Consequences of microbial diversity in forest nitrogen cycling: diverse ammonifiers and specialized ammonia oxidizers

Abstract

We tested the ecosystem functions of microbial diversity with a focus on ammonification (involving diverse microbial taxa) and nitrification (involving only specialized microbial taxa) in forest nitrogen cycling. This study was conducted on a forest slope, in which the soil environment and plant growth gradually changed. We measured the gross and net rates of ammonification and nitrification, the abundance of predicted ammonifiers and nitrifiers, and their community compositions in the soils. The abundance of predicted ammonifiers did not change along the soil environmental gradient, leading to no significant change in the gross ammonification rate. On the other hand, the abundance of nitrifiers and the gross nitrification rate gradually changed. These accordingly determined the spatial distribution of net accumulation of ammonium and nitrate available to plants. The community composition of predicted ammonifiers gradually changed along the slope, implying that diverse ammonifiers were more likely to include taxa that were acclimated to the soil environment and performed ammonification at different slope locations than specialized nitrifiers. Our findings suggest that the abundance of ammonifiers and nitrifiers directly affects the corresponding nitrogen transformation rates, and that their diversity affects the stability of the rates against environmental changes. This study highlights the role of microbial diversity in biogeochemical processes under changing environments and plant growth.

Drought and rewetting events enhance nitrate leaching and seepage-mediated translocation of microbes from beech forest soils

“…This result is in contrast to multiple previous studies which found that AOA are more abundant than AOB in soils and the main driver of nitrification in forest soils (Isobe et al, 2020;Lu et al, 2015) and agricultural soils (Leininger et al, 2006;Sterngren et al, 2015). In particular, an acidic pH below 5 was reported to favor AOA activity rather than AOB (Lu et al, 2015).…”

Biological Soil Crust Bacterial Communities Vary Along Climatic and Shrub Cover Gradients Within a Sagebrush Steppe Ecosystem

“…The relative abundance of an individual gene in each sample was calculated as copies of that gene per average bacterial genome after considering 16S rRNA gene copies per genome. Similar strategies of N-cycling pathway inference have been previously applied to microbial communities from tallgrass prairie (Mackelprang et al, 2018), forest (Isobe et al, 2020), and crop rhizospheres (Zhu et al, 2016), where the functional predictions were considered alongside other lines of evidence. Here, the relative abundance of a putative taxon harboring an individual pathway was calculated as reads of the taxon within the whole community after considering 16S rRNA gene copies per genome.…”

Identifying Hidden Viable Bacterial Taxa in Tropical Forest Soils Using Amplicon Sequencing of Enrichment Cultures

“…It is well known that bacteria are important drivers for nitrogen fixation in soil [16]. Furthermore, they are also a part of several processes in the nitrogen cycle including nitrification, denitrification and ammonification [17,18]. Besides, forest soil bacteria are considered as crucial decomposers degrading organic material (cellulose, hemicellulose and pectin, for example) [19][20][21] and solubilizing soil macro-and micronutrients (such as phosphorus, potassium and sulfur) [15,22,23].…”