Root Trait Inventory

In total, the observations in FRED 2.0 encompass 328 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 here.

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).

Use the search box to see whether FRED 2.0 has a particular root trait of interest, or choose combinations from the Trait Category and Trait Type boxes below and click the "Filter" button to view subsets of the data.

Trait Category Trait Type Traits Description Species observations Community Observations Total observations
Root System Allocation within plant Aboveground/belowground net primary production ratio Annual aboveground net primary production (NPP) divided by belowground NPP. 101 47 148
Root System Standing crop Belowground biomass per ground area Root mass per square meter for the specified depth increment. 2405 7096 9501
Root System Standing crop Belowground biomass per plant Total root mass for the entire plant. 6371 300 6671
Root System Standing crop Belowground biomass per soil volume Kilograms of root mass per cubic meter of soil. 102 12 114
Root System Standing crop Belowground necromass per ground area Dead root mass per square meter for the specified depth increment. 256 784 1040
Root System Allocation within plant Belowground/aboveground mass ratio Ratio of belowground biomass (g m-2) to aboveground biomass (g m-2). 496 130 626
Root System Allocation within root system Coarse root/fine root mass ratio Ratio of coarse root biomass to fine root biomass. 1608 37 1645
Root System Allocation within plant Fine root C/leaf C ratio Ratio of fine root carbon to leaf carbon. 30 40 70
Root System Allocation within plant Fine root mass/leaf mass ratio Ratio of fine-root mass to leaf mass. 1789 69 1858
Microbial associations Other rhizosphere microbes Mycoheterotrophy x denotes the presence of mycoheterotrophy. Blank indicates the data are not related to mycoheterotrophy or that mycoheterotrophy data were not available. 1 2 3
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction contact exploration mycorrhizae Percentage of mycorrhizal tips that are of the contact exploration type. 12 0 12
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction long-distance exploration mycorrhizae Percentage of mycorrhizal tips that are of the long-distance exploration type. 12 0 12
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction medium-distance exploration mycorrhizae Percentage of mycorrhizal tips that are of the medium-distance exploration type. 12 0 12
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction mycorrhizal root tips that are living Percentage of mycorrhizal tips that are living. 24 0 24
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction of root length Percentage of root length colonized by mycorrhizal fungi, identified by the presence of mycorrhizal hyphae, arbuscules, or vesicles. This column contains information from both AM and EM colonization reported in columns F00622 and F00626, and additional data when mycorrhizal type was unspecified or both colonization types were present. 304 62 366
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction root length colonized by AM mycorrhizae Percentage of root length which shows colonization by arbuscular mycorrhizal fungi. These data may also be contained in column F00638. 106 10 116
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction root length colonized by EM mycorrhizae Percentage of root length which shows colonization by ectomycorrhizal fungi. These data may also be contained in column F00638. 8 4 12
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction root tips colonized by mycorrhizae Percentage of root tips that are colonized by mycorrhizal fungi. 273 10 283
Microbial associations Mycorrhizal fungi Mycorrhiza_Fraction short-distance exploration mycorrhizae Percentage of mycorrhizal tips that are of the short-distance exploration type. 12 0 12
Microbial associations Mycorrhizal fungi Mycorrhiza_Length of AM hyphae per soil mass Millimeters 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. 0 31 31
Microbial associations Mycorrhizal fungi Mycorrhiza_Number of AM spores per soil mass Number of arbuscular mycorrhizae spores per gram of soil, determined by isolating the spores using the wet-sieving technique and counting them under a microscope. 0 6 6
Microbial associations Mycorrhizal fungi Mycorrhiza_Number of root tips per root length colonized by mycorrhizae Number of tips per cm of root on root branch that contains mycorrhizal fungi. 16 0 16
Microbial associations Mycorrhizal fungi Mycorrhiza_PLFA proxy for EM mass per ground area Grams 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. 12 0 12
Microbial associations Mycorrhizal fungi Mycorrhiza_PLFA proxy for mycorrhizal hyphal C per soil mass Milligrams of mycorrhizal hyphal carbon per kilogram of soil mass, estimated from PLFA biomarkers as specified in Chen et al 2016 (DOI: 10.1073/pnas.1601006113). 26 0 26
Anatomy Internal mycological structures Mycorrhiza_Root length fraction that contains arbuscules Percentage of root length that contains arbuscules, determined using a random intercept method. 0 4 4
Anatomy Internal mycological structures Mycorrhiza_Root length fraction that contains vesicles Percentage of root length that contains fungal vesicles, determined using a random intercept method. 0 4 4
Microbial associations Mycorrhizal fungi Mycorrhiza_Type Type 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. 3005 249 3254
Microbial associations Mycorrhizal fungi Mycorrhiza_Visual estimate of root colonization intensity Intensity of mycorrhizal colonization based on the following classes: 0% for 0 class; 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). 24 6 30
Physiology Nutrient uptake Plant N uptake rate_Annual N uptake per ground area Total amount of nitrogen taken up by plants per hectare over the course of a year. 174 81 255
Physiology Nutrient uptake Plant N uptake_daily uptake of molar 15N-Glycine per shoot dry mass Uptake of 15N-Glycine tracer over the course of 24 hours per root dry mass, estimated with the equation F = [T(AS-AB)]/AF, where T is the plant N concentration AS is the atom percent excess 15N in the sample, AB is the atom percent excess 15N in the natural sample, and AF is the atom percent excess 15N in the tracer. 10 0 10
Physiology Nutrient uptake Plant N uptake_daily uptake of molar 15NH4+ per shoot dry mass Uptake of 15N-NH4+ tracer over the course of 24 hours per root dry mass, estimated with the equation F = [T(AS-AB)]/AF, where T is the plant N concentration AS is the atom percent excess 15N in the sample, AB is the atom percent excess 15N in the natural sample, and AF is the atom percent excess 15N in the tracer. 10 0 10
Physiology Nutrient uptake Plant N uptake_daily uptake of molar 15NO3- per shoot dry mass Uptake of 15N-NO3- tracer over the course of 24 hours per root dry mass, estimated with the equation F = [T(AS-AB)]/AF, where T is the plant N concentration AS is the atom percent excess 15N in the sample, AB is the atom percent excess 15N in the natural sample, and AF is the atom percent excess 15N in the tracer. 10 0 10
Physiology Nutrient uptake Plant N uptake_daily uptake of molar total 15N per shoot dry mass Combined uptake of 15N-NH4+, 15N-NO3-, and 15N-Glycine tracers over the course of 24 hours per root dry mass, estimated with the equation F = [T(AS-AB)]/AF, where T is the plant N concentration AS is the atom percent excess 15N in the sample, AB is the atom percent excess 15N in the natural sample, and AF is the atom percent excess 15N in the tracer. 10 0 10
Chemistry Secondary compounds Root 12 phenol content per root C content Total concentration of twelve monophenols extracted from root per root C content. 35 0 35
Chemistry Macronutrients Root 15N content Concentration of nitrogen stable isotope in sampled roots, determined with a mass spectrometer. 5 0 5
Chemistry Stoichiometry Root 3,5-dihydroxybenzoic acid groups/vanillyl phenols ratio Percent of 3,5-dihydroxybenzoic acid to vanillyl phenols in root. Indicative of degradation status. 5 0 5
Chemistry Secondary compounds Root acid hydrolyzable compounds content Concentration of acid soluble compounds in root. 140 3 143
Chemistry Secondary compounds Root acid insoluble fraction (AIF) Root acid-insoluble carbon fraction. 143 7 150
Physiology Exudation Root acid phosphatase activity per root mass Acid phosphatase activity per unit root mass. 149 3 152
Chemistry Stoichiometry Root acid/aldehyde ratio for syringyl phenols Ratio of acid to aldehyde in root syringyl phenols. Indicative of diagenetic state of lignin. 5 0 5
Chemistry Stoichiometry Root acid/aldehyde ratio for vanillyl phenols Ratio of acid to aldehyde in root vanillyl phenols. Indicative of diagenetic state of lignin. 5 0 5
Anatomy Aerenchyma Root aerenchyma fraction of cross section Percentage of root cross-sectional area that consists of aerenchyma. 13 0 13
Anatomy Aerenchyma Root aerenchyma porosity fraction Percent porosity of root aerenchyma. 3 0 3
Anatomy Aerenchyma Root aerenchyma presence Whether aerenchyma are present in root. 12 0 12
Dynamics Lifespan Root age survivorship fraction Percentage of roots that live to the age presented in the "root age" column. 308 87 395
Chemistry Micronutrients Root Al content Mass of aluminum per root mass for sampled roots. 55 40 95
Chemistry Micronutrients Root Al content per root fresh mass Mass of root aluminum per fresh mass for sampled roots. 6 0 6
Chemistry Secondary compounds Root alkyl C content per root C content Fraction of root carbon that is in alkyl groups. 8 0 8
Chemistry Secondary compounds Root arabinans content Concentration of arabinans in root. 10 0 10
Chemistry Secondary compounds Root aromatic C content per root C content Fraction of root carbon that is in aromatic groups. 4 0 4
Chemistry Micronutrients Root As content Mass of arsenic per root mass for sampled roots. 36 16 52
Chemistry Secondary compounds Root ash C content per root C content Percentage of root carbon that is ash. 13 0 13
Chemistry Secondary compounds Root ash content Concentration of ash in root. 13 0 13
Chemistry Micronutrients Root B content Mass of boron per root mass for sampled roots. 0 9 9
Chemistry Secondary compounds Root bound phenol content per root C content Concentration of phenolic compounds that are bound to cell walls through ester/ether linkages per root carbon content. 35 0 35
Architecture Topology Root branching architecture_Root length per higher order root length Root length for a given order divided by the length of the roots in the higher order. 232 0 232
Architecture Topology Root branching intensity (branching ratio)_Number of roots per higher order root Number of roots in a given order divided by the number of roots in the higher order. 474 6 480
Architecture Topology Root branching intensity_root tips per higher order root length Number of lower order roots per centimeter length of higher-order root. 24 2 26
Architecture Topology Root branching intensity_root tips per total root length Number of lower-order roots per total root length. 183 12 195
Chemistry Macronutrients Root C content Mass of carbon per root mass for sampled roots. 2223 166 2389
Root System Standing crop Root C content per ground area Total mass of root carbon per ground area. 73 175 248
Root System Standing crop Root C content per soil mass Mass of root carbon per gram of soil. 9 3 12
Chemistry Stoichiometry Root C/N ratio Ratio of carbon to nitrogen in root by mass. 2952 307 3259
Chemistry Macronutrients Root Ca content Mass of calcium per root mass for sampled roots. 457 156 613
Chemistry Micronutrients Root Ca content per root fresh mass Mass of calcium per root fresh weight for sampled roots. 6 0 6
Chemistry Micronutrients Root Cd content Mass of cadmium per root mass for sampled roots. 36 0 36
Chemistry Cellulose Root cellulose and hemicellulose content per root mass Sum of concentrations of cellulose and all hemicelluloses in root. 15 0 15
Chemistry Cellulose Root cellulose content Concentration of cellulose in root. 164 15 179
Chemistry Cellulose Root cellulose content per root C content Percentage of root carbon that is cellulose. 7 0 7
Chemistry Secondary compounds Root cinnamyl phenol content per root C content Concentration of cinnamyl phenols in root per root carbon content. 5 0 5
Chemistry Stoichiometry Root cinnamyl phenol/vanillyl phenol ratio Ratio of cinnamyl phenol to vanillyl phenol in root. Index for woody or nonwoody source. 5 0 5
Chemistry Micronutrients Root Cl- ion content Mass of Cl- ions per root mass for sampled roots, determined with flame photometer. 12 0 12
Morphology Root color Root color_White or brown Whether observed roots are considered to be white or brown. 98 0 98
Chemistry Secondary compounds Root condensed tannins Concentration of condensed tannins in root. 23 0 23
Anatomy Vessels or Tracheids Root conduit density Number of conduits per stele cross-section area. 24 0 24
Anatomy Vessels or Tracheids Root conduit diameter D_h=[(1/n)sigma(n/i=1)d^4]^(1/4) where d is conduit lumen diameter and n is conduit number. 63 0 63
Anatomy Vessels or Tracheids Root conduit wall thickness Thickness of conduit wall from root scans. 24 0 24
Chemistry Construction cost Root construction cost Grams of glucose equivalent per gram of root dry weight. 27 0 27
Anatomy Cortex Root cortex thickness Thickness of root cortex. 258 6 264
Chemistry Micronutrients Root Cr content Mass of chromium per root mass for sampled roots. 36 8 44
Morphology Diameter Root cross-sectional area Cross-sectional area of root. 62 0 62
Chemistry Micronutrients Root Cu content Mass of copper per root mass for sampled roots. 41 42 83
Dynamics Decomposition Root decomposition_Annual k constant The 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. 547 197 744
Dynamics Decomposition Root decomposition_Annual N immobilized in decomposing roots Amount of nitrogen immobilized over the course of a year in decomposing roots. 4 0 4
Dynamics Decomposition Root decomposition_Annual necromass decomposition rate per ground area Amount of root necromass that decomposes over the course of a year. 0 15 15
Dynamics Decomposition Root decomposition_Estimated cumulative monthly mass loss Difference between cumulative growth rate and fine root biomass. 0 6 6
Dynamics Decomposition Root decomposition_Fraction C remaining For decomposition experiment, percentage of original root carbon remaining. 30 9 39
Dynamics Decomposition Root decomposition_Fraction mass remaining For decomposition experiment, percentage of original root mass remaining. 1034 426 1460
Dynamics Decomposition Root decomposition_Fraction N remaining For decomposition experiment, percentage of original root nitrogen remaining. 679 105 784
Dynamics Decomposition Root decomposition_Monthly k constant K constant for a single month. 0 12 12
Dynamics Decomposition Root decomposition_Monthly necromass decomposition rate per ground area Amount of root necromass that decomposes over the course of a month. 0 12 12
Morphology Diameter Root diameter Diameter of roots observed. 4957 555 5512
Architecture Topology Root dichotomous branching index Determined 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. 4 0 4
Morphology Dry matter content Root dry matter content (RDMC) Root dry mass divided by root fresh mass. 217 0 217
Chemistry Secondary compounds Root ethanol soluble fraction Percentage of root tissue that is soluble in ethanol. 10 0 10
Anatomy Hypodermis Root exodermal wall thickness Thickness of exodermal wall from root scans. 27 0 27
Architecture Topology Root 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). 803 202 1005
Physiology Exudation Root exudation_C exudation rate per root mass Carbon exudation rate by mass of fine roots. 24 0 24
Physiology Exudation Root exudation_Fraction estimated root mass Collected exudates scaled as proportion of estimated biomass accumulation. 4 0 4
Physiology Exudation Root exudation_molar C exudation rate per root area Root carbon exudation rate in terms of micromoles of Carbon exuded per root area. 32 0 32
Chemistry Micronutrients Root Fe content Mass of iron per root mass for sampled roots. 40 50 90
Architecture Topology Root forks per root length Number of root forks per cm of root length. 0 24 24
Architecture Topology Root fractal dimension Fractal dimension of scanned roots. 833 313 1146
Chemistry Secondary compounds Root free phenol content per root C content Concentration of phenolic compounds that are nonassociated forms in cell vacuoles per root carbon content. 35 0 35
Chemistry Secondary compounds Root galactans fraction Concentration of galactans in root. 10 0 10
Dynamics Root Growth Root growth_Annual C production per ground area Amount of root carbon produced in one year. 6 197 203
Dynamics Root Growth Root growth_Annual length production per ground area Annual increase in total root length per unit ground area. 145 148 293
Dynamics Root Growth Root growth_Annual length production per minirhizotron surface area New root length observed per square centimeter of minirhizotron surface per year. 5 8 13
Dynamics Root Growth Root growth_Annual mass production per ground area Amount of root mass produced in one year. 608 527 1135
Dynamics Root Growth Root growth_Annual net new length production per ground area Live 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. 44 0 44
Dynamics Root Growth Root growth_Annual surface area production per ground area Root surface area produced per square meter of ground area per year. 24 18 42
Dynamics Root Growth Root growth_Bimonthly number of roots born per ingrowth screen area Inferred number of roots born per square centimeter of in-growth screen per two months. 0 16 16
Dynamics Root Growth Root growth_Cumulative length production per ground area Cumulative root length density appearance per unit ground area. 376 0 376
Dynamics Root Growth Root growth_Cumulative mass production per ground area Total root mass produced since the beginning of the study. 0 93 93
Dynamics Root Growth Root growth_Cumulative monthly mass ingrowth per screen area Cumulative rate of root growth into in-growth mesh, in kg per mesh cross-sectional area per month. 0 6 6
Dynamics Root Growth Root growth_Cumulative net length production per ground area Difference between cumulative live root appearance and cumulative live root disappearance. 46 0 46
Dynamics Root Growth Root growth_Daily elongation rate Rate at which elongation occurs for the roots where it does occur. 0 192 192
Dynamics Root Growth Root growth_Daily length production per coarse root length Total fine root length production per day per length of woody root. 10 2 12
Dynamics Root Growth Root growth_Daily length production per minirhizotron surface area New root length observed per square centimeter of minirhizotron surface per day. 108 138 246
Dynamics Root Growth Root growth_Daily mass production per coarse root length Total fine root mass produced per day per length of woody root. 10 2 12
Dynamics Root Growth Root growth_Daily mass production per ground area Amount of root mass produced in one day. 0 40 40
Dynamics Root Growth Root growth_Elongation fraction Percentage of roots that have elongated since the previous measurement. 0 196 196
Dynamics Root Growth Root growth_Fraction peak production The root production rate observed at a specific point divided by the maximum root production rate observed during the entire observation period. 126 0 126
Dynamics Root Growth Root growth_Length produced per P content Root length produced per unit mass of root phosphorus. 13 0 13
Dynamics Root Growth Root growth_Length production per ground area and exposition period Increase 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. 0 16 16
Dynamics Root Growth Root growth_Length production per minirhizotron frame Root length produced per minirhizotron frame. 32 0 32
Dynamics Root Growth Root growth_Length recovery from pruning Root length recovery from pruning. 56 4 60
Dynamics or F01280)." Root growth_Mass production per ground area and exposition period Root biomass produced for the time interval specified in main exposition period" and "production duration" or "in growth duration" (columns F01294 and F0076 0 74 0
Dynamics Root growth Root growth_Mass production per plant per growing season Increase in biomass per plant (by dry weight) over the course of one growing season. 0 8 8
Dynamics Root Growth Root growth_Monthly mass ingrowth per screen area Monthly rate of root growth into in-growth mesh, in kg per mesh cross sectional area per month. 0 6 6
Dynamics Root Growth Root growth_Monthly mass production per ground area Amount of root mass produced in one month. 45 30 75
Dynamics Root Growth Root growth_Monthly mass production per soil volume Root mass produced per cubic centimeter of soil each month. 84 0 84
Root System Standing crop Root growth_Number of roots per area of ingrowth screen Number of roots per square cm of in-growth screen. 0 89 89
Dynamics Root Growth Root growth_Predicted amplitude of monthly net root production Log 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. 0 26 26
Dynamics Root Growth Root growth_Surface area production per ground area and exposition period Increase in root surface area per square meter of ground area during the observation period specified in the "Exposition period_main" column [F01294]. 0 16 16
Morphology Root hairs Root hair density Number of root hairs per root surface area. 25 0 25
Morphology Root hairs Root hair diameter Diameter of root hairs. 25 0 25
Morphology Root hairs Root hair incidence Percentage of fine roots that contain root hairs, by the gridline method. 0 62 62
Morphology Root hairs Root hair length Length of root hairs. 65 62 127
Morphology Root hairs Root hair volume per root mass Volume of root hairs per gram of root mass, estimated using specific root length. 28 0 28
Chemistry Cellulose Root hemicellulose content per root C content Percentage of root carbon that is hemicellulose. 2 0 2
Chemistry Cellulose Root hemicellulose content per root mass Percentage of root mass that is hemicellulose. 152 11 163
Root System Standing crop Root intact branch length Total root length contained within an intact root branch. 4 0 4
Chemistry Macronutrients Root K content Mass of potassium per root mass for sampled roots. 416 233 649
Chemistry Micronutrients Root K content per root fresh mass Mass of root potassium per fresh mass for sampled roots. 6 0 6
Physiology Nutrient uptake Root K uptake_Fraction K uptake capacity per soil depth interval Estimated potassium uptake capacity of roots at the depth interval specified in Soil depth_Upper sampling depth (F00068) and Soil depth_Lower sampling depth (F00069) relative to the plant's total uptake capacity. 15 0 15
Root System Standing crop Root length density (RLD)_Root length per ground area Root length divided by soil core cross-sectional area. 673 349 1022
Root System Standing crop Root length density (RLD)_Root length per soil volume Root length divided by the sampled soil volume. 496 196 692
Root System Allocation within root system Root length fraction per root diameter class Percentage of root length composed of a specific root diameter class. 89 33 122
Root System Allocation within root system Root length fraction per root order class Percentage of root length composed of a specific root order. 200 7 207
Morphology Root length Root length from base to tip Distance from root base to tip. 980 35 1015
Root System Standing crop Root length per minirhizotron frame Total root length observed per minirhizotron frame. 32 0 32
Root System Standing crop Root length per minirhizotron surface area Meters of root length visible per square meter of minirhizotron surface. 170 137 307
Root System Standing crop Root length per plant Total length of all roots for an entire plant. 1226 214 1440
Root System Standing crop Root length ratio (RLR) Root length per gram of plant mass. 56 0 56
Root System Standing crop Root length_Fraction per species Percentage of total root length belonging to an individual species. 8 10 18
Chemistry Secondary compounds Root lignin content Concentration of lignin in root. 411 163 574
Chemistry Secondary compounds Root lignin content per root C content Percentage of root carbon that exists as lignin. 7 0 7
Chemistry Secondary compounds Root lignin phenol content per root C content Total concentration of monophenols that constitute lignin in root per root carbon content. 35 0 35
Chemistry Secondary compounds Root 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. 5 0 5
Chemistry Stoichiometry Root lignin/N ratio Ratio of lignin concentration to N concentration in root. 73 10 83
Architecture Topology Root link branching angle Mean angle between a link (segments of roots between two nodes or a node and a tip) and the extension of the link before it. 803 313 1116
Architecture Topology Root link length Length of root links (segments of roots between two nodes or a node and a tip). 957 313 1270
Architecture Topology Root links per root branch Number of links (segments of roots between two nodes or a node and a tip) per root branch. 4 0 4
Chemistry Secondary compounds Root lipid content Concentration of lipids in root. 18 0 18
Chemistry Secondary compounds Root mannans content Concentration of mannans in root. 10 0 10
Root System Allocation within plant Root mass fraction (RMF) Root biomass divided by total plant biomass. 5307 116 5423
Root System Allocation within root system Root mass fraction per root diameter class Percentage of root biomass contributed by a particular diameter class. 140 16 156
Root System Allocation within root system Root mass fraction per root order class Percentage of root biomass contributed by a particular root order. 233 0 233
Root System Allocation within root system Root mass_Fraction per species Percentage of total root mass composed of a particular species in a community. 34 17 51
Dynamics Lifespan Root mean lifespan_d Mean lifespan of roots observed, expressed in days. 191 45 236
Dynamics 289 Root mean lifespan_Main_d Mean lifespan in days. This column combines data from both Root mean lifespan_d" (F00470) and "Root mean lifespan_yr" (F01292) columns. If source originally presents lifespan in years or months 0 45 244
Dynamics Lifespan Root mean lifespan_yr Mean lifespan of roots observed, expressed in years. 53 0 53
Dynamics Lifespan Root median lifespan_d Median lifespan of roots observed, expressed in days. 220 10 230
Dynamics 241 Root median lifespan_Main_d Median 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 0 10 231
Dynamics Lifespan Root median lifespan_yr Median lifespan of roots observed, expressed in years. 11 0 11
Anatomy Vessels or Tracheids Root metaxylem cell wall thickness Thickness of the cell wall in the root metaxylem. 4 0 4
Anatomy Vessels or Tracheids Root metaxylem cell wall thickness/vessel diameter ratio Percentage of metaxylem vessel diameter that consists of cell wall thickness. 4 0 4
Anatomy Vessels or Tracheids Root metaxylem vessel diameter Vessel diameter of root metaxylem. 4 0 4
Chemistry Macronutrients Root Mg content Mass of magnesium per root mass for sampled roots. 378 147 525
Chemistry Micronutrients Root Mg content per root fresh mass Mass of magnesium per root fresh weight for sampled roots. 6 0 6
Microbial associations Other rhizosphere microbes Root microbes_Bacterial biomass C content per root mass Concentration of bacterial carbon in root material, estimated based on calculated average conversion factor of muramic acid to fungal carbon. 15 1 16
Microbial associations Other rhizosphere microbes Root microbes_Fungal biomass C content per root mass Concentration of fungal carbon in root material, estimated based on calculated average conversion factor of glucosamine to fungal carbon. 15 1 16
Microbial associations Other rhizosphere microbes Root microbes_Fungal C/bacterial C ratio Ratio of root fungal carbon to root bacterial carbon. 15 1 16
Microbial associations Other rhizosphere microbes Root microbes_Microbial biomass C content per root mass Carbon from microbial biomass in roots, calculated from root ergosterol and the ergosterol/microbial biomass carbon ratio of the rhizosphere soil. 14 4 18
Microbial associations Other rhizosphere microbes Root microbes_Microbial biomass N content per root mass Nitrogen from microbial biomass in roots, calculated from root ergosterol and microbial biomass C/N ratio of the rhizosphere soil. 14 1 15
Microbial associations Other rhizosphere microbes Root microbes_Root glucosamine content per root mass Concentration of glucosamine measured in root material. 15 4 19
Microbial associations Other rhizosphere microbes Root microbes_Root length hyphal fraction Percentage of root length that contains fungal hyphae, determined using a random intercept method. 0 4 4
Chemistry Micronutrients Root Mn content Mass of manganese per root mass for sampled roots. 192 52 244
Chemistry Micronutrients Root Mn content per root fresh mass Mass of root manganese per fresh mass for sampled roots. 6 0 6
Dynamics Root Mortality Root mortality_Annual root length mortality per ground area Annual mortality of root length density. 112 0 112
Dynamics Root Mortality Root mortality_Annual root length mortality per minirhizotron surface area Observed length of roots which dies per minirhizotron surface per year. 5 13 18
Dynamics Root Mortality Root mortality_Annual root mass mortality per ground area Amount of root biomass that dies in one year per square meter of ground area. 43 45 88
Dynamics Root Mortality Root mortality_Cumulative root length disappearance per ground area Cumulative root length density disappearance observed per ground area. 374 0 374
Dynamics Root Mortality Root mortality_Cumulative root length mortality per minirhizotron frame Root length mortality observed per minirhizotron frame since the beginning of observation. 28 0 28
Dynamics Root Mortality Root mortality_Daily root length mortality per minirhizotron surface area Observed length of roots which dies per minirhizotron surface per day. 104 130 234
Dynamics Root Mortality Root mortality_Fraction initial intersections with ingrowth screen lost For in-growth screen, percentage of root-screen contacts lost after installation. 0 28 28
Dynamics Root Mortality Root mortality_Monthly mass disappearance per soil volume Mass of root biomass that disappears per cubic centimeter of soil per month. 72 0 72
Dynamics Root Mortality Root mortality_Monthly necromass increase per soil volume Amount of root biomass that dies per cubic centimeter of soil per month. 72 30 102
Dynamics Root Mortality Root mortality_Monthly number of roots lost per ingrowth screen area Inferred number of roots to die per square centimeter of in-growth screen per two months. 0 16 16
Dynamics Root Turnover Root mortality_Root N loss per annual plant N uptake Nitrogen lost through fine root mortality as a percentage of annual nitrogen uptake. 5 0 5
Dynamics Root Turnover Root mortality_Root N loss per plant N content per ground area Nitrogen lost through fine root mortality as a percentage of whole-plant N storage (root nitrogen per ground area). 5 0 5
Microbial associations Other rhizosphere microbes Root muramic acid content Concentration of muramic acid measured in root material. 15 4 19
Chemistry Macronutrients Root N content Mass of nitrogen per root mass for sampled roots. 4688 910 5598
Root System Standing crop Root N content per ground area Total mass of root nitrogen per ground area for the specified depth increment. 124 333 457
Chemistry Macronutrients Root N content per root length Root nitrogen mass per meter of root length. 131 4 135
Physiology Nutrient uptake Root N uptake_Cumulative N uptake Total root nitrogen uptake since the first observation per meter square of ground area. 20 0 20
Physiology Nutrient uptake Root N uptake_Hourly uptake of 15NH4+ per root fresh mass Hourly uptake of nitrogen by roots per root fresh mass, as determined by a root bioassay using 15NH4+. Reported in terms of nanograms of NH4+. 4 0 4
Physiology Nutrient uptake Root N uptake_Hourly uptake of molar NH4+ per root fresh mass Hourly uptake of nitrogen by roots per root fresh mass, as determined by a root bioassay using 15NH4+. Reported in terms of nmol of NH4+. 6 0 6
Physiology Nutrient uptake Root N uptake_Hourly uptake per unit root mass Amount of nitrogen taken up per unit root mass per hour. 24 0 24
Physiology Nutrient uptake Root N uptake_molar inorganic N uptak_e per root area Hourly uptake of inorganic nitrogen in terms of micromoles of nitrogen per root area. 8 0 8
Physiology Nutrient uptake Root N uptake_molar NH4+ uptake per root area Hourly uptake of nitrogen by roots per root surface area, as determined by a root bioassay using 15NH4+. Reported in terms of umol of NH4+. 8 0 8
Physiology Nutrient uptake Root N uptake_molar NO3- uptake per root area Hourly uptake of nitrogen by roots per root surface area, as determined by a root bioassay using 15NO3-. Reported in terms of nmol of NO3-. 8 0 8
Physiology Nutrient uptake Root N uptake_molar organic N uptake per root area Hourly uptake of organic nitrogen in terms of micromoles of nitrogen per root area. 8 0 8
Chemistry Micronutrients Root Na content Mass of sodium per root mass for sampled roots. 47 38 85
Chemistry Micronutrients Root Na+ content Mass of Na+ ions per root mass, determined by silver ion titration. 12 0 12
Chemistry Stoichiometry Root NAH/root N ratio Ratio of non-acid hydrolysable compounds to nitrogen in root tissue. 102 3 105
Root System Allocation within root system Root necromass/biomass ratio Dead root mass divided by live root mass. 278 501 779
Chemistry Secondary compounds Root neutral detergent soluble fraction Percentage of root mass that is soluble in neutral detergent. 6 1 7
Chemistry Micronutrients Root Ni content Mass of nickel per root mass for sampled roots. 36 9 45
Microbial associations Nitrogen fixers Root nodules_Nodule mass on dead roots per ground area Total dry weight of all root nodules collected from dead roots in soil cores. 2 0 2
Microbial associations Nitrogen fixers Root nodules_Nodule mass on living roots per ground area Total dry weight of all root nodules collected from living roots in soil cores. 3 0 3
Chemistry Secondary compounds Root non-acid hydrolyzable compounds content Concentration of compounds in root that are not acid soluble. 127 3 130
Chemistry Total non-structural carbohydrates Root non-structural C content per root C content Percentage of root carbon that is non-structural 2 0 2
Chemistry Secondary compounds Root nonpolar compounds content Concentration of nonpolar compounds in root. 127 10 137
Anatomy Vessels or Tracheids Root number of tracheary elements Number of tracheary elements present in root, with secondary cell-wall thickening counted per xylem pole. 5 0 5
Anatomy Vessels or Tracheids Root number of vessels Number of vessels per root cross-section. 62 0 62
Physiology Nutrient uptake Root N_Annual turnover per ground area Annual nitrogen turnover per meter square of ground area. 14 12 26
Chemistry Macronutrients Root N_Molar organic N content Millimoles of organic nitrogen in root per gram of root mass. 20 0 20
Root System Standing crop Root N_Root N mass per soil mass Mass of root nitrogen per gram of soil. 9 3 12
Chemistry Secondary compounds Root O-alkyl C content per root C content Fraction of root carbon that is in O-alkyl groups. 4 0 4
Chemistry Stoichiometry Root organic N/root total N ratio Root organic N concentration divided by total root N concentration. 20 0 20
Chemistry Macronutrients Root P content Mass of phosphorous per root mass for sampled roots. 1220 322 1542
Chemistry Micronutrients Root P content per root fresh mass Mass of root phosphorus per fresh mass for sampled roots. 6 0 6
Physiology Nutrient uptake Root P uptake_Fraction maximum P uptake rate Fraction of maximum phosphorus uptake rate achieved by age group specified in F00062 and F00063. 22 0 22
Physiology Nutrient uptake Root P uptake_Hourly uptake of H2PO4- Hourly uptake of H2PO4, as determined by a root bioassay. 4 0 4
Physiology Nutrient uptake Root P uptake_Rate per root mass Rate of phosphorus uptake per gram of root per second. 12 0 12
Physiology Nutrient uptake Root P uptake_Rate per root surface area per second Phosphorus uptake per unit root area, determined with tissue cassettes. 18 0 18
Chemistry Secondary compounds Root p-hydroxy phenol content per root C content Concentration of p-hydroxybenzoic acid, p-hydroxyacetophenon, and p-hydroxybenzaldehyde phenols in root per root C content. 5 0 5
Anatomy Hypodermis Root passage cell number in exodermis Number of passage cells in exodermis. 27 0 27
Anatomy Hypodermis Root passage cell number per root circumference Number of passage cells per mm root circumference. 27 0 27
Chemistry Micronutrients Root Pb content Mass of lead per root mass for sampled roots. 38 8 46
Anatomy Phellem Root phellem Number of phellem layers on root. 187 0 187
Chemistry Secondary compounds Root phenols content Concentration of phenols per unit root dry mass. 39 1 40
Chemistry Secondary compounds Root phenols_chlorogenic acid molarity per root mass Micromoles of chlorogenic acid yielded per root mass from ethanol boiling extraction and Folin-Ciocalteu's phenol reagent. See page 1221 of Zadworny et al. 2017, DOI: 10.1111/gcb.13514, for further information. 212 0 212
Physiology Exudation Root phosphatase activity per root length Phosphatase activity of roots, based on release of p-nitrophenol from a solution of p-nitrophenyl phosphate per meter of root length per hour. 13 0 13
Anatomy Aerenchyma Root phosphatase activity per root mass

Hydrolysis of p-nitrophenyl phosphatase to p-nitrophenol after incubation at 37°C for 1 hour.

14 0 14
Chemistry Secondary compounds Root polar compounds content Concentration of polar compounds in root. 102 3 105
Chemistry Secondary compounds Root polyphenol content Concentration of polyphenols in root. 19 1 20
Chemistry Stoichiometry Root polyphenol/root N ratio Ratio of root polyphenol concentration to root N concentration. 6 0 6
Physiology Nutrient uptake Root preferred N form Form 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 >=, 35 2 37
Anatomy Vessels or Tracheids Root protoxylem cell wall thickness Thickness of the cell wall in the root protoxylem. 4 0 4
Anatomy Vessels or Tracheids Root protoxylem cell wall thickness per protoxylem diameter Percentage of protoxylem vessel diameter that consists of cell wall thickness. 4 0 4
Anatomy Vessels or Tracheids Root protoxylem diameter Vessel diameter of root protoxylem. 4 0 4
Dynamics Root Growth Root pruning recovery Percentage pruned woody roots that recovered by proliferating fine roots. 5 1 6
Physiology Nutrient uptake Root Rb uptake_Hourly Rb uptake per root mass Hourly uptake rate of rubidium by roots, as determined by a root bioassay using 86Rb+, reported in terms of nanograms taken up per fresh weight of roots per hour. 19 0 19
Physiology Nutrient uptake Root Rb uptake_Hourly uptake of molar Rb+ per root fresh mass Hourly 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. 19 0 19
Dynamics Root Growth Root 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. 60 0 60
Physiology Respiration Root respiration rate per root dry mass_CO2 release Root respiration rate of CO2 per g root dry mass per second. 202 67 269
Physiology Respiration Root respiration rate per root dry mass_O2 uptake Root respiration rate of O2 per root dry mass, as measured in a respiration chamber. 1388 160 1548
Physiology Respiration Root respiration rate per root length_CO2 release Root respiration rate of CO2 per meter of root length, as measured in a respiration chamber. 36 0 36
Anatomy Aerenchyma Root respiration rate per root mass_C release

Root 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.

20 0 20
Chemistry Secondary compounds Root rhamnan content Concentration of rhamnans in root. 10 0 10
Chemistry Macronutrients Root S content Mass of sulfur per root mass for sampled roots. 59 46 105
Chemistry Micronutrients Root S content per root fresh mass Mass of root sulfur per fresh mass for sampled roots. 6 0 6
Chemistry Micronutrients Root Si content Mass of silicon per root mass for sampled roots. 17 8 25
Chemistry Secondary compounds Root starch fraction Fraction of root mass consisting of starches. 256 0 256
Anatomy Vessels or Tracheids Root stele cross-sectional area Cross-sectional area of root stele. 9 0 9
Anatomy Stele Root stele cross-sectional fraction Percentage of root cross-sectional area that is occupied by the stele. 99 0 99
Anatomy Stele Root stele diameter Diameter of root stele. 318 10 328
Anatomy Stele Root stele diameter/root diameter ratio Stele diameter divided by root diameter. 299 0 299
Anatomy Stele Root stele/root cortex ratio Proportion of root cross sectional area occupied by the stele divided by proportion of root cross sectional area occupied by the cortex. 25 0 25
Chemistry Secondary compounds Root structural C content per root C content Percentage of root carbon that is structural. 2 0 2
Root System Allocation within root system Root surface area fraction per root order class Percentage of total root surface area that a specific root order comprises. 41 0 41
Root System Standing crop Root surface area per ground area Total surface area of roots per square meter of ground area. 114 9 123
Dynamics Lifespan Root survivorship_Fraction of root tips surviving after one year Percentage of root tips that survive after one year. 62 9 71
Dynamics Lifespan Root survivorship_Fraction roots surviving for exposition period Percentage 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)." 24 0 24
Dynamics Lifespan Root survivorship_Fraction roots surviving for growing season Percentage of roots which survive over the course of a growing season. 28 0 28
Chemistry Secondary compounds Root syringyl phenol content per root C content Concentration of syringyl phenols in root per root C content. 5 0 5
Chemistry Stoichiometry Root syringyl/vanillyl phenol ratio Ratio of syringyl phenol to vanillyl phenol in root. Index for taxonomic level (angiosperm or gymnosperm) of plant from which phenol was derived. 5 0 5
Root System Allocation within root system Root tip fraction per root diameter class Proportion of total number of root tips comprised by a particular diameter class. 354 0 354
Architecture Topology Root tips per ground area Total number of root tips per square meter of ground area (sampled from a given depth increment). 76 0 76
Architecture Topology Root tips per minirhizotron frame Number of root tips observed per minirhizotron frame. 36 0 36
Architecture Topology Root tips per plant Total number of root tips for an entire plant. 821 202 1023
Architecture Topology Root tips per root branch Number of root tips and root endings per root branch. 4 0 4
Architecture Topology Root tips per soil volume Number of root tips per liter of soil. 24 2 26
Morphology Root tissue density Root tissue density (RTD) Weight of roots sampled divided by volume of roots. 3264 308 3572
Architecture Topology Root 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."

803 313 1116
Chemistry Total non-structural carbohydrates Root total non-structural carbohydrate content (TNC) Glucose equivalents per dry weight of roots, determined colorimetrically. 663 26 689
Dynamics Root Turnover Root turnover_Annual biomass turnover per ground area Root mass multiplied by turnover rate. 32 27 59
Dynamics Root Turnover Root turnover_Annual root system replacement Turnover as the inverse of belowground net primary productivity. 463 360 823
Dynamics Root Turnover Root turnover_Estimated rate per growing season Number of days in growing season divided by median lifespan of roots. 16 0 16
Dynamics Root Turnover Root turnover_Mass per dry season Turnover during dry season as defined in original data source. 0 8 8
Dynamics Root Turnover Root turnover_Mass per wet season Turnover during wet season as defined in original data source. 0 8 8
Chemistry Secondary compounds Root vanillyl phenol content per root C content Concentration of vanillyl phenols in root per root C content. 5 0 5
Chemistry Stoichiometry Root vanillyl phenol/lignin phenol ratio Ratio of vanillyl phenol to lignin phenol in root. Indicative of lignin quality. 5 0 5
Anatomy Vessels or Tracheids Root vessel cross-sectional area Cross-sectional area per root vessel. 62 0 62
Anatomy Vessels or Tracheids Root vessel diameter Diameter of root vessels. 165 0 165
Anatomy Vessels or Tracheids Root vessel number per root cross-sectional area Number of vessels in root per root cross-sectional area. 53 0 53
Root System Standing crop Root volume per ground area Total volume of roots per square meter of ground area for the specified depth increment. 86 0 86
Chemistry Secondary compounds Root water or ethanol soluble compounds fraction Percentage of root tissue that is soluble in water or ethanol. 29 7 36
Chemistry Secondary compounds Root water soluble compounds fraction Percentage of root tissue that is soluble in water. 142 17 159
Chemistry Secondary compounds Root water soluble compounds per root mass Percentage of root tissue that consist of water-soluble sugars, as determined by a phenol-sulfuric acid assay. 44 7 51
Chemistry Secondary compounds Root water soluble phenol compounds per root mass Percentage of root tissue that consists of water-soluble phenols. 5 0 5
Physiology Water uptake Root water uptake per root length Daily water uptake in milliliters, per centimeter of root length. 52 0 52
Physiology Water uptake Root water uptake per root surface area Water absorption rate per surface area of root. 9 0 9
Physiology Water uptake Root water uptake_Hourly uptake rate per soil volume Rate of water uptake by roots, divided by the volume of soil from which roots take up water. 149 0 149
Physiology Water uptake Root water uptake_Hydraulic conductivity (Lp) Hydraulic conductivity of roots. 140 0 140
Chemistry Secondary compounds Root xylan content Concentration of xylans in root. 10 0 10
Anatomy Vessels or Tracheids Root xylem cross-sectional area Cross-sectional area of root xylem. 53 0 53
Anatomy Vessels or Tracheids Root xylem cross-sectional fraction Percentage of root cross-sectional area occupied by xylem. 53 0 53
Anatomy Vessels or Tracheids Root xylem vessel number per root stele area Number of xylem vessels per root stele cross-sectional area. 129 0 129
Chemistry Micronutrients Root Zn content Mass of zinc per root mass for sampled roots. 67 43 110
Root System Allocation within plant Root/shoot ratio Ratio of root tissue mass to shoot mass, where rhizomes are counted as shoot mass. 236 40 276
Root System Depth distribution Rooting depth Depth which includes all observed roots. 1829 448 2277
Root System Depth distribution Rooting depth_Extrapolated 50 percent rooting depth Depth which includes 50 percent of total roots in profile, extrapolated from LDR model. 0 564 564
Root System Depth distribution Rooting depth_Extrapolated 95 percent rooting depth Depth which includes 95 percent of total roots in profile, extrapolated from LDR model. 23 564 587
Root System Depth distribution Rooting depth_Fraction roots in soil depth increment Proportion of observed roots (quantified by column F00961, Notes_Rooting depth measurement") contained in depth interval." 82 180 262
Root System Depth distribution Rooting depth_Interpolated 50 percent rooting depth Depth 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. 0 564 564
Root System Depth distribution Rooting depth_Interpolated 95 percent rooting depth Depth 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). 4 564 568
Root System Depth distribution Rooting depth_Main Depth where most of the root activity of interest occurs. 0 201 201
Root System Depth distribution Rooting depth_max Maximum depth which includes all observed roots. 49 5 54
Root System Depth distribution Rooting depth_min Minimum depth which includes all observed roots. 122 29 151
Morphology Specific root length Specific root area (SRA) Root surface area divided by root mass. 1363 367 1730
Architecture Topology Specific root forks density (SRFD) Number of root bifurcations per gram of root mass. 3 9 12
Morphology Specific root length Specific root length (SRL) Length of roots divided by root mass. 5073 535 5608
Architecture Topology Specific root tip abundance (SRTA) Number of root tips per milligram of root mass. 1037 326 1363
Root System Allocation within root system Taproot mass fraction Percentage of root mass that consists of the taproot. 13 0 13