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, Oct 13, 2015
164 Reads
  • 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.
    Forest Ecology and Management 09/2015; 359. DOI:10.1016/j.foreco.2015.09.026 · 2.66 Impact Factor
  • 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. "
    Journal of Soils and Sediments 08/2015; DOI:10.1007/s11368-015-1200-9 · 2.14 Impact Factor
    • "Microbial immobilization of N and P might result in changes in microbial biomass stoichiometry. Microbial C:N:P stoichiometry also affects mineralization of organic C, N and P in soils (Mooshammer et al., 2012). Organic C, N, and P in soils are mineralized by enzymes released by soil microorganisms and plants. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Microbial mineralization and immobilization of nutrients strongly influence soil fertility. We studied microbial biomass stoichiometry, microbial community composition, and microbial use of carbon (C) and phosphorus (P) derived from glucose-6-phosphate in the A and B horizons of two temperate Cambisols with contrasting P availability. In a first incubation experiment, C, nitrogen (N) and P were added to the soils in a full factorial design. Microbial biomass C, N and P concentrations were analyzed by the fumigation-extraction method and microbial community composition was analyzed by a community fingerprinting method (automated ribosomal intergenic spacer analysis, ARISA). In a second experiment, we compared microbial use of C and P from glucose-6-phosphate by adding 14C or 33P labeled glucose-6-phosphate to soil. In the first incubation experiment, the microbial biomass increased up to 30-fold due to addition of C, indicating that microbial growth was mainly C limited. Microbial biomass C:N:P stoichiometry changed more strongly due to element addition in the P-poor soils, than in the P-rich soils. The microbial community composition analysis showed that element additions led to stronger changes in the microbial community in the P-poor than in the P-rich soils. Therefore, the changed microbial biomass stoichiometry in the P-poor soils was likely caused by a shift in the microbial community composition. The total recovery of 14C derived from glucose-6-phosphate in the soil microbial biomass and in the respired CO2 ranged between 28.2 and 37.1% 66 h after addition of the tracer, while the recovery of 33P in the soil microbial biomass was 1.4–6.1%. This indicates that even in the P-poor soils microorganisms mineralized organic P and took up more C than P from the organic compound. Thus, microbial mineralization of organic P was driven by microbial need for C rather than for P. In conclusion, our experiments showed that (i) the microbial biomass stoichiometry in the P-poor soils was more susceptible to additions of C, N and P than in the P-rich soils and that (ii) even in the P-poor soils, microorganisms were C-limited and the mineralization of organic P was mainly driven by microbial C demand.
    Soil Biology and Biochemistry 06/2015; 85. DOI:10.1016/j.soilbio.2015.02.029 · 3.93 Impact Factor
Show more