an overall trend exhibiting positive, linear, biodiversity:multifunctionality relationships. These implications inform management of healthy soils in agronomic systems.

Technical Abstract: Issue: Soil microorganisms are critical drivers of soil organic matter turnover and nitrogen (N) cycling and community diversity is a common metric used to profile soil biological health. However, the relationships between soil microbial diversity and ecosystem functions are not always linear. Hence, fundamental insights into components of microbial diversity that impact process rates are needed. Objective: To examine biodiversity and function relationships in soil microbial communities in response to carbon (C) and N inputs. Approach: We developed a series of soil microcosms with scaled bacterial/archaeal, fungal, and eukaryotic biodiversity profiles using size-exclusion and serial dilution techniques. Sequencing of 16S rRNA (bacterial/archaeal), ITS (fungal), and 18S rRNA (eukaryotic) genes was performed to approximate biodiversity of microbial groups. Results/ Findings: Functional proxies for soil phosphorus (P), C and N cycling were assayed in response to nitrate fertilization and plant residue inputs. Significant correlations were revealed between functional proxies related to N and C cycling (nitrification potential, soil NO3-, NH4+, total carbon, % organic matter, and respiration rates) and bacterial/ archaeal and fungal diversity indices, but not eukaryotic taxonomic diversity (R2 > 0.15, P < 0.05). Soil P and microbial community substrate use profiles did not correlate with diversity indices of bacterial/ archaeal, fungal, and/or eukaryotic groups (Linear regression analyses, R2 < 0.15, P > 0.05). Nitrification potential was completely lost in the communities with the lowest biodiversity. Comparing the biodiversity-function relationships in response to inputs, community diversity exhibited the strongest correlations with carbon cycling proxies after the input of plant residues, when soil respiration rates were highest and soil N became limited. Whereas, initial community diversity and diversity of communities assayed after N fertilization, had stronger correlations to N cycling proxies. Conclusion/Implications: In conclusion, soil biodiversity exhibited positive linear correlations for important ecosystem functions relating to C and N cycling. These correlations were driven by bacterial/ archaeal and fungal groups, which showed variable associations with functional proxies. These results highlight the importance of biodiversity to different ecosystem functions and provide insights into how these relationships shift with varying inputs into soils.