Stoichiometric controls of nitrogen and phosphorus cycling in decomposing beech litter

Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
Ecology (Impact Factor: 4.66). 04/2012; 93(4):770-82. DOI: 10.2307/23213726
Source: PubMed


Resource stoichiometry (C:N:P) is an important determinant of litter decomposition. However, the effect of elemental stoichiometry on the gross rates of microbial N and P cycling processes during litter decomposition is unknown. In a mesocosm experiment, beech (Fagus sylvatica L.) litter with natural differences in elemental stoichiometry (C:N:P) was incubated under constant environmental conditions. After three and six months, we measured various aspects of nitrogen and phosphorus cycling. We found that gross protein depolymerization, N mineralization (ammonification), and nitrification rates were negatively related to litter C:N. Rates of P mineralization were negatively correlated with litter C:P. The negative correlations with litter C:N were stronger for inorganic N cycling processes than for gross protein depolymerization, indicating that the effect of resource stoichiometry on intracellular processes was stronger than on processes catalyzed by extracellular enzymes. Consistent with this, extracellular protein depolymerization was mainly limited by substrate availability and less so by the amount of protease. Strong positive correlations between the interconnected N and P pools and the respective production and consumption processes pointed to feed-forward control of microbial litter N and P cycling. A negative relationship between litter C:N and phosphatase activity (and between litter C:P and protease activity) demonstrated that microbes tended to allocate carbon and nutrients in ample supply into the production of extracellular enzymes to mine for the nutrient that is more limiting. Overall, the study demonstrated a strong effect of litter stoichiometry (C:N:P) on gross processes of microbial N and P cycling in decomposing litter; mineralization of N and P were tightly coupled to assist in maintaining cellular homeostasis of litter microbial communities.

Download full-text


Available from: Florian Hofhansl
  • Source
    • "Decomposition rates are usually negatively correlated with the C:N ratio (Melillo et al., 1982) and C:P ratio (Enriquez et al., 1993). However, no significant correlation was found between the decomposition rates and C:N ratios for residues of 37 crops (Jensen et al., 2005), and C:P ratios for Fagus sylvatica leaf litter (Mooshammer et al., 2012). Some studies have also reported positive correlations between C:N and decomposition rates (Gödde et al., 1996; Berg and Matzner, 1997; Michel and Matzner, 2002; Berg and McClaugherty, 2003; Craine et al., 2007). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Unlike Eucalyptus monocultures, nitrogen fixing trees are likely to improve the soil nutrient status through the decomposition of N-enriched litter. The Home Field Advantage (HFA) hypothesis states that plants can create conditions that increase the decomposition rates of their own litter. However, there may not be any HFA when most of the decomposers are generalists. A reciprocal transplant decomposition experiment of fine roots and leaves of Acacia mangium and Eucalyptus grandis was undertaken in monocultures of these two species to test the HFA hypothesis using a complete randomized design with three blocks. Three litterbags containing leaf or fine root residues of each species were collected every 3 months from each plot over 12 months for fine roots and 24 months for leaves. The litter mass and C, N and P concentrations were measured at each sampling date. The concentrations of C-compounds were measured 0, 12 and 24 months from the start of the experiment. There was no evidence of HFA for either the leaves or the fine roots of either species. The decomposition rates were slower for Acacia litter than for Eucalyptus litter even though initial N concentrations were 1.9–2.9 times higher and P concentrations were 1.5–3.3 times higher in the Acacia residues. N:P ratios were greater than 20–30 for the residues of both species, with the highest values for Acacia. Litter decomposition depended partly on the C quality of the litter, primarily in terms of water soluble compounds and lignin content. As shown recently in tropical rainforests, these results suggest that the activity of decomposers is limited by energy starvation in tropical planted forests. Decomposer activity may also have been limited by P availability which may not have been directly related to the P concentrations or C:P ratios in the residues.
    Full-text · Article · Sep 2015 · Forest Ecology and Management
  • Source
    • "Whether a similar stoichiometric ratio of carbon (C), nitrogen (N), and phosphorus (P) exists across terrestrial ecosystems has been explored to understand their biogeochemical processes and nutrient limitation (Elser et al. 2000; McGroddy et al. 2004; Mooshammer et al. 2012; Beermann et al. 2015). Unlike marine ecosystems, terrestrial ecosystems are more complex due to the various conditions (e.g., topography, vegetation , human intervene, etc.), and hence, result in a large spatial heterogeneity of biogenic element distribution and their ratios. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose The main objectives of this research are to decipher the stoichiometric characteristics of carbon (C), nitrogen (N), and phosphorus (P) in soils from the alpine ecosystem and to obtain information about nutrient limitation on plants and microbes. Materials and methods The soils were sampled along an altitudinal gradient (2000 to 4300 m above sea level) from the eastern slope of Gongga Mountain in eastern Tibetan Plateau. In total of 102 soil samples in profiles and 27 soil microbial biomass (SMB) samples from five vegetation zones were collected to analyze the concentrations of C, N, and P as well as their ratios. The concentrations of C and N were measured using an automated C/N analyzer, total P was detected by inductively coupled plasma-atomic emission spectrometer, and the concentrations of microbial biomass C, N, and P were measured by the chloroform fumigation-extraction method. Soil P fractions were extracted by modified Hedley sequential extraction method. Results and discussion The concentrations of C, N, and P in the soils and SMB varied spatially, whereas the variation of their ratios was constrained. The C:N:P ratios were 556:22:1 for the O horizon, 343:16:1 for the A horizon, 154:7:1 for the B horizon, and 63:3:1 for the C horizon, indicating a significant decrease with depth. The mean ratio in the SMB was 51:6.6:1. Microbial biomass C, N, and P were important components of soil nutrients, especially the microbial biomass P which accounted for 40.8 % of soil available P. The C:P and N:P were higher in the soils of broadleaf-coniferous and coniferous forests, whereas the ratios in the SMB were higher in the broadleaf forest. The ratios of C and N to available P in the soils decreased significantly with altitude. Conclusions The local climate, vegetation succession, and soil development in the high mountain resulted in the soil nutrient cycling different from that in other terrestrial ecosystems. Among the different vegetation zones, the P-limitation of plants and microbial communities might be possible in the soils of lower land forests in the long term.
    Full-text · Article · Aug 2015 · Journal of Soils and Sediments
  • Source
    • "This can explain the observed lower N/P ratio (19.1 in surface litter or 20.0 in buried litter) after 12 months of incubation. Our results suggest that the dynamics in litter stoichiometry during different incubation periods accounted for the patterns of N and P loss rates well (Mooshammer et al. 2012). In addition, the N/P ratio of simulated standing litter over 6 months of incubation Table 2 Pearson correlation analyses between 13 traits of green leaves and initial leaf litter and k values of litter decomposition for different litter positions, and Chi-square statistic and P values (n=51). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background and aims: Higher than expected litter decomposition rates have been observed in dry, sunny environments due to photochemical or physical degradation. However, our understanding of carbon and nutrient fluxes of standing and buried litters compared to surface litter in such areas is still scarce. Methods: We sampled leaf litters from 51 species in a semiarid dune ecosystem and incubated them in three positions: surface, sand-buried and simulated standing. Results: Decomposition was much faster in buried litter and somewhat faster in simulated standing litter than in surface litter. This pattern was independent of the incubation period, phylogenetic group or growth form. Litter position and incubation period significantly impacted litter nutrient dynamics. The nitrogen (N) and phosphorus (P) losses were faster in buried and simulated standing litters than in surface litter. The N loss was slower than P loss in 6-month decomposed litter but the former was relatively faster than the latter in the second phase up to 12 months of incubation. Conclusions: Our study shows that substantial mass and nutrient losses in simulated standing and buried litters can be a candidate explanation why drylands have higher carbon and nutrient fluxes than expected based on surface litter decomposition data alone.
    Full-text · Article · Jul 2015
Show more