Soil data from Picea mariana stands near Delta 

Junction, Alaska of different ages and soil drainage 

type 

By Kristen L. Manies1, Jennifer W. Harden1, Steven R. Silva1, Paul H. Briggs2, and Brian M. 

Schmid3 

Any use of trade, firm, or product names is for descriptive purposes only and does not 

imply endorsement by the U.S. Government 

Open-File Report 2004–1271 

U.S. Department of the Interior 

U.S. Geological Survey 

1

Menlo Park, CA

2

Denver, CO

3

Iowa State, Department of Agronomy, 2101 Agronomy Hall, Iowa State University, Ames, Iowa 

50011-1010. 

i 
Contents 

Contents .............................................................................................................................................. ii 

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

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

Background...................................................................................................................................... 1 

Site Descriptions.............................................................................................................................. 2 

Collaborations and Ancillary Data .................................................................................................. 4 

Sample Collection............................................................................................................................... 4 

Sample Preparation and Drying .......................................................................................................... 6 

Laboratory Methods............................................................................................................................ 7 

Total Carbon, Total Nitrogen, δ 13C, δ 15N ...................................................................................... 7 

14C Analyses .................................................................................................................................... 9 

Elemental Analyses ....................................................................................................................... 10 

Particle Size Analyses ................................................................................................................... 10 

Sample Nomenclature ....................................................................................................................... 11 

Data-set descriptions ......................................................................................................................... 11 

Acknowledgements........................................................................................................................... 12 

Literature Cited ................................................................................................................................. 13 

ii 
Abstract 

The U.S. Geological Survey project Fate of Carbon in Alaskan Landscapes (FOCAL) is 

studying the effect of fire and soil drainage on soil carbon storage in the boreal forest. This project 

has selected several sites to study within central Alaska of varying ages (time since fire) and soil 

drainage types. This report describes the location of these sampling sites, as well as the procedures 

used to describe, sample, and analyze the soils. This report also contains data tables with this 

information, including, but not limited to field descriptions, bulk density, particle size distribution, 

moisture content, carbon (C) concentration, nitrogen (N) concentration, isotopic data for C, and 

major, minor and trace elemental concentration. 

Introduction 

Background 

Boreal forests, which contain approximately 30% of all carbon (C) present in the terrestrial 

biome [Hom, 2003; Kasischke, 2000], play an important role in the global C cycle. Approximately 

60% of the C within this ecosystem occurs within the organic and mineral soil horizons [McGuire 

et al., 1997]. Therefore, to understand the boreal C cycle one must understand how C is gained 

and lost from the soil system. The main C input to soil is plant detritus, while C losses can result 

from decomposition, leaching, and the main disturbance of the boreal forest, fire. 

Fire affects C storage of the boreal forest both directly (fire emissions) and indirectly. 

Indirect effects include altering the soil temperature regime through changes in albedo and the loss 

of organic layers, which play an important role in soil insulation [Viereck, 1981]. Changes in soil 

temperature in turn affects decomposition rates 

1
Delta R. 

Tanana River 

Gerstle River 

Alaska Highway 

Tanana River 

Alaska Highway 

DF56 

DF87 

DFDC 

DF94 

0 1 2 3 

Delta Junction 

Richardson Highway 

DFTB & DFTC 

DFCB & DFCC 

Delta Junction 

Fairbanks 

kilometers 

Figure 1. Location of sites in relation to Delta Junction, Alaska. 

[Dioumaeva et al., 2003; Hirsch et al., 2003; Hobbie, 1996; Robinson, 2002] and vegetative 

regrowth [Chipman and Johnson, 2002]. The effects of fire differ depending on drainage type. 

Soil drainage affects factors such as fire frequency and severity [Harden et al., 2000], vegetation 

recovery [Bond-Lamberty et al., 2004; Viereck et al., 1983], and rates of decomposition [Flanagan 

and Van Cleve, 1983]. 

The U.S. Geological Survey (U.S.G.S.) project Fate of Carbon in Alaskan Landscapes was 

created, in part, to examine in more detail how fire affects the C storage of boreal forests and how 

this response varies with soil drainage type. For this purpose we are studying several black spruce 

(Picea mariana (Mill.) BSP) dominated forests within central Alaska. These sites are at different 

stages of post-fire recovery and represent different soil moisture regimes. 

Site Descriptions 

The sites within this study are located in the Donnelly Flats area (lat 63° N., long 145° W.), 

which is ~95 mi (153 km) southeast of Fairbanks, near Delta Junction (Fig. 1). This area is 

2
Drainage Relative time since last burn

 Recent Recovering Mature 

well-drained DFTB DF87 DFTC 

(1999) (1987) (<1950) 

moderately well-drained DFCB DF94 DF56 DFCC 

(1999) (1994) (1956) (<1860) 

somewhat poorly drained DFDC 

(<1860) 

Table 1. Matrix of study areas by soil drainage class and relative time since last fire. 

comprised of flood plains, alluvial plains, and low terraces dissected by glacier-fed streams. Soils 

within this area are mainly derived from the Donnelly moraine and wind blown loess [O'Neill, 

2000]. Eight sites within this region were located within three different soil drainage types: well-, 

moderately well-, and somewhat poorly-drained. Soil drainage was based on depth to water table 

and hydraulic conductivity [Harden et al., 2003]. Depth to water table was estimated using mineral 

soil characteristics, such as mottling, and depth to gravel. Hydraulic conductivity was estimated 

based on soil texture, where sand and soils with gravel were assumed to drain quickly and have 

higher hydraulic conductivity, while silt and clay dominated soils drain slower and were assumed 

to have lower hydraulic conductivities. Within soil drainage, sites also varied in their stage of 

recovery from fire (Table 1). 

All sites, except the DFDC site, had organic layer/soil-horizon thickness described every 10 

to 20 m along two linear transects within the site. These transects were laid out perpendicular to 

each other to negate any possible directional influences due to slope or dominant wind direction. 

Samples were taken from a subset of transect sites and were analyzed for properties such as 

moisture content, bulk density, and C and nitrogen (N) elemental composition. No samples were 

taken for the 1994 burn (DF94) due to previous sampling efforts [O'Neill et al., 2003]. The 

somewhat poorly-drained, or DFDC, site was primarily a U.S. Forest Service (U.S.F.S.) site. 

3
Therefore, site setup was different than the other sites (no linear transects) and no soil descriptions 

were done other than for those locations which were sampled. 

Collaborations and Ancillary Data 

The sampling sites described here are the focus of several ongoing investigations. 

Therefore, many measurements, in addition to soil sampling, occurred at each site. These 

measurements may include percent coverage for different moss species and lichen, tree density, soil 

temperature and moisture, woody debris inventories, and ecosystem carbon exchange. Studies (and 

collaborators) include ecosystem recovery following fire (M. Mack1

), post-fire soil respiration (T. 

Schuur1, J. Randerson2), soil moisture and temperature (J. Neff3, J. Randerson2, K. Yoshikawa4), 

CO2 fluxes using eddy covariance towers (J. Randerson2

), remote sensing of stand characteristics 

and fire history (E. Kasischke5), and the influence of fire on N budgets (M. Mack1). 

Sample Collection 

Soil was excavated by shovel or auger to the depth of mineral soil. The profile was then 

divided into distinct soil horizons and described according to USDA-NRCS [Staff, 1998] and 

Canadian [Committee, 1998] methodologies. We modified soil horizon codes according to the 

following scheme: 

L Live moss, which are green and generally contain some leaf and needle litter. 

D Dead moss, which is comprised of non- or slightly-decomposed dead moss. The dead moss 

layer is characterized by fibric organic horizons that contain more moss than roots. 

1

 Department of Botany, University of Florida, Gainesville 

2

 Department of Earth System Science, University of California, Irvine 

3

 Department of Geological Sciences, Colorado State at Boulder 

4 Water and Environmental Research Center, University of Alaska, Fairbanks 

5

 Department of Geography, University of Maryland, College Park 

4
F Fibric (according to Canadian soil system) or fibrous organic layers, which vary in degree 

of decomposition but in which roots are more abundant than recognizable moss parts. In 

most cases these layers would be considered Oi layers (U.S. soil system) or upper duff 

(U.S.F.S. system). 

M Mesic (according to Canadian soil system) organic layers, which are moderately 

decomposed with few if any recognizable plant parts other than roots. M layers are 

generally Oe horizons (U.S. soil system) or lower duff layers (U.S.F.S. system). 

H Humic (Canadian soil system) or sapric organic layers, which are highly decomposed. This 

layer generally smears upon squeezing and has no recognizable plant parts. H layers are 

generally Oa horizons (U.S. soil system) or lower duff (U.S.F.S. soil system) layers. 

A Mineral soil that forms at the surface or below organic horizons (U.S. and Canadian soil 

system), with less than 20% organic matter, as judged in the field. 

B Mineral soil that has formed below an A horizon (U.S. and Canadian soil system), with little 

or none of its original rock structure. 

C Mineral soil that has been little affected by pedogenic processes (U.S. and Canadian soil 

system). 

LT Litter layer (dead leaves, twigs, etc.) 

LN Lichen 

Horizon codes could be further described with one of three qualifiers placed before the main code. 

A lower case ‘b’ indicated the horizon had been burned. This code could indicate anything from 

light scorching to deep charring. A lower case ‘f’ indicated the horizon was frozen at the time of 

sampling. A lower case ‘g’ indicates gravel was noted within the layer. 

5
A subset of the soil profiles was sampled by soil horizons. Samples were collected for bulk 

density, analytical purposes, and to determine moisture content. In most cases, one sample was 

collected for both bulk density and chemical analyses, while a second sample was collected for 

moisture content. Bulk density samples were collected with a variety of tools, including cores of 

known volume (mineral soil) and rectangles (litter and organic horizons) of known area. Cores 

used for mineral soil sampling include, in order of relative accuracy, a Soil Moisture Equipment 

Corporation Model 0200 core (Goleta, CA), an AMS Inc. regular soil auger (American Falls, ID), 

or a bevel-ended cylinder (individually manufactured, based on corers by Eijkelkamp Agrisearch 

Equipment, BV, Netherlands). After collection, all U.S.G.S. samples were weighed within 24 hours 

and air-dried. U.S.F.S. samples were immediately put into a 68 °C oven and dried for 48 hours. 

Samples were then sent to U.S.G.S. for sample preparation. 

Sample Preparation and Drying 

Field notes were used to inventory all samples entering the laboratory. Any discrepancy 

between field descriptions and laboratory observations was resolved before sample preparation 

began or the sample was discarded. All U.S.G.S. soil samples were immediately placed on open 

shelves in an isolated room and allowed to air dry to a constant weight. Temperature during airdrying ranged from 20 to 30 °C. Samples that did not have separate moisture and analytical 

samples taken in the field were split at this point. Air dry moistures of both splits were recorded. 

Bulk density calculations for these samples assumed that the air-to-oven dry moisture ratio in the 

entire sample was the same as for the moisture split. After air-drying, moisture samples/splits were 

oven dried for 48 hours in a forced-draft oven. Moisture samples that appeared to contain greater 

than 20 % organic matter (e.g., moss, litter) were oven dried at 65 °C to avoid loss or alteration of 

6
organic matter by oxidation or decomposition. The remaining moisture samples were oven dried at 

105 °C. 

Air-dry analytical samples/splits were thoroughly mixed, then split into subsamples for 

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

contacting J. Harden at the Menlo Park, CA office of U.S.G.S.) These samples were then 

processed one of two ways, depending on horizon code. Mineral samples were gently crushed 

using a ceramic mallet and plate, being careful to break only aggregates. The crushed sample was 

mixed and split into subsamples for analysis and archiving. The chemical fraction was weighed and 

sieved using a 2 mm screen. Soil particles not passing the 2 mm screen were removed, weighed, 

and saved separately. Soil passing the 2 mm screen was ground by hand using a mortar and pestle 

or ceramic mallet and plate 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 greater than 1 cm in diameter were removed, weighed, and saved 

separately. The remaining sample was then milled in an Udy Corporation Cyclone mill (Ft. 

Collins, CO) to pass through a 0.5 mm screen. The milled sample was thoroughly mixed and a 

representative sample placed in a labeled, glass sample bottle for analytical chemistry. 

Laboratory Methods 

Total Carbon, Total Nitrogen, δ 13C, δ 15N 

δ

A Carlo Erba NA1500 elemental analyzer (EA) coupled to a Micromass Optima isotope 

ratio mass spectrometer (IRMS) in continuous flow mode was used to determine total C, total N, 

13C and δ 15N. Because carbonates tend not to exist in this region and all mineral soil pH values 

were ≤ 7.0 [Staff, 1951], all (or the vast majority) of this C can be considered organic. Samples 

7
were combusted in the presence of excess oxygen. The resulting sample gasses were swept in 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 entering the Micromass Optima IRMS for quantification of 

C, N, δ 13C and δ 15N. Carbon and N were determined by integrating the major ion peaks (mass 44 

for CO2, and mass 28 for N2). For reliable quantification of δ 15N, 15 to 30 μg N are generally 

needed and few samples met this criterion. Thus the δ 15N data are not reported here; these data are 

available from the authors by special request. The δ 13C data are reported as deviations in parts per 

thousand (‰) relative to a standard, here Vienna Pee Dee Belemnite (V-PDB). δ 13C was calculated 

as: 

δ 13C ‰ = (((13C sample/12C sample) / (13C standard/12C standard)) – 1) * 1000 (1) 

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

(EDTA), which has been calibrated to air nitrogen through a set of international standards. The 

chemical formula for this compound corresponds to a C concentration of 41.09 % and N 

concentration of 9.59 %. Additional working standards were analyzed as samples in all runs to 

check consistency and overall precision. Two working standards were included in all runs: a 

marine sediment (MESS-1), issued by the Chemistry Division of the Canadian National Research 

Council, and a river sediment (NBS 1645), issued by the National Bureau of Standards, now the 

National Institute of Standards and Technology (NIST). Certified values were obtained from 

Govindaraju [1989]. These working standards are more representative of mineral soil samples. 

Over half the runs also included NIST-1547, N certified at 2.94 ± 0.12 % by weight [Becker, 1990]. 

8
Standard Carbon (%) Nitrogen (%) δ 13C (‰) 

EDTA 41.05 (1.05) 9.54 (0.60) -32.24 (0.16) 

n = 599 n = 599 n = 599 

MESS-1 3.02 (0.15) 0.18 (0.01) -25.64 (0.14) 

n = 49 n = 49 n = 49 

NBS-1645 5.21 (0.39) 0.09 (0.01) -22.29 (0.27) 

n = 53 n = 55 n = 53 

NIST-1547 46.81 (0.98) 2.79 (0.09) -26.11 (0.30) 

n = 133 n = 133 n = 134 

Table 2. Statistics analyses for EA-IRMS standards run from mid-April 2001 through mid-January 

2004. The average value is followed by the standard deviation (in parentheses) and the number of 

samples run. Certified values are as follows: MESS-1 = 2.99 %C; NBS-1645 = 0.0797 %N; NIST 

1547 = 2.94 %N. 

NIST-1547 peach leaves are more similar to the highly organic surface soils. Our values were 

generally in good agreement with those for which the standard had been certified (Table 2). 

14C Analyses 

A subset of samples were run for 14C activity. Most of these samples where chosen to aid in 

modeling soil turnover and (or) partition carbon into more labile versus stabile pools. The 14C 

content of ground, untreated soil was measured by vacuum sealing a homogenized sample 

containing ~1 mg C with cupric oxide and elemental silver in a quartz tube. The sample was then 

combusted at 850 °C and the resulting CO2 was purified cryogenically and reduced to graphite 

using a modified reduction method with titanium hydride, zinc, and cobalt catalyst [Vogel, 1992]. 

The graphite target was measured directly for 14C at Lawrence Livermore National Laboratory, 

Center for Accelerator Mass Spectrometry. 

The 14C data are expressed in Delta notation (δ 14C), which similar to δ 13C, expresses the deviation 

in the 14C/C in parts per thousand (‰) as compared to the standard NIST Oxalic Acid I (C2H2O4), 

9
with additional correction for fractionation, based on generalized 13C values [see Stuiver, 1980; 

Stuiver and Polach, 1977]. δ 14C values can also be converted to percent Modern (pM) values by 

dividing by 10 and adding 100. A δ 14C of 0 ‰ or 100 pM or 14C/C of 1.176 x 10-12 approximately 

represents the 14C/C of atmospheric CO2 in the year 1890. 

Elemental Analyses 

Elemental concentrations within the samples were analyzed for forty major, minor, and 

trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The 

sample was pretreated with nitric acid and hydrogen peroxide and brought to dryness at low 

temperature to help reduce the organic content and reduce reactivity. The sample was then digested 

using a mixture of hydrochloric, nitric, perchloric, and hydrofluoric acids at low temperatures. This 

final solution was introduced into the ICP-AES, where the elemental emission signals were 

measured simultaneously for the forty elements. More information regarding this procedure, 

calibration techniques, and its detection limits can be found in Briggs [2002]. 

Particle Size Analyses 

A limited number of mineral soil samples were selected for particle size analyses by 

conventional pipette analyses [Walter et al., 1978]. Due to the large amounts of organic matter in 

some of the samples, the 35% hydrogen peroxide treatment was repeated three times. Even after 

these treatments some organic matter persisted, skewing the results toward overestimation of the 

sand fraction. The samples for which organic matter may have been problematic in particle size 

analyses are indicated in the “Notes” column of the file called Delta_Physical. 

10
Sample Nomenclature 

All samples are labeled with a code describing the site and location from which the samples 

were obtained. All sample names begin with the same two letters (DF), representing Donnelly 

Flats, the region in which these sites are located. These two letters are followed by two characters 

indicating the site. For organizational sake, the eight sites have been subdivided into three sections 

(represented by worksheets in the data files). The first section (Tower) contains data from the two 

sites that have an eddy covariance tower: Tower Burn (DFTB), which burned in 1999, and Tower 

Control (DFTC), which is a mature site. Both of these sites have well-drained soils. The second 

section (Creek) is for another burn/control pair, located near Twelve-mile Creek: Creek Burn 

(DFCB), which burned in the same 1999 wildfire as Tower Burn, and Creek Control (DFCC), a 

mature site. Both of these sites are located on moderately-well drained soils. The last section 

(Misc.) contains data for stands that burned in 1994 (DF94; moderately well-drained soils), 1987 

(DF87; well drained), 1956 (DF56; moderately well-drained), and DFDC, the mature somewhat 

poorly drained U.S.F.S. site. 

Samples are further labeled with two numbers representing the profile number and basal 

depth of the sample (in cm). A decimal point separates the profile number from the basal depth. 

For example, DFTC 1.20 denotes a sample from Donnelly Flats Tower Control, profile 1 with a 

basal depth of 20 cm. 

Data-set descriptions 

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

eight sites described in this report. The first file, Delta_Site_Descriptions, is a Word (Microsoft, 

Inc.) file describing the location of each site and, within a site, where soils were sampled. General 

11
information such as sampling date, investigators, and vegetative cover is also noted. The next file, 

Delta_File_Descriptions, also a Word file, describes in detail the data within the following five 

Excel (Microsoft, Inc.) files. Delta_Field, contains field descriptions, such as root abundance, 

color, and soil texture, of the sampled soils. Delta_Physical contains physical descriptions of the 

samples, such as volumetric field moisture and bulk density. It also contains particle size, where 

applicable. Delta_Chemistry contains elemental C, N, and δ13C values for all samples. 

Delta_Suppl_Chemistry contains 14C and ICP-AES values for samples on which these analyses 

were run. The last file, Delta_Transects, contains sample locations and field descriptions for those 

profiles that were described, but not sampled. 

Acknowledgements 

We would like to thank Sue Trumbore and her lab at U.C. Irvine for their work on the 14C 

analyses. Jay Raymond and Elizabeth Langenburg were invaluable with their help in field 

sampling. Jennie Munster provided great support in both the field and the lab, while Stagg King 

helped oversee sample analysis and the related data in 2001. We would also like to thank U.S.G.S. 

staff in Fairbanks, including, but not limited to Mark Castor, Matt Schellekens, and Bob Burrows, 

who provided logistical support. U.A.F. affiliates, in particular Terry Chapin and A. Dave Mcguire 

provided both logistical support and advice on field designs, while Kenji Yoshikawa assisted 

greatly with instrumentation and site characterization. Jason Neff, Ted Schuur, Michelle Mack, 

Jim Randerson, Kathy O’Neill, and Eric Kasischke were all involved in site selection and sampling 

design. This work was supported by the U.S.G.S. Earth Surface Dynamics Program. 

12
Literature Cited 

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

Nuclear analytical methods in the life sciences, edited by R. Zeisler, and V.P. Guinn, pp. 

571-577, National Institute of Standards, Gaithersburg, MD, 1990. 

Bond-Lamberty, B.P., C. Wang, and S.T. Gower, Net primary production and net ecosystem 

production of a boreal black spruce wildfire chronosequence, Global Change Biology, 10 

(4), 473-487, 2004. 

Briggs, P.H., The determination of forty elements in geological and botanical samples by 

inductively coupled plasma-atomic emission spectrometry, in Analytical methods for 

chemical analysis of geologic and other materials, U.S. Geological Survey, edited by J. 

Taggart, J.E., pp. G1-G18, U.S. Geological Survey Open File Report 02-223, U.S. 

Geological Survey, 2002. 

Chipman, S.J., and E.A. Johnson, Understory vascular plant species diversity in the mixedwood 

boreal forest of western Canada, Ecological Applications, 12 (2), 588-601, 2002. 

Committee, C.A.S.C., The Canadian system of soil classification, 187 pp., NRC Canada Research 

Press, Ontario, 1998. 

13
Dioumaeva, I., S.E. Trumbore, E.A.G. Schuur, M.L. Goulden, M. Litvak, and A. Hirsch, 

Decomposition of peat from upland boreal forest: Temperature dependance and sources of 

respired carbon, Journal of Geophysical Research, D108 (D3), doi:10.1029/2001JH000848, 

2003. 

Flanagan, P.W., and K. Van Cleve, Nutrient cycling in relation to decomposition and organicmatter quality in taiga ecosystems, Canadian Journal of Forest Research, 13, 795-817, 

1983. 

Govindaraju, K., Compliation of working value and sample description for 272 geostandards, 

Geostandards Newsletter, 13, 1-113, 1989. 

Harden, J.W., R. Meier, C. Silapaswan, D.K. Swanson, and A.D. McGuire, Soil drainage and its 

potential for influencing wildfires in Alaska, in Studies by the U.S. Geological Sruvey in 

Alaska, 2001, U.S. Geological Survey Professional Paper 1678, edited by J. Galloway, pp. 

139-144, U.S. Geological Survey, 2003. 

Harden, J.W., S.E. Trumbore, B.J. Stocks, A. Hirsch, S.T. Gower, K.P. O'Neill, and E.S. 

Kaisischke, The role of fire in the boreal carbon budget, Global Change Biology, 6 (S1), 

S174-S184, 2000. 

14
Hirsch, A., S.E. Trumbore, and M.L. Goulden, Direct measurement of the deep soil respiration 

accompanying seasonal thawing of a boreal forest soil, Journal of Geophysical Research, 

108 (D3), doi:10.1029/2001JD000921, 2003. 

Hobbie, S.E., Temperature and plant species control over litter decomposition in Alaskan tundra, 

Ecological Monographs, 66 (4), 503-522, 1996. 

Hom, J., Soil carbon in permafrost-dominated boreal forests, in The potential of U.S. forest soils to 

sequester carbon and mitigate the greenhouse effect, edited by J.M. Kimble, L.S. Heath, 

R.A. Birdsey, and R. Lal, pp. 259-278, CRC Press, Boca Raton, 2003. 

Kasischke, E.S., Boreal ecosystems in the global carbon cycle, in Fire, Climate Change, and 

Carbon Cycling in the Boreal Forest, edited by E.S. Kasischke, and B.J. Stocks, pp. 19-30, 

Springer-Velag, New York, 2000. 

McGuire, A.D., J.M. Melillo, D.W. Kicklighter, Y. Pan, X. Xiao, J. Helfrich, B. Moore, III, C.J. 

Vorosmarty, and A.L. Schloss, Equilibrium responses of global net primary production and 

carbon storage to doubled atmospheric carbon dioxide: Sensitivity to changes in vegetation 

nitrogen concentration, Global Biogeochemical Cycles, 11 (2), 173-189, 1997. 

15
O'Neill, K.P., Changes in carbon dynamics following wildfire in soils of interior Alaska, Ph.D 

thesis, Duke University, 2000. 

O'Neill, K.P., E.S. Kasischke, and D.D. Richter, Seasonal and decadal patterns of soil carbon 

uptake and emission along an age-sequence of burned black spruce stands in interior 

Alaska, Journal of Geophysical Research, 108 (D1), doi:1029/2001JD000443, 2003. 

Robinson, C.H., Controls on decomposition and soil nitrogen availability at high latitudes, Plant 

and Soil, 242, 65-81, 2002. 

Staff, S.S., Soil survey manual, 503 pp., Agricultural Research Administration, United States 

Department of Agriculture, Washington, D.C., 1951. 

Staff, S.S., Keys to Soil Taxonomy, 599 pp., Pocahontas Press, Inc., Blacksburg, Virginia, 1998. 

Stuiver, M., Workshop on 14C data reporting, Radiocarbon, 22 (3), 964-966, 1980. 

Stuiver, M., and H.A. Polach, Discussion reporting of 14C data, Radiocarbon, 19 (3), 355-363, 

1977. 

Viereck, L.A., Effects of fire and firelines on active layer thickness and soil temperatures in interior 

Alaska, in Fourth Canadian Permafrost Conference, edited by H.M. French, pp. 123-135, 

National Research Council of Canada, Calgary, Alberta, 1981. 

16
Viereck, L.A., C.T. Dyrness, K. Van Cleve, and M.J. Foote, Vegetation, soils, and forest 

productivity in selected forest types in interior Alaska, Canadian Journal of Forest 

Research, 13, 703-720, 1983. 

Vogel, J.S., Rapid production of graphite without contamination for biomedical AMS, 

Radiocarbon, 34 (3), 344-350, 1992. 

Walter, N.F., G.R. Hallberg, and T.E. Fenton, Particle size analysis by the Iowa State University 

Soil Survey Laboratory, in Standard procedures for evaluation of Quaternary materials in 

Iowa., edited by G.R. Hallberg, pp. 61-90, Iowa Geological Survey, Iowa City, IA, 1978. 

17