scholarly journals Interactive Effects of Nitrogen and Water Addition on Soil Microbial Metabolic Limitation in Temperate Desert Shrublands

2021 ◽  
Author(s):  
Jiwei Li ◽  
Jiangbo Xie ◽  
Yu Zhang ◽  
Dong Lingbo ◽  
Zhouping Shangguan ◽  
...  
Keyword(s):  
Interactive Effects ◽  
Desert Ecosystem ◽  
N Addition ◽  
Water Addition ◽  
Desert Ecosystems ◽  
Organic C ◽  
Soil Microbial ◽  
P Limitation ◽  
Microbial C ◽  
C Limitation

Abstract Aims Soil microbes play critical roles in regulating the turnover of soil organic carbon (SOC) and nutrients, and microbial metabolic limitation should draw more attention in desert ecosystems. However, soil extracellular enzymes activity (EEA) response and microbial metabolic limitation to atmospheric N deposition and increased precipitation in desert-shrubland are still poorly understood. Methods The study examined the effects of long-term (9 year) N and water additions (i.e., 5 g N m−2 yr−1, 30% ambient precipitation increase and their combination) on EEAs and soil microbial resource limitation, as well as explored their controlling factors in the Gurbantunggut Desert in northwestern China. Results The results showed that N and water additions significantly enhanced soil EEAs and considerably aggravated microbial phosphorous (P) limitation. Water addition and the N-water combination addition alleviated carbon (C) limitation, but N addition alone strengthened microbial C limitation. The interaction of N and water additions relieved the negative impact of N addition on soil microbial C limitation, and positively aggravated microbial P limitation. Soil microbial C limitation was primarily driven by soil moisture and organic C concentration, while the soil microbial N/P limitation was chiefly controlled by soil water and available P contents. Conclusions The influences of either N- or water addition alone on desert ecosystem biogeochemical processes may be altered by their concurrent occurrence. Overall, these findings highlight water availability is more effective at modifying microbial metabolisms than N accumulation in desert ecosystems. Altogether, this may help to predict how terrestrial C and nutrient flow could be induced by global change factors..

scholarly journals Parent material and organic matter control soil microbial processes in African tropical rainforests 

2021 ◽  
Author(s):  
Laurent Kidinda Kidinda ◽  
Folasade Kemi Ologoke ◽  
Cordula Vogel ◽  
Karsten Kalbitz ◽  
Sebastian Doetterl
Keyword(s):  
Microbial Biomass ◽  
Tropical Rainforest ◽  
Parent Material ◽  
Microbial Processes ◽  
Tropical Rainforests ◽  
Microbial Biomass C ◽  
Organic C ◽  
Soil Microbial ◽  
Microbial C ◽  
C Limitation

<p>Microbial processes are one of the key factors driving carbon (C) and nutrient cycling in terrestrial ecosystems, and are strongly controlled by the equilibrium between resource availability and demand. In deeply weathered tropical rainforest soils of Africa, it remains unclear whether patterns of microbial processes differ between soils developed from geochemically contrasting parent material. Here, we investigate patterns of soil microbial processes and their controls in tropical rainforests of Africa. We used soil developed from three geochemically distinct parent material (mafic, felsic, mixed sedimentary rocks) and three soil depths (0−70 cm). We measured microbial biomass C and enzyme activity at the beginning and end of a 120-day incubation experiment. We also conducted a vector analysis based on ecoenzymatic stoichiometry to assess microbial C and nutrient limitations. We found that microbial C limitation was highest in the mixed sedimentary region and lowest in the felsic region, which we propose was related to the strength of contrasting C stabilization mechanisms and varying C quality. None of the investigated regions and soil depths showed signs of nitrogen (N) limitation for microbial processes. Microbial phosphorus (P) limitation increased with soil depth, indicating that subsoils in the investigated soils were depleted in rock-derived nutrients and are therefore dependent on efficient nutrient recycling. Microbial C limitation was lowest in subsoils, indicating that subsoil microbes cannot significantly participate in C cycling and limit C storage if oxygen is not available, but can do so in our laboratory incubation experiment under well aerated conditions. Using multivariable regressions, we demonstrate that microbial biomass C normalized to soil organic C content (MBC<sub>SOC</sub>) is controlled by soil geochemistry and substrate quality, while microbial biomass C normalized to soil weight (MBC<sub>Soil</sub>) is predominantly driven by resource distribution (i.e., depth distribution of organic C). We conclude that due to differences in resource availability, microbial processes in deeply weathered tropical rainforest soils greatly vary across geochemical regions.</p>

scholarly journals Topography modulates effects of nitrogen deposition on microbial resource limitation in a nitrogen-saturated subtropical forest

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hao Chen ◽  
Junjie Tang ◽  
Xibin Sun ◽  
Kayan Ma ◽  
Huaihai Chen ◽  
...  
Keyword(s):  
Resource Limitation ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Saturation ◽  
N Addition ◽  
Microbial Decomposition ◽  
Organic C ◽  
Soil Microbial ◽  
N Limitation ◽  
P Limitation

Abstract Background Nitrogen (N) saturation theory proposes that an ecosystem might switch from N limitation to carbon (C), phosphorus (P), or other nutrient limitations if it receives continuous N input. Yet, after N limitation is removed, which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level. Here, we conducted a two-year N addition experiment under two different topography positions (i.e. a slope and a valley) in a N-saturated subtropical forest. Soil enzyme activity was measured, and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation. Results In the valley, two-year N addition changed the activity of all studied enzymes to various degrees. As a result, microbial C limitation was aggravated in the valley, and consequently microbial decomposition of soil labile organic C increased, but microbial P limitation was alleviated due to the stoichiometry balance. On the slope, however, N addition did not significantly change the activity of the studied enzymes, and did not alter the status of microbial resource limitation. Conclusions These results indicate that C is a more limited element for microbial growth than P after removing N limitation, but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests. These findings provide useful supplements to the N saturation theory.

scholarly journals Patterns of microbial processes shaped by parent material and soil depth in tropical rainforest soils

2020 ◽  
Author(s):  
Laurent K. Kidinda ◽  
Folasade K. Olagoke ◽  
Cordula Vogel ◽  
Karsten Kalbitz ◽  
Sebastian Doetterl
Keyword(s):  
Microbial Biomass ◽  
Resource Availability ◽  
Tropical Rainforest ◽  
Soil Depth ◽  
Microbial Processes ◽  
Microbial Biomass C ◽  
Organic C ◽  
Soil Microbial ◽  
Microbial C ◽  
C Limitation

Abstract. Microbial processes are one of the key factors driving carbon (C) and nutrient cycling in terrestrial ecosystems, and are strongly driven by the equilibrium between resource availability and demand. In deeply weathered tropical rainforest soils of Africa, it remains unclear whether patterns of microbial processes differ between soils developed from geochemically contrasting parent materials. Here we show that resource availability across soil depths and regions from mafic to felsic geochemistry shape patterns of soil microbial processes. During a 120-day incubation experiment, we found that microbial biomass C and extracellular enzyme activity were highest in the mafic region. Microbial C limitation was highest in the mixed sedimentary region and lowest in the felsic region, which we propose is related to the strength of contrasting C stabilization mechanisms and varying C quality. None of the investigated regions and soil depths showed signs of nitrogen (N) limitation for microbial processes. Microbial phosphorus (P) limitation increased with soil depth but was similar across geochemical regions, indicating that subsoils in the investigated soils were depleted in rock-derived nutrients and are therefore dependent on efficient biological recycling of nutrients. Microbial C limitation was lowest in subsoils, indicating that subsoil microbes can significantly participate in C cycling and limit C storage if increased oxygen availability is prevalent. Using multivariable regressions, we demonstrate that microbial biomass C normalized to soil organic C content (MBCSOC) is controlled by soil geochemistry and substrate quality, while microbial biomass C normalized to soil weight (MBCSoil) is predominantly driven by resource distribution. We conclude that due to differences in resource availability, microbial processes in deeply weathered tropical rainforest soils greatly vary across geochemical regions which must be considered when assessing soil microbial processes in organic matter turnover models.

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

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4007 ◽  
Author(s):  
Cristina Montiel-González ◽  
Yunuen Tapia-Torres ◽  
Valeria Souza ◽  
Felipe García-Oliva
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Soil Water Potential ◽  
Soil Microbial Communities ◽  
Desert Ecosystem ◽  
Annual Precipitation ◽  
Climate Change Scenarios ◽  
Desert Ecosystems ◽  
Soil Microbial ◽  
Physiological Adjustments

Background Soil 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. Methods We 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. Results In 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. Discussion Soil 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.

scholarly journals Increased microbial sequestration of soil organic carbon under nitrogen deposition over China’s terrestrial ecosystems

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Shu Liao ◽  
Siyi Tan ◽  
Yan Peng ◽  
Dingyi Wang ◽  
Xiangyin Ni ◽  
...  
Keyword(s):  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
N Addition ◽  
Soil Organic C ◽  
Organic C ◽  
Soil Microbial ◽  
Biomass Turnover ◽  
Microbial Residues ◽  
Stimulation Of

Abstract Background China’s terrestrial ecosystems have been receiving increasing amounts of reactive nitrogen (N) over recent decades. External N inputs profoundly change microbially mediated soil carbon (C) dynamics, but how elevated N affects the soil organic C that is derived from microbial residues is not fully understood. Here, we evaluated the changes in soil microbial necromass C under N addition at 11 forest, grassland, and cropland sites over China’s terrestrial ecosystems through a meta-analysis based on available data from published articles. Results Microbial necromass C accounted for an average of 49.5% of the total soil organic C across the studied sites, with higher values observed in croplands (53.0%) and lower values in forests (38.6%). Microbial necromass C was significantly increased by 9.5% after N addition, regardless of N forms, with greater stimulation observed for fungal (+ 11.2%) than bacterial (+ 4.5%) necromass C. This increase in microbial necromass C under elevated N was greater under longer experimental periods but showed little variation among different N application rates. The stimulation of soil microbial necromass C under elevated N was proportional to the change in soil organic C. Conclusions The stimulation of microbial residues after biomass turnover is an important pathway for the observed increase in soil organic C under N deposition across China’s terrestrial ecosystems.

scholarly journals Salinity Is a Key Determinant for Soil Microbial Communities in a Desert Ecosystem

mSystems ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Kaoping Zhang ◽  
Yu Shi ◽  
Xiaoqing Cui ◽  
Ping Yue ◽  
Kaihui Li ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Diversity ◽  
Community Assembly ◽  
Salinity Gradient ◽  
Soil Microbial Communities ◽  
Desert Ecosystem ◽  
Desert Ecosystems ◽  
Soil Microbial ◽  
Deterministic Processes ◽  
Community Dissimilarity

ABSTRACT Soil salinization is a growing environmental problem caused by both natural and human activities. Excessive salinity in soil suppresses growth, decreases species diversity, and alters the community composition of plants; however, the effect of salinity on soil microbial communities is poorly understood. Here, we characterize the soil microbial community along a natural salinity gradient in Gurbantunggut Desert, Northwestern China. Microbial diversity linearly decreased with increases in salinity, and community dissimilarity significantly increased with salinity differences. Soil salinity showed a strong effect on microbial community dissimilarity, even after controlling for the effects of spatial distance and other environmental variables. Microbial phylotypes (n = 270) belonging to Halobacteria, Nitriliruptoria, [Rhodothermi], Gammaproteobacteria, and Alphaproteobacteria showed a high-salinity niche preference. Out of nine potential phenotypes predicted by BugBase, oxygen-related phenotypes showed a significant relationship with salinity content. To explore the community assembly processes, we used null models of within-community (nearest-taxon index [NTI]) and between-community (βNTI) phylogenetic composition. NTI showed a significantly negative relationship with salinity, suggesting that the microbial community was less phylogenetically clustered in more-saline soils. βNTI, the between-community analogue of NTI, showed that deterministic processes have overtaken stochastic processes across all sites, suggesting the importance of environmental filtering in microbial community assembly. Taken together, these results suggest the importance of salinity in soil microbial community composition and assembly processes in a desert ecosystem. IMPORTANCE Belowground microorganisms are indispensable components for nutrient cycling in desert ecosystems, and understanding how they respond to increased salinity is essential for managing and ameliorating salinization. Our sequence-based data revealed that microbial diversity decreased with increasing salinity, and certain salt-tolerant phylotypes and phenotypes showed a positive relationship with salinity. Using a null modeling approach to estimate microbial community assembly processes along a salinity gradient, we found that salinity imposed a strong selection pressure on the microbial community, which resulted in a dominance of deterministic processes. Studying microbial diversity and community assembly processes along salinity gradients is essential in understanding the fundamental ecological processes in desert ecosystems affected by salinization.

Impacts of urea N addition on soil microbial community in a semi-arid temperate steppe in northern China

2008 ◽  
Vol 311 (1-2) ◽  
pp. 19-28 ◽  
Author(s):  
Naili Zhang ◽  
Shiqiang Wan ◽  
Linghao Li ◽  
Jie Bi ◽  
Mingming Zhao ◽  
...  
Keyword(s):  
Microbial Community ◽  
Soil Microbial Community ◽  
Northern China ◽  
N Addition ◽  
Temperate Steppe ◽  
Soil Microbial ◽  
Semi Arid

scholarly journals Perennial herbaceous legumes as live soil mulches and their effects on C, N and P of the microbial biomass

2003 ◽  
Vol 60 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Gustavo Pereira Duda ◽  
José Guilherme Marinho Guerra ◽  
Marcela Teixeira Monteiro ◽  
Helvécio De-Polli ◽  
Marcelo Grandi Teixeira
Keyword(s):  
Microbial Biomass ◽  
Soil Depth ◽  
Vegetation Management ◽  
Pueraria Phaseoloides ◽  
Organic C ◽  
Arachis Pintoi ◽  
Factorial Combination ◽  
C And N ◽  
Microbial C ◽  
Macroptilium Atropurpureum

The use of living mulch with legumes is increasing but the impact of this management technique on the soil microbial pool is not well known. In this work, the effect of different live mulches was evaluated in relation to the C, N and P pools of the microbial biomass, in a Typic Alfisol of Seropédica, RJ, Brazil. The field experiment was divided in two parts: the first, consisted of treatments set in a 2 x 2 x 4 factorial combination of the following factors: live mulch species (Arachis pintoi and Macroptilium atropurpureum), vegetation management after cutting (leaving residue as a mulch or residue remotion from the plots) and four soil depths. The second part had treatments set in a 4 x 2 x 2 factorial combination of the following factors: absence of live mulch, A. pintoi, Pueraria phaseoloides, and M. atropurpureum, P levels (0 and 88 kg ha-1) and vegetation management after cutting. Variation of microbial C was not observed in relation to soil depth. However, the amount of microbial P and N, water soluble C, available C, and mineralizable C decreased with soil depth. Among the tested legumes, Arachis pintoi promoted an increase of microbial C and available C content of the soil, when compared to the other legume species (Pueraria phaseoloides and Macroptilium atropurpureum). Keeping the shoot as a mulch promoted an increase on soil content of microbial C and N, total organic C and N, and organic C fractions, indicating the importance of this practice to improve soil fertility.

scholarly journals Soil moisture modifies the response of soil respiration to temperature in a desert shrub ecosystem

2014 ◽  
Vol 11 (2) ◽  
pp. 259-268 ◽  
Author(s):  
B. Wang ◽  
T. S. Zha ◽  
X. Jia ◽  
B. Wu ◽  
Y. Q. Zhang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Seasonal Cycle ◽  
Northwest China ◽  
Interactive Effects ◽  
Co2 Efflux ◽  
Diel Variation ◽  
Desert Ecosystems ◽  
Volumetric Soil Water Content ◽  
Desert Shrub

Abstract. The current understanding of the responses of soil respiration (Rs) to soil temperature (Ts) and soil moisture is limited for desert ecosystems. Soil CO2 efflux from a desert shrub ecosystem was measured continuously with automated chambers in Ningxia, northwest China, from June to October 2012. The diurnal responses of Rs to Ts were affected by soil moisture. The diel variation in Rs was strongly related to Ts at 10 cm depth under moderate and high volumetric soil water content (VWC), unlike under low VWC. Ts typically lagged Rs by 3–4 h. However, the lag time varied in relation to VWC, showing increased lag times under low VWC. Over the seasonal cycle, daily mean Rs was correlated positively with Ts, if VWC was higher than 0.08 m3 m−3. Under lower VWC, it became decoupled from Ts. The annual temperature sensitivity of Rs (Q10) was 1.5. The short-term sensitivity of Rs to Ts varied significantly over the seasonal cycle, and correlated negatively with Ts and positively with VWC. Our results highlight the biological causes of diel hysteresis between Rs and Ts, and that the response of Rs to soil moisture may result in negative feedback to climate warming in desert ecosystems. Thus, global carbon cycle models should account the interactive effects of Ts and VWC on Rs in desert ecosystems.

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