Root Trait Inventory

In total, the observations in FRED 1.0 encompass 316 root traits. To better understand the breadth and depth of these traits, we have grouped them into eight categories: root anatomy, architecture, chemistry, dynamics, morphology, physiology, and the whole-root system, as well as microbial associations. These root trait categories, along with others, are described and mapped in relation to one-another in a recent publication.

Each observation in FRED is based on a single trait measurement made by an investigator on fine roots taken from a defined species or plant community at a specific location, date, and time. Many observations are plot or treatment means, and we include measures of variation and sample size where available (statistical data are not shown here). In some cases, multiple trait observations were taken from one collection of fine roots, but no sample has observations of all fine-root traits (most samples are associated with one or a few traits).

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Trait CategoryTrait TypeTraitsDescriptionSpecies ObservationsCommunity ObservationsTotal Observations
AnatomyAerenchymaRoot aerenchyma fraction of crosssectionPercentage of root cross-sectional area that consists of aerenchyma.13013
AnatomyAerenchymaRoot aerenchyma porosity fractionPercent porosity of root aerenchyma.303
AnatomyAerenchymaRoot aerenchyma presenceWhether aerenchyma is present in root.12012
AnatomyCortexRoot cortex thicknessThickness of root cortex.1886194
AnatomyHypodermisRoot exodermal wall thicknessThickness of exodermal wall from root scans.27027
AnatomyHypodermisRoot passage cell number in exodermisNumber of passage cells in exodermis.27027
AnatomyHypodermisRoot passage cell number per root circumferenceNumber of passage cells per mm root circumference.27027
AnatomyInternal mycological structuresMycorrhiza_Root length fraction that contains arbusculesPercentage of root length that contains arbuscules, determined using a random intercept method.044
AnatomyInternal mycological structuresMycorrhiza_Root length fraction that contains vesiclesPercentage of root length that contains fungal vesicles, determined using a random intercept method.044
AnatomySteleRoot stele cross-sectional fractionPercentage of root cross-sectional area that is occupied by the stele.38038
AnatomySteleRoot stele diameterDiameter of root stele.17110181
AnatomySteleRoot stele diameter/root diameter ratioStele diameter divided by root diameter.1620162
AnatomySteleRoot stele/root cortex ratioProportion of root cross sectional area occupied by the stele divided by proportion of root cross sectional area occupied by the cortex.25025
AnatomyVessels or TracheidsRoot conduit densityNumber of conduits per stele cross-section area.24024
AnatomyVessels or TracheidsRoot conduit diameterD_h=[(1/n)sigma(n/i=1)d^4]^(1/4) where d is conduit lumen diameter and n is conduit number.63063
AnatomyVessels or TracheidsRoot conduit wall thicknessThickness of conduit wall from root scans.24024
AnatomyVessels or TracheidsRoot metaxylem cell wall thicknessThickness of the cell wall in the root metaxylem.404
AnatomyVessels or TracheidsRoot metaxylem cell wall thickness/vessel diameter ratioPercentage of metaxylem vessel diameter that consists of cell wall thickness.404
AnatomyVessels or TracheidsRoot metaxylem vessel diameterVessel diameter of root metaxylem.404
AnatomyVessels or TracheidsRoot number of tracheary elementsNumber of tracheary elements present in root, with secondary cell-wall thickening counted per xylem pole.505
AnatomyVessels or TracheidsRoot protoxylem cell wall thicknessThickness of the cell wall in the root protoxylem.404
AnatomyVessels or TracheidsRoot protoxylem cell wall thickness per protoxylem diameterPercentage of protoxylem vessel diameter that consists of cell wall thickness.404
AnatomyVessels or TracheidsRoot protoxylem diameterVessel diameter of root protoxylem.404
AnatomyVessels or TracheidsRoot vessel diameterDiameter of root vessels.1030103
AnatomyVessels or TracheidsRoot xylem vessel number per root stele areaNumber of xylem vessels per square millimeter of root stele.1290129
ArchitectureTopologyRoot branching architecture_Root length per higher order root lengthRoot length for a given order divided by the length of the roots in the higher order.2320232
ArchitectureTopologyRoot branching intensity (branching ratio)_Number of roots per higher order rootNumber of roots in a given order divided by the number of roots in the higher order.4105415
ArchitectureTopologyRoot branching intensity_root tips per higher order root lengthNumber of lower order roots  per centimeter length of higher-order root.1589167
ArchitectureTopologyRoot dichotomous branching indexDetermined by formula [Pe ? min(Pe)] / [max(Pe) ? min(Pe)]. DBI of 1 indicates a completely herringbone topology, while DBI of 0 indicates a completely dichotomous topology.404
ArchitectureTopologyRoot external path length (Pe)Sum of the number of links in all paths from each external link (root segment between two nodes) to the base link (the link from which all other links descend). (Definition from Beidler et al 2015, DOI: 10.1111/nph.13123).404
ArchitectureTopologyRoot fractal dimensionFractal dimension of scanned roots.34034
ArchitectureTopologyRoot link branching angleMean angle between a link (segments of roots between two nodes or a node and a tip) and the extension of the link before it.404
ArchitectureTopologyRoot link lengthLength of root links (segments of roots between two nodes or a node and a tip).38038
ArchitectureTopologyRoot links per root branchNumber of links (segments of roots between two nodes or a node and a tip) per root branch.404
ArchitectureTopologyRoot tip fraction per root diameter classProportion of total number of root tips comprised by a particular diameter class.3300330
ArchitectureTopologyRoot tips per ground areaTotal number of root tips per square meter of ground area (sampled from a given depth increment).51051
ArchitectureTopologyRoot tips per minirhizotron frameNumber of root tips observed per minirhizotron frame.36036
ArchitectureTopologyRoot tips per plantTotal number of root tips for an entire plant.707
ArchitectureTopologyRoot tips per root branchNumber of root tips and root endings per root branch.404
ArchitectureTopologyRoot tips per root massNumber of root tips per gram of root mass.24226
ArchitectureTopologyRoot tips per soil volumeNumber of root tips per liter of soil.24226
ArchitectureTopologyRoot topological index (TI)Slope of the linear regression of log10(Pe) against log10µ, in which Pe is external path length and µ represents magnitude (number of root tips in the system). A greater TI indicates a more ?herringbone? branching system.404
ArchitectureTopologySpecific root forks density (SRFD)Number of root bifurcations per gram of root mass.3912
ArchitectureTopologySpecific root tip abundance (SRTA)Number of root tips per milligram of root mass.73982
ChemistryCelluloseRoot cellulose and hemicellulose content per root massSum of concentrations of cellulose and all hemicelluloses in root.15015
ChemistryCelluloseRoot cellulose contentConcentration of cellulose in root.8815103
ChemistryCelluloseRoot cellulose content per root C contentPercentage of root carbon that is cellulose.707
ChemistryCelluloseRoot hemicellulose content per root C contentPercentage of root carbon that is hemicellulose.202
ChemistryCelluloseRoot hemicellulose content per root dry massSum of concentrations of all hemicelluloses in root.761187
ChemistryConstruction costRoot construction costGrams of glucose equivalent per gram of root dry weight.27027
ChemistryMacronutrientsRoot 15N contentConcentration of nitrogen stable isotope in sampled roots, determined with a mass spectrometer.505
ChemistryMacronutrientsRoot C contentMass of carbon per root mass for sampled roots.70572777
ChemistryMacronutrientsRoot Ca contentMass of calcium per root mass for sampled roots.349152501
ChemistryMacronutrientsRoot growth_Length produced per P contentRoot length produced per unit mass of root phosphorus.13013
ChemistryMacronutrientsRoot K contentMass of potassium per root mass for sampled roots.327233560
ChemistryMacronutrientsRoot Mg contentMass of magnesium per root mass for sampled roots.307147454
ChemistryMacronutrientsRoot N contentMass of nitrogen per root mass for sampled roots.28567383594
ChemistryMacronutrientsRoot N content per root lengthRoot nitrogen mass per meter of root length.1314135
ChemistryMacronutrientsRoot N_Molar organic N contentMillimoles of organic nitrogen in root per gram of root mass.20020
ChemistryMacronutrientsRoot P contentMass of phosphorous per root mass for sampled roots.690242932
ChemistryMacronutrientsRoot S contentMass of sulfur per root mass for sampled roots.5946105
ChemistryMicronutrientsRoot Al contentMass of aluminum per root mass for sampled roots.434083
ChemistryMicronutrientsRoot Al content per root fresh massMass of root aluminum per fresh mass for sampled roots.606
ChemistryMicronutrientsRoot As contentMass of arsenic per root mass for sampled roots.361652
ChemistryMicronutrientsRoot B contentMass of boron per root mass for sampled roots.099
ChemistryMicronutrientsRoot Ca content per root fresh massMass of calcium per root fresh weight for sampled roots.606
ChemistryMicronutrientsRoot Cd contentMass of cadmium per root mass for sampled roots.36036
ChemistryMicronutrientsRoot Cl- ion contentMass of Cl- ions per root mass for sampled roots, determined with flame photometer.12012
ChemistryMicronutrientsRoot Cr contentMass of chromium per root mass for sampled roots.36844
ChemistryMicronutrientsRoot Cu contentMass of copper per root mass for sampled roots.414283
ChemistryMicronutrientsRoot Fe contentMass of iron per root mass for sampled roots.405090
ChemistryMicronutrientsRoot K content per root fresh massMass of root potassium per fresh mass for sampled roots.606
ChemistryMicronutrientsRoot Mg content per root fresh massMass of magnesium per root fresh weight for sampled roots.606
ChemistryMicronutrientsRoot Mn contentMass of manganese per root mass for sampled roots.17652228
ChemistryMicronutrientsRoot Mn content per root fresh massMass of root manganese per fresh mass for sampled roots.606
ChemistryMicronutrientsRoot Na contentMass of sodium per root mass for sampled roots.313869
ChemistryMicronutrientsRoot Na+ contentMass of Na+ ions per root mass, determined by silver ion titration.12012
ChemistryMicronutrientsRoot Ni contentMass of nickel per root mass for sampled roots.36945
ChemistryMicronutrientsRoot P content per root fresh massMass of root phosphorus per fresh mass for sampled roots.606
ChemistryMicronutrientsRoot Pb contentMass of lead per root mass for sampled roots.38846
ChemistryMicronutrientsRoot S content per root fresh massMass of root sulfur per fresh mass for sampled roots.606
ChemistryMicronutrientsRoot Si contentMass of silicon per root mass for sampled roots.17825
ChemistryMicronutrientsRoot Zn contentMass of zinc per root mass for sampled roots.6743110
ChemistrySecondary compoundsRoot 12 phenol content per root C contentTotal concentration of twelve monophenols extracted from root per root C content.35035
ChemistrySecondary compoundsRoot acid hydrolyzable compounds contentConcentration of acid soluble compounds in root.1213124
ChemistrySecondary compoundsRoot acid insoluble fraction (AIF)Root acid-insoluble carbon fraction.1217128
ChemistrySecondary compoundsRoot alkyl C content per root C contentFraction of root carbon that is in alkyl groups.808
ChemistrySecondary compoundsRoot arabinans contentConcentration of arabinans in root.1217128
ChemistrySecondary compoundsRoot aromatic C content per root C contentFraction of root carbon that is in aromatic groups.404
ChemistrySecondary compoundsRoot ash C content per root C contentPercentage of root carbon that is ash.13013
ChemistrySecondary compoundsRoot ash contentConcentration of ash in root.13013
ChemistrySecondary compoundsRoot bound phenol content per root C contentConcentration of phenolic compounds that are bound to cell walls through ester/ether linkages per root carbon content.35035
ChemistrySecondary compoundsRoot cinnamyl phenol content per root C contentConcentration of cinnamyl phenols in root per root carbon content.505
ChemistrySecondary compoundsRoot ethanol soluble fractionPercentage of root tissue that is soluble in ethanol.10010
ChemistrySecondary compoundsRoot free phenol content per root C contentConcentration of phenolic compounds that are nonassociated forms in cell vacuoles per root carbon content.35035
ChemistrySecondary compoundsRoot galactans fractionConcentration of galactans in root.10010
ChemistrySecondary compoundsRoot lignin contentConcentration of lignin in root.16156217
ChemistrySecondary compoundsRoot lignin content per root C contentPercentage of root carbon that exists as lignin.707
ChemistrySecondary compoundsRoot lignin phenol content per root C contentTotal concentration of monophenols that constitute lignin in root per root carbon content.35035
ChemistrySecondary compoundsRoot lignin phenol vegetation index (LPVI)[S%(S% + 1)/(V% + 1) + 1] * [C%(C% + 1)/(V% + 1) + 1], where V%, S%, and C% are the respective percentages of vanillyl phenol, syringyl phenol, and cinnamyl phenol in root lignin. Indicator for taxonomic source identification.505
ChemistrySecondary compoundsRoot lipid contentConcentration of lipids in root.707
ChemistrySecondary compoundsRoot lipid content per root C contentPercentage of root carbon that exists as lipids.101
ChemistrySecondary compoundsRoot mannans contentConcentration of mannans in root.10010
ChemistrySecondary compoundsRoot neutral detergent soluble fractionPercentage of root mass that is soluble in neutral detergent.617
ChemistrySecondary compoundsRoot non-acid hydrolyzable compounds contentConcentration of compounds in root that are not acid soluble.1163119
ChemistrySecondary compoundsRoot nonpolar compounds contentConcentration of nonpolar compounds in root.12710137
ChemistrySecondary compoundsRoot O-alkyl C content per root C contentFraction of root carbon that is in O-alkyl groups.404
ChemistrySecondary compoundsRoot phenols contentConcentration of phenols per unit root dry mass.24125
ChemistrySecondary compoundsRoot p-hydroxy phenol content per root C contentConcentration of p-hydroxybenzoic acid, p-hydroxyacetophenon, and p-hydroxybenzaldehyde phenols in root per root C content.505
ChemistrySecondary compoundsRoot polar compounds contentConcentration of polar compounds in root.1023105
ChemistrySecondary compoundsRoot polyphenol contentConcentration of polyphenols in root.19120
ChemistrySecondary compoundsRoot rhamnan contentConcentration of rhamnans in root.10010
ChemistrySecondary compoundsRoot structural C content per root C contentPercentage of root carbon that is structural.202
ChemistrySecondary compoundsRoot syringyl phenol content per root C contentConcentration of syringyl phenols in root per root C content.505
ChemistrySecondary compoundsRoot vanillyl phenol content per root C contentConcentration of vanillyl phenols in root per root C content.505
ChemistrySecondary compoundsRoot water or ethanol soluble compounds fractionPercentage of root tissue that is soluble in water or ethanol.29736
ChemistrySecondary compoundsRoot water soluble compounds fractionPercentage of root tissue that is soluble in water.711788
ChemistrySecondary compoundsRoot water soluble compounds per root dry massPercentage of root tissue that consist of water-soluble sugars, as determined by a phenol?sulfuric acid assay.44751
ChemistrySecondary compoundsRoot water soluble phenol compounds per root dry massPercentage of root tissue that consists of water-soluble phenols.505
ChemistrySecondary compoundsRoot xylan contentConcentration of xylans in root.10010
ChemistryStoichiometryRoot 3,5-dihydroxybenzoic acid groups/vanillyl phenols ratioPercent of 3,5-dihydroxybenzoic acid to vanillyl phenols in root. Indicative of degradation status.505
ChemistryStoichiometryRoot acid/aldehyde ratio for syringyl phenolsRatio of acid to aldehyde in root syringyl phenols. Indicative of diagenetic state of lignin.505
ChemistryStoichiometryRoot acid/aldehyde ratio for vanillyl phenolsRatio of acid to aldehyde in root vanillyl phenols. Indicative of diagenetic state of lignin.505
ChemistryStoichiometryRoot C/N ratioRatio of carbon to nitrogen in root by mass.10722091281
ChemistryStoichiometryRoot cinnamyl phenol/vanillyl phenol ratioRatio of cinnamyl phenol to vanillyl phenol in root. Index for woody or nonwoody source.505
ChemistryStoichiometryRoot lignin/N ratioRatio of lignin concentration to N concentration in root.211031
ChemistryStoichiometryRoot NAH/root N ratioRatio of non-acid hydrolysable compounds to nitrogen in root tissue.1023105
ChemistryStoichiometryRoot organic N/root total N ratioRoot organic N concentration divided by total root N concentration.20020
ChemistryStoichiometryRoot polyphenol/root N ratioRatio of root polyphenol concentration to root N concentration.606
ChemistryStoichiometryRoot syringyl/vanillyl phenol ratioRatio of syringyl phenol to vanillyl phenol in root. Index for taxonomic level (angiosperm or gymnosperm) of plant from which phenol was derived.505
ChemistryStoichiometryRoot vanillyl phenol/lignin phenol ratioRatio of vanillyl phenol to lignin phenol in root. Indicative of lignin quality.505
ChemistryTotal non-structural carbohydratesRoot non-structural carbohydrate content per root C contentPercentage of root carbon that exists as non-structural carbohydrates.101
ChemistryTotal non-structural carbohydratesRoot non-structural carbon content per root C contentPercentage of root carbon that is non-structural202
ChemistryTotal non-structural carbohydratesRoot total non-structural carbohydrate content (TNC)Glucose equivalents per dry weight of roots, determined colorimetrically.38726413
DynamicsDecompositionRoot decomposition_Annual k constantThe K constant for the root in the exponential decay function Mt = M0 e-kt, where Mt is the mass of litter after time t, and M0 is the initial mass of litter.17520195
DynamicsDecompositionRoot decomposition_Annual N immobilized in decomposing rootsAmount of nitrogen immobilized over the course of a year in decomposing roots.404
DynamicsDecompositionRoot decomposition_Annual necromass decomposition rate per ground areaAmount of root necromass that decomposes over the course of a year.01515
DynamicsDecompositionRoot decomposition_Estimated cumulative monthly mass lossDifference between cumulative growth rate and fine root biomass.066
DynamicsDecompositionRoot decomposition_Fraction mass remainingFor decomposition experiment, percentage of original root mass remaining.6924261118
DynamicsDecompositionRoot decomposition_Fraction N remainingFor decomposition experiment, percentage of original root nitrogen remaining.48096576
DynamicsDecompositionRoot decomposition_Monthly k constantK constant for a single month.01212
DynamicsDecompositionRoot decomposition_Monthly necromass decomposition rate per ground areaAmount of root necromass that decomposes over the course of a month.01212
DynamicsLifespanRoot age survivorship fractionPercentage of roots that live to the age presented in the ?root age? column.12287209
DynamicsLifespanRoot mean lifespan_dMean lifespan of roots observed, expressed in days.13845183
DynamicsLifespanRoot mean lifespan_Main_dMean Lifespan in days. This column combines data from both ?Lifespan_days? and ?Lifespan_years? columns. If source originally presents lifespan in years, lifespan is converted to days for this value.17746223
DynamicsLifespanRoot mean lifespan_yrMean lifespan of roots observed, expressed in years.40040
DynamicsLifespanRoot median lifespan_dMedian lifespan of roots observed, expressed in days.18010190
DynamicsLifespanRoot median lifespan_Main_dMedian lifespan in days. This column combines data from both ?Root median lifespan_d? (F00470) and ?Root median lifespan_yr? (F01293) columns. If source originally presents lifespan in years, lifespan is converted to days for this value.19110201
DynamicsLifespanRoot median lifespan_yrMedian lifespan of roots observed, expressed in years.11011
DynamicsLifespanRoot survivorship_Fraction of root tips surviving after one yearPercentage of root tips that survive after one year.14923
DynamicsLifespanRoot survivorship_Fraction roots surviving for exposition periodPercentage of roots which survive for the time interval represented in the row (i.e., the time period between the dates in the ?[date] beginning collection? and ?[date] ending collection? columns).24024
DynamicsLifespanRoot survivorship_Fraction roots surviving for growing seasonPercentage of roots which survive over the course of a growing season.28028
DynamicsRoot growthBelowground annual biomass production per plantIncrease in biomass (by dry weight) over the course of one growing season.088
DynamicsRoot GrowthRoot growth_Annual C production per ground areaAmount of root carbon produced in one year.3197200
DynamicsRoot GrowthRoot growth_Annual length production per ground areaAnnual increase in total root length per unit ground area.121148269
DynamicsRoot GrowthRoot growth_Annual length production per minirhizotron or rhizotron surfaceRoot length produced over one year, as observed with minirhizotrons or rhizotrons.202
DynamicsRoot GrowthRoot growth_Annual length production per minirhizotron surface areaNew root length observed per square centimeter of minirhizotron surface per year.5813
DynamicsRoot GrowthRoot growth_Annual mass production per ground areaAmount of root mass produced in one year.5365091045
DynamicsRoot GrowthRoot growth_Annual net new length production per ground areaLive root length density appearance minus live root length density disappearance, adjusted to an annual value by subtracting net new length growth from the value for the previous sampling date, dividing by the number of days between sampling dates, and multiplying the result by the number of days in the year.44044
DynamicsRoot GrowthRoot growth_Annual surface area production per ground areaRoot surface area produced per square meter of ground area per year.01818
DynamicsRoot GrowthRoot growth_Bimonthly number of roots born per ingrowth screen areaInferred number of roots born per square centimeter of in-growth screen per two months.01616
DynamicsRoot GrowthRoot growth_Cumulative length production per ground areaCumulative root length density appearance per unit ground area.3760376
DynamicsRoot GrowthRoot growth_Cumulative mass production per ground areaTotal root mass produced since the beginning of the study.09393
DynamicsRoot GrowthRoot growth_Cumulative monthly mass ingrowth per screen areaCumulative rate of root growth into in-growth mesh, in kg per mesh cross-sectional area per month.066
DynamicsRoot GrowthRoot growth_Cumulative net length production per ground areaDifference between cumulative live root appearance and cumulative live root disappearance.46046
DynamicsRoot GrowthRoot growth_Daily elongation rateRate at which elongation occurs for the roots where it does occur.0192192
DynamicsRoot GrowthRoot growth_Daily length production per coarse root lengthTotal fine root length production per day for a 20-cm length of woody root.10212
DynamicsRoot GrowthRoot growth_Daily length production per minirhizotron surface areaNew root length observed per square centimeter of minirhizotron surface per day.108138246
DynamicsRoot GrowthRoot growth_Daily mass production per coarse root lengthTotal fine root mass produced per day for a 20-cm length of woody root.10212
DynamicsRoot GrowthRoot growth_Daily mass production per ground areaAmount of root mass produced in one day.04040
DynamicsRoot GrowthRoot growth_Elongation fractionPercentage of roots that have elongated since the previous measurement.0196196
DynamicsRoot GrowthRoot growth_Fraction peak productionThe root production rate observed at a specific point divided by the maximum root production rate observed during the entire observation period.1260126
DynamicsRoot GrowthRoot growth_Length production per ground area and exposition periodIncrease in root length per square meter of ground area during the observation period specified in the ?[year/month/day] beginning data collection? and ?[year/month/day] ending data collection? columns.01616
DynamicsRoot GrowthRoot growth_Length production per minirhizotron frameRoot length produced per minirhizotron frame.32032
DynamicsRoot GrowthRoot growth_Length recovery from pruningRoot length recovery from pruning.56460
DynamicsRoot GrowthRoot growth_Mass production per ground area and exposition periodRoot mass produced for the time interval specified in ?main exposition period? and ?production duration? or ?in growth duration? (columns F01294 and F0076,F01283,F01284, or F01280).07474
DynamicsRoot GrowthRoot growth_Monthly mass ingrowth per screen areaMonthly rate of root growth into in-growth mesh, in kg per mesh cross sectional area per month.066
DynamicsRoot GrowthRoot growth_Monthly mass production per ground areaAmount of root biomass produced in one month.03030
DynamicsRoot GrowthRoot growth_Monthly mass production per soil volumeRoot mass produced per cubic centimeter of soil each month.72072
DynamicsRoot GrowthRoot growth_Predicted amplitude of monthly net root productionLog of predicted amplitude of monthly net root production if it occurs (ie if mRLQ>0), based on negative binomial distribution. See Mao et al. 2013 (DOI: 10.1007/s11104-012-1324-2)for further details.02626
DynamicsRoot GrowthRoot growth_Surface area production per ground area and exposition periodIncrease in root surface area per square meter of ground area during the observation period specified in the ?[year/month/day] beginning data collection? and ?[year/month/day] ending data collection? columns.01616
DynamicsRoot GrowthRoot pruning recoveryPercentage pruned woody roots that recovered by proliferating fine roots.516
DynamicsRoot GrowthRoot relative growth rate (RGR)_Root length[In (each growth response at 30, 60 and 90 days of the treatments) - In (each growth response at 0, 30 and 60 days of the treatments, respectively)]/30 days; see Imada et al. 2008 (DOI: 10.1111/j.1365-2435.2008.01454.x) for more details.60060
DynamicsRoot MortalityRoot mortality_Annual root length mortality per ground areaAnnual mortality of root length density.1120112
DynamicsRoot MortalityRoot mortality_Annual root length mortality per minirhizotron surface areaObserved length of roots which dies per minirhizotron surface per year.51318
DynamicsRoot MortalityRoot mortality_Annual root mass mortality per ground areaAmount of root biomass that dies in one year per square meter of ground area.434588
DynamicsRoot MortalityRoot mortality_Cumulative root length disappearance per ground areaCumulative root length density disappearance observed by minirhizotron per ground area.3740374
DynamicsRoot MortalityRoot mortality_Cumulative root length mortality per minirhizotron frameRoot length mortality observed per minirhizotron frame since the beginning of observation.28028
DynamicsRoot MortalityRoot mortality_Daily root length mortality per minirhizotron surface areaObserved length of roots which dies per minirhizotron surface per day.104130234
DynamicsRoot MortalityRoot mortality_Fraction initial intersections with ingrowth screen lostFor in-growth screen, percentage of root-screen contacts lost after installation.02828
DynamicsRoot MortalityRoot mortality_Monthly mass disappearance per soil volumeMass of root biomass that disappears per cubic centimeter of soil per month.72072
DynamicsRoot MortalityRoot mortality_Monthly necromass increase per soil volumeAmount of root biomass that dies per cubic centimeter of soil per month.7230102
DynamicsRoot MortalityRoot mortality_Monthly number of roots lost per ingrowth screen areaInferred number of roots to die per square centimeter of in-growth screen per two months.01616
DynamicsRoot TurnoverRoot mortality_Root N loss per annual plant N uptakeNitrogen lost through fine root mortality as a percentage of annual whole-plant nitrogen uptake.505
DynamicsRoot TurnoverRoot mortality_Root N loss per plant N content per ground areaNitrogen lost through fine root mortality as a percentage of whole-plant N storage.505
DynamicsRoot TurnoverRoot turnover_Annual biomass turnover per ground areaRoot mass multiplied by turnover rate.322759
DynamicsRoot TurnoverRoot turnover_Estimated rate per growing seasonNumber of days in growing season divided by median lifespan of roots.16016
DynamicsRoot TurnoverRoot turnover_Mass per dry seasonTurnover during dry season as defined in original data source.088
DynamicsRoot TurnoverRoot turnover_Mass per wet seasonTurnover during wet season as defined in original data source.088
DynamicsRoot TurnoverRoot turnover_Mass per yearTurnover as the inverse of belowground net primary productivity.443360803
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction contact exploration mycorrhizaePercentage of mycorrhizal tips that are of the contact exploration type.12012
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction long-distance exploration mycorrhizaePercentage of mycorrhizal tips that are of the long-distance exploration type.12012
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction medium-distance exploration mycorrhizaePercentage of mycorrhizal tips that are of the medium-distance exploration type.12012
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction mycorrhizal root tips that are livingPercentage of mycorrhizal tips that are living.24024
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction of root lengthPercentage of root length containing mycorrhizal hyphae, arbuscules, of vesicles.76682
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction root length colonized by AM mycorrhizaePercentage of root length which shows colonization by arbuscular mycorrhizal fungi.501060
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction root length colonized by EM mycorrhizaePercentage of root length which shows colonization by arbuscular mycorrhizal fungi.044
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction root tips colonized by mycorrhizaePercentage of root tips that are colonized by mycorrhizal fungi.27310283
Microbial associationsMycorrhizal fungiMycorrhiza_Fraction short-distance exploration mycorrhizaePercentage of mycorrhizal tips that are of the short-distance exploration type.12012
Microbial associationsMycorrhizal fungiMycorrhiza_Length of AM hyphae per soil massMillimeters of arbuscular mycorrhizal hyphae per gram of soil, determined by dispersing soils in sodium metaphosphate solution, passing through a series of sieves, collecting hyphae on filters, and examining hyphae through a microscope.03131
Microbial associationsMycorrhizal fungiMycorrhiza_Number of AM spores per soil massNumber of arbuscular mycorrhizae spores per gram of soil, determined by isolating the spores using the wet-sieving technique and counting them under a microscope.066
Microbial associationsMycorrhizal fungiMycorrhiza_Number of root tips per root length colonized by mycorrhizaeNumber of tips per cm of root on root branch that contains mycorrhizal fungi.16016
Microbial associationsMycorrhizal fungiMycorrhiza_PLFA proxy for EM mass per ground areaGrams of external ectomycorrhizal mycelium biomass in soil per square meter of ground area for a given sampling depth, estimated based on PLFA with a conversion factor of 2 nmol 18:2omega6.9 per milligram of fungal biomass.12012
Microbial associationsMycorrhizal fungiMycorrhiza_TypeType of mycorrhizae formed. ?AM? = arbuscular mycorrhizae; ?EM? = ectomycorrhizae; ?EeM? = ectendomycorrhizae; ?ErM? = ericoid mycorrhizae?; ?mycorrhizal? means mycorrhizae are present but type is unknown; ?NM? = non-mycorrhizal.24262392665
Microbial associationsMycorrhizal fungiMycorrhiza_Visual estimate of root colonization intensityIntensity of mycorrhizal colonization based on the following classes: 0% for 0 class; < 1% for first; 1?10% for second; 10?50% for third; 50?90% for fourth; and finally > 90% for the fifth class. The mean of each class was then used in calculating a mean percent intensity of all the roots examined using the program MYCOCALC? (AMI).246286
Microbial associationsNitrogen fixersRoot nodules_Nodule mass on dead roots per ground areaTotal dry weight of all root nodules collected from dead roots in soil cores.202
Microbial associationsNitrogen fixersRoot nodules_Nodule mass on living roots per ground areaTotal dry weight of all root nodules collected from living roots in soil cores.303
Microbial associationsOther rhizosphere microbesMycoheterotrophy?x? denotes the presence of mycoheterotrophy. Blank indicates the data are not related to mycoheterotrophy or that mycoheterotrophy data were not available.123
Microbial associationsOther rhizosphere microbesRoot microbes_Bacterial biomass C content per root massConcentration of bacterial carbon in root material, estimated based on calculated average conversion factor of muramic acid to fungal carbon.15116
Microbial associationsOther rhizosphere microbesRoot microbes_Fungal biomass C content per root massConcentration of fungal carbon in root material, estimated based on calculated average conversion factor of glucosamine to fungal carbon.15116
Microbial associationsOther rhizosphere microbesRoot microbes_Fungal C/bacterial C ratioRatio of root fungal carbon to root bacterial carbon.15116
Microbial associationsOther rhizosphere microbesRoot microbes_Microbial biomass C content per root massCarbon from microbial biomass in roots, calculated from root ergosterol and the ergosterol/microbial biomass carbon ratio of the rhizosphere soil.14418
Microbial associationsOther rhizosphere microbesRoot microbes_Microbial biomass N content per root massNitrogen from microbial biomass in roots, calculated from root ergosterol and microbial biomass C/N ratio of the rhizosphere soil.14115
Microbial associationsOther rhizosphere microbesRoot microbes_Root glucosamine content per root massConcentration of glucosamine measured in root material.15419
Microbial associationsOther rhizosphere microbesRoot microbes_Root length hyphal fractionPercentage of root length that contains fungal hyphae, determined using a random intercept method.044
Microbial associationsOther rhizosphere microbesRoot muramic acid contentConcentration of muramic acid measured in root material.15419
Microbial associationsOther rhizosphere microbesSoil microbes_Ergosterol contentMass of ergosterol per gram of soil or growth medium.18624
Microbial associationsOther rhizosphere microbesSoil microbes_Fungal/bacterial rRNA copy number ratioRatio of fungal rRNA gene copy number to bacterial rRNA gene copy number ratio from DNA extraction and PCR runs from soil.24024
Microbial associationsOther rhizosphere microbesSoil microbes_PLFA proxy for fungal mass per soil massAmount of phospholipid fatty acid 18.2?6.9 lost during soil incubation, used as an indicator of fungal biomass in the soil.15015
MorphologyDiameterRoot diameterDiameter of roots observed.26742342908
MorphologyDry matter contentRoot dry matter content (RDMC)Root dry mass divided by root fresh mass.1040104
MorphologyRoot colorRoot color_White or brownWhether observed roots are considered to be white or brown.10010
MorphologyRoot hairsRoot hair densityNumber of root hairs per root surface area.25025
MorphologyRoot hairsRoot hair diameterDiameter of root hairs.25025
MorphologyRoot hairsRoot hair incidencePercentage of fine roots that contain root hairs, by the gridline method.06262
MorphologyRoot hairsRoot hair lengthLength of root hairs.6562127
MorphologyRoot hairsRoot hair volume per root massVolume of root hairs per gram of root mass, estimated using specific root length.28028
MorphologyRoot lengthRoot length from base to tipDistance from root base to tip.84933882
MorphologyRoot tissue densityRoot tissue density (RTD)Weight of roots sampled divided by volume of roots.1620711691
MorphologySpecific root lengthSpecific root area (SRA)Root surface area divided by root mass.47152523
MorphologySpecific root lengthSpecific root length (SRL)Length of roots divided by root mass.28612003061
PhysiologyExudationRoot acid phosphatase activity per root massAcid phosphatase activity per unit root mass.1493152
PhysiologyExudationRoot exudation_C exudation rate per root massCarbon exudation rate by mass of fine roots.808
PhysiologyExudationRoot exudation_Fraction estimated root massCollected exudates scaled as proportion of estimated biomass accumulation.404
PhysiologyExudationRoot phosphatase activity per root lengthPhosphatase activity of roots, based on release of p-nitrophenol from a solution of p-nitrophenyl phosphate per meter of root length per hour.13013
PhysiologyExudationRoot phosphatase activity per root massHydrolysis of p-nitrophenyl phosphatase to p-nitrophenol after incubation at 37°C for 1 hour.14014
PhysiologyNutrient uptakePlant N uptake rate_Annual N uptake per ground areaTotal amount of nitrogen taken up by plants per hectare over the course of a year.17481255
PhysiologyNutrient uptakeRoot Ca turnover_Annual turnover per ground areaAnnual root calcium turnover per meter square of ground area.202
PhysiologyNutrient uptakeRoot K uptake_Fraction K uptake capacity per soil depth intervalEstimated potassium uptake capacity of roots at the depth interval relative to the plant?s total uptake capacity.15015
PhysiologyNutrient uptakeRoot K_Annual turnover per ground areaAnnual root potassium turnover per meter square of ground area.202
PhysiologyNutrient uptakeRoot Mg_Annual turnover per ground areaAnnual root magnesium turnover per meter square of ground area.202
PhysiologyNutrient uptakeRoot N turnover_Annual turnover per ground areaAnnual nitrogen turnover per meter square of ground area.141226
PhysiologyNutrient uptakeRoot N uptake_Cumulative N uptakeTotal root nitrogen uptake since the first observation per meter square of ground area.20020
PhysiologyNutrient uptakeRoot N uptake_Hourly uptake of 15NH4+ per root fresh massHourly uptake of nitrogen by roots, as determined by a root bioassay using 15NH4+. Reported in terms of nanograms of NH4+.404
PhysiologyNutrient uptakeRoot N uptake_Hourly uptake of molar NH4+ per root fresh massHourly uptake of nitrogen by roots per root fresh mass, as determined by a root bioassay using 15NH4+. Reported in terms of nmol of NH4+.606
PhysiologyNutrient uptakeRoot N uptake_Hourly uptake per unit root massAmount of nitrogen taken up per unit root mass per hour.24024
PhysiologyNutrient uptakeRoot P turnover_Annual turnover per ground areaAnnual root phosphorus turnover per meter squared of ground area.202
PhysiologyNutrient uptakeRoot P uptake_Fraction maximum P uptake rateFraction of maximum phosphorus uptake rate achieved by age group  specified in F00062 and F00063.22022
PhysiologyNutrient uptakeRoot P uptake_Hourly uptake of H2PO4-Hourly uptake of H2PO4, as determined by a root bioassay.404
PhysiologyNutrient uptakeRoot P uptake_Rate per root massRate of phosphorus uptake per gram of root per second.12012
PhysiologyNutrient uptakeRoot P uptake_Rate per root surface area per secondPhosphorus uptake per unit root area, determined with tissue cassettes.18018
PhysiologyNutrient uptakeRoot preferred N formForm or forms of nitrogen preferentially taken up by roots. NH4-N is NH4, NO3-N is NO3, and ON is organic nitrogen. If multiple forms are preferred, their relative preference to each other is shown with >=,<=, or = symbols.35237
PhysiologyNutrient uptakeRoot Rb uptake_Hourly Rb uptake per root massHourly uptake rate of rubidium by roots, as determined by a root bioassay using 86Rb+. 19019
PhysiologyNutrient uptakeRoot Rb uptake_Hourly uptake of molar Rb+ per root fresh massHourly uptake rate of rubidium by roots per root fresh mass, as determined by a root bioassay using 86Rb+, reported in nmol taken up per fresh weight of roots per hour.19019
PhysiologyRespirationRoot respiration rate per root fresh mass_CO2 releaseRoot respiration rate of CO2 per g root fresh mass per second.8467151
PhysiologyRespirationRoot respiration rate per root fresh mass_O2 uptakeRoot respiration rate of O2 per root fresh mass, as measured in a respiration chamber.438160598
PhysiologyRespirationRoot respiration rate per root length_CO2 releaseRoot respiration rate of CO2 per meter of root length, as measured in a respiration chamber.36036
PhysiologyRespirationRoot respiration rate per root mass_C releaseRoot respiration rate, converted from terms of nmol O2 g-1 s-1,converted to µg C g-1 s-1using a respiratory quotient of 1.25. See Matamala & Schlesinger 2000 (DOI: 10.1046/j.1365-2486.2000.00374.x) for further details.20020
PhysiologyWater uptakeRoot water uptake per root lengthDaily water uptake in milliliters, per centimeter of root length.52052
PhysiologyWater uptakeRoot water uptake per root surface areaWater absorption rate per surface area of root.909
PhysiologyWater uptakeRoot water uptake_Hourly uptake rate per soil volumeRate of water uptake by roots, divided by the volume of soil from which roots take up water.1490149
PhysiologyWater uptakeRoot water uptake_Hydraulic conductivity (Lp)Hydraulic conductivity of roots.1400140
PhysiologyWater uptakeRoot water uptake_Treatment/control ratioWater absorption rate of treatment divided by that of the control.1780178
Root SystemAllocation within plantAboveground/belowground net primary production ratioAnnual aboveground net primary production (NPP) divided by belowground NPP.9547142
Root SystemAllocation within plantBelowground/aboveground mass ratioRatio of belowground biomass (g m-2) to aboveground biomass (g m-2).414130544
Root SystemAllocation within plantFine root C/leaf C ratioRatio of fine-root carbon to leaf carbon.304070
Root SystemAllocation within plantFine root mass/leaf mass ratioRatio of fine-root mass to leaf mass.1773691842
Root SystemAllocation within plantRoot mass fraction (RMF)Root biomass divided by total plant biomass.52631165379
Root SystemAllocation within plantRoot/shoot ratioRatio of root tissue mass to shoot mass, where rhizomes are counted as shoot mass.17440214
Root SystemAllocation within root systemCoarse root/fine root mass ratioRatio of coarse-root biomass to fine-root biomass.1608371645
Root SystemAllocation within root systemRoot length fraction per root diameter classPercentage of root length composed of a specific root diameter class.8933122
Root SystemAllocation within root systemRoot length fraction per root order classPercentage of root length composed of a specific root order.1998207
Root SystemAllocation within root systemRoot mass fraction per root diameter classPercentage of root biomass contributed by a particular diameter class.61622
Root SystemAllocation within root systemRoot mass fraction per root order classPercentage of fine-root biomass contributed by a particular root order.1570157
Root SystemAllocation within root systemRoot mass_Fraction per speciesPercentage of root mass composed of a particular species in a community.331851
Root SystemAllocation within root systemRoot necromass/biomass ratioDead root mass divided by live root mass.231477708
Root SystemAllocation within root systemRoot surface area fraction per root order classPercentage of total root surface area that a specific root order comprises.41041
Root SystemAllocation within root systemTaproot mass fractionPercentage of root mass that consists of the taproot.13013
Root SystemStanding cropBelowground biomass per ground areaRoot mass per square meter for the specified depth increment.203170649095
Root SystemStanding cropBelowground biomass per plantTotal root mass for the entire plant.5305985403
Root SystemStanding cropBelowground biomass per soil volumeKilograms of root mass per cubic meter of soil.10212114
Root SystemStanding cropBelowground necromass per ground areaDead root mass per square meter for the specified depth increment.229760989
Root SystemStanding cropMax_Root annual C content per ground areaMaximum value of root carbon stock measured per year, in mass of carbon per ground area for the specified depth increment.055
Root SystemStanding cropMin_Root annual C content per ground areaMinimum value of root carbon stock per year, in mass of carbon per ground area.055
Root SystemStanding cropRoot C content per ground areaTotal mass of root carbon per ground area.67175242
Root SystemStanding cropRoot C content per soil massMass of root carbon per gram of soil.9312
Root SystemStanding cropRoot growth_Number of roots per area of ingrowth screenNumber of roots per square cm of in-growth screen.08989
Root SystemStanding cropRoot intact branch lengthTotal root length contained within an intact root branch.404
Root SystemStanding cropRoot length density (RLD)_Root length per ground areaRoot length divided by soil core cross-sectional area.9004121312
Root SystemStanding cropRoot length density (RLD)_Root length per soil volumeRoot length divided by the sampled soil volume.3099129
Root SystemStanding cropRoot length per minirhizotron frameTotal root length observed per minirhizotron frame.32032
Root SystemStanding cropRoot length per minirhizotron surface areaMeters of root length visible per square meter of minirhizotron surface.114137251
Root SystemStanding cropRoot length per plantTotal length of all roots for an entire plant.18012192
Root SystemStanding cropRoot length ratio (RLR)Root length per gram of plant mass.56056
Root SystemStanding cropRoot length_Fraction per speciesPercentage of total root length belonging to an individual species.81018
Root SystemStanding cropRoot N content per ground areaTotal mass of root nitrogen per ground area for the specified depth increment.123332455
Root SystemStanding cropRoot N_Root N mass per soil massMass of root nitrogen per gram of soil.9312
Root SystemStanding cropRoot surface area per ground areaTotal surface area of roots per square meter of ground area.1149123
Root SystemStanding cropRoot volume per ground areaTotal volume of roots per square meter of ground area for the specified depth increment.76076
Root SystemStanding cropRooting depthDepth which includes all observed roots.129234363
Root SystemStanding cropRooting depth_Extrapolated 50 percent rooting depthDepth which includes 50 percent of total roots in profile, extrapolated from LDR model.0564564
Root SystemStanding cropRooting depth_Extrapolated 95 percent rooting depthDepth which includes 95 percent of total roots in profile, extrapolated from LDR model.0564564
Root SystemStanding cropRooting depth_Fraction roots in soil depth incrementProportion of observed roots (quantified by parameter in ?rooting depth measurement? column) contained in depth interval.57180237
Root SystemStanding cropRooting depth_Interpolated 50 percent rooting depthDepth which includes 50 percent of all observed roots in profile, calculated by fitting logistic dose-response curve to cumulative root profile and interpolating to maximum sampling depth, using the equation D_S50=D_50*([R_max/0.5R_Smax]-1)^(1/c) where Rmax is the estimated total amount of roots, RSmax is the total amount of roots in sampled profile, and C is a dimensionless shape parameter.0564564
Root SystemStanding cropRooting depth_Interpolated 95 percent rooting dephDepth which includes 95 percent of roots in profile, calculated by fitting logistic dose-response curve to cumulative root profile and interpolating to maximum sampling depth, using the equation D_S95=D_50*([R_max/0.95R_Smax]-1)^(1/c).4564568
Root SystemStanding cropRooting depth_MainDepth where most of the root activity of interest occurs.0201201