Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming

2015 ◽  
Vol 89 ◽  
pp. 123-134 ◽  
Author(s):  
Loïc Nazaries ◽  
William Tottey ◽  
Lucinda Robinson ◽  
Amit Khachane ◽  
Waleed Abu Al-Soud ◽  
...  
2020 ◽  
Author(s):  
Klaus Jarosch ◽  
Luis Carlos Colocho Hurtarte ◽  
Konstantin Gavazov ◽  
Aleksander Westphal Muniz ◽  
Christoph Müller ◽  
...  

<p>The conversion of tropical forest for cassava cultivation is widely known to decrease the soil organic matter (OM) and nutrient contents of highly weathered soils in the tropics. Amazonian Dark Earth (ADE) might be affected less due to their historical anthropogenic amelioration with e.g. charcoal, ceramics and bones, leading to higher soil OM and nutrient concentrations. In this study, we analysed the effect of land use change on the OM dynamics and its composition under tropical conditions, using ADE and an adjacent Acrisol (ACR) as model systems. Soil samples were obtained south of Manaus (Brazil), from a secondary forest and an adjacently located 40-year-old cassava plantation. The land use change induced a severe decrease of organic carbon (OC) concentrations in ADE (from 35 to 15 g OC kg<sup>‑1</sup>) while OC in the adjacent ACR was less affected (18 to 16 g OC kg<sup>‑1</sup>). Soils were analysed by <sup>13</sup>C NMR spectroscopy to obtain information on how the conversion of secondary forest to cassava affected the chemical composition of OM. Our results show that land use change induces differences in the OM composition: The OM in ADE changes to a more decomposed state (increase of alkyl:O/N-alkyl ratio) whereas the OM in ACR changes to a less decomposed state (decrease of alkyl:O/N-alkyl ratio). According to a molecular mixing model, land use change influenced mostly the proportion of lipids, which might be related with a change of the plant input. The incubation of the soils with <sup>13</sup>C glucose enabled resolving how soil microorganisms were affected by land use change. In both soil types ADE and ACR, land use change caused a reduction of the total <sup>13</sup>C glucose respiration by approximately one third in a 7-days incubation, implying lower microbial activity. Microorganisms in both soil types appear to be more readily active in soils under forest, since we observed a distinct lag time between <sup>13</sup>C glucose addition and respiration under cassava planation. This indicated differences in microbial community structure, which we will assess further by determining the <sup>13</sup>C label uptake by the microbial biomass and the microbial community structure using <sup>13</sup>C PLFA analysis. Preliminary results from synchrotron-based STXM demonstrate a distinct arrangement of OM at fine-sized charcoal-particle interfaces. Samples of soils receiving <sup>13</sup>C label will be further analysed by NanoSIMS with the hypothesis that charcoal interfaces foster nutrient dynamics at the microscale. Despite the high loss of OC in the ameliorated ADE through land use change, the remaining OM might improve the nutrient availability thanks to charcoal interactions compared to the ACR. Our results contribute to a better understanding of the sensitivity of OM upon land use change and how the microbial community is responding to land use change in highly weathered tropical soils.</p>


2021 ◽  
Author(s):  
Klaus A Jarosch ◽  
Luis Carlos Colocho Hurtarte ◽  
Konstantin Gavazov ◽  
Aleksander Westphal Muniz ◽  
Christoph Müller ◽  
...  

<p>The conversion of tropical forest for cassava cultivation is widely known to decrease the soil organic matter (OM) and nutrient contents of highly weathered soils in the tropics. Amazonian Dark Earth (ADE) might be more resistant to this process due to their historical anthropogenic amelioration with e.g. charcoal, ceramics and bones, leading to higher soil OM and nutrient concentrations. In this study, we analyzed the effect of land use change on the OM dynamics under tropical conditions and how this is related with P distribution at the microscale, using ADE and an adjacent Acrisol (ACR) as model systems. Soil samples were obtained south of Manaus (Brazil), from a secondary forest and an adjacently located 40-year-old cassava plantation. The land use change induced a severe decrease of organic carbon (OC) concentrations in ADE (from 35 to 15 g OC kg<sup>‑1</sup>) while OC in the adjacent ACR was less affected (18 to 16 g OC kg<sup>‑1</sup>). The analysis by <sup>13</sup>C NMR spectroscopy showed that the conversion of secondary forest to cassava changed the chemical composition of OM to a more decomposed state (increase of alkyl:O/N-alkyl ratio) in the ADE whereas the OM in ACR changed to a less decomposed state (decrease of alkyl:O/N-alkyl ratio). According to neutral sugar and lipid extraction analyses, land use change led to a larger impact on the microbial-derived and plant-derived compounds in the ADE compared to the ACR. In order to analyze the interactions of OC and P at the microscale, we conducted an incubation experiment with <sup>13</sup>C glucose for the analysis with Scanning X-ray Microscopy (SXM) and Nano scale Secondary Ion Mass Spectrometry (NanoSIMS). In both soil types ADE and ACR, land use change caused a reduction of the total <sup>13</sup>C glucose respiration by approximately one third in a 7-days incubation, implying lower microbial activity. Microorganisms in both soil types appear to be more readily active in soils under forest, since we observed a distinct lag time between <sup>13</sup>C glucose addition and respiration under cassava planation. This indicated differences in microbial community structure, which we will be assessed further by determining the <sup>13</sup>C label uptake by the microbial biomass and the microbial community structure using <sup>13</sup>C PLFA analysis. Preliminary results from synchrotron-based STXM demonstrate a distinct arrangement of OM at fine-sized charcoal-particle interfaces. From ongoing NanoSIMS analyses, we expect further insights on the co-localization of P and <sup>13</sup>C-labelled spots at the microscale. Despite the high loss of OC in the ameliorated ADE through land use change, the remaining OM might foster nutrient dynamics at the microscale thanks to charcoal interactions compared to the ACR. Our results contribute to a better understanding of the C and P interactions and how these respond to land use change in highly weathered tropical soils.</p>


Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 435 ◽  
Author(s):  
Jiacong Zhou ◽  
Xiaofei Liu ◽  
Jinsheng Xie ◽  
Maokui Lyu ◽  
Yong Zheng ◽  
...  

Forest soil respiration plays an important role in global carbon (C) cycling. Owing to the high degree of C and nitrogen (N) cycle coupling, N deposition rates may greatly influence forest soil respiration, and possibly even global C cycling. Soil microbes play a crucial role in regulating the biosphere–atmosphere C exchange; however, how microbes respond to N addition remains uncertain. To better understand this process, the experiment was performed in the Castanopsis kawakamii Hayata Nature Reserve, in the subtropical zone of China. Treatments involved applying different levels of N (0, 40, and 80 kg ha−2 year−1) over a three-year period (January 2013–December 2015) to explore how soil physicochemical properties, respiration rate, phospholipid fatty acid (PLFA) concentration, and solid state 13C nuclear magnetic resonance responded to various N addition rate. Results showed that high levels of N addition significantly decreased soil respiration; however, low levels of N addition significantly increased soil respiration. High levels of N reduced soil pH and enhanced P and C co-limitation of microorganisms, leading to significant reductions in total PLFA and changes in the structure of microbial communities. Significant linear relationships were observed between annual cumulative respiration and the concentration of microbial biomass (total PLFA, gram-positive bacteria (G+), gram-negative bacteria (G−), total bacteria, and fungi) and the microbial community structure (G+: G− ratio). Taken together, increasing N deposition changed microbial community structure and suppressed microbial biomass, ultimately leading to recalcitrant C accumulation and soil C emissions decrease in subtropical forest.


2021 ◽  
Vol 237 ◽  
pp. 01010
Author(s):  
Tian-Peng Gao ◽  
Jing-Wen Fu ◽  
Ming-Bo Zuo ◽  
Yu-Bing Liu ◽  
Dang-Hui Xu ◽  
...  

Five different land use types (desert, farmland, mining park, slag heap and tailing dam) were selected as variables around the Jinchuan Cu-Ni mining area in Jinchang, Gansu Province in the present study. The Atriplex canescens (Pursh) Nutt.’s rhizosphere bacterial abundance, diversity and community composition were examined taking advantage of High-throughput sequencing technology to discuss the effect of soil physicochemical properties on soil microbial community structure. The result indicated that the phylum Proteobacteria and Firmicutes was the most dominant taxon in desert, farmland and mining park, with a high abundance more than 30%. The phylum Proteobacteria was the most dominant taxon in slag heap and tailing dam, with a high abundance more than 40%. The tailing dam had the highest bacterial Chao indexes and the farmland had the highest bacterial Observed species indexes, Shannon indexes and Simpson indexes. Observed species indexes and Shannon indexes between the five sites were significantly different. The redundancy analysis and principal component analysis showed that the main environmental factors caused the different of rhizosphere bacterial community structure in five land use types were Mg, Ca, Cu, TN and moisture, followed by Ni, Cr, K, Pb, Zn content and pH. Hence, the result indicates that land use and soil environmental factors had significant impact on the diversity of soil microbial community structure.


2014 ◽  
Vol 78 ◽  
pp. 97-108 ◽  
Author(s):  
Francy Junio Gonçalves Lisboa ◽  
Guilherme Montandon Chaer ◽  
Marcelo Ferreira Fernandes ◽  
Ricardo Luis Louro Berbara ◽  
Beata Emoke Madari

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