Dataset Information

Leaf and root C-to-N ratios are poor predictors of soil microbial biomass C and respiration across 32 tree species.

ABSTRACT: Soil microorganisms are the main primary decomposers of plant material and drive biogeochemical processes like carbon and nitrogen cycles. Hence, knowledge of their nutritional demands and limitations for activity and growth is of particular importance. However, potential effects of the stoichiometry of soil and plant species on soil microbial activity and carbon use efficiency are poorly understood. Soil properties and plant traits are assumed to drive microbial carbon and community structure. We investigated the associations between C and N concentrations of leaf, root, and soil as well as their ratios and soil microbial biomass C and activity (microbial basal respiration and specific respiratory quotient) across 32 young native angiosperm tree species at two locations in Central Germany. Correlations between C:N ratios of leaves, roots, and soil were positive but overall weak. Only regressions between root and leaf C:N ratios as well as between root and soil C:N ratios were significant at one site. Soil microbial properties differed significantly between the two sites and were significantly correlated with soil C:N ratio across sites. Soil C concentrations rather than N concentrations drove significant effects of soil C:N ratio on soil microbial properties. No significant correlations between soil microbial properties and leaf as well as root C:N ratios were found. We found weak correlations of C:N ratios between plant aboveground and belowground tissues. Furthermore, microorganisms were not affected by the stoichiometry of plant tissues in the investigated young trees. The results suggest that soil stoichiometry represents a consistent determinant of soil microbial biomass and respiration. Our study indicates that stoichiometric relationships among tree organs can be weak and poor predictors of soil microbial properties in young tree stands. Further research in controlled experimental settings with a wide range of tree species is needed to study the role of plant chemical traits like the composition and stoichiometry of root exudates in determining interactions between above- and belowground compartments.

SUBMITTER: Ferlian O

PROVIDER: S-EPMC5714262 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Leaf and root C-to-N ratios are poor predictors of soil microbial biomass C and respiration across 32 tree species.

Ferlian Olga O Wirth Christian C Eisenhauer Nico N

Pedobiologia 20170627

Soil microorganisms are the main primary decomposers of plant material and drive biogeochemical processes like carbon and nitrogen cycles. Hence, knowledge of their nutritional demands and limitations for activity and growth is of particular importance. However, potential effects of the stoichiometry of soil and plant species on soil microbial activity and carbon use efficiency are poorly understood. Soil properties and plant traits are assumed to drive microbial carbon and community structure. ...[more]

PMID: 29217869

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Project description:Predicting respiration from roots and soil microbes is important in agricultural landscapes where net flux of carbon from the soil to the atmosphere is of large concern. Yet, in riparian agroecosystems that buffer aquatic environments from agricultural fields, little is known on the differential contribution of CO2 sources nor the systematic patterns in root and microbial communities that relate to these emissions. We deployed a field-based root exclusion experiment to measure heterotrophic and autotrophic-rhizospheric respiration across riparian buffer types in an agricultural landscape in southern Ontario, Canada. We paired bi-weekly measurements of in-field CO2 flux with analysis of soil properties and fine root functional traits. We quantified soil microbial community structure using qPCR to estimate bacterial and fungal abundance and characterized microbial diversity using high-throughput sequencing. Mean daytime total soil respiration rates in the growing season were 186.1 ± 26.7, 188.7 ± 23.0, 278.6 ± 30.0, and 503.4 ± 31.3 mg CO2-C m-2 h-1 in remnant coniferous and mixed forest, and rehabilitated forest and grass buffers, respectively. Contributions of autotrophic-rhizospheric respiration to total soil CO2 fluxes ranged widely between 14 and 63% across the buffers. Covariation in root traits aligned roots of higher specific root length and nitrogen content with higher specific root respiration rates, while microbial abundance in rhizosphere soil coorindated with roots that were thicker in diameter and higher in carbon to nitrogen ratio. Variation in autotrophic-rhizospheric respiration on a soil area basis was explained by soil temperature, fine root length density, and covariation in root traits. Heterotrophic respiration was strongly explained by soil moisture, temperature, and soil carbon, while multiple factor analysis revealed a positive correlation with soil microbial diversity. This is a first in-field study to quantify root and soil respiration in relation to trade-offs in root trait expression and to determine interactions between root traits and soil microbial community structure to predict soil respiration.

Project description:BackgroundVegetation succession is one of the major driving processes of grassland degradation. Stoichiometry significantly contributes to vegetation dynamics. However, a knowledge gap exists in how soil nutrients and root enzymes influence the stoichiometric ratio to affect vegetation dynamics.MethodsTo address these questions, we selected a dominant species (Leymus chinensis (Trin.) Tzvel.) and a degraded-dominant species (Artemisia frigida Willd.) under different management regimes (enclosure and grazing) on the Inner Mongolia steppe. We measured (i) plant nutrient concentrations, (ii) root enzymes and (iii) soil nutrients to investigate how the selected plant species responded to grazing.ResultsThe results show that: (i) N and P concentrations and the C:N:P ratio in different organs are significantly affected by grazing, and there is variation in the plant species' response. Grazing significantly increased N and P in the leaves and stems of L. chinensis and the stems and roots of A. frigida. (ii) Grazing significantly increased the activities of glutamine synthase but decreased the activities of acid phosphatase in L. chinensis. The nitrate reductase and acid phosphatase activities significantly increased in A. frigida under grazing conditions. (iii) Grazing decreased the total nitrogen, total phosphorus, and available nitrogen, but increased the available phosphorus in the soil.ConclusionWe conclude that A. frigida is better adapted to grazing than L. chinensis, possibly because of its relatively increased stem and root growth, which enhance population expansion following grazing. Conversely, L. chinensis showed increased leaf and stem growth, but suffered nutrient and biomass loss as a result of excessive foraging by livestock, which severely affected its ability to colonize. Root enzymes coupled with soil nutrients can regulate plant nutrients and stoichiometric ratios as an adaptive response to grazing. Thus, we demonstrated that stoichiometric ratios allow species to better withstand grazing disturbances. This study provides a new understanding of the mechanisms involved in grazing-resistance within a plant-soil system.

Project description:Background and aimsThe reliance on external support by lianas has been hypothesized to imply a reduction in the biomass cost of stem construction and root anchorage, and an increased investment in leaves, relative to self-supporting plants. These evolutionary trade-offs have not been adequately tested in an ontogenetic context and on the whole-plant scale. Moreover, the hypothesis may be extended to other potentially limiting resources, such as nitrogen (N.).MethodsPlants belonging to five con-familiar pairs of temperate liana/shrub species were cultivated in 120 L barrels and sequentially harvested over up to three growing seasons. To account for the ontogenetic drift, organ biomass and nitrogen fractions were adjusted for plant biomass and N pool, respectively.Key resultsLianas invested, on average, relatively less biomass in the root fraction in comparison with shrubs. This was offset by only insignificant increases in leaf or stem investment. Even though liana stems and roots showed higher N concentration in comparison with shrubs, plant N distribution was mostly driven by, and largely matched, the pattern of biomass distribution. Lianas also showed a greater relative growth rate than shrubs. The differences between the growth forms became apparent only when ontogenetic drift was controlled for. These results were confirmed regardless of whether reproductive biomass was included in the analysis.ConclusionsOur results suggest that temperate lianas, in spite of their diverse, species-specific resource distribution patterns, preferentially allocate resources to above-ground organs at the expense of roots. By identifying this trade-off and demonstrating the lack of a general trend for reduction in stem investment in lianas, we significantly modify the prevailing view of liana allocation strategies and evolutionary advantages. Such a resource distribution pattern, along with the cheap unit leaf area and stem unit length construction, situates lianas as a group close to the fast acquisition/rapid growth end of the life strategy spectrum.

Dataset Information

Leaf and root C-to-N ratios are poor predictors of soil microbial biomass C and respiration across 32 tree species.

Publications

Leaf and root C-to-N ratios are poor predictors of soil microbial biomass C and respiration across 32 tree species.

Similar Datasets

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