10.5061/DRYAD.MS2NP57
Wilson, Chris H.
University of Florida
Strickland, Michael S.
Virginia Tech
Hutchings, Jack A.
University of Florida
Bianchi, Thomas S.
University of Florida
Flory, S. Luke
University of Florida
Data from: Grazing enhances belowground carbon allocation, microbial
biomass, and soil carbon in a subtropical grassland
Dryad
dataset
2018
Lignin Phenols
belowground carbon allocation
microbial biomass
Paspalum notatum
soil organic carbon
Large Herbivore Grazing
subtropical pasture
National Science Foundation
https://ror.org/021nxhr62
DEB-1501686
2018-02-13T17:51:22Z
2018-02-13T17:51:22Z
en
https://doi.org/10.1111/gcb.14070
18152 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Despite the large contribution of rangeland and pasture to global soil
organic carbon (SOC) stocks, there is considerable uncertainty about the
impact of large herbivore grazing on SOC, especially for understudied
subtropical grazing lands. It is well known that root system inputs are
the source of most grassland SOC, but the impact of grazing on
partitioning of carbon allocation to root tissue production compared to
fine root exudation is unclear. Given that different forms of root C have
differing implications for SOC synthesis and decomposition, this
represents a significant gap in knowledge. Root exudates should contribute
to SOC primarily after microbial assimilation, and thus promote microbial
contributions to SOC based on stabilization of microbial necromass,
whereas root litter deposition contributes directly as plant-derived SOC
following microbial decomposition. Here we used in situ isotope
pulse-chase methodology paired with plant and soil sampling to link plant
carbon allocation patterns with SOC pools in replicated long-term grazing
exclosures in subtropical pasture in Florida, USA. We quantified
allocation of carbon to root tissue and measured root exudation across
grazed and ungrazed plots and quantified lignin phenols to assess the
relative contribution of microbial versus plant products to total SOC. We
found that grazing exclusion was associated with dramatically less overall
belowground allocation, with lower root biomass, fine root exudates, and
microbial biomass. Concurrently, grazed pasture contained greater total
SOC, and a larger fraction of SOC that originated from plant tissue
deposition, suggesting that larger root litter deposition under grazing
promotes greater SOC. We conclude that grazing effects on SOC depend on
root system biomass, a pattern that may generalize to other C4-dominated
grasslands, especially in the subtropics. Improved understanding of
ecological factors underlying root system biomass may be the key to
forecasting SOC and optimizing grazing management to enhance SOC
accumulation.
Lignin PhenolsData file with results from lignin phenol extraction of soil
samples, and plant tissue end-members (i.e. shoots, rhizomes and roots of
Bahiagrass from inside and outside grazing exclosure). The major families
are summarized as v (vannilyl), c (cinnamyl) and s (syringyl). Column
'vsc' represents the sum of v,s, and c, standardized per 100 mg
organic carbon, whereas 'vsc.sed' is standardized per 1 g of
soil weight. 'adal.v' is the acid-aldehyde ratio of the vanillyl
family.gcb_lignin.csvSoils EA/IRMSFile with results of elemental analysis
and isotope ratio mass spectrometry. Note that plot number needs to be
paired with treatment ('trt') to generate a unique ID.
'Back' column identifies whether data is from background survey
of exclosures, or from pulse-chase plots.Soils_EAIRMS.csvPulse Chase
Vegetation EA/IRMSData with results of EA/IRMS analysis on plant samples
from pulse chase experiment. Note that plot number and treatment must be
combined to generate a unique plot ID. Harvest identifies time post pulse
(2 days, 7 days, or 32 days). Pool identifies whether it is shoots
('Ag Veg'), roots or rhizomes ('Rh'). 'Sub'
represents replicated harvested swaths ('A' or 'B')
per harvest date (for 2 day and 7 day only, hence 32 day is identified as
AA). One sample was accidentally combined in the field and is identified
with A/B. Biomass is reported only for the t = 0 initial harvests of
aboveground material.PulseChase_VegDataALL.csvPulse Chase Vegetation
MassContains dry weight biomass for all plant samples collected in pulse
chase experiment. Note that treatment and plot number must be combined to
generate unique plot ID. 'Sub' identifies replicate harvest
swath collected at each harvest date (2 day and 7 day only, 32 day only
had one swath and is thus identified as AA, as is the t=0 harvest of
aboveground tissue immediately post pulse). 'Harvest' identifies
time of harvest post pulse and is either 0 (immediately post pulse,
aboveground tissue only), '2d' (2 day), '7d' (7 day),
or '32day' (32 days). 'Pool' identifies the plant
tissue and is either shoots ('Ag Veg'), roots ('Root')
or rhizomes ('Rh'). Biomass is in grams. 'Standing
dead' represents the senesced tissue sorted out of the sample prior
to analysis, and is also in grams.PlantData_MassALL.csvPulse Chase
Microbial DataMicrobial biomass and isotope ratio data. Note that
treatment and plot number must be combined to generate a unique sample ID.
Harvest indicates time since post pulse: '48' represents 2 days,
'336' represents 7 days, and 4 represents 32 days.
'Sub' represents replicated harvest swath within a given harvest
date (2 day and 7 day only). Column 'Rep' can be ignored.
'mgC/dry_mass_soil(g)' represents the carbon concentration of
the extract, standardized per gram of soil extracted. 'd13c (permil,
versus VPDB)' is the standard isotope delta 13C value, and
'Fumigated' identifies fumigated extracts (containing lysed
microbial cell contents in addition to dissolved organic carbon, DOC) and
'unfumigated' extracts (which contain just DOC). Formulae for
calculating microbial biomass and isotope enrichment are in the main
paper, and are also explained in the open source code used to process and
analyze data available at
https://github.com/chwilson/GCB_2018).PulseChase_MicrobialData.csv
USA
Florida