Dominant Tree Mycorrhizal Associations Affect Soil Nitrogen Transformation Rates Through Mediating Microbial Abundances in a Temperate Forest

2021 ◽  
Author(s):  
Guigang Lin ◽  
Zuoqiang Yuan ◽  
Yansong Zhang ◽  
De-Hui Zeng ◽  
Xugao Wang
Keyword(s):  
Soil Nitrogen ◽  
Enzyme Activities ◽  
Temperate Forest ◽  
Soil Microbes ◽  
Net N Mineralization ◽  
N Transformations ◽  
Net Nitrification ◽  
N Transformation ◽  
Mycorrhizal Associations ◽  
Transformation Rates

Abstract Tree-fungal symbioses are increasingly recognized to affect soil nitrogen (N) transformations, yet the role of soil microbes in the process is largely unclear. Soil microbes directly interact with trees and are a primary driver of many N transformation processes. Here, we explored the linkage among tree mycorrhizal associations, soil microbes and N transformation rates in a temperate forest of Northeast China. Across a gradient of increasing ectomycorrhizal (ECM) tree dominance, we measured soil acid-base chemistry, bacterial and fungal abundances, N-hydrolyzing enzyme activities, abundances and community composition of ammonia-oxidizing archaea (AOA) and bacteria, and net N mineralization and net nitrification rates. Results showed that soil pH, exchangeable base cations, inorganic N concentrations and N transformation rates decreased with increasing ECM tree dominance. The ECM tree dominance was negatively related to soil bacterial and AOA amoA gene abundances, and positively to soil fungal abundances and β-N-acetylglucosaminidase activities. These shifts in soil microbial abundances and enzyme activities along the mycorrhizal gradient were linked with the increase in soil acidity with increasing ECM tree dominance. Structural equation models revealed that ECM tree dominance was not directly related to N transformation rates, but indirectly to net N mineralization rates via affecting bacterial and fungal abundances, and indirectly to net nitrification rates via influencing AOA amoA gene abundances. Collectively, our results indicate that soil microbes provide a mechanistic link between mycorrhizal associations and soil N transformations, and suggest that shifts in forest mycorrhizal associations under global change could have profound consequences for biogeochemical cycling of temperate forests.

scholarly journals The simulated N deposition accelerates net N mineralization and nitrification in a tropical forest soil

2019 ◽  
Vol 16 (21) ◽  
pp. 4277-4291
Author(s):  
Yanxia Nie ◽  
Xiaoge Han ◽  
Jie Chen ◽  
Mengcen Wang ◽  
Weijun Shen
Keyword(s):  
N Deposition ◽  
Functional Genes ◽  
Net N Mineralization ◽  
Soil N ◽  
Wet Season ◽  
Inorganic N ◽  
N Transformations ◽  
N Transformation ◽  
Soil N Transformation ◽  
N Additions

Abstract. Elevated nitrogen (N) deposition affects soil N transformations in the N-rich soil of tropical forests. However, the change in soil functional microorganisms responsible for soil N cycling remains largely unknown. Here, we investigated the variation in soil inorganic N content, net N mineralization (Rm), net nitrification (Rn), inorganic N leaching (Rl), N2O efflux and N-related functional gene abundance in a tropical forest soil over a 2-year period with four levels of N addition. The responses of soil net N transformations (in situ Rm and Rn) and Rl to N additions were negligible during the first year of N inputs. The Rm, Rn, and Rl increased with the medium nitrogen (MN) and high nitrogen (HN) treatments relative to the control treatments in the second year of N additions. Furthermore, the Rm, Rn, and Rl were higher in the wet season than in the dry season. The Rm and Rn were mainly associated with the N addition-induced lower C:N ratio in the dry season but with higher microbial biomass in the wet season. Throughout the study period, high N additions increased the annual N2O emissions by 78 %. Overall, N additions significantly facilitated Rm, Rn, Rl and N2O emission. In addition, the MN and HN treatments increased the ammonia-oxidizing archaea (AOA) abundance by 17.3 % and 7.5 %, respectively. Meanwhile, the HN addition significantly increased the abundance of nirK denitrifiers but significantly decreased the abundance of ammonia-oxidizing bacteria (AOB) and nosZ-containing N2O reducers. To some extent, the variation in functional gene abundance was related to the corresponding N-transformation processes. Partial least squares path modelling (PLS-PM) indicated that inorganic N contents had significantly negative direct effects on the abundances of N-related functional genes in the wet season, implying that chronic N deposition would have a negative effect on the N-cycling-related microbes and the function of N transformation. Our results provide evidence that elevated N deposition may impose consistent stimulatory effects on soil N-transformation rates but differentiated impacts on related microbial functional genes. Long-term experimentation or observations are needed to decipher the interrelations between the rate of soil N-transformation processes and the abundance or expression of related functional genes.

scholarly journals Long-term elevation of temperature affects organic N turnover and associated N2O emissions in a permanent grassland soil

2016 ◽  
Author(s):  
Anne B. Jansen-Willems ◽  
Gary J. Lanigan ◽  
Timothy J. Clough ◽  
Louise C. Andresen ◽  
Christoph Müller
Keyword(s):  
Organic N ◽  
N2o Emissions ◽  
Inorganic N ◽  
Soil Warming ◽  
N Transformations ◽  
Permanent Grassland ◽  
N Transformation ◽  
Legacy Effect ◽  
Transformation Rates

Abstract. Over the last century an increase in mean soil surface temperature has been observed and it is predicted to increase further in the future. To evaluate the legacy effects of increased temperature on both nitrogen (N) transformation rates in the soil and nitrous oxide (N2O) emissions, an incubation experiment was conducted with soils taken from a long term in situ warming experiment on temperate permanent grassland. In this experiment the soil temperature was elevated by 0 (control), 1, 2 or 3 °C (4 replicates per treatment) using IR-lamps over a period of 6 years. The soil was subsequently incubated under common conditions (20 °C and 50 % humidity) and labelled with NO315NH4 Gly, 15NO3NH4 Gly or NO3NH4 15N-Gly. Both inorganic N (NO3−NH4+) and NO32− contents were higher in soil subjected to the +2 and +3 °C temperature elevations. Analyses of N transformations using a 15N tracing model, showed that, following incubation, gross organic (and not inorganic) N transformation rates decreased in response to the prior soil warming treatment. This was also reflected in reduced N2O emissions associated with organic N oxidation and denitrification. A newly developed source partitioning model showed the importance of oxidation of organic N as a source of N2O. Concluding, long term soil warming can cause a legacy effect which diminishes organic N turn over and the release of N2O from organic N and denitrification.

scholarly journals Effect of iron oxide on nitrification in two agricultural soils with different pH

2016 ◽  
Author(s):  
Xueru Huang ◽  
Xia Zhu-Barker ◽  
William R. Horwath ◽  
Sarwee J. Faeflen ◽  
Hongyan Luo ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Soil Ph ◽  
N Mineralization ◽  
Agricultural Soils ◽  
Low Ph ◽  
N Transformations ◽  
Fe Oxide ◽  
High Ph ◽  
N Transformation ◽  
Transformation Rates

Abstract. Iron (Fe) affects soil nitrogen (N) cycling processes both in anoxic and oxic environments. The role of Fe on soil N transformations such as mineralization, immobilization, and nitrification depends on its redox activity, which can be regulated by soil pH. We hypothesized that the effect of Fe oxide on N transformation processes would be different in soils as a function of pH. This study aimed to investigate N mineralization-immobilization, especially nitrification, as affected by Fe oxide in soils with different pH. A set of lab incubations under 100 % water holding capacity were carried out to investigate the effect of Fe oxide on N transformation rates in two subtropical agricultural soils with a low pH (pH 5.1) and a high pH (pH 7.8). 15N-labelled ammonium and nitrate were used separately to determine N transformation rates combined with Fe oxide (ferrihydrite) addition. Iron oxide addition stimulated net nitrification in the low pH soil (pH 5.1), while the opposite occurred in the high pH soil (pH 7.8). An explanation for this could be at low pH, Fe oxide increased NH3-N availability by stimulating N mineralization and inhibiting N immobilization. These results suggested that Fe oxide plays an important role in N transformations in soil ecosystem, and the effect of Fe oxide on N transformations depends on soil pH.

scholarly journals Soil nitrogen transformation responses to seasonal precipitation changes are regulated by changes in functional microbial abundance in a subtropical forest

2017 ◽  
Vol 14 (9) ◽  
pp. 2513-2525 ◽  
Author(s):  
Jie Chen ◽  
Guoliang Xiao ◽  
Yakov Kuzyakov ◽  
G. Darrel Jenerette ◽  
Ying Ma ◽  
...  
Keyword(s):  
N Mineralization ◽  
N2o Emission ◽  
Dry Season ◽  
Subtropical Forest ◽  
Microbial Abundance ◽  
Wet Season ◽  
N Transformations ◽  
Net Nitrification ◽  
N Transformation ◽  
Precipitation Changes

Abstract. The frequency of dry-season droughts and wet-season storms has been predicted to increase in subtropical areas in the coming decades. Since subtropical forest soils are significant sources of N2O and NO3−, it is important to understand the features and determinants of N transformation responses to the predicted precipitation changes. A precipitation manipulation field experiment was conducted in a subtropical forest to reduce dry-season precipitation and increase wet-season precipitation, with annual precipitation unchanged. Net N mineralization, net nitrification, N2O emission, nitrifying (bacterial and archaeal amoA) and denitrifying (nirK, nirS and nosZ) gene abundance, microbial biomass carbon (MBC), extractable organic carbon (EOC), NO3−, NH4+ and soil water content (SWC) were monitored to characterize and explain soil N transformation responses. Dry-season precipitation reduction decreased net nitrification and N mineralization rates by 13–20 %, while wet-season precipitation addition increased both rates by 50 %. More than 20 % of the total variation of net nitrification and N mineralization could be explained by microbial abundance and SWC. Notably, archaeal amoA abundance showed the strongest correlation with net N transformation rates (r  ≥  0.35), suggesting the critical role of archaeal amoA abundance in determining N transformations. Increased net nitrification in the wet season, together with large precipitation events, caused substantial NO3− losses via leaching. However, N2O emission decreased moderately in both dry and wet seasons due to changes in nosZ gene abundance, MBC, net nitrification and SWC (decreased by 10–21 %). We conclude that reducing dry-season precipitation and increasing wet-season precipitation affect soil N transformations through altering functional microbial abundance and MBC, which are further affected by changes in EOC and NH4+ availabilities.

Deer browsing effects on temperate forest soil nitrogen cycling shift from positive to negative across fertility gradients

2020 ◽  
Vol 50 (12) ◽  
pp. 1281-1288
Author(s):  
Jacqueline M.A. Popma ◽  
Knute J. Nadelhoffer
Keyword(s):  
Nutrient Cycling ◽  
Forest Soil ◽  
Nutrient Availability ◽  
Soil Nitrogen ◽  
N Mineralization ◽  
Temperate Forest ◽  
Net N Mineralization ◽  
Deer Browsing ◽  
Respiration Rates ◽  
High Nutrient

Herbivores impact soil biogeochemical processes, often increasing nutrient cycling rates under high nutrient availability and decreasing nutrient cycling rates under low nutrient availability. These patterns are far from universal, and interactions between habitat fertility and herbivore effects are under continuing investigation. By sampling inside and outside a network of deer exclosures, we determined deer browsing effects on temperate forest soil nitrogen (N) and carbon (C) cycling along a gradient of soil and litter C–N ratios across our network of sites. Deer browsing increased net N mineralization rates in high nutrient environments and decreased N mineralization rates in low nutrient environments, whereas browsing decreased CO2 respiration rates in high nutrient environments and increased CO2 respiration rates in low nutrient environments. Differences in deer browsing effects on soil processes could be explained by plant responses to herbivory across gradients of resource availability. To our knowledge, our study is one of the first to show that deer browsing can have significant effects on net N mineralization and C respiration in temperate forest soils and that the direction and magnitude of deer browsing effects on soil N and C cycling vary across fertility gradients.

scholarly journals Soil nitrogen transformation responses to seasonal precipitation changes are regulated by changes in functional microbial abundance in a subtropical forest

2017 ◽  
Author(s):  
Jie Chen ◽  
Guoliang Xiao ◽  
Yakov Kuzyakov ◽  
Darrel Jenerette ◽  
Ying Ma ◽  
...  
Keyword(s):  
N Mineralization ◽  
N2o Emission ◽  
Dry Season ◽  
Subtropical Forest ◽  
Net N Mineralization ◽  
Microbial Abundance ◽  
Wet Season ◽  
Net Nitrification ◽  
N Transformation ◽  
Precipitation Changes

Abstract. More dry-season droughts and wet-season storms have been predicted in subtropical areas. Since subtropical forest soils are significant sources of N2O and NO3−, it is important to understand the features and determinants of N transformation responses to the predicted precipitation changes. A precipitation manipulation field experiment was conducted to reduce dry-season precipitation and increase wet-season precipitation, while keeping the annual precipitation unchanged in a subtropical forest. Net N mineralization, net nitrification, N2O emission, nitrifying (bacterial and archaeal amoA) and denitrifying (nirK, nirS and nosZ) genes abundance, microbial biomass carbon (MBC) and soil physicochemical properties were monitored to characterize and explain soil N transformation responses. Dry-season precipitation reduction decreased net nitrification and N mineralization rates by 13–20 %, while wet-season precipitation addition increased both rates by 50 %. More than 20 % of the total variation of net nitrification and N mineralization could be explained by microbial abundance and soil water content (SWC), but archaeal amoA abundance was the main factor. Increased net nitrification in wet season together with large precipitation events caused substantial NO3− losses via leaching. However, N2O emission decreased moderately either in dry or wet seasons due to changes in nosZ gene abundance, MBC, net nitrification and SWC (decreased by 10–21 %). We conclude that reducing dry-season precipitation and increasing wet-season precipitation affect N transformation mainly through altering functional microbial abundance and MBC, which are further determined by changes in DOC and NH4+ availabilities. Such contrasting precipitation pattern will increase droughts and NO3− leaching in subtropical forests.

Drying-Rewetting Effects on Soil Nitrogen and Enzyme Activities Dynamics

2013 ◽  
Vol 409-410 ◽  
pp. 256-261
Author(s):  
Yuan Wang ◽  
Yingying Zheng ◽  
Xin Shan Song ◽  
Deng Hua Yan
Keyword(s):  
Soil Moisture ◽  
Soil Nitrogen ◽  
Enzyme Activities ◽  
Climate Changes ◽  
Inorganic N ◽  
N Transformations ◽  
High Positive Correlation ◽  
Drying And Rewetting ◽  
Soil Inorganic N ◽  
Stress Influences

With climate changes, soil may experience frequent drying-rewetting events. Water stress influences soil nitrogen transformation by affecting microbial growth and enzyme activities. The objective of this study was to determine effects of drying-rewetting cycles on soil N transformations and enzyme activities involved. The results show high correlations between soil inorganic N (NH4+-N & NO3--N) concentrations and soil moisture. Drying and rewetting events contributed to the accumulation of NO3--N. There was a significant correlation between NH4+-N/TDN and urease activities with a correlation coefficient of 0.88. Denitrifying enzyme activity showed a high positive correlation with soil moisture.

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

2017 ◽  
Vol 29 (3) ◽  
pp. 647-656 ◽  
Author(s):  
Peng Tian ◽  
Jinbo Zhang ◽  
Christoph Müller ◽  
Zucong Cai ◽  
Guangze Jin
Keyword(s):  
Temperate Forest ◽  
N Deposition ◽  
Soil N ◽  
Old Growth ◽  
N Transformation ◽  
Transformation Rates ◽  
Soil N Transformation

scholarly journals Effects of experimental freezing on soil nitrogen dynamics in soils from a net nitrification gradient in a nitrogen-saturated hardwood forest ecosystem

2010 ◽  
Vol 40 (3) ◽  
pp. 436-444 ◽  
Author(s):  
Frank S. Gilliam ◽  
Adam Cook ◽  
Salina Lyter
Keyword(s):  
N Mineralization ◽  
Soil Freezing ◽  
N Saturation ◽  
Net N Mineralization ◽  
N Dynamics ◽  
Net Nitrification ◽  
Soil Nitrogen Dynamics ◽  
Soil N Cycle ◽  
N Mineralization Potential ◽  
Fernow Experimental Forest

This study examined effects of soil freezing on N dynamics in soil along an N processing gradient within a mixed hardwood dominated watershed at Fernow Experimental Forest, West Virginia. Sites were designated as LN (low rates of N processing), ML (moderately low), MH (moderately high), and HN (high). Soils underwent three 7-day freezing treatments (0, –20, or –80 °C) in the laboratory. Responses varied between temperature treatments and along the gradient. Initial effects differed among freezing treatments for net N mineralization, but not nitrification, in soils across the gradient, generally maintained at LN < ML ≤ MH < HN for all treatments. Net N mineralization potential was higher following freezing at –20 and –80 °C than control; all were higher than at 0 °C. Net nitrification potential exhibited similar patterns. LN was an exception, with net nitrification low regardless of treatment. Freezing response of N mineralization differed greatly from that of nitrification, suggesting that soil freezing may decouple two processes of the soil N cycle that are otherwise tightly linked at our site. Results also suggest that soil freezing at temperatures commonly experienced at this site can further increase net nitrification in soils already exhibiting high nitrification from N saturation.

Nitrogen availability from peat amendments used in boreal oil sands reclamation

2010 ◽  
Vol 90 (1) ◽  
pp. 165-175 ◽  
Author(s):  
S S Hemstock ◽  
S A Quideau ◽  
D S Chanasyk
Keyword(s):  
Soil Nitrogen ◽  
Seasonal Variability ◽  
Oil Sands ◽  
Nitrogen Availability ◽  
Organic N ◽  
Soil Reclamation ◽  
Microbial Biomass N ◽  
Net Nitrification ◽  
Resin Core ◽  
Net Mineralization

Following surface mining, peat is typically used as an organic amendment to cap reconstructed soils in the Athabasca oil sands region of Alberta. Yet, very little is known about its ability to provide available nitrogen (N) in these soils. Hence, the overall objective of this study was to measure soil nitrogen (N) availability throughout the year in five peat amendments. Specific objectives were: (1) to examine seasonal variability in soil labile N pool sizes (nitrate, ammonium, dissolved organic N, and microbial biomass N), and (2) to determine in situ net nitrification, ammonification, and mineralization rates using the resin-core technique. Results from this field incubation method indicated a strong seasonal variability in net mineralization rates, with maximum positive values in the fall, and low or negative rates in winter. Net ammonification rates, which were significantly correlated to soil moisture content, were significantly smaller and showed smaller seasonal fluctuations and fewer differences among peat materials than net nitrification rates. Furthermore, the contribution of net nitrification to total net mineralization rates was characteristically higher than what is typically observed in undisturbed boreal forest soils. Taken together, results indicate that net nitrification processes may control nitrogen availability in these reclaimed soils.Key words: Soil nitrogen, soil reclamation, nitrification, mineralization, boreal soils

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