n dynamics
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Author(s):  
Enzhu Hu ◽  
Zhimin Ren ◽  
Xiaoke Wang ◽  
Hongxing Zhang ◽  
Weiwei Zhang

Abstract Elevated tropospheric ozone concentration ([O3]) may substantially influence the belowground processes of the terrestrial ecosystem. Nevertheless, a comprehensive and quantitative understanding of the responses of soil C and N dynamics to elevated [O3] remains elusive. In this study, the results of 41 peer-reviewed studies were synthesized using meta-analytic techniques, to quantify the impact of O3 on ten variables associated with soil C and N, i.e., total C (TC, including soil organic C), total N (TN), dissolved organic C (DOC), ammonia N (NH4 +), nitrate N (NO3 -), microbial biomass C (MBC) and N (MBN), rates of nitrification (NTF) and denitrification (DNF), as well as C/N ratio. The results depicted that all these variables showed significant changes (P < 0.05) with [O3] increased by 27.6 ± 18.7 nL/L (mean ± SD), including decreases in TC, DOC, TN, NH4 +, MBC, MBN and NTF, and increases in C/N, NO3 - and DNF. The effect sizes of TN, NTF, and DNF were significantly correlated with O3 fumigation level and experimental duration (P < 0.05). Soil pH and climate were essential in analyses of O3 impacts on soil C and N. However, the responses of most variables to elevated [O3] were generally independent of O3 fumigation method, terrestrial ecosystem type, and additional [CO2] exposure. The altered soil C and N dynamics under elevated [O3] may reduce its C sink capacity, and change soil N availability thus impact plant growth and enhance soil N losses.


2022 ◽  
Vol 802 ◽  
pp. 149924
Author(s):  
Enrique Albert-Belda ◽  
M. Belén Hinojosa ◽  
Vito Armando Laudicina ◽  
Roberto García-Ruiz ◽  
Beatriz Pérez ◽  
...  

2022 ◽  
Vol 302 ◽  
pp. 114075
Author(s):  
Ana Cervera-Mata ◽  
Gabriel Delgado ◽  
Alejandro Fernández-Arteaga ◽  
Flavio Fornasier ◽  
Claudio Mondini

Author(s):  
Qingqing Liang ◽  
Heidi Mod ◽  
Shuaiwei Luo ◽  
Beibei Ma ◽  
Kena Yang ◽  
...  

The processes governing soil bacteria biogeography are still not fully understood. It remains unknown how the importance of environmental filtering and dispersal differs between bacterial taxonomic and functional biogeography, and whether their importance is scale-dependent. We sampled soils at 195 plots across the Tibet plateau, with distances among plots ranging from 20 m to 1 550 km. Taxonomic composition of bacterial community was characterized by 16S amplicon sequencing, and functional community composition by qPCR targeting 9 functional groups involved in N dynamics. Twelve climatic and soil characteristics were also measured. Both taxonomic and functional dissimilarities were more related to environmental dissimilarity than geographic distance. Taxonomic dissimilarity was mostly explained by soil pH and organic matter, while functional dissimilarity was mostly linked to moisture, temperature and N, P and C availabilities. The roles of environmental filtering and dispersal were, however, scale-dependent and varied between taxonomic and functional dissimilarities, with distance affecting taxonomic dissimilarity over short distances (<~300 km) and functional dissimilarity over long distances (>~600 km). The importance of different environmental predictors varied across scales more for functional than taxonomic dissimilarity. Our results demonstrate how biodiversity dimension (taxonomic versus functional) and spatial scale strongly influence the conclusions derived from bacterial biogeography studies.


Author(s):  
Chih-Yu Hung ◽  
Naseer Hussain ◽  
Barry Husk ◽  
Joann K. Whalen

Ammonia (NH3) volatilization from ammonia-based fertilizer and animal manure reduces their nitrogen fertilizer value and is a source of environmental pollution. Mixing manure with biochar may lower NH3 volatilization from manure by adding H+, adsorbing mineral nitrogen (N), or increasing N immobilization in microbial biomass. The objective of this study was to determine whether wood-based biochar could lower NH3 volatilization from vented pails containing manure (liquid swine, dairy slurry, and solid poultry manure) or a urea ammonium nitrate solution (UAN). Two types of wood-based biochar (BlueLeaf and Dynamotive) were mixed with three types of manure and UAN fertilizer solution at 0, 2.5, 5, 10, and 25 % biochar by volume in vented pails. After 21 d storage in an outdoor shaded area, the greatest NH3 volatilization was from poultry manure, which had pH 9.4 on average and low water content regardless of the biochar source and application rate. There was less NH3 volatilization from UAN fertilizer solution when mixed with 25% (v/v) of Dynamotive biochar compared to NH3 volatilization from UAN fertilizer solution mixed with 0–10% (%) of Dynamotive biochar, probably because pH decreased from 7.0 to 6.4 after 21 d contact. Mixing wood-based biochar with manure had no impact on NH3 volatilization, suggesting that these biochar sources did not appreciably change the pH and N dynamics in stored manure after 21 d.


2021 ◽  
Vol 20 (11) ◽  
pp. 3039-3059
Author(s):  
Cyrine REZGUI ◽  
Isabelle TRINSOUTROT-GATTIN ◽  
Marie BENOIT ◽  
Karine LAVAL ◽  
Wassila RIAH-ANGLET

2021 ◽  
Author(s):  
Mercedes Ibañez ◽  
Salvador Aljazairi ◽  
María José Leiva ◽  
Roland A. Werner ◽  
Jaleh Ghashghaie ◽  
...  

Abstract Purpose: Mediterranean wood pastures are the largest agroforestry system in Europe. Traditional silvo-pastoral uses shaped these systems into a mosaic of trees and open grassland. However, little is known about how this structure may influence ecosystem carbon (C) and nitrogen (N) dynamics, considering different canopy types and interactions with the herbaceous layer.Aims: To unravel the canopy effect on C and N dynamics (1) under representative canopy types, including traditional Quercus stands and Pinus pinea L. plantations; and (2) in interaction with the herbaceous plant functional types (PFT).Methods: We analysed C and N content and the isotopic natural abundance on soil and plant materials at the open grassland and under the different tree canopies.Results: Under the canopy, soil C and N content, and N availability for the herbaceous layer increased. The canopy effect performed differences between Quercus and P. pinea plots, as detected on the belowground biomass C content. Also, the canopy effect was more pronounced with increasing environmental constraints, highlighting the relevance of trees in more restrictive environments. PFT ecophysiological characteristics interacted with tree canopies, as reflected the enhanced efficiency taking-up N, and/or exploiting symbiotic N of grasses, which was probably one of the causes of their dominancy under the canopy, at higher N availability.Conclusion: Changes in the tree coverage and tree species will significantly change ecosystem C and N storage and cycling. Therefore, it is highly advisable to preserve a balance between trees and open grassland, and traditional Quercus stands, to keep ecosystem services provisioning.


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