# 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 | Column ID | Description | Single-species Observations | Multi-species Observations | Total observations |
---|---|---|---|---|---|---|---|

Root System | Allocation within plant | Aboveground/belowground net primary production ratio | F00841 | Annual aboveground net primary production (NPP) divided by belowground NPP. | 118 | 30 | 148 |

Root System | Standing crop | Belowground biomass per ground area | F00885 | Root mass per square meter for the specified depth increment. | 4350 | 7028 | 11378 |

Root System | Standing crop | Belowground biomass per plant | F00898 | Total root mass for the entire plant. | 7211 | 127 | 7338 |

Root System | Standing crop | Belowground biomass per soil volume | F00896 | Kilograms of root mass per cubic meter of soil. | 897 | 230 | 1127 |

Root System | Standing crop | Belowground necromass per ground area | F00917 | Dead root mass per square meter for the specified depth increment. | 448 | 795 | 1243 |

Root System | Allocation within plant | Belowground/aboveground mass ratio | F00838 | Ratio of belowground biomass (g m-2) to aboveground biomass (g m-2). | 677 | 67 | 744 |

Root System | Allocation within root system | Coarse root/fine root mass ratio | F00854 | Ratio of coarse root biomass to fine root biomass. | 1636 | 9 | 1645 |

Root System | Allocation within plant | Fine root C/leaf C ratio | F00844 | Ratio of fine root carbon to leaf carbon. | 40 | 30 | 70 |

Root System | Allocation within plant | Fine root mass/leaf mass ratio | F00843 | Ratio of fine-root mass to leaf mass. | 1831 | 27 | 1858 |

Microbial associations | Other rhizosphere microbes | Mycoheterotrophy | F01288 | “x” denotes the presence of mycoheterotrophy. Blank indicates the data are not related to mycoheterotrophy or that mycoheterotrophy data were not available. | 3 | 0 | 3 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction contact exploration mycorrhizae | F00609 | Percentage of mycorrhizal tips that are of the contact exploration type. | 12 | 0 | 12 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction long-distance exploration mycorrhizae | F00611 | 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 | F00613 | 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 | F00617 | Percentage of mycorrhizal tips that are living. | 12 | 0 | 12 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction of root length | F00638 | 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. | 602 | 62 | 664 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction root length colonized by AM mycorrhizae | F00622 | Percentage of root length which shows colonization by arbuscular mycorrhizal fungi. These data may also be contained in column F00638. | 547 | 48 | 595 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction root length colonized by EM mycorrhizae | F00626 | Percentage of root length which shows colonization by ectomycorrhizal fungi. These data may also be contained in column F00638. | 14 | 4 | 18 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction root tips colonized by mycorrhizae | F00619 | Percentage of root tips that are colonized by mycorrhizal fungi. | 279 | 4 | 283 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Fraction short-distance exploration mycorrhizae | F00615 | 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 | F00606 | 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 | F00641 | 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. | 2 | 4 | 6 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Number of root tips per root length colonized by mycorrhizae | F00635 | 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 | F00607 | 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 | F01333 | 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 | F00111 | 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 | F00113 | Percentage of root length that contains fungal vesicles, determined using a random intercept method. | 0 | 4 | 4 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Type_Data source | F00645 | Type of mycorrhizae formed. "AbtM" = arbutoid mycorrhizae; “AM” = arbuscular mycorrhizae; “DS” = dark septate endophyte mycorrhizae; “EeM” = ectendomycorrhizae; “EM” = ectomycorrhizae; “ErM” = ericoid mycorrhizae”;, "OrM" = orchid mycorrhizae; “mycorrhizal” means mycorrhizae are present but type is unknown; “NM” = non-mycorrhizal. | 9577 | 194 | 9771 |

Microbial associations | Mycorrhizal fungi | Mycorrhiza_Visual estimate of root colonization intensity | F00631 | Intensity of mycorrhizal colonization based on five categories of mycorrhizal intensity, estimated visually and averaged across samples examined. | 5554 | 0 | 5554 |

Physiology | Nutrient uptake | Plant N uptake rate_Annual N uptake per ground area | F00780 | 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 | F01396 | Uptake of 15N-Glycine tracer over the course of 24 hours per shoot 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 | F01392 | Uptake of 15N-NH4+ tracer over the course of 24 hours per shoot 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 | F01394 | Uptake of 15N-NO3- tracer over the course of 24 hours per shoot 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 | F01398 | Combined uptake of 15N-NH4+, 15N-NO3-, and 15N-Glycine tracers over the course of 24 hours per shoot 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 |

Microbial associations | Rhizosphere | Rhizosphere soil_specific rhizosheath mass by FW | F01453 | Mass of soil left on root after all bulk soil is shaken off, divided by root fresh mass | 58 | 0 | 58 |

Chemistry | Secondary Compounds | Root 12 phenol content per root C content | F00380 | Total concentration of twelve monophenols extracted from root per root C content. | 35 | 0 | 35 |

Chemistry | Macronutrients | Root 15N content | F00273 | 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 | F00407 | 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 | F00342 | Concentration of acid soluble compounds in root. | 156 | 3 | 159 |

Physiology | Exudation | Root acid phosphatase activity per root mass | F00743 | Acid phosphatase activity per unit root mass. | 333 | 3 | 336 |

Chemistry | Stoichiometry | Root acid/aldehyde ratio for syringyl phenols | F00403 | 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 | F00405 | 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 | F00100 | Percentage of root cross-sectional area that consists of aerenchyma. | 13 | 0 | 13 |

Anatomy | Aerenchyma | Root aerenchyma porosity fraction | F00097 | Percent porosity of root aerenchyma. | 787 | 0 | 787 |

Anatomy | Aerenchyma | Root aerenchyma presence | F00103 | Whether aerenchyma are present in root. | 12 | 0 | 12 |

Dynamics | Lifespan | Root age survivorship fraction | F00476 | Percentage of roots that live to the age presented in the “root age” column. | 308 | 87 | 395 |

Chemistry | Micronutrients | Root Al content | F00296 | Mass of aluminum per root mass for sampled roots. | 115 | 43 | 158 |

Chemistry | Micronutrients | Root Al content per root fresh mass | F01304 | Mass of root aluminum per fresh mass for sampled roots. | 6 | 0 | 6 |

Chemistry | Secondary Compounds | Root alkyl C content per root C content | F00431 | Fraction of root carbon that is in alkyl groups. | 8 | 0 | 8 |

Chemistry | Secondary Compounds | Root arabinans content | F00346 | Concentration of arabinans in root. | 13 | 1 | 14 |

Chemistry | Secondary Compounds | Root aromatic C content per root C content | F00437 | Fraction of root carbon that is in aromatic groups. | 4 | 0 | 4 |

Chemistry | Micronutrients | Root As content | F00298 | Mass of arsenic per root mass for sampled roots. | 36 | 16 | 52 |

Chemistry | Secondary Compounds | Root ash C content per root C content | F00340 | Percentage of root carbon that is ash. | 13 | 0 | 13 |

Chemistry | Secondary Compounds | Root ash content | F00347 | Concentration of ash in root. | 32 | 1 | 33 |

Chemistry | Micronutrients | Root B content | F00301 | Mass of boron per root mass for sampled roots. | 4 | 9 | 13 |

Chemistry | Secondary Compounds | Root bound phenol content per root C content | F00348 | 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 | F00187 | 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 | F00179 | Number of roots in a given order divided by the number of roots in the higher order. | 497 | 6 | 503 |

Architecture | Topology | Root branching intensity_root tips per higher order root length | F00182 | Number of lower-order roots per centimeter length of higher-order root. | 79 | 0 | 79 |

Architecture | Topology | Root branching intensity_root tips per total root length | F01339 | Number of lower-order roots per total root length in category. | 1504 | 8 | 1512 |

Chemistry | Macronutrients | Root C content | F00253 | Mass of carbon per root mass for sampled roots. | 2817 | 284 | 3101 |

Root System | Standing crop | Root C content per ground area | F00909 | Total mass of root carbon per ground area. | 96 | 172 | 268 |

Root System | Standing crop | Root C content per soil mass | F00906 | Mass of root carbon per gram of soil. | 236 | 0 | 236 |

Chemistry | Stoichiometry | Root C/N ratio | F00413 | Ratio of carbon to nitrogen in root by mass. | 3686 | 499 | 4185 |

Chemistry | Macronutrients | Root Ca content | F00249 | Mass of calcium per root mass for sampled roots. | 633 | 141 | 774 |

Chemistry | Macronutrients | Root Ca content per root fresh mass | F01299 | Mass of calcium per root fresh weight for sampled roots. | 6 | 0 | 6 |

Chemistry | Micronutrients | Root Cd content | F00305 | Mass of cadmium per root mass for sampled roots. | 36 | 3 | 39 |

Chemistry | Cellulose | Root cellulose and hemicellulose content per root mass | F00245 | Sum of concentrations of cellulose and all hemicelluloses in root. | 15 | 0 | 15 |

Chemistry | Cellulose | Root cellulose content | F00237 | Concentration of cellulose in root. | 246 | 72 | 318 |

Chemistry | Cellulose | Root cellulose content per root C content | F00240 | Percentage of root carbon that is cellulose. | 7 | 0 | 7 |

Chemistry | Secondary Compounds | Root cinnamyl phenol content per root C content | F00350 | Concentration of cinnamyl phenols in root per root carbon content. | 5 | 0 | 5 |

Chemistry | Stoichiometry | Root cinnamyl phenol/vanillyl phenol ratio | F00417 | Ratio of cinnamyl phenol to vanillyl phenol in root. Index for woody or nonwoody source. | 5 | 0 | 5 |

Chemistry | Micronutrients | Root Cl- ion content | F00308 | 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 | F00691 | Whether observed roots are considered to be white or brown. | 98 | 0 | 98 |

Chemistry | Secondary Compounds | Root condensed tannins | F01330 | Concentration of condensed tannins in root. | 23 | 0 | 23 |

Anatomy | Vessels or Tracheids | Root conduit diameter | F00142 | D_h=[(1/n)sigma(n/i=1)d^4]^(1/4) where d is conduit lumen diameter and n is conduit number. | 75 | 0 | 75 |

Anatomy | Vessels or Tracheids | Root conduit number per root stele area | F00134 | Number of conduits per stele cross-section area. | 24 | 0 | 24 |

Anatomy | Vessels or Tracheids | Root conduit wall thickness | F00154 | Thickness of conduit wall from root scans. | 69 | 0 | 69 |

Chemistry | Construction cost | Root construction cost | F00246 | Grams of glucose equivalent per gram of root dry weight. | 28 | 0 | 28 |

Anatomy | Cortex | Root cortex thickness | F00104 | Thickness of root cortex. | 353 | 0 | 353 |

Chemistry | Micronutrients | Root Cr content | F00311 | Mass of chromium per root mass for sampled roots. | 36 | 8 | 44 |

Morphology | Diameter | Root cross-sectional area | F01317 | Cross-sectional area of root. | 76 | 0 | 76 |

Chemistry | Micronutrients | Root Cu content | F00314 | Mass of copper per root mass for sampled roots. | 67 | 27 | 94 |

Dynamics | Decomposition | Root decomposition_Annual k constant | F00461 | 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. | 613 | 184 | 797 |

Dynamics | Decomposition | Root decomposition_Annual N immobilized in decomposing roots | F00466 | 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 | F00465 | Amount of root necromass that decomposes over the course of a year. | 0 | 15 | 15 |

Dynamics | Decomposition | Root decomposition_Estimated cumulative monthly mass loss | F00457 | Difference between cumulative growth rate and fine root biomass. | 0 | 6 | 6 |

Dynamics | Decomposition | Root decomposition_Fraction C remaining | F01364 | For decomposition experiment, percentage of original root carbon remaining. | 39 | 0 | 39 |

Dynamics | Decomposition | Root decomposition_Fraction mass remaining | F00458 | For decomposition experiment, percentage of original root mass remaining. | 2007 | 1758 | 3765 |

Dynamics | Decomposition | Root decomposition_Fraction N remaining | F00591 | For decomposition experiment, percentage of original root nitrogen remaining. | 716 | 136 | 852 |

Dynamics | Decomposition | Root decomposition_Monthly k constant | F00463 | K constant (decomposition constant, see F00461) for a single month. | 0 | 12 | 12 |

Dynamics | Decomposition | Root decomposition_Monthly necromass decomposition rate per ground area | F00464 | Amount of root necromass that decomposes over the course of a month. | 0 | 12 | 12 |

Morphology | Diameter | Root diameter | F00679 | Diameter of roots observed. | 8729 | 487 | 9216 |

Architecture | Topology | Root dichotomous branching index | F00210 | 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) | F00689 | Root dry mass divided by root fresh mass. | 2102 | 159 | 2261 |

Chemistry | Secondary Compounds | Root ethanol soluble fraction | F00352 | Percentage of root tissue that is soluble in ethanol. | 10 | 0 | 10 |

Anatomy | Hypodermis | Root exodermal wall thickness | F00108 | Thickness of exodermal wall from root scans. | 27 | 0 | 27 |

Architecture | Topology | Root external path length (Pe) | F00213 | 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). | 878 | 127 | 1005 |

Physiology | Exudation | Root exudation_C exudation rate per plant | F01418 | Total carbon exudation rate by fine roots per individual plant. | 4 | 0 | 4 |

Physiology | Exudation | Root exudation_C exudation rate per root length | F01416 | Carbon exudation rate by length of fine roots. | 4 | 0 | 4 |

Physiology | Exudation | Root exudation_C exudation rate per root mass | F00754 | Carbon exudation rate by mass of fine roots. | 28 | 0 | 28 |

Physiology | Exudation | Root exudation_Concentration in soil | F01430 | Concentration of root exudates in the soil, estimated using 13C labelling. | 6 | 0 | 6 |

Physiology | Exudation | Root exudation_Fraction estimated root mass | F00751 | Collected exudates scaled as proportion of estimated biomass accumulation. | 4 | 0 | 4 |

Physiology | Exudation | Root exudation_molar C exudation rate per root area | F01404 | Root carbon exudation rate in terms of micromoles of Carbon exuded per root area. | 32 | 0 | 32 |

Chemistry | Micronutrients | Root Fe content | F00318 | Mass of iron per root mass for sampled roots. | 81 | 22 | 103 |

Architecture | Topology | Root forks per root length | F01414 | Number of root forks per cm of root length. | 0 | 24 | 24 |

Architecture | Topology | Root fractal dimension | F00199 | Fractal dimension of scanned roots. | 908 | 238 | 1146 |

Chemistry | Secondary Compounds | Root free phenol content per root C content | F00353 | Concentration of phenolic compounds that are nonassociated forms in cell vacuoles per root carbon content. | 35 | 0 | 35 |

Chemistry | Secondary Compounds | Root galactans fraction | F00355 | Concentration of galactans in root. | 13 | 1 | 14 |

Dynamics | Root Growth | Root growth_Annual C production per ground area | F00518 | Amount of root carbon produced in one year. | 10 | 193 | 203 |

Dynamics | Root Growth | Root growth_Annual length production per ground area | F00546 | 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 | F00553 | New root length observed per square centimeter of minirhizotron surface per year. | 5 | 38 | 43 |

Dynamics | Root Growth | Root growth_Annual mass production per ground area | F00521 | Amount of root mass produced in one year. | 778 | 503 | 1281 |

Dynamics | Root Growth | Root growth_Annual net new length production per ground area | F00510 | 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 | F00571 | 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 | F00559 | 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 | F00543 | Cumulative root length density appearance per unit ground area. | 376 | 0 | 376 |

Dynamics | Root Growth | Root growth_Cumulative mass production per ground area | F00527 | 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 | F00526 | 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 | F00507 | Difference between cumulative live root appearance and cumulative live root disappearance. | 46 | 0 | 46 |

Dynamics | Root Growth | Root growth_Daily elongation rate | F00538 | 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 | F00568 | Total fine root length production per day per length of woody root. | 12 | 0 | 12 |

Dynamics | Root Growth | Root growth_Daily length production per minirhizotron surface area | F00551 | New root length observed per square centimeter of minirhizotron surface per day. | 108 | 164 | 272 |

Dynamics | Root Growth | Root growth_Daily mass production per coarse root length | F00569 | Total fine root mass produced per day per length of woody root. | 12 | 0 | 12 |

Dynamics | Root Growth | Root growth_Daily mass production per ground area | F00529 | Amount of root mass produced in one day. | 0 | 52 | 52 |

Dynamics | Root Growth | Root growth_Elongation fraction | F00537 | Percentage of roots that have elongated since the previous measurement. | 0 | 196 | 196 |

Dynamics | Root Growth | Root growth_Fraction peak production | F00513 | 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 | F00286 | 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 | F00556 | 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 | F00540 | Root length produced per minirhizotron frame. | 32 | 0 | 32 |

Dynamics | Root Growth | Root growth_Length recovery from pruning | F00566 | Root length recovery from pruning. | 56 | 4 | 60 |

Dynamics | Root Growth | Root growth_Mass production per ground area and exposition period | F00534 | Root biomass 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). | 82 | 74 | 156 |

Dynamics | Root Growth | Root growth_Mass production per plant per growing season | F01276 | Increase in belowground biomass per plant (by dry weight) over the course of one growing season. | 8 | 0 | 8 |

Dynamics | Root Growth | Root growth_Monthly mass ingrowth per screen area | F00531 | 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 | F00532 | Amount of root mass produced in one month. | 123 | 0 | 123 |

Dynamics | Root Growth | Root growth_Monthly mass production per soil volume | F00533 | Root mass produced per cubic centimeter of soil each month. | 108 | 0 | 108 |

Dynamics | Root Growth | Root growth_Number of roots per area of ingrowth screen | F00903 | 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 | F00561 | 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 | F00574 | 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 | F00733 | Number of root hairs per root surface area. | 25 | 0 | 25 |

Morphology | Root Hairs | Root hair diameter | F00736 | Diameter of root hairs. | 25 | 0 | 25 |

Morphology | Root Hairs | Root hair incidence | F00692 | Percentage of fine roots that contain root hairs, by the gridline method. | 2 | 60 | 62 |

Morphology | Root Hairs | Root hair length | F00696 | Length of root hairs. | 231 | 60 | 291 |

Morphology | Root Hairs | Root hair volume per root mass | F00700 | 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 | F00242 | Percentage of root carbon that is hemicellulose. | 2 | 0 | 2 |

Chemistry | Cellulose | Root hemicellulose content per root mass | F00243 | Percentage of root mass that is hemicellulose. | 174 | 2 | 176 |

Root System | Standing crop | Root intact branch length | F00196 | Total root length contained within an intact root branch. | 4 | 0 | 4 |

Chemistry | Macronutrients | Root K content | F00289 | Mass of potassium per root mass for sampled roots. | 561 | 223 | 784 |

Chemistry | Macronutrients | Root K content per root fresh mass | F01302 | 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 | F00766 | 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 | F00934 | Root length divided by soil core cross-sectional area. | 3224 | 409 | 3633 |

Root System | Standing crop | Root length density (RLD)_Root length per soil volume | F00938 | Root length divided by the sampled soil volume. | 647 | 152 | 799 |

Root System | Allocation within root system | Root length fraction per root diameter class | F00864 | Percentage of root length composed of a specific root diameter class. | 137 | 24 | 161 |

Root System | Allocation within root system | Root length fraction per root order class | F00867 | Percentage of root length composed of a specific root order. | 204 | 3 | 207 |

Root System | Standing crop | Root length fraction per species | F00933 | Percentage of total root length belonging to an individual species. | 18 | 0 | 18 |

Morphology | Root Length | Root length from base to tip | F00703 | Distance from root base to tip. | 1034 | 28 | 1062 |

Root System | Standing crop | Root length per minirhizotron frame | F00930 | Total root length observed per minirhizotron frame. | 32 | 0 | 32 |

Root System | Standing crop | Root length per minirhizotron surface area | F00944 | Meters of root length visible per square meter of minirhizotron surface. | 170 | 137 | 307 |

Root System | Standing crop | Root length per plant | F00942 | Total length of all roots for an entire plant. | 1907 | 127 | 2034 |

Root System | Standing crop | Root length ratio (RLR) | F00927 | Root length per gram of plant mass. | 68 | 0 | 68 |

Physiology | Nutrient uptake | Root Li uptake_Daily uptake of molar Li per root length | F01427 | Daily uptake rate of lithium by roots, reported in terms of micrograms taken up per meter of root length. | 16 | 0 | 16 |

Chemistry | Secondary Compounds | Root lignin content | F00358 | Concentration of lignin in root. | 553 | 208 | 761 |

Chemistry | Secondary Compounds | Root lignin content per root C content | F00361 | Percentage of root carbon that exists as lignin. | 7 | 0 | 7 |

Chemistry | Secondary Compounds | Root lignin phenol content per root C content | F00356 | 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) | F00338 | [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 | F00419 | Ratio of lignin concentration to N concentration in root. | 118 | 15 | 133 |

Architecture | Topology | Root link branching angle | F00170 | 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. | 878 | 238 | 1116 |

Architecture | Topology | Root link length | F00203 | Length of root links (segments of roots between two nodes or a node and a tip). | 1138 | 238 | 1376 |

Architecture | Topology | Root links per root branch | F00173 | 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 | F00362 | Concentration of lipids in root. | 18 | 0 | 18 |

Chemistry | Secondary Compounds | Root mannans content | F00364 | Concentration of mannans in root. | 13 | 1 | 14 |

Root System | Allocation within plant | Root mass fraction (RMF) | F00846 | Root biomass divided by total plant biomass. | 6003 | 8 | 6011 |

Root System | Allocation within root system | Root mass fraction per root diameter class | F00855 | Percentage of root biomass contributed by a particular diameter class. | 210 | 16 | 226 |

Root System | Allocation within root system | Root mass fraction per root order class | F00858 | Percentage of root biomass contributed by a particular root order. | 297 | 0 | 297 |

Root System | Allocation within root system | Root mass fraction per species | F00884 | Percentage of total root mass composed of a particular species in a community. | 48 | 12 | 60 |

Dynamics | Lifespan | Root mean lifespan_d | F00469 | Mean lifespan of roots observed, expressed in days. | 203 | 45 | 248 |

Dynamics | Lifespan | Root mean lifespan_Main_d | F01295 | 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, lifespan is converted to days for this value. | 256 | 45 | 301 |

Dynamics | Lifespan | Root mean lifespan_yr | F01292 | Mean lifespan of roots observed, expressed in years. | 53 | 0 | 53 |

Dynamics | Lifespan | Root median lifespan_d | F00470 | Median lifespan of roots observed, expressed in days. | 232 | 10 | 242 |

Dynamics | Lifespan | Root median lifespan_Main_d | F01296 | 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 or months, lifespan is converted to days for this value. | 243 | 10 | 253 |

Dynamics | Lifespan | Root median lifespan_yr | F01293 | Median lifespan of roots observed, expressed in years. | 11 | 0 | 11 |

Anatomy | Vessels or Tracheids | Root metaxylem cell wall thickness | F00150 | Thickness of the cell wall in the root metaxylem. | 4 | 0 | 4 |

Anatomy | Vessels or Tracheids | Root metaxylem cell wall thickness/vessel diameter ratio | F00128 | Percentage of metaxylem vessel diameter that consists of cell wall thickness. | 4 | 0 | 4 |

Anatomy | Vessels or Tracheids | Root metaxylem vessel diameter | F00140 | Vessel diameter of root metaxylem. | 4 | 0 | 4 |

Chemistry | Macronutrients | Root Mg content | F00257 | Mass of magnesium per root mass for sampled roots. | 525 | 133 | 658 |

Chemistry | Macronutrients | Root Mg content per root fresh mass | F01300 | 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 | F00659 | 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 | F00658 | 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 | F00660 | 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 | F00656 | Carbon from microbial biomass in roots, calculated from root ergosterol and the ergosterol/microbial biomass carbon ratio of the rhizosphere soil. | 17 | 1 | 18 |

Microbial associations | Other rhizosphere microbes | Root microbes_Microbial biomass N content per root mass | F00657 | 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 | F00652 | Concentration of glucosamine measured in root material. | 18 | 1 | 19 |

Microbial associations | Other rhizosphere microbes | Root microbes_Root length hyphal fraction | F00629 | Percentage of root length that contains fungal hyphae, determined using a random intercept method. | 0 | 4 | 4 |

Chemistry | Micronutrients | Root Mn content | F00322 | Mass of manganese per root mass for sampled roots. | 247 | 30 | 277 |

Chemistry | Micronutrients | Root Mn content per root fresh mass | F01305 | 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 | F00500 | Annual mortality of root length density. | 112 | 30 | 142 |

Dynamics | Root Mortality | Root mortality_Annual root length mortality per minirhizotron surface area | F00498 | 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 | F00490 | Amount of root biomass that dies in one year per square meter of ground area. | 44 | 44 | 88 |

Dynamics | Root Mortality | Root mortality_Cumulative root length disappearance per ground area | F00487 | Cumulative root length density disappearance observed per ground area. | 374 | 0 | 374 |

Dynamics | Root Mortality | Root mortality_Cumulative root length mortality per minirhizotron frame | F00493 | 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 | F00496 | 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 | F00505 | 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 | F00485 | Mass of root biomass that disappears per cubic centimeter of soil per month. Calculated based on loss of mass. | 72 | 0 | 72 |

Dynamics | Root Mortality | Root mortality_Monthly necromass increase per soil volume | F00486 | Amount of root biomass that dies per cubic centimeter of soil per month. Calculated based on change in necromass. | 102 | 0 | 102 |

Dynamics | Root Mortality | Root mortality_Monthly number of roots lost per ingrowth screen area | F00503 | 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 | F00577 | Nitrogen lost through fine root mortality as a percentage of annual whole-plant nitrogen uptake. | 5 | 0 | 5 |

Dynamics | Root Turnover | Root mortality_Root N loss per plant N content per ground area | F00578 | Nitrogen lost through fine root mortality as a percentage of whole-plant N storage (root nitrogen per ground area). | 5 | 3 | 8 |

Microbial associations | Other rhizosphere microbes | Root muramic acid content | F00653 | Concentration of muramic acid measured in root material. | 18 | 1 | 19 |

Chemistry | Macronutrients | Root N content | F00261 | Mass of nitrogen per root mass for sampled roots. | 5717 | 1047 | 6764 |

Root System | Standing crop | Root N content per ground area | F00921 | Total mass of root nitrogen per ground area for the specified depth increment. | 166 | 382 | 548 |

Chemistry | Macronutrients | Root N content per root length | F00270 | Root nitrogen mass per meter of root length. | 249 | 0 | 249 |

Root System | Standing crop | Root N mass per soil mass | F00924 | Mass of root nitrogen per gram of soil. | 236 | 0 | 236 |

Physiology | Nutrient uptake | Root N uptake_Cumulative N uptake | F00770 | Total root nitrogen uptake since the first observation per meter square of ground area. | 20 | 0 | 20 |

Physiology | Nutrient uptake | Root N uptake_Hourly NO3- uptake per root mass | F01459 | Hourly maximum uptake capacity of NO3- per root mass, determined by colorometric methods. | 0 | 0 | 0 |

Physiology | Nutrient uptake | Root N uptake_Hourly uptake of 15NH4+ per root fresh mass | F00773 | 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 | F00775 | 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+. | 22 | 0 | 22 |

Physiology | Nutrient uptake | Root N uptake_Hourly uptake of molar NH4+ per root mass | F01457 | Hourly maximum uptake capacity of NH4+ per root mass, determined by colorometric methods. | 0 | 0 | 0 |

Physiology | Nutrient uptake | Root N uptake_Hourly uptake per unit root mass | F00777 | 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 | F01405 | 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 | F01406 | 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 | F01407 | Hourly uptake of nitrogen by roots per root surface area, as determined by a root bioassay using 15NO3-. Reported in terms of umol of NO3-. | 8 | 0 | 8 |

Physiology | Nutrient uptake | Root N uptake_Molar organic N uptake per root area | F01408 | Hourly uptake of organic nitrogen in terms of micromoles of nitrogen per root area. | 8 | 0 | 8 |

Chemistry | Micronutrients | Root Na content | F00334 | Mass of sodium per root mass for sampled roots. | 51 | 42 | 93 |

Chemistry | Micronutrients | Root Na+ content | F00331 | Mass of Na+ ions per root mass, determined by silver ion titration. | 32 | 0 | 32 |

Chemistry | Stoichiometry | Root NAH/root N ratio | F00409 | Ratio of non-acid hydrolysable compounds to nitrogen in root tissue. | 102 | 3 | 105 |

Root System | Allocation within root system | Root necromass/biomass ratio | F00870 | Dead root mass divided by live root mass. | 751 | 882 | 1633 |

Chemistry | Secondary Compounds | Root neutral detergent soluble fraction | F00365 | Percentage of root mass that is soluble in neutral detergent. | 7 | 0 | 7 |

Chemistry | Micronutrients | Root Ni content | F00326 | Mass of nickel per root mass for sampled roots. | 40 | 12 | 52 |

Microbial associations | Nitrogen fixers | Root nodules_Nodule mass on dead roots per ground area | F00649 | Total dry weight of all root nodules collected from dead roots in soil cores. | 25 | 0 | 25 |

Microbial associations | Nitrogen fixers | Root nodules_Nodule mass on living roots per ground area | F00646 | 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 (NAH) | F00366 | Concentration of compounds in root that are not acid soluble. Also known as Root acid insoluble fraction (AIF). | 310 | 10 | 320 |

Chemistry | Total non-structural carbohydrates | Root non-structural C content per root C content | F00427 | Percentage of root carbon that is non-structural | 2 | 0 | 2 |

Chemistry | Secondary Compounds | Root nonpolar compounds content | F00374 | Concentration of nonpolar compounds in root. | 146 | 11 | 157 |

Anatomy | Vessels or Tracheids | Root number of tracheary elements | F00132 | 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 | F01313 | Number of vessels per root cross-section. | 202 | 0 | 202 |

Physiology | Nutrient uptake | Root N_Annual turnover per ground area | F00769 | Annual root nitrogen turnover per meter square of ground area. | 26 | 0 | 26 |

Chemistry | Macronutrients | Root N_Molar organic N content | F00276 | Millimoles of organic nitrogen in root per gram of root mass. | 20 | 0 | 20 |

Chemistry | Secondary Compounds | Root O-alkyl C content per root C content | F00434 | Fraction of root carbon that is in O-alkyl groups. | 4 | 0 | 4 |

Chemistry | Stoichiometry | Root organic N/root total N ratio | F00421 | Root organic N concentration divided by total root N concentration. | 20 | 0 | 20 |

Chemistry | Macronutrients | Root P content | F00277 | Mass of phosphorous per root mass for sampled roots. | 1603 | 310 | 1913 |

Chemistry | Macronutrients | Root P content per root fresh mass | F01301 | Mass of root phosphorus per fresh mass for sampled roots. | 6 | 0 | 6 |

Physiology | Nutrient uptake | Root P uptake_Fraction maximum P uptake rate | F00763 | 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- | F00784 | Hourly uptake of H2PO4, as determined by a root bioassay. | 4 | 0 | 4 |

Physiology | Nutrient uptake | Root P uptake_Rate per root mass | F00786 | 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 | F00788 | 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 | F00378 | 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 | F00109 | Number of passage cells in exodermis. | 27 | 0 | 27 |

Anatomy | Hypodermis | Root passage cell number per root circumference | F00110 | Number of passage cells per mm root circumference. | 27 | 0 | 27 |

Chemistry | Micronutrients | Root Pb content | F00319 | Mass of lead per root mass for sampled roots. | 41 | 11 | 52 |

Anatomy | Phellem | Root phellem | F00157 | Number of phellem layers in root. | 187 | 0 | 187 |

Chemistry | Secondary Compounds | Root phenols content | F00382 | Concentration of phenols per unit root dry mass. | 45 | 0 | 45 |

Chemistry | Secondary Compounds | Root phenols_chlorogenic acid molarity per root mass | F01328 | 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 | F00760 | 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 |

Physiology | Exudation | Root phosphatase activity per root mass | F00757 | Hydrolysis of p-nitrophenyl phosphatase to p-nitrophenol after incubation at 37°C for 1 hour. | 14 | 0 | 14 |

Chemistry | pH | Root pH_Water | F01461 | pH of root powder, measured in water. | 48 | 0 | 48 |

Chemistry | Secondary Compounds | Root polar compounds content | F00384 | Concentration of polar compounds in root. | 142 | 3 | 145 |

Chemistry | Secondary Compounds | Root polyphenol content | F00388 | Concentration of polyphenols in root. | 20 | 0 | 20 |

Chemistry | Stoichiometry | Root polyphenol/root N ratio | F00422 | Ratio of root polyphenol concentration to root N concentration. | 6 | 0 | 6 |

Physiology | Nutrient uptake | Root preferred N form | F00791 | 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 >=, | 37 | 0 | 37 |

Anatomy | Vessels or Tracheids | Root protoxylem cell wall thickness | F00152 | Thickness of the cell wall in the root protoxylem. | 4 | 0 | 4 |

Anatomy | Vessels or Tracheids | Root protoxylem cell wall thickness per protoxylem diameter | F00130 | Percentage of protoxylem vessel diameter that consists of cell wall thickness. | 4 | 0 | 4 |

Anatomy | Vessels or Tracheids | Root protoxylem diameter | F00148 | Vessel diameter of root protoxylem. | 4 | 0 | 4 |

Dynamics | Root Growth | Root pruning recovery | F00570 | Percentage pruned woody roots that recovered by proliferating fine roots. | 6 | 0 | 6 |

Physiology | Nutrient uptake | Root Rb uptake_Daily uptake of molar Rb+ per root length | F01425 | Daily uptake rate of rubidium by roots, reported in terms of nanograms taken up per meter of root length. | 0 | 0 | 0 |

Physiology | Nutrient uptake | Root Rb uptake_Hourly Rb uptake per root mass | F00796 | 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 | F00792 | 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 | F00515 | [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. | 68 | 0 | 68 |

Physiology | Respiration | Root respiration rate per root dry mass_CO2 release | F00802 | Root respiration rate of CO2 per g root dry mass per second. | 278 | 59 | 337 |

Physiology | Respiration | Root respiration rate per root dry mass_O2 uptake | F00799 | Root respiration rate of O2 per root dry mass, as measured in a respiration chamber. | 1448 | 162 | 1610 |

Physiology | Respiration | Root respiration rate per root length_CO2 release | F00807 | Root respiration rate of CO2 per meter of root length, as measured in a respiration chamber. | 43 | 0 | 43 |

Physiology | Respiration | Root respiration rate per root mass_C release | F00805 | 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 | F00391 | Concentration of rhamnans in root. | 10 | 0 | 10 |

Chemistry | Macronutrients | Root S content | F00293 | Mass of sulfur per root mass for sampled roots. | 111 | 41 | 152 |

Chemistry | Macronutrients | Root S content per root fresh mass | F01303 | Mass of root sulfur per fresh mass for sampled roots. | 6 | 0 | 6 |

Chemistry | Micronutrients | Root Si content | F00329 | Mass of silicon per root mass for sampled roots. | 29 | 0 | 29 |

Chemistry | Secondary Compounds | Root starch fraction | F01329 | Percentage of root mass consisting of starches. | 274 | 21 | 295 |

Anatomy | Vessels or Tracheids | Root stele cross-sectional area | F01324 | Cross-sectional area of root stele. | 9 | 0 | 9 |

Anatomy | Stele | Root stele cross-sectional fraction | F00122 | Percentage of root cross-sectional area that is occupied by the stele. | 120 | 0 | 120 |

Anatomy | Stele | Root stele diameter | F00118 | Diameter of root stele. | 417 | 0 | 417 |

Anatomy | Stele | Root stele diameter/root diameter ratio | F00115 | Stele diameter divided by root diameter. | 343 | 0 | 343 |

Anatomy | Stele | Root stele/root cortex ratio | F00125 | Proportion of root cross sectional area occupied by the stele divided by proportion of root cross sectional area occupied by the cortex. | 93 | 0 | 93 |

Chemistry | Secondary Compounds | Root structural C content per root C content | F00392 | Percentage of root carbon that is structural. | 2 | 0 | 2 |

Root System | Allocation within root system | Root surface area fraction per root order class | F00872 | 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 | F00878 | Total surface area of roots per square meter of ground area. | 126 | 99 | 225 |

Dynamics | Lifespan | Root survivorship_Fraction of root tips surviving after one year | F00483 | Percentage of root tips that survive after one year. | 62 | 9 | 71 |

Dynamics | Lifespan | Root survivorship_Fraction roots surviving for exposition period | F00480 | 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 | F00479 | 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 | F00393 | Concentration of syringyl phenols in root per root carbon. | 5 | 0 | 5 |

Chemistry | Stoichiometry | Root syringyl/vanillyl phenol ratio | F00423 | 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 | F00953 | Proportion of total number of root tips comprised by a particular diameter class. | 354 | 0 | 354 |

Architecture | Topology | Root tips per ground area | F00219 | Total number of root tips per square meter of ground area (sampled from a given depth increment). | 76 | 16 | 92 |

Architecture | Topology | Root tips per minirhizotron frame | F00216 | Number of root tips observed per minirhizotron frame. | 36 | 0 | 36 |

Architecture | Topology | Root tips per plant | F00222 | Total number of root tips for an entire plant. | 896 | 127 | 1023 |

Architecture | Topology | Root tips per root branch | F00176 | Number of root tips and root endings per root branch. | 4 | 0 | 4 |

Architecture | Topology | Root tips per soil volume | F00224 | Number of root tips per liter of soil. | 38 | 0 | 38 |

Morphology | Root tissue density | Root tissue density (RTD) | F00709 | Weight of roots sampled divided by volume of roots. | 6432 | 268 | 6700 |

Architecture | Topology | Root topological index (TI) | F00226 | 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. | 878 | 238 | 1116 |

Chemistry | Total non-structural carbohydrates | Root total non-structural carbohydrate content (TNC) | F00428 | Glucose equivalents per dry weight of roots, determined colorimetrically. | 717 | 26 | 743 |

Dynamics | Root Turnover | Root turnover_Annual biomass turnover per ground area | F00579 | Root mass multiplied by turnover rate. | 18 | 25 | 43 |

Dynamics | Root Turnover | Root turnover_Annual root system replacement | F00582 | Turnover as the inverse of belowground net primary productivity. | 652 | 268 | 920 |

Dynamics | Root Turnover | Root turnover_Estimated rate per growing season | F00589 | Number of days in growing season divided by median lifespan of roots. | 16 | 0 | 16 |

Dynamics | Root Turnover | Root turnover_Mass per dry season | F00585 | Turnover during dry season as defined in original data source. | 0 | 8 | 8 |

Dynamics | Root Turnover | Root turnover_Mass per wet season | F00587 | Turnover during wet season as defined in original data source. | 0 | 8 | 8 |

Chemistry | Secondary Compounds | Root vanillyl phenol content per root C content | F00395 | Concentration of vanillyl phenols in root per root carbon. | 5 | 0 | 5 |

Chemistry | Stoichiometry | Root vanillyl phenol/lignin phenol ratio | F00425 | 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 | F01319 | Cross-sectional area per root vessel. | 76 | 0 | 76 |

Anatomy | Vessels or Tracheids | Root vessel diameter | F00145 | Diameter of root vessels. | 209 | 0 | 209 |

Anatomy | Vessels or Tracheids | Root vessel number per root cross-sectional area | F01321 | Number of vessels in root per root cross-sectional area. | 97 | 0 | 97 |

Root System | Standing crop | Root volume per ground area | F00946 | Total volume of roots per square meter of ground area for the specified depth increment. | 86 | 74 | 160 |

Chemistry | Secondary Compounds | Root water or ethanol soluble compounds fraction | F00397 | Percentage of root tissue that is soluble in water or ethanol. | 29 | 7 | 36 |

Chemistry | Secondary Compounds | Root water soluble compounds fraction | F00399 | Percentage of root tissue that is soluble in water. | 178 | 71 | 249 |

Chemistry | Secondary Compounds | Root water soluble compounds per root mass | F00401 | 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 | F01281 | Percentage of root tissue that consists of water-soluble phenols. | 10 | 0 | 10 |

Physiology | Water uptake | Root water uptake per root length | F00819 | Daily water uptake in milliliters, per centimeter of root length. | 52 | 0 | 52 |

Physiology | Water uptake | Root water uptake per root surface area | F00815 | Water absorption rate per surface area of root. | 9 | 0 | 9 |

Physiology | Water uptake | Root water uptake_Hourly uptake rate per soil volume | F00822 | 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) | F00812 | Hydraulic conductivity of roots. | 140 | 0 | 140 |

Chemistry | Secondary Compounds | Root xylan content | F00402 | Concentration of xylans in root. | 10 | 0 | 10 |

Anatomy | Vessels or Tracheids | Root xylem cross-sectional area | F01311 | Cross-sectional area of root xylem. | 67 | 0 | 67 |

Anatomy | Vessels or Tracheids | Root xylem cross-sectional fraction | F01315 | Percentage of root cross-sectional area occupied by xylem. | 67 | 0 | 67 |

Anatomy | Vessels or Tracheids | Root xylem vessel number per root stele area | F00137 | Number of xylem vessels per root stele cross-sectional area. | 129 | 0 | 129 |

Chemistry | Micronutrients | Root Zn content | F00335 | Mass of zinc per root mass for sampled roots. | 94 | 29 | 123 |

Root System | Allocation within plant | Root/shoot ratio | F00851 | Ratio of root tissue mass to shoot mass, where rhizomes are counted as shoot mass. | 341 | 34 | 375 |

Root System | Depth distribution | Rooting depth | F00954 | Depth which includes all observed roots. | 2554 | 514 | 3068 |

Root System | Depth distribution | Rooting depth_Active | F00956 | Depth where most of the root activity of interest occurs. | 0 | 201 | 201 |

Root System | Depth distribution | Rooting depth_Extrapolated 50 percent rooting depth | F00959 | Depth which includes 50 percent of total roots in profile, extrapolated from logistic dose-response model described in Schenk & Jackson 2003, DOI: 10.3334/ORNLDAAC/659 | 176 | 388 | 564 |

Root System | Depth distribution | Rooting depth_Extrapolated 95 percent rooting depth | F00960 | Depth which includes 95 percent of total roots in profile, extrapolated from logistic dose-response model described in Schenk & Jackson 2003, 10.3334/ORNLDAAC/659 | 199 | 388 | 587 |

Root System | Depth distribution | Rooting depth_Fraction roots in soil depth increment | F00963 | Proportion of observed roots (quantified by column F00961, “Notes_Rooting depth measurement”) contained in depth interval. | 248 | 180 | 428 |

Root System | Depth distribution | Rooting depth_Interpolated 50 percent rooting depth | F00957 | 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. | 176 | 388 | 564 |

Root System | Depth distribution | Rooting depth_Interpolated 95 percent rooting depth | F00958 | 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). | 204 | 388 | 592 |

Root System | Depth distribution | Rooting depth_min | F01409 | Minimum depth which includes all observed roots. | 131 | 20 | 151 |

Morphology | Specific root length | Specific root area (SRA) | F00718 | Root surface area divided by root mass. | 1829 | 365 | 2194 |

Architecture | Topology | Specific root forks density (SRFD) | F00207 | Number of root bifurcations per gram of root mass. | 3 | 9 | 12 |

Morphology | Specific root length | Specific root length (SRL) | F00727 | Length of roots divided by root mass. | 8336 | 607 | 8943 |

Architecture | Topology | Specific root tip abundance (SRTA) | F00192 | Number of root tips per milligram of root mass. | 1232 | 255 | 1487 |

Root System | Allocation within root system | Taproot mass fraction | F00875 | Percentage of root mass that consists of the taproot. | 13 | 0 | 13 |