Soil Data for a Vegetation Gradient Located at Bonanza 

Creek Long Term Ecological Research Site, Interior Alaska

By Kristen L. Manies, Jennifer W. Harden, Christopher C. Fuller, Xiaomei Xu, and John P. McGeehin

Open-File Report 2016–1034

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

For more information on the USGS—the Federal source for science about the Earth,

its natural and living resources, natural hazards, and the environment—visit

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endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may

contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items

must be secured from the copyright owner.

Suggested citation:

Manies, K.L., Harden, J.W., Fuller, C.C., Xu, X., and McGeehin, J.P., 2016, Soil data for a vegetation gradient 

located at Bonanza Creek Long Term Ecological Research Site, interior Alaska: U.S. Geological Survey Open-File 

Report 2016–1034, 10 p., http://dx.doi.org/10.3133/ofr20161034. 

ISSN 2331-1258 (online)
iii

Contents

Abstract ......................................................................................................................................................... 1

Introduction.................................................................................................................................................... 1

Site Description.............................................................................................................................................. 2

Soil Sampling................................................................................................................................................. 2

Soil-Sample Preparation and Drying.............................................................................................................. 3

Soil Laboratory Methods................................................................................................................................ 4

Total Carbon, Total Nitrogen, δ13C Measurements .................................................................................... 4

Radiocarbon Measurements ...................................................................................................................... 4

210Pb, 226Ra, and 137Cs Measurements ...................................................................................................... 5

Dataset Descriptions...................................................................................................................................... 5

Acknowledgments.......................................................................................................................................... 6

References Cited........................................................................................................................................... 6

Appendix 1. Data File Descriptions................................................................................................................ 8

Bonanza_Gradient_Field ........................................................................................................................... 8

Bonanza_Gradient_Physical...................................................................................................................... 9

Bonanza_Gradient_Chemistry ................................................................................................................. 10

Tables

1. Statistics of analyses for working standards run on the Carlo Erba 1500, from 2006–2010. ............ 4
iv

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

meter (m) 1.094 yard (yd) 

Area

square meter (m2) 10.76 square foot (ft2) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × °C) + 32.

Datum

Horizontal coordinate information is referenced to the World Geodetic System of 1984 (WGS84). 
Soil Data for a Vegetation Gradient Located at 

Bonanza Creek Long Term Ecological Research Site, 

Interior Alaska 

By Kristen L. Manies1, Jennifer W. Harden1, Christopher C. Fuller1, Xiaomei Xu2, and John P. McGeehin1

Abstract

Boreal soils play an important role in the global carbon cycle owing to the large amount 

of carbon stored within this northern region. To understand how carbon and nitrogen storage 

varied among different ecosystems, a vegetation gradient was established in the Bonanza Creek 

Long Term Ecological Research (LTER) site, located in interior Alaska. The ecosystems 

represented are a black spruce (Picea mariana)–feather moss (for example, Hylocomium sp.) 

forest ecosystem, a shrub-dominated ecosystem, a tussock-grass-dominated ecosystem, a sedgedominated ecosystem, and a rich fen ecosystem. Here, we report the physical, chemical, and 

descriptive properties for the soil cores collected at these sites. These data have been used to 

calculate carbon and nitrogen accumulation rates on a long-term (decadal and century) basis 

(Manies and others, in press). 

Introduction

High-latitude soils contain approximately 50 percent of the carbon (C) within the global 

soil C pool (Kasischke, 2000; Tarnocai and others, 2009) and, therefore, play an important role 

in the global C cycle. Climate change is expected to impact the boreal region in many ways 

(Hinzman and others, 2005), which in turn will affect the balance of C inputs and losses to the 

soil C pool. It is also important to understand nitrogen (N) stocks and availability because N 

controls many aspects of plant productivity and, therefore, cycling of C and N are closely linked 

(Vile and others, 2014). 

To help our understanding of C and N stocks in a variety of boreal ecosystems, we 

measured physical, chemical, and descriptive soil properties in five different ecosystems in 

interior Alaska. These ecosystems were situated along gradients of soil moisture and dominant 

vegetation. Factors such as parent material, climate, and topography, which influence soil 

formation (Jenny, 1941), were consistent along these gradients. We used these data to calculate 

C and N accumulation rates on both decadal and century timescales to determine how the 

interaction of soil and vegetation influences these rates, and thus, C and N storage over time 

(Manies and others, in press). Findings from this study indicate that the C and N dynamics of the 

 

1

U.S. Geological Survey 

2

University of California, Irvine 
2

rich fen are different from the other four ecosystems, likely the result of differences in nutrient 

cycling and the fire return interval. 

Site Description

Study sites were located on State land adjacent to the U.S. Forest Service Bonanza Creek 

Experimental Forest, approximately 30 km southwest of Fairbanks, Alaska, near the floodplain 

of the Tanana River (lat 64.696° N., lon 148.321° W.). These sites were part of the network of 

sites in the Bonanza Creek Long Term Ecological Research (LTER) program. We studied soils 

in five ecosystems located along a ~300-m transect. Each ecosystem was dominated by a 

different type of vegetation: (1) a closed-canopy black spruce (Picea mariana) forest with a 

feather moss (for example, Hylocomium sp.) and ericaceous shrub understory (herein, “black

spruce”); (2) a shrub system consisting of willow (Salix sp.) and birch (Betula sp.) with an 

understory dominated by leatherleaf (Chamaedaphne calyculata) and sparse moss cover (herein, 

“shrub”); (3) a tussock-grass system dominated by Calamagrostis canadensis with some brown 

mosses present (herein, “tussock grass”); (4) a peatland dominated by emergent vegetation such 

as sedges (herein, “sedge”); and (5) a moss-dominated rich fen, consisting of both Sphagnum sp. 

and brown mosses (herein, “rich fen”). Several publications describe other data obtained from 

these sites, including ecosystem respiration (McConnell and others, 2013) and microbial 

abundance (Waldrop and others, 2012). 

Soil Sampling

Three soil cores, encompassing all of the organic soil and extending into the mineral soil 

below, were collected at each site at randomly selected locations within an area of less than ~10 

m

2

. Sampling for the black spruce and low shrub site occurred during the summer and samples 

were obtained using a combination of soil blocks cut to a known volume and a Makita coring 

device (4.8 cm diameter; Nalder and Wein, 1998). Soil cores from the other three sites were 

obtained in the spring, when the ground was frozen, using a SIPRE corer (7.6 cm diameter; Rand 

and Mellor, 1985). 

Each soil profile was then divided into subsamples representing soil horizons and (or) 

subsections of different soil horizons. This separation occurred either in the field or, if frozen, in 

the lab, based on visual factors such as level of decomposition and root abundance. These

horizon samples were described using modified soil survey techniques following the U.S. 

Department of Agriculture’s Natural Resource Conservation Service (USDA-NRCS; Soil Survey 

Staff, 1998) and Canadian (Soil Classification Working Group, 1998) methodologies. We 

modified horizon codes according to the following scheme: 

L Live moss, which is green and generally contains some leaf and needle litter. 

D Dead moss, which is undecomposed or slightly decomposed. This horizon is the 

upper fibric organic horizon that contains more moss than roots. This horizon would be 

considered an Oi horizon (U.S. soil system).

F Fibric (Canadian soil system) or fibrous organic horizon, which varies in the 

degree of decomposition, but in which roots are more abundant than recognizable plant parts.

This horizon would be considered an Oi horizon (U.S. soil system). 

M Mesic (Canadian soil system) organic horizon, which is moderately decomposed, 

with few, if any, recognizable plant parts other than roots. This horizon is generally considered 

an Oe horizon (U.S. soil system). 
3

H Humic (Canadian soil system) or sapric organic horizon, which is highly 

decomposed. The soil in this horizon smears when rubbed and contains no recognizable plant 

parts. The H horizon is generally considered an Oa horizon (U.S. soil system). 

A Upper mineral soil that forms at the surface or just below organic soil horizons 

(U.S. and Canadian soil systems), which contains less than 20-volume-percent organic matter, as 

judged in the field. 

B Lower mineral soil that has formed below an A horizon (U.S. and Canadian soil 

systems), with little or none of its original lithologic structure.

GR Horizon of matted grass (mostly dead, but some live) at the soil surface. 

LT Litter horizon (dead leaves, twigs).

LW Liverwort. 

X Unknown (not described). 

Each soil horizon was labeled with a four-letter code representing the site, core, and basal 

depth of the sample. The first two letters of the site code, BZ, denoted that the samples were 

from the Bonanza Creek LTER. The next third and fourth letters represent the site from which 

the samples were obtained: BS, black spruce; WB, shrub site; GR, tussock-grass site; EC, sedge 

site; and MR, rich fen. The BZMR cores were obtained outside a plot that was part of a raised 

water table experiment (MR signifies manipulated-raised, see Chivers and others, 2009). After 

the site code, each sample was labeled with a number representing the core/soil-profile, followed 

by a decimal point and the basal depth of the sample (in centimeters). For example, BZWB 1.8.5 

denotes a sample from the shrub site, soil profile 1, with a basal depth of 8.5 cm.

Soil-Sample Preparation and Drying 

All samples were placed on open shelves in an isolated room and allowed to air-dry to a 

constant weight, as determined by weights measured at least 1 week apart. Temperature during 

air-drying ranged from 20 °C to 30 °C. After air-drying, samples were oven-dried for 48 hours in 

a forced-draft oven. Samples that were classified as organic soil horizons (for example, moss, 

litter) were oven-dried at 65 °C to avoid loss or alteration of organic matter by oxidation or 

decomposition. The remaining samples were oven-dried at 105 °C. 

After oven-drying, samples were thoroughly mixed and split into subsamples for analysis 

and archiving. (Archive fractions of most of the samples described here are available by 

contacting K. Manies at the U.S. Geological Survey in Menlo Park, Calif.). Samples were then 

processed in one of two ways, depending on the horizon code. Mineral soil samples were gently 

crushed using a mortar and pestle, with care to break only aggregates, and then sieved through a 

2-mm screen. Soil particles that did not pass through the screen were removed, weighed, and 

saved separately; soil that passed through the screen was then ground by using a mortar and 

pestle to pass through a 60-mesh (0.246-mm) screen. The ground material was mixed and placed 

in a labeled glass sample bottle for subsequent analyses. Organic samples were weighed, and 

roots wider than 1 cm in diameter were removed, weighed, and saved separately. The remaining 

sample material was then milled in an Udy Corp. Cyclone Sample Mill to pass through a 0.5-mm 

screen. The milled samples were thoroughly mixed, and a representative sample was placed in a 

labeled glass sample bottle for analytical chemistry.
4

Soil Laboratory Methods

Total Carbon, Total Nitrogen, δ13C Measurements

We analyzed soil samples for total carbon and nitrogen using a Carlo Erba NA1500 

elemental analyzer. Samples were combusted in the presence of excess oxygen. The resulting 

sample gases were carried by a continuous flow of helium through an oxidation furnace, 

followed by a reduction furnace, to yield CO2, N2, and water vapor. Water was removed by a 

chemical trap and CO2 and N2 were chromatographically separated before the quantification of C 

and N (Pella, 1990a,b). For samples that also have δ13C, the elemental analyzer was coupled to a 

Micromass Optima isotope ratio mass spectrometer (IRMS) in continuous flow mode. For these 

samples C and N were determined by integrating the major ion peaks (mass of 44 for CO2, and 

mass of 28 for N2). For reliable quantification of δ15N, 15 to 30 μg N are generally needed and 

few samples met this criterion. Thus the δ15N data are not reported here; these data are available 

from the authors by request. The δ13C data are reported as deviations in parts per thousand (‰) 

relative to a standard, here Vienna Pee Dee Belemnite (V-PDB). δ13C was calculated using the 

following equation: 

δ13C ‰ = (((13C sample/12C sample) / (13C standard/12C standard)) – 1) × 1000 (1)

where all C measured was considered organic C because carbonates tend not to exist in the study 

area. 

All samples were compared to a main working standard, ethylene diamine tetra-acetic 

acid (EDTA), for which the δ13C value has been determined through a set of international 

standards. The chemical formula of this compound corresponds to a C concentration of 41.09 

percent and N concentration of 9.59 percent. Additional working standards were analyzed as 

samples in all runs to check consistency and overall precision. Peach tree leaves (SRM-1547), 

issued by the National Institute of Standards and Technology (NIST), were included in runs 

composed of organic soil. A marine sediment (MESS-1), issued by the Chemistry Division of the 

Canadian National Research Council, was included in runs composed of mineral soils. Certified 

values for these standards were obtained from Becker (1990) and Govindaraju (1989), 

respectively. Average measured values and standard deviations of these working standards are 

shown in table 1. 

Table 1. Statistics of analyses for working standards run on the Carlo Erba 1500, from 2006–2010. [Certified values: MESS-1, 2.99 percent carbon; SRM-1547, 2.94 percent nitrogen. Stdev., standard deviation; N, 

number of samples] 

Standard Percent carbon Percent nitrogen

Average Stdev. N Average Stdev. N

MESS-1 2.92 0.10 148 0.20 0.03 148

SRM-1547 46.79 0.46 177 2.84 0.13 177

Radiocarbon Measurements

A subset of bulk organic matter and picked macrofossil samples were analyzed for 

radiocarbon (14C) to evaluate the ages of C in the soil profile. A little more than half of the 

samples were processed at the U.S. Geological Survey (USGS) Radiocarbon Laboratory in 

Reston, Va. and analyzed by accelerator mass spectrometry at the Lawrence Livermore National 

Laboratory Center for Accelerator Mass Spectrometry (CAMS). The other samples were sent to 
5

the W.M. Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory at the University of 

California, Irvine. For all samples, subsamples were combusted at 900 °C in evacuated, sealed 

quartz tubes in the presence of cupric oxide (CuO) and silver (Ag) wire. Following cryogenic 

purification, CO2 was reduced to graphite in a reaction at 500–550 °C using the sealed-tube Znreduction method at the Keck laboratory (Xu and others, 2007) and the H2-reduction method at 

USGS/CAMS (Vogel and others, 1984). Radiocarbon data are reported as Δ14C, fraction modern 

(FM), and radiocarbon age following the conventions of (Stuiver and Polach, 1977). At the Keck 

laboratory, the reported Δ14C values have been corrected for mass-dependent fractionation to a 

common value of −25 parts per thousand using the simultaneous accelerator mass spectrometry

(AMS) δ13C measurement. At USGS/CAMS an aliquot of CO2 from the sample combustion was 

independently analyzed for δ13C to correct for fractionation in each sample.

210Pb, 226Ra, and 137Cs Measurements

Dried and ground subsections of cores were analyzed for 210Pb, 226Ra, and 137Cs activities 

as measured by gamma spectrometry. We used a Princeton Gamma HPGe germanium well 

detector to estimate dry matter accumulation rates for assigning dates to core profiles following 

methods described in Van Metre and Fuller (2009) and references therein. Briefly, detector 

efficiency for each isotope was determined using NIST traceable standards (137Cs = NBS SRM 

4350b; 210Pb = NBS SRM 4337; 226Ra = NBS SRM 4969). Total 210Pb activity is the 

combination of supported 210Pb (produced within the soil through the decay of 226Ra) and 

unsupported 210Pb (produced in the atmosphere by radon decay and added to the ecosystem 

through atmospheric deposition). Unsupported 210Pb was defined as the difference between 

measured total 210Pb and 226Ra, its long-lived progenitor determined from the activities of 214Pb 

and 214Bi gamma-emitting daughters of 226Ra. Horizon subsamples from each soil profile were 

measured until unsupported 210Pb was no longer detected. Unsupported 210Pb values were then 

used to calculate dry mass accumulation rates (MAR, in grams per cubic centimeter per year) for 

each soil horizon, from which dates of formation were calculated using the Constant Rate of 

Supply (CRS) model (Appleby and Oldfield, 1978; these dates can be found in the Supplemental 

section of Manies et al., 2016). Note that for the three grass-soil profiles we did not reach the 

point at which unsupported 210Pb could not detected. Because we found 210Pb in the mineral soil 

for the grass soil profiles we do not suggest using these data for dating purposes at this site.

137Cs, an anthropogenic radionuclide (half-life of 30.1 years), provides a means to constrain 

sediment accumulation rates and chronology because of its well-known input history from 

atmospheric fallout from aboveground nuclear weapons testing in the 1950s and first half of the 

1960s, with maximum deposition occurring during the years 1963 and 1964 (Callender and 

Robbins, 1993). Measured 137Cs activities were decay corrected for the period of time between 

sample collection and analysis. Uncertainty in the measured activity of 137Cs, 210Pb, and 226Ra 

was calculated from the counting error of samples and background spectra; it’s reported at the 

one-standard-deviation level. 

Dataset Descriptions

There are three separate downloadable files containing the soil data collected from the 

sites described in this report. Appendix 1 lists in detail the data within the following three

spreadsheet files: (1) BZ_Gradient_Field, contains field descriptions of the sampled soils, such 
6

as root abundance, color, and soil texture; (2) BZ_Gradient_Physical contains physical 

descriptions of the samples, such as volumetric field moisture and bulk density; (3) 

BZ_Gradient_Chemistry contains elemental C, elemental N, 14C, and the radioactive isotope 

values. 

Acknowledgments

We thank the Bonanza Creek LTER for allowing us to set up these research sites. Their 

personnel, especially Jamie Hollingsworth, have been instrumental in this research. Merritt 

Turetsky aided in site identification and characterization; A. David McGuire supported LTER 

coordination; Lee Pruett, Renata Mendieta, and Pedro Rodriguez assisted with core collection, 

processing samples, or analyses of core chemistry. We also thank Sara Peek and A.D. McGuire 

for providing helpful comments on an earlier version of this report. Funding for this work was 

provided by the National Science Foundation collaborative grant EAR-0630249 and the USGS

Global Change program. 

References Cited

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rate of supply of unsupported 210Pb to the sediment: Catena, v. 5, no. 1, p. 1-8. 

Becker, D.A., 1990, Homogeneity and evaluation of the new NIST leaf certified reference 

materials, in Zeisler, R., and Guinn, V.P., eds., Proceedings of the International Conference on 

Nuclear Analytical Methods in the Life Sciences: Gaithersburg, MD, National Institute of 

Standards, p. 571–577. 

Callender, E., and Robbins, J.A., 1993, Transport and accumulation of radionuclides and stable 

elements in a Missouri River reservoir: Water Resources Research, v. 29, no. 6, p. 1787-1804. 

Chivers, M.R., Turetsky, M.R., Waddington, J.M., Harden, J.W., and McGuire, A.D., 2009, 

Effects of Experimental Water Table and Temperature Manipulations on Ecosystem CO2 

Fluxes in an Alaskan Rich Fen: Ecosystems, v. 12, p. 1329-1342. 

Damman, A.W.H., and French, T.W., 1987, The ecology of peat bogs of the glaciated 

northeastern United States-A community profile: U.S. Fish and Wildlife Service Biological 

Report 85, no 7.16, 100 p. 

Govindaraju, K., 1989, Compilation of working value and sample description for 272 

geostandards: Geostandards Newsletter, v. 13, p. 1–113. 

Hinzman, L.D., Bettez, N.D., Bolton, W.R., Chapin, F.S., Dyurgerov, M.B., Fastie, C.L., 

Griffith, B., Hollister, R.D., Hope, A., Huntington, H.P., Jensen, A.M., Jia, G.J., Jorgenson, T., 

Kane, D.L., Klein, D.R., Kofinas, G., Lynch, A.H., Lloyd, A.H., McGuire, A.D., Nelson, F.E., 

Oechel, W.C., Osterkamp, T.E., Racine, C.H., Romanovsky, V.E., Stone, R.S., Stow, D.A., 

Sturm, M., Tweedie, C.E., Walker, M.D., Walker, D.A., Webber, P.J., Welker, J.M., Winker, 

K.S., and Yoshikawa, K., 2005, Evidence and implications of recent climate change in 

northern Alaska and other arctic regions: Climatic Change, v. 72, p. 251–298. 

Jenny, H., 1941, Factors of soil formation; a system of quantitative pedology (1st ed.): New 

York, McGraw-Hill, 281 p. 

Kasischke, E.S., 2000, Boreal ecosystems in the global carbon cycle, in Kasischke, E.S., and 

Stocks, B.J., eds., Fire, Climate Change, and Carbon Cycling in the Boreal Forest: New York, 

Springer-Velag, p. 19–30. 
7

Manies, K.L., Harden, J.W., Fuller, C.C., and Turetsky, M.R., in press, Decadal and long-term 

boreal soil carbon and nitrogen sequestration rates across a variety of ecosystems: 

Biogeosciences.

McConnell, N.A., Turetsky, M.R., McGuire, A.D., Kane, E.S., Waldrop, M.P., and Harden, 

J.W., 2013, Controls on ecosystem and root respiration across a permafrost and wetland 

gradient in interior Alaska: Environmental Research Letters, v. 8, no. 4, p. 45029-45029. 

Nalder, I.A., and Wein, R.W., 1998, A new forest floor corer for rapid sampling, minimal 

disturbance and adequate precision: Silva Fennica, v. 32, no. 4, p. 373–381. 

Pella, E., 1990a, Elemental organic analysis—Part 1-Historical developments: American 

Laboratory, v. 22, no. 2, p. 116–125. 

Pella, E., 1990b, Elemental organic analyzer—Part 2-State of the art: American Laboratory, v. 

22, no. 12, p. 28–32. 

Rand, J., and Mellor, M., 1985, Ice-coring augers for shallow depth sampling: U.S. Army Cold 

Regions Research and Engineering Laboratory CRREL Report 85-21, 27 p. 

Soil Classification Working Group, 1998, Canadian System of Soil Classification (3rd ed.): 

Ontario, National Research Council Canada Research Press, 188 p. 

Soil Survey Staff, 1998, Keys to soil taxonomy (8th ed.): Blacksburg, Virginia, Pocahontas 

Press, 599 p. 

Stuiver, M., and Polach, H.A., 1977, Discussion reporting of 14C data: Radiocarbon, v. 19, no. 3, 

p. 355–363. 

Tarnocai, C., Canadell, J.G., Schuur, E.A.G., Kuhry, P., Mazhitova, G., and Zimov, S., 2009, 

Soil organic carbon pools in the northern circumpolar permafrost region: Global 

Biogeochemical Cycles, v. 23, p. GB2023. 

Van Metre, P.C., and Fuller, C.C., 2009, Dual-core mass-balance approach for evaluating 

mercury and 210Pb atmospheric fallout and focusing to lakes: Environmental Science & 

Technology, v. 43, p. 26-32. 

Vile, M.A., Kelman Wieder, R., Živković, T., Scott, K.D., Vitt, D.H., Hartsock, J.A., Iosue, C.L., 

Quinn, J.C., Petix, M., Fillingim, H.M., Popma, J.M.A., Dynarski, K.A., Jackman, T.R., 

Albright, C.M., and Wykoff, D.D., 2014, N2-fixation by methanotrophs sustains carbon and 

nitrogen accumulation in pristine peatlands: Biogeochemistry, v. 121, no. 2, p. 317-328. 

Vogel, J.S., Southon, J.R., Nelson, D.E., and Brown, T.A., 1984, Performance of catalytically 

condensed carbon for use in accelerator mass spectrometry: Nuclear Instruments and Methods 

in Physics Research Section B: Beam Interactions with Materials and Atoms, v. 5, no. 2, p. 

289-293. 

Waldrop, M.P., Harden, J.W., Turetsky, M.R., Petersen, D.G., McGuire, A.D., Briones, M.J.I., 

Churchill, A.C., Doctor, D.H., and Pruett, L.E., 2012, Bacterial and enchytraeid abundance 

accelerate soil carbon turnover along a lowland vegetation gradient in interior Alaska: Soil 

Biology & Biochemistry, v. 50, p. 188-198. 

Xu, X., Trumbore, S.E., Zheng, S., Southon, J.R., McDuffee, K.E., Luttgen, M., and Lui, J.C., 

2007, Modifying a sealed tube zinc reduction method for preparation of AMS graphite targets: 

Reducing background and attaining high precision: Nuclear Instruments and Methods in 

Physics Research Section B: Beam Interactions with Materials and Atoms, v. 259, no. 1, p. 

320-329. 
8

Appendix 1. Data File Descriptions

The data files are available online only as Excel (.xlsx) spreadsheets. The zip file (.zip) 

containing these files is available at http://dx.doi.org/10.3133/ofr20161034. The content of these 

files is described in this appendix. 

Bonanza_Gradient_Field

This file contains the field descriptions of the sampled soils. Units for each column are 

given on row 2 of the file. This file includes the following columns: 

Sample ID Sample identification: The first two letters in the sample ID represent the area

of study, Bonanza Creek LTER (BZ). The next two letters represent the 

ecosystem (BS, black spruce; WB, shrub; GR, tussock grass; EC, sedge; 

MR, rich fen). Then there is a space. The number that follows indicates the 

sample number. A decimal point separates the sample number from the 

basal depth of the sample (in centimeters).

Depth Indicates the basal depth, in centimeters, of sampling increment.

Field horizon code Horizon type of the sample, as defined in the field. L, live moss; D, dead 

moss; F, fibric organic matter (OM); M, mesic OM; H, humic OM; A, A 

mineral soil horizon; B, B mineral soil horizon; GR, grass; LT, litter; LW, 

liverwort; X, unknown horizon. For more information about these horizon 

types see the Soil Sampling section of this report.

Sample description Brief description of the sample.

Roots Root abundance and size using conventions of USDA-NRCS (Soil Survey 

Staff, 1998).

Lab pH pH value of mineral soil measured in the laboratory. Deionized water was 

added to create a soil slurry (50 percent soil, 50 percent water) prior to 

measurement. 

Munsell moist color Munsell color value according to the Munsell Soil Color Chart, measured on 

moist soil

Von Post or texture If organic soil, the classification using the von Post scale of humification 

(Damman and French, 1987). If mineral soil, the soil texture class as 

described in the field, following conventions of USDA-NRCS (Soil Survey 

Staff, 1998).

Height above mineral Height of each basal depth above the mineral soil boundary. Therefore, the 

bottom organic layer equals zero and mineral horizons are negative 

numbers.
9

Bonanza_Gradient_Physical

This file contains physical data such as bulk density and volumetric moisture content. 

Units for each column are given on row two of the file. Column definitions are as follows: 

Sample ID Sample identification: The first two letters in the sample ID represent the area

of study, Bonanza Creek LTER (BZ). The next two letters represent the 

ecosystem (BS, black spruce; WB, shrub; GR, tussock grass; EC, sedge; 

MR, rich fen). Then there is a space. The number that follows indicates the 

sample number. A decimal point separates the sample number from the 

basal depth of the sample (in centimeters).

Depth Indicates the basal depth, in centimeters, of sampling increment.

Field horizon code Horizon type of the sample, as defined in the field. L, live moss; D, dead 

moss; F, fibric organic matter (OM); M, mesic OM; H, humic OM; A, A 

mineral soil horizon; B, B mineral soil horizon; GR, grass; LT, litter; LW, 

liverwort; X, unknown horizon. For more information about these horizon 

types see the Soil Sampling section of this report.

Sample description Brief description of the sample.

Date sampled Date the sample was taken (month/day/year).

Thickness Thickness of soil horizon.

>2 mm in sample Dry weight percent of soil particles not passing through a 2 mm sieve after 

gentle crushing.

>1 cm in sample Dry weight percent of roots larger than 1 cm in diameter in the sample.

Bulk density (<2 mm) Grams of oven-dried soil per cubic centimeter, with soil particles greater than 

2 mm and roots greater that 1 cm diameter removed.

Bulk density Grams of oven-dried soil per cubic centimeter for the entire soil sample with 

no fractions excluded. Calculated similarly to “Bulk density (<2 mm)” 

except the weight of particles greater than 2 mm and roots greater than 1 

cm diameter have been included.

Volumetric field moisture (OD) The percentage of water in the sample, by volume, of the oven dried (OD) 

sample.

Convert from AD to OD bulk 

density

Moisture remaining in a sample after air-drying (AD) to constant weight as 

determined by subsequently oven-drying (OD) the sample. Bulk density, on 

an air-dried basis, equals Bulk densityoven dry / (1 – (Convert from AD to OD

bulk density/100)).
10

Bonanza_Gradient_Chemistry

This file contains analytical data for the samples. Units for each column are given on row 

2 of the file. Column definitions are as follows:

Sample ID Sample identification: The first two letters in the sample ID represent the 

area of study, Bonanza Creek LTER (BZ). The next two letters represent 

the ecosystem (BS, black spruce; WB, shrub; GR, tussock grass; EC, 

sedge; MR, rich fen). Then there is a space. The number that follows 

indicates the sample number. A decimal point separates the sample

number from the basal depth of the sample (in centimeters).

Depth Indicates the basal depth, in centimeters, of sampling increment.

Field horizon code Horizon type of the sample, as defined in the field. L, live moss; D, dead 

moss; F, fibric organic matter (OM); M, mesic OM; H, humic OM; A, A 

mineral soil horizon; B, B mineral soil horizon; GR, grass; LT, litter; LW, 

liverwort; X, unknown horizon. For more information about these horizon 

types see the Soil Sampling section of this report.

Sample description Brief description of the sample.

Carbon Percentage by weight of total carbon (C) in an oven-dried soil sample with 

material greater than 2 mm or 1 cm diameter removed.

Nitrogen Percentage by weight of total nitrogen (N) in an oven-dried soil sample with 

material greater than 2 mm or 1 cm diameter removed.

δ13C Stable isotope signature of oven-dried sample with material >2 mm or 1 cm 

diameter removed.

LOI Loss-on-ignition value of oven-dried sample with material >2 mm or 1 cm 

diameter removed. 137Cs Amount of 137Cs measured in the sample. 137Cs error Laboratory error associated with the 137Cs measurement. 210Pb Amount of 210Pb measured in the sample. 210Pb error Laboratory error associated with the 210Pb measurement. 226Ra Amount of 226Ra measured in the sample. 226Ra Laboratory error associated with the 226Ra measurement.

Bulk sample: lab number Laboratory number for the sample when submitted for 14C values. Sample 

numbers in the form of WW#### are from Lawrence Livermore, ones in 

the form of UCIT#### are from UC Irvine.

Bulk sample: fraction modern Fraction modern for the bulk soil sample.

Bulk sample: ± fraction modern Analytical error associated with the fraction modern value for the bulk soil 

sample.

Bulk sample: Δ14C Δ14C value (‰) for the bulk soil sample. 

Bulk sample: ± Δ14C Analytical error of Δ14C value (‰) for the bulk soil sample. 

Bulk sample: 14C age Radiocarbon age (years, uncorrected) of the bulk soil sample.

Bulk sample: ± 14C age Analytical error of radiocarbon age (years) for the bulk soil sample.

Picked material: lab number Laboratory number for the sample when submitted for 14C values. Sample 

numbers in the form of WW#### are from Lawrence Livermore, ones in 

the form of UCIT#### are from UC Irvine.

Picked material: fraction modern Fraction modern for picked material.

Picked material: ± fraction modern Analytical error of the fraction modern value for picked material.

Picked material: Δ14C Δ14C value for picked material.

Picked material: ± Δ14C Analytical error of Δ14C value for picked material.

Picked material: 14C age Radiocarbon age (uncorrected) of picked material.

Picked material: ± 14C age Analytical error of radiocarbon age for picked material.

Notes Information regarding what type of material was picked and submitted for 14C analysis.

ISSN 2331-1258 (online) 

http://dx.doi.org/10.3133/

ofr20161034