The response of soil microbial communities to variation in annual precipitation depends on soil nutritional status in an oligotrophic desert

Abstract

BackgroundSoil microbial communities (SMC) play a central role in the structure and function of desert ecosystems. However, the high variability of annual precipitation could results in the alteration of SMC and related biological processes depending on soil water potential. The nature of the physiological adjustments made by SMC in order to obtain energy and nutrients remains unclear under different soil resource availabilities in desert ecosystems. In order to examine this dynamic, the present study examined the effects of variation in annual precipitation on physiological adjustments by the SMC across two vegetation-soil systems of different soil organic matter input in an oligotrophic desert ecosystem.MethodsWe collected soil samples in the Cuatro Ciénegas Basin (Mexico) under two vegetation covers: rosetophylous scrub (RS) and grassland (G), that differ in terms of quantity and quality of organic matter. Collections were conducted during the years 2011, 2012, 2013 and 2014, over which a noticeable variation in the annual precipitation occurred. The ecoenzymatic activity involved in the decomposition of organic matter, and the concentration of dissolved, available and microbial biomass nutrients, were determined and compared between sites and years.ResultsIn 2011, we observed differences in bacterial taxonomic composition between the two vegetation covers. The lowest values of dissolved, available and microbial nutrients in both cover types were found in 2012. The G soil showed higher values of dissolved and available nutrients in the wet years. Significant positive correlations were detected between precipitation and the ratios Cmic:Nmic and Cmic:Pmic in the RS soil and Cmic:Pmic and Nmic:Pmic in the G soil. The slopes of the regression with Cmic and Nmic were higher in the G soil and lower in the RS soil. Moreover, the SMC under each vegetation cover were co-limited by different nutrients and responded to the sum of water stress and nutrient limitation.DiscussionSoil community within both sites (RS and G) may be vulnerable to drought. However, the community of the site with lower resources (RS) is well adapted to acquire P resources by ecoenzyme upregulation during years with adequate precipitation, suggesting that this community is resilient after drought occurs. Under the Global Climate Change scenarios for desert ecosystems that predict reduced annual precipitation and an increased intensity and frequency of torrential rains and drought events, the soil microbial communities of both sites could be vulnerable to drought through C and P co-limitation and reallocation of resources to physiological acclimatization strategies in order to survive.

Oligotrophic Nitrification and Denitrification Bacterial Communities in a Constructed Sewage Treatment Ecosystem and Nitrogen Removal of Delftia tsuruhatensis NF4

“…The nutritional status, like the amounts of carbon (C) and nitrogen (N) in the environments, will regulate the nitrifiers and denitrifiers community in the system (Meyer-Reil et al 2000). Numerous oligotrophic microorganisms have been isolated from oligotrophic environments, such as water reservoirs, deserts, and oceans (Anderson et al 2003;Huang et al 2015a;Montiel-González et al 2017). Oligotrophic nitrifiers and denitrifiers have important theoretical and engineering application values for micro-polluted water treatment (Su et al 2015).…”

Ecoenzymatic Stoichiometry Reveals Microbial Carbon and Phosphorus Limitations under Elevated CO2, Warming and Drought at Different Winter Wheat Growth Stages

“…Since soil enzymatic activities reflect microbial attempts to meet their metabolic demands in response to soil resource availability [7,8], the ratios of enzymatic activities (ecoenzymatic stoichiometry) can be used to reveal the elemental limitations and microbial metabolism characteristics represented by C, nitrogen (N) or phosphorus (P) [9][10][11]. For example, ecoenzymatic stoichiometry analysis has been used to identify both C and P limitations in desert ecosystems [12] and grassland ecosystems [13], as well as C and N limitations in agroecosystems [14]. It was proposed that the length and angle created by connecting a line between the plot origin and point, a process represented by enzyme C:N vs. C:P acquisition activities, can be used to determine the relative microbial C limitation and P vs. N limitation [15].…”

“…Additionally, drought can indirectly affect soil microbial communities and their activities through its influence on plant growth, which results from the sensitivity of photosynthesis, root exudation and litter production to drought [27]. Several studies have focused on the effect of precipitation on soil ecoenzymatic stoichiometry [10,12,51], while the effects of drought are rarely considered. In their research, Yan et al [52] suggested that activities of the C-acquiring enzyme and enzymatic C:P and N:P ratios increased under extreme levels of drought in peatland environments.…”