Microbial-derived phospholipid fatty acids approve the link of stable isotope depth pattern to peatland hydrology

2020 ◽  
Author(s):  
Miriam Groß-Schmölders ◽  
Axel Birkholz ◽  
Kristy Klein ◽  
Jens Leifeld ◽  
Christine Alewell
Keyword(s):  
Stable Isotope ◽  
Microbial Activity ◽  
Turning Point ◽  
Phospholipid Fatty Acid ◽  
Microbial Community Composition ◽  
Microbial Metabolism ◽  
Nutrient Sources ◽  
Peatland Hydrology ◽  
Peatland Restoration ◽  
Peatland Degradation

<p>Ongoing peatland degradation calls for an efficient method to indicate peatland hydrology and the success of restoration effort. In previous studies we found specific depth patterns of 13C and 15N depending on peatland hydrology (drained, rewetted or natural), but were unable to find an explanation of these patterns. As degradation is mostly connected to drainage we assumed an increase of microbial activity. This microbial activity should then be imprinted in stable isotope signatures (15N, 13C) due to differences in microorganism communities, their metabolic pathways and nutrient sources. We aimed to find a link between our investigated isotope depth patterns to microbial community composition. Therefore, we conducted a phospholipid fatty acid (PLFAs) analysis. As a marker for bacteria we used PLFAs i-C15:0 and a-C-15:0 as well as the C18:2,9c as a marker for fungi. We studied two nutrient poor peatlands in Northern Europe: Lakkasuo (Central Finland) and Degerö Stormyr (Northern Sweden). At all locations cores were taken from adjacent drained (or rewetted) and natural sites. At Lakkasuo drained site, we found a high humification index (HI, after van Post), shown by less plant residuals and a high amount of matrix. For Degerö Stormyr the picture looks different. Above the drained horizon (high HI) peat was light, with a smaller amount of matrix and lots of plant residuals (low HI), like it was also seen in the natural cores. At the drained (and rewetted) sites we found distinct peaks in microbial PLFA concentrations, which correlate to the stable isotope peaks ("turning point”) we found before. At the 15N turning point, in the center of the drained horizon, overall microbial-derived PLFA abundance is also the highest. Furthermore, the overall microbial-derived PLFA abundance is positively correlated with 15N values (r<sup>2</sup>=0.5). Fungi-derived PLFAs are negatively correlated (r<sup>2</sup>=0.4) to 13C. Fungi-derived PLFAs showed the highest amount at the uppermost part of the drained horizon and low amounts in the waterlogged conditions below the drained horizon, whereas 13C showed lowest values at the surface and high values below the drained horizon. Our results suggest, that fungi dominate microbial metabolism in the upper, aerobic peat horizon. Downwards the drained horizon conditions slowly switch to oxygen limitation. Thus, fungal-derived PLFAs decrease whereas bacterial-derived PLFAs are increasing. The highest diversity of microbial-derived PLFAs is indicated by the 15N turning point. Below this point, oxygen is increasingly limited and concentrations of all microbial-derived PLFAs are decreasing down to the 13C turning point and the onset of the permanently waterlogged, anaerobic horizon. Cores from rewetted peatlands show no depth trend of 15N values above the formerly drained horizon and a low amount of microbial-derived PLFAs. Hence, we conclude that stable isotope values reflect microbial metabolism processes, which differ between drained, rewetted and natural peatlands. Additionally, stable isotope patterns reflect a switch in the predominant communities from fungi to bacteria within a drained horizon. Summing up, the PLFA analysis approved that stable isotope measurements can serve as a cost and work efficient monitoring tool for peatland history as well as peatland restoration success.</p>

scholarly journals Switch of fungal to bacterial degradation in natural, drained and rewetted oligotrophic peatlands reflected in δ<sup>15</sup>N and fatty acid composition

2020 ◽  
Author(s):  
Miriam Groß-Schmölders ◽  
Pascal von Sengbusch ◽  
Jan Paul Krüger ◽  
Kristy Woodard ◽  
Axel Birkholz ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Microbial Community ◽  
Stable Isotope ◽  
Community Composition ◽  
Turning Point ◽  
Phospholipid Fatty Acid ◽  
Microbial Community Composition ◽  
Microscopic Analysis ◽  
Bacterial Degradation ◽  
Ecosystem Functions

Abstract. During the last centuries major parts of European peatlands were degraded along with drainage and land use changes. Peatland biodiversity and essential ecosystem functions (e.g. flood prevention, groundwater purification and CO2 sink) were dramatically impaired. Moreover, climate change threatens peatlands in the near future. Increasing pressure to peatland ecosystems calls for a more cost-efficient method to indicate the current state of peatlands and the success of restoration effort. Metabolism processes in peatland soils are imprinted in stable isotope signatures due to differences in microorganism communities and their metabolic pathways. Therefore we hypothesize that depth profiles of nitrogen stable isotope values provide a promising opportunity to detect peatland decomposition or restoration. We studied five peatlands: Degerö Stormyr (Northern Sweden), Lakkasuo (Central Finland) and three mires in the Black Forest (Southern Germany). At all locations cores were taken from adjacent drained (or rewetted) and natural sites to identify δ15N trends that could indicate changes due to drainage and restoration. At all drained (and rewetted) sites we found a distinct peak (turning point) of the δ15N values in the center of the drained horizon. To verify our interpretation δ13C, the C / N ratio and the bulk density were measured and a microscopic analysis of the macro residuals in the peat cores was made. In addition we did a phospholipid fatty acid (PLFAs) analysis to link our results to microbial community composition. We distinguished between fungal and bacterial-derived PLFAs. In accordance with other studies, our results suggest, that fungi dominate the microbial metabolism in the upper, aerobic peat horizon. This is reflected by depleted δ15N values. Downwards the drained horizon conditions slowly switch to oxygen limitation. In consequence fungal-derived PLFAs decreases whereas bacterial-derived PLFAs are rising. The highest diversity of microbial-derived PLFAs is indicated by the δ15N turning point. Below the δ15N turning point, oxygen is increasingly limited and concentrations of all microbial-derived PLFAs are decreasing down to the onset of the permanently waterlogged, anaerobic horizon. Peatland cores with restoration success show, above the formerly drainage-affected horizon, again no depth trend of the isotopic values. Hence, we conclude that δ15N stable isotope values reflect microbial community composition, which differ between drained and natural peatlands.

Challenges to peatland restoration in Indonesia

2020 ◽  
Author(s):  
Nyoman Suryadiputra
Keyword(s):  
Water Level ◽  
Government Regulation ◽  
Landscape Restoration ◽  
Water Release ◽  
Peatland Hydrology ◽  
Long Run ◽  
Peatland Restoration ◽  
Drainage Canals ◽  
High Level ◽  
Peatland Degradation

&lt;p&gt;Challenges to peatland restoration in Indonesia&lt;br&gt;By&amp;#160;&lt;br&gt;Nyoman Suryadiputra*)&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;br&gt;Tropical peat swamps in Indonesia are currently experiencing degradation at a very alarming rate. Degradation starts from the time of land clearing (generally burned / uses fire) for both private and community-owned plantations, then a very massive network of drainage canals is built (every 1 Ha of peat land cleared, about 120 m - 700 m long canals are needed). These drainage canals aim to reduce the surface water level of peat so that the land can be planted (especially for) oil palm or acacia. However, peat water release can go out of control, beyond the peatland water level threshold determined by government regulation No 71/2014 on Peatland Management, as a result peat becomes dry, flammable and emits large amount of GHGs. In the long run, if drainage and fires continue, peatlands will experience subsidence, form basins, peat even disappear, flooded during rain and eventually the land becomes unproductive (stranded) and difficult to restore. Such conditions will be more severe and difficult to overcome if in the landscape (peatland hydrology unit) there are various activities by various parties, each of whom has different interests and understandings of peatland use. Regarding the above, restoration of peatland that has been damaged has a very serious challenge. Damage that is getting heavier will have a high level of difficulty and a long recovery time. In addition, the success rate of restoration is determined by benchmarks or recovery criteria that have not been scientifically determined and adopted by the Indonesian government.&lt;/p&gt;&lt;p&gt;&lt;em&gt;Keywords : peatland, degradation, landscape, restoration &amp;#160; &amp;#160;&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;br&gt;*) &amp;#160;Director of Wetlands International Indonesia&lt;/p&gt;

scholarly journals Switch of fungal to bacterial degradation in natural, drained and rewetted oligotrophic peatlands reflected in <i>δ</i><sup>15</sup>N and fatty acid composition

SOIL ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 299-313
Author(s):  
Miriam Groß-Schmölders ◽  
Pascal von Sengbusch ◽  
Jan Paul Krüger ◽  
Kristy Klein ◽  
Axel Birkholz ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stable Isotope ◽  
Community Composition ◽  
Metabolic Pathways ◽  
Turning Point ◽  
Microbial Community Composition ◽  
Bacterial Degradation ◽  
Gram Positive Bacteria ◽  
Current State ◽  
Cost Efficient

Abstract. For centuries European peatlands have been degrading along with drainage, land use and climate changes. Increasing pressure on peatland ecosystems calls for a more cost-efficient method to indicate the current state of peatlands and the success of restoration efforts. Metabolic pathways in peatland soils are imprinted in stable isotope compositions due to differences in microorganism communities and their metabolic pathways. Therefore, we hypothesize that depth profiles of nitrogen stable isotope values provide a promising opportunity to detect peatland decomposition or restoration. We studied five peatlands, namely Degerö Stormyr (northern Sweden), Lakkasuo (central Finland) and three mires in the Black Forest (southern Germany). At all locations, cores were taken from adjacent drained (or rewetted) and natural sites to identify δ15N trends that could indicate changes due to drainage and restoration. At all drained (and rewetted) sites we found a distinct peak (“turning point”) of the δ15N values in the center of the drained horizon. We did a fatty acids (FAs) analysis to link our results to microbial community composition. As markers, we distinguished between one fungal-derived FA (C18:2ω9c) and four bacterial-derived FAs. For bacteria, we looked for one general bacterial-derived FA (C14:0), two FAs for gram-positive bacteria (i-C15:0; a-C15:0), and one FA for gram-negative bacteria (C16:1ω9c). In accordance with other studies, our results suggest that fungi dominate the microbial metabolism in the upper aerobic peat horizon. This is reflected by depleted δ15N values. Moving downwards, the drained horizon conditions slowly switch to oxygen limitation. Consequently, fungal-derived FAs decrease whereas bacterial-derived FAs rise. The highest diversity of microbial-derived FAs is indicated by the δ15N turning point. Below the δ15N turning point, oxygen is increasingly limited and concentrations of all microbial-derived FAs are decreasing down to the onset of the permanently waterlogged anaerobic horizon. Peatland cores with restoration successes again show, above the formerly drained horizon, no depth trend of the isotopic values. Hence, we conclude that δ15N stable isotope values reflect microbial community composition, which differs between drained and natural peatlands.

Soil microbial communities in microaggregates are less affected by top-down effects of collembolans than those in macroaggregates

2021 ◽  
Author(s):  
Amandine Erktan ◽  
MD Ekramul Haque ◽  
Jérôme Cortet ◽  
Paul Henning Krogh ◽  
Stefan Scheu
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Community Composition ◽  
Trophic Interactions ◽  
Phospholipid Fatty Acid ◽  
Microbial Community Composition ◽  
Soil Microbial Communities ◽  
Trophic Levels ◽  
Soil Matrix ◽  
Fungal Abundance

&lt;p&gt;Trophic regulation of microbial communities is receiving growing interest in soil ecology. Most studies investigated the effect of higher trophic levels on microbial communities at the bulk soil level. However, microbes are not equally accessible to consumers. They may be hidden in small pores and thus protected from consumers, suggesting that trophic regulation may depend on the localization of microbes within the soil matrix. As microaggregates (&lt; 250 &amp;#181;m) usually are more stable than macroaggregates (&gt; 250 &amp;#181;m) and embedded in the latter, we posit that they will be less affected by trophic regulations than larger aggregates. We quantified the effect of four contrasting species of collembolans (Ceratophysella denticulata, Protaphorura fimata, Folsomia candida, Sinella curviseta) on the microbial community composition in macro- (250 &amp;#181;m &amp;#8211; 2mm) and microaggregates (50 &amp;#8211; 250 &amp;#181;m). To do so, we re-built consumer-prey systems comprising remaining microbial background (post-autoclaving), fungal prey (Chaetomium globosum), and collembolan species (added as single species or combined). After three months, we quantified microbial community composition using phospholipid fatty acid markers (PLFAs). We found that the microbial communities in macroaggregates were more affected by the addition of collembolans than the communities in microaggregates. In particular, the fungal-to-bacterial (F:B) ratio significantly decreased in soil macroaggregates in the presence of collembolans. In the microaggregates, the F:B ratio remained lower and unaffected by collembolan inoculation. Presumably, fungal hyphae were more abundant in macroaggregates because they offered more habitat space for them, and the collembolans reduced fungal abundance because they consumed them. On the contrary, microaggregates presumably contained microbial communities protected from consumers. In addition, collembolans increased the formation of macroaggregates but did not influence their stability, despite their negative effect on fungal abundance, a well-known stabilizing agent. Overall, we show that trophic interactions between microbial communities and collembolans depend on the aggregate size class considered and, in return, soil macroaggregation is affected by these trophic interactions.&lt;/p&gt;

scholarly journals Formulating Popular Policies for Peat Restoration Based on Livelihoods of Local Farmers

2018 ◽  
Vol 11 (3) ◽  
pp. 85 ◽  
Author(s):  
Elisa Wildayana ◽  
M. Edi M. Edi Armanto
Keyword(s):  
Political Institutions ◽  
Poverty Alleviation ◽  
Rural Livelihoods ◽  
Political Aspect ◽  
Qualitative And Quantitative ◽  
Peatland Restoration ◽  
Intrinsic Quality ◽  
Peatland Degradation ◽  
Local Farmers

Important peatland issues developed were how to restore peatlands and followed by increasing rural livelihoods. This research aimed to analyze how peatlands can be utilized to alleviate poverty? and how to integrate peatland restoration with poverty alleviation. This research has been conducted in peatlands of OKI district, South Sumatra Indonesia in 2017. Data about bio geophysical aspects of peatlands, social, economic and political institutions of farmers were surveyed in the fields, performed in qualitative and quantitative approach, and analyzed in forms of tables and descriptions. Important themes have been discussed in formulating popular policies for peat restoration based on livelihoods of local farmers, among others poor groups; characteristics of farmers from the socio-political aspect; concept of peatland restoration and other lessons-learnt; compatibility of peat-based poverty alleviation; and need to improve policy making. The chronic poor sites tend to overlap with peatland degradation; it is more important to cultivate peatlands to prevent farmers from falling into deeper poverty than to reduce farmers out of poverty, and the intrinsic quality of peatlands and their contents tends to conflict with poverty alleviation goals, but there are some possible trends to minimize peatlands degradation and to alleviate poverty simultaneously. The best approach is to apply the 'win-lose' or 'lose-win' approach, even though we are not able to avoid peatland degradation at a zero level, but at least it can be inhibited. Cooperation between investors and farmers in managing peatlands is needed, so that the peatland resources are not completely degraded.

Forest floor microbial community response to tree species and fertilization of regenerating coniferous forests

2004 ◽  
Vol 34 (7) ◽  
pp. 1426-1435 ◽  
Author(s):  
S E Leckie ◽  
C E Prescott ◽  
S J Grayston
Keyword(s):  
Fatty Acid ◽  
Microbial Community ◽  
Tree Species ◽  
Forest Floor ◽  
Phospholipid Fatty Acid ◽  
Microbial Community Composition ◽  
Community Response ◽  
Community Level ◽  
Thuja Plicata ◽  
Culturable Bacteria

We studied the effect of tree species and fertilization on the forest floor microbial community of 15-year-old regenerating forests. We sampled F and H forest floor layers of plots planted to Thuja plicata (Donn ex D. Don.) or Tsuga heterophylla (Raf.) Sarg. on N-poor and N-rich sites, with and without fertilizer treatments. Microbial community composition was assessed using phospholipid fatty acid analysis and by enumerating populations of culturable bacteria and fungi. Potential microbial functioning was assessed using community-level physiological profiling. There was little differentiation of community-level physiological profiles of F and H layers and few differences among the treatments. Total microbial biomass was greater in the F than H layer, and the two layers had distinct phospholipid fatty acid profiles. Site effects were detected mainly in the residual H layer, and tree species effects were seen mainly in the F layer, which has developed since harvesting. The effect of fertilization depended on site and tree species, with very little response in cedar plots, and the greatest effects in hemlock plots, coinciding with the greater growth response of hemlock. These results indicate that differences in plant growth rates, rather than direct effects of fertilization, influenced the microbial communities.

River flow controls ecological processes and invertebrate assemblages in subsurface flowpaths of an ephemeral river reach

2008 ◽  
Vol 65 (8) ◽  
pp. 1532-1544 ◽  
Author(s):  
Thibault Datry ◽  
Scott T. Larned
Keyword(s):  
Microbial Activity ◽  
River Flow ◽  
Riparian Zone ◽  
Taxon Richness ◽  
Ecological Processes ◽  
Zone Length ◽  
Nutrient Sources ◽  
Subsurface Zones ◽  
Invertebrate Assemblages ◽  
Reactive Phosphorus

We present the first measurements of solutes, invertebrates, and microbial activity in the semi-perched hyporheic, parafluvial, and riparian flowpaths of an ephemeral river channel. Dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations decreased as water from an adjacent river mainstem moved through the flowpaths. DOC, DON, and DOP processing rates decreased with increasing mainstem flow and increased with parafluvial zone length. These patterns suggest that the surface water zones of perched river systems are organic nutrient sources to subsurface flowpaths and that parafluvial zones of these systems are strong sinks for organic matter. No longitudinal changes were detected in NO3–concentrations, and relationships between NO3–processing and hydrological variables were not significant. NO3–concentrations were uniformly high, and microbial activity and DOC and dissolved reactive phosphorus (DRP) concentrations were low, suggesting that biological NO3–removal was carbon- or phosphorus-limited. Invertebrate assemblages also varied between subsurface zones: density and taxon richness in the hyporheic and parafluvial zones were higher than in the riparian zone, and evenness was higher in the riparian zone than in the hyporheic or parafluvial zones. Distinct invertebrate assemblages in riparian zones may reflect greater hydrologic stability compared with hyporheic and parafluvial zones.

Sign in / Sign up

Export Citation Format

Share Document