How do soil micro‐organisms respond to N, P and NP additions? Application of the ecological framework of (co‐)limitation by multiple resources

Abstract

Nitrogen (N) and phosphorus (P) often limit biological processes in terrestrial ecosystems. Based on previous studies mainly focusing on plants, the concept of resource limitation has evolved towards a theory of (co)limitations by multiple resources. However, this ecological framework has not been applied to analyse how soil micro‐organisms and plants concurrently respond to N and/or P addition, and whether these responses are constrained by phylogenetic relatedness. Here, we applied this framework to analyse microbial and plant responses at community and taxon levels to different fertilization treatments (four N levels without P; four P levels without N and four NP levels) in Tibetan grasslands. Total plant biomass showed serial limitation by N then P, and most plant species were limited by N only. Total archaeal abundance decreased with P addition, but diverse nutrient limitation types were observed for archaeal taxa. Closely related archaeal taxa tended to similarly respond to N, and functional similarity between distant archaeal groups was observed for response to P, possibly due to functional convergence. In contrast, total bacteria slightly increased with P addition only when plants remained N limited, whereas without N limitation, plants rather than bacteria benefited from P addition. Most bacterial taxa were limited by other resources than N and P, and no clear phylogenetic signals were observed regarding bacterial responses to N/P additions. Synthesis. We propose a novel approach for characterizing microbial response types to nutrient addition. It demonstrates that in Tibetan meadows, most dominant plant species, archaea and bacteria, respectively, depend on N, both N and P and other resources.

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

“…The N and P pools are closely related, and their consumption processes control the N and P circulation within microorganisms [13,50]. The increase in the average value of TN in this study showed that exogenous N input alleviated nitrogen deficiency in the moso bamboo ecosystem, which is similar to the results of most studies [5,31,42,51].…”

Soil GHG fluxes are altered by N deposition: New data indicate lower N stimulation of the N2O flux and greater stimulation of the calculated C pools

“…The differences may have largely resulted from the greater stimulation of autotrophic respiration in croplands and grasslands than in forests, where there was no significant change (Zhou et al, 2014). Unlike in forestlands, N enrichment in grasslands often increases photosynthesis, which means that more NPP and energy are invested in roots to maintain soil/root water transport and nutrient absorption (Ma et al, 2019). This increases soil CO 2 emissions (Schindlbacher, Zechmeister-Boltenstern, & Jandl, 2009;Zhou, Talley, & Luo, 2009), and this process also occurs in wetlands (Wang, Cheng, et al, 2014;Wang, Liu, et al, 2014).…”

Increasing soil pH enhances the network interactions among bacterial and archaeal microbiota in alpine grasslands of the Tibetan Plateau

“…The maps showed that soil bacterial and archaeal taxa in the alpine steppe (high soil pH) had closer relationships than in the alpine meadow (low soil pH). One plausible explanation for this observation is that the bacterial and archaeal communities in N-and P-limited alpine grasslands [55,56] are dominated by oligotrophic clades such as Actinobacteria, Acidobacteria, and ammonia-oxidizing archaea [38,57]. Therefore, soil bacterial and archaea have stronger connections in the alpine steppe (oligotrophic conditions and high soil pH) to resist pressure caused by an energy deficit [30].…”