Limits...
Root traits predict decomposition across a landscape-scale grazing experiment.

Smith SW, Woodin SJ, Pakeman RJ, Johnson D, van der Wal R - New Phytol. (2014)

Bottom Line: Livestock grazing increased soil temperatures, but this did not affect root decomposition.Grazing had no effect on soil moisture, but wetter soils retarded root decomposition.Our results suggest that large herbivores alter below-ground carbon and nitrogen dynamics more through their effects on plant species composition and associated root traits than through effects on the soil microclimate.

View Article: PubMed Central - PubMed

Affiliation: IBES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK; The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK; ACES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK.

Show MeSH
Root traits predicting root decomposition for microcosm species: (a) specific root area (SRA), that is, the surface area of the root per unit of mass (m2 g−1); (b) phosphorus content as predictors of loss of carbon from roots; and (c) nitrogen content as a predictor of loss of N from roots. Microcosm species roots are in dark grey with a dashed line for linear model fit for microcosm species only. Average traits and rates of root decomposition for field species from the main grazing experiment are in light grey. Species abbreviations: Ac, Agrostis capillaris; Ao, Anthoxanthum odoratum; Cf, Cerastium fontanum; Cn, Carex nigra; Fo, Festuca ovina; Hl, Holcus lanatus; Je, Juncus effusus; Mc, Molinia caerulea; Ns, Nardus stricta; Rac, Ranunculus acris; Ra, Rumex acetosa.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4260134&req=5

fig04: Root traits predicting root decomposition for microcosm species: (a) specific root area (SRA), that is, the surface area of the root per unit of mass (m2 g−1); (b) phosphorus content as predictors of loss of carbon from roots; and (c) nitrogen content as a predictor of loss of N from roots. Microcosm species roots are in dark grey with a dashed line for linear model fit for microcosm species only. Average traits and rates of root decomposition for field species from the main grazing experiment are in light grey. Species abbreviations: Ac, Agrostis capillaris; Ao, Anthoxanthum odoratum; Cf, Cerastium fontanum; Cn, Carex nigra; Fo, Festuca ovina; Hl, Holcus lanatus; Je, Juncus effusus; Mc, Molinia caerulea; Ns, Nardus stricta; Rac, Ranunculus acris; Ra, Rumex acetosa.

Mentions: Specific root area was the strongest predictor of root decomposition in the laboratory microcosm experiment from the selection of root traits measured (Tables2, S2). Root decomposition (defined here as the principal component of root mass and C loss, ex situ CO2-C efflux and phenol peroxidase activity) was greater for species with a low SRA (Fig. 4). In microcosms, the SRA of R. acris roots was far smaller than that of any other species, yet SRA remained a significant predictor without R. acris in the statistical analysis (Table 2). In the field experiment, M. caerulea had the greatest loss of mass and C from roots and an SRA 61% lower than the mean of all the other species (Table 3).


Root traits predict decomposition across a landscape-scale grazing experiment.

Smith SW, Woodin SJ, Pakeman RJ, Johnson D, van der Wal R - New Phytol. (2014)

Root traits predicting root decomposition for microcosm species: (a) specific root area (SRA), that is, the surface area of the root per unit of mass (m2 g−1); (b) phosphorus content as predictors of loss of carbon from roots; and (c) nitrogen content as a predictor of loss of N from roots. Microcosm species roots are in dark grey with a dashed line for linear model fit for microcosm species only. Average traits and rates of root decomposition for field species from the main grazing experiment are in light grey. Species abbreviations: Ac, Agrostis capillaris; Ao, Anthoxanthum odoratum; Cf, Cerastium fontanum; Cn, Carex nigra; Fo, Festuca ovina; Hl, Holcus lanatus; Je, Juncus effusus; Mc, Molinia caerulea; Ns, Nardus stricta; Rac, Ranunculus acris; Ra, Rumex acetosa.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260134&req=5

fig04: Root traits predicting root decomposition for microcosm species: (a) specific root area (SRA), that is, the surface area of the root per unit of mass (m2 g−1); (b) phosphorus content as predictors of loss of carbon from roots; and (c) nitrogen content as a predictor of loss of N from roots. Microcosm species roots are in dark grey with a dashed line for linear model fit for microcosm species only. Average traits and rates of root decomposition for field species from the main grazing experiment are in light grey. Species abbreviations: Ac, Agrostis capillaris; Ao, Anthoxanthum odoratum; Cf, Cerastium fontanum; Cn, Carex nigra; Fo, Festuca ovina; Hl, Holcus lanatus; Je, Juncus effusus; Mc, Molinia caerulea; Ns, Nardus stricta; Rac, Ranunculus acris; Ra, Rumex acetosa.
Mentions: Specific root area was the strongest predictor of root decomposition in the laboratory microcosm experiment from the selection of root traits measured (Tables2, S2). Root decomposition (defined here as the principal component of root mass and C loss, ex situ CO2-C efflux and phenol peroxidase activity) was greater for species with a low SRA (Fig. 4). In microcosms, the SRA of R. acris roots was far smaller than that of any other species, yet SRA remained a significant predictor without R. acris in the statistical analysis (Table 2). In the field experiment, M. caerulea had the greatest loss of mass and C from roots and an SRA 61% lower than the mean of all the other species (Table 3).

Bottom Line: Livestock grazing increased soil temperatures, but this did not affect root decomposition.Grazing had no effect on soil moisture, but wetter soils retarded root decomposition.Our results suggest that large herbivores alter below-ground carbon and nitrogen dynamics more through their effects on plant species composition and associated root traits than through effects on the soil microclimate.

View Article: PubMed Central - PubMed

Affiliation: IBES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK; The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK; ACES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK.

Show MeSH