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A closeup study of early beech litter decomposition: potential drivers and microbial interactions on a changing substrate.

Brandstätter C, Keiblinger K, Wanek W, Zechmeister-Boltenstern S - Plant Soil (2013)

Bottom Line: At the beginning of the experiment microbial biomass increased and pools of inorganic nitrogen (N) decreased, followed by an increase in fungal PLFAs.The C:N ratio of the dissolved pool, rather than the quantity of N, was the major driver of decomposition rates.We saw dynamic changes in the microbial community from the beginning through the termination of the experiment.

View Article: PubMed Central - PubMed

Affiliation: BFW - Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Seckendorff-Gudent Weg 8, 1131 Vienna, Austria ; Institute for Water Quality, Resources and Waste Management, Vienna University of Technology, Karlsplatz 13/226, 1040 Vienna, Austria.

ABSTRACT

Aims: Litter decomposition and subsequent nutrient release play a major role in forest carbon and nutrient cycling. To elucidate how soluble or bulk nutrient ratios affect the decomposition process of beech (Fagus sylvatica L.) litter, we conducted a microcosm experiment over an 8 week period. Specifically, we investigated leaf-litter from four Austrian forested sites, which varied in elemental composition (C:N:P ratio). Our aim was to gain a mechanistic understanding of early decomposition processes and to determine microbial community changes.

Methods: We measured initial litter chemistry, microbial activity in terms of respiration (CO2), litter mass loss, microbial biomass C and N (Cmic and Nmic), non purgeable organic carbon (NPOC), total dissolved nitrogen (TDN), NH4 (+), NO3 (-) and microbial community composition (phospholipid fatty acids - PLFAs).

Results: At the beginning of the experiment microbial biomass increased and pools of inorganic nitrogen (N) decreased, followed by an increase in fungal PLFAs. Sites higher in NPOC:TDN (C:N of non purgeable organic C and total dissolved N), K and Mn showed higher respiration.

Conclusions: The C:N ratio of the dissolved pool, rather than the quantity of N, was the major driver of decomposition rates. We saw dynamic changes in the microbial community from the beginning through the termination of the experiment.

No MeSH data available.


Related in: MedlinePlus

Time course of a) microbial biomass C (Cmic), b) microbial biomass N (Nmic) and d) the microbial metabolic quotient (qCO2). The remaining graph c) represents a quadratic regression between NH4+ and microbial biomass N (Nmic). The outer lines of the regression curves indicate a 95 % confidence interval and the line in between is the regression line. In a) and b) an ANOVA was conducted for week four and eight to detect significant differences between the four sites, and in d) for week eight only. Where brackets indicate a violation of the prerequisite of homogenous variances, a non-parametric Kruskal-Wallis test was computed (ns p > 0.5; * p < 0.05; ** p < 0.01; *** p < 0.001). AK Achenkirch, KL Klausen-Leopoldsdorf, OR Ort, PE Perg
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Fig3: Time course of a) microbial biomass C (Cmic), b) microbial biomass N (Nmic) and d) the microbial metabolic quotient (qCO2). The remaining graph c) represents a quadratic regression between NH4+ and microbial biomass N (Nmic). The outer lines of the regression curves indicate a 95 % confidence interval and the line in between is the regression line. In a) and b) an ANOVA was conducted for week four and eight to detect significant differences between the four sites, and in d) for week eight only. Where brackets indicate a violation of the prerequisite of homogenous variances, a non-parametric Kruskal-Wallis test was computed (ns p > 0.5; * p < 0.05; ** p < 0.01; *** p < 0.001). AK Achenkirch, KL Klausen-Leopoldsdorf, OR Ort, PE Perg

Mentions: For Cmic and Nmic (Table 2, Fig. 3a and b) a similar trend over time was observed and they were well correlated (Spearman’s r = 0.66, p < 0.001). Initially Nmic was low but sharply increased in the first 3 weeks. For the time period of the whole experiment Cmic and Nmic mostly was highest in KL. The C:N-ratio in microbial biomass (Cmic:Nmic) declined over time starting from 18.1 in week 0 to 6.7 in week 8 for all sites. The course of Nmic inversely matched the development of NH4+ and a highly significant quadratic relationship was observed between those two variables (Fig. 3c). This suggests that most of the NH4+ was incorporated into microbial biomass within the first week.Fig. 3


A closeup study of early beech litter decomposition: potential drivers and microbial interactions on a changing substrate.

Brandstätter C, Keiblinger K, Wanek W, Zechmeister-Boltenstern S - Plant Soil (2013)

Time course of a) microbial biomass C (Cmic), b) microbial biomass N (Nmic) and d) the microbial metabolic quotient (qCO2). The remaining graph c) represents a quadratic regression between NH4+ and microbial biomass N (Nmic). The outer lines of the regression curves indicate a 95 % confidence interval and the line in between is the regression line. In a) and b) an ANOVA was conducted for week four and eight to detect significant differences between the four sites, and in d) for week eight only. Where brackets indicate a violation of the prerequisite of homogenous variances, a non-parametric Kruskal-Wallis test was computed (ns p > 0.5; * p < 0.05; ** p < 0.01; *** p < 0.001). AK Achenkirch, KL Klausen-Leopoldsdorf, OR Ort, PE Perg
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4372839&req=5

Fig3: Time course of a) microbial biomass C (Cmic), b) microbial biomass N (Nmic) and d) the microbial metabolic quotient (qCO2). The remaining graph c) represents a quadratic regression between NH4+ and microbial biomass N (Nmic). The outer lines of the regression curves indicate a 95 % confidence interval and the line in between is the regression line. In a) and b) an ANOVA was conducted for week four and eight to detect significant differences between the four sites, and in d) for week eight only. Where brackets indicate a violation of the prerequisite of homogenous variances, a non-parametric Kruskal-Wallis test was computed (ns p > 0.5; * p < 0.05; ** p < 0.01; *** p < 0.001). AK Achenkirch, KL Klausen-Leopoldsdorf, OR Ort, PE Perg
Mentions: For Cmic and Nmic (Table 2, Fig. 3a and b) a similar trend over time was observed and they were well correlated (Spearman’s r = 0.66, p < 0.001). Initially Nmic was low but sharply increased in the first 3 weeks. For the time period of the whole experiment Cmic and Nmic mostly was highest in KL. The C:N-ratio in microbial biomass (Cmic:Nmic) declined over time starting from 18.1 in week 0 to 6.7 in week 8 for all sites. The course of Nmic inversely matched the development of NH4+ and a highly significant quadratic relationship was observed between those two variables (Fig. 3c). This suggests that most of the NH4+ was incorporated into microbial biomass within the first week.Fig. 3

Bottom Line: At the beginning of the experiment microbial biomass increased and pools of inorganic nitrogen (N) decreased, followed by an increase in fungal PLFAs.The C:N ratio of the dissolved pool, rather than the quantity of N, was the major driver of decomposition rates.We saw dynamic changes in the microbial community from the beginning through the termination of the experiment.

View Article: PubMed Central - PubMed

Affiliation: BFW - Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Seckendorff-Gudent Weg 8, 1131 Vienna, Austria ; Institute for Water Quality, Resources and Waste Management, Vienna University of Technology, Karlsplatz 13/226, 1040 Vienna, Austria.

ABSTRACT

Aims: Litter decomposition and subsequent nutrient release play a major role in forest carbon and nutrient cycling. To elucidate how soluble or bulk nutrient ratios affect the decomposition process of beech (Fagus sylvatica L.) litter, we conducted a microcosm experiment over an 8 week period. Specifically, we investigated leaf-litter from four Austrian forested sites, which varied in elemental composition (C:N:P ratio). Our aim was to gain a mechanistic understanding of early decomposition processes and to determine microbial community changes.

Methods: We measured initial litter chemistry, microbial activity in terms of respiration (CO2), litter mass loss, microbial biomass C and N (Cmic and Nmic), non purgeable organic carbon (NPOC), total dissolved nitrogen (TDN), NH4 (+), NO3 (-) and microbial community composition (phospholipid fatty acids - PLFAs).

Results: At the beginning of the experiment microbial biomass increased and pools of inorganic nitrogen (N) decreased, followed by an increase in fungal PLFAs. Sites higher in NPOC:TDN (C:N of non purgeable organic C and total dissolved N), K and Mn showed higher respiration.

Conclusions: The C:N ratio of the dissolved pool, rather than the quantity of N, was the major driver of decomposition rates. We saw dynamic changes in the microbial community from the beginning through the termination of the experiment.

No MeSH data available.


Related in: MedlinePlus