Responses of soil microbial functional genes to global changes are indirectly influenced by aboveground plant biomass variation

Abstract

a b s t r a c tGlobal nitrogen (N) deposition and precipitation change are two important factors influencing the diversity and function of terrestrial ecosystems. While considerable efforts have been devoted to investigate the responses of aboveground plant communities to altered precipitation regimes and N enrichment, the variations of belowground soil microbial communities are not well understood, particularly at the functional gene structure level. Based on a 9-year field experiment established in a typical steppe in Inner Mongolia, China, we examined the impacts of projected N deposition and precipitation increment on soil microbial functional gene composition, and assessed the soil/plant factors associated with the observed impacts. The overall functional gene composition significantly shifted in response to precipitation increment, N deposition and their combinations (all ADONIS P < 0.05), and such changes were primarily correlated with soil pH, microbial biomass, and microbial respiration. Water supply increased the abundances of both carbon (C) and N cycling genes, suggesting that the projected precipitation increment could accelerate nutrient cycling in this semi-arid region. N effects were mainly observed on the genes involved in vanillin/lignin degradations, implying that the recalcitrant C would not accumulate in soil under future scenarios of higher N deposition. Structural equation modeling (SEM) analysis revealed that soil dissolved organic carbon (DOC) was a key factor directly determining the abundance of C degradation and N cycling genes, and aboveground plant biomass indirectly influenced gene abundance through enhancing DOC. The present work provides important insights on the microbial functional feedbacks to projected global change in this semi-arid grassland ecosystem, and the mechanisms governing C and N cycles at the regional scale.

Ecostoichiometry Reveals the Separation of Microbial Adaptation Strategies in a Bamboo Forest in an Urban Wetland under Simulated Nitrogen Deposition

“…After SND, F:B decreased due to the decline in C:N, mainly because K-strategy fungi had higher biomass C:N than bacteria [3]. Li et al [48] suggested that N deposition can increase the soil MBC content, thus increasing MBC:MBN and reducing competition between plants and microorganisms [58]. Our results showed some differences from those conclusions, as they indicated that MBC decreased while MBC:MBN changed little.…”

Soil microbial beta-diversity is linked with compositional variation in aboveground plant biomass in a semi-arid grassland

“…Soil samples were passed through a 2.0 mm sieve and stored at 4 °C before soil property analysis, and −80 °C before soil genomic DNA extraction. Soil physicochemical properties, including total carbon (TC), total nitrogen (TN), C/N ratio, total phosphorous (TP), total sulfur (TS), nitrate-N (NO 3 − -N) and ammonium-N (NH 4 + -N), dissolved organic carbon (DOC), moisture, and pH were determined by regular methods as described previously (Li et al 2016;Li et al 2017). Soil microbial biomass carbon (MBC) and nitrogen (MBN) were determined using the fumigation-extraction method (Brookes et al 1985).…”

The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History

“…A study in a long-term grassland experimental site revealed that DOC is the key factor directly determining soil microbial diversity [52]. As a substrate of microbial metabolic processes, DOC is of great significance to microbial assimilation and dissimilation [52].…”