United States 

Department of Assessing the Vegetation History 

Agriculture 

Forest Service 

of Three Southern Appalachian Balds 

through Soil Organic Matter Analysis 

Southern Jennifer D. Knoepp, Larry L. Tieszen, and Glen G. Fredlund 

Research Station 

Research Paper 

SRS-13 

Rocky Ba/d 
The Authors: 

Jennifer D. Knwpp, Research Soil Scientist, USDA Forest Service, 

Soutfiern Research Station, Coweeta Hydrologic Laboratory, 3 160 

Coweeta Lab Road, Otto, NC 28763; Larry L. Tieszen, Professor, 

Department sf Biology, Augustma College, Sioux Falls, SL) 57 197; 

Glen G. Fredlnn&, Associate Professor, Department of Geography, 

University of Wiseonsin-hllilwaukee, Milwaukee, WI 5320 1. 

September 1998 

Southern Research Station 

P.O. Box 2680 

Asheville, NC 28802 
Assessing the Vegetation History of 

Three Southern Appalachian Balds 

through Soil Organic Matter Analysis 

Jennifer D. Knoepp, Larry L. Tieszen, and Glen G. Fredlund 

Abstract 

The history of Southern Appalachian grassy balds has long been a topic of 

speculation. Two types have been identified: those completely covered by 

grass and those occupied by a mixed-hardwood overstory with a grassy 

herbaceous layer. Three areas historically known as balds were identified 

in the Wine Spring Ecosystem Project Area. Each is currently under a 

different management regime. The objective of this assessment was to 

determine the vegetative history of these balds through soil organic matter 

(SOM) analysis. Soil was collected from each horizon through the profile 

on the bald sites using a nearby forest for reference. The 6°C values were 

determined for the green vegetation, litter, and soils of the bald sites and 

reference forests. Samples were selected for determination of phytolith 

and charcoal content and for dating. The 6IT value of plant tissues 

varies with photosynthetic pathway and plant type, providing a distinctive 

signature in SOM. Significant shifts in SOM 6°C values with depth in the 

profile would suggest changes in site vegetation. Organic matter analysis 

indicated that two of the bald sites were never completely covered by grass 

without a woody component. The third bald may have undergone a 

vegetative shift in more recent times. Data also suggest that a vegetative 

shift may have occurred on two of the reference forest sites. 

Keywords: Carbon dating, grassy bald hardwood, prescribed burn, soil 

organic matter, Southern Appalachians. 

Introduction 

The origin of Southern Appalachian balds has been a subject 

of speculation since botanical inventories were conducted in 

the 1930's (Camp 1931, Camp 1936, Wells 1937). Balds 

are distinguished by high elevation and general lack of forest 

cover. Some are characterized as heath balds, with 

ericaceous shrubs being the dominant vegetation. Grassy 

balds, on the other hand, have grasses dominating the 

herbaceous layer, and include both those completely covered 

by grass and those with a sparse, mixed-hardwood overstory 

and grassy herbaceous layer. Historically, the latter type 

often had a completely grassy center (Lindsay 1976). 

Suggestions about the origins of the grassy balds include 

proposals that they represent natural plant communities 

maintained by frequent fire, or are a result of clearing by 

aboriginal peoples or early settlers for grazing (Fink 193 1, 

Wells 1936). Following extensive logging in the 1920's and 

1930's, the Federal Government acquired land in the 

Southern Appalachians for the national forests and the Great 

Smoky Mountains National Park. Since then fire has been 

excluded from the balds, and grazing has ceased. This has 

allowed the surrounding woody vegetation to encroach on 

these areas. The balds are maintained in an open condition 

as both wildlife areas and scenic vistas, which requires 

vegetation management including prescribed burning and 

clearing by hand and mechanical means (Lindsay and 

Bratton 1979). 

The carbon 6°C isotope signature present in soil organic 

matter (SOM) has been used to document vegetation 

changes over time (Andreux and others 1992, Balesdent and 

others 1993, Dzurec and others 1985, Mariotti and 

Peterschmitt 1994, Schwartz and others 1986, Tieszen 199 1, 

Vitorello and others 1989, Volkoff and Cerri 1987) and to 

reconstruct paleoenvironments (Cerling 1992, 

Krishnamurthy and DeNiro 1982, Sukumar 1993). Plant 

tissue tji7C values fall into modal groups based on their 

photosynthetic pathway. Plants that fix C02 by the C, 

(Hatch-Slack) mechanism have 613C values ranging from - 17 

to -9%0, while those that use the C, (Calvin cycle) 

mechanism are significantly more negative: -32 to -20% 

(O'kary 1988, Tieszen 1994). As a result, the isotopic 

value of SOM pools represents the vegetation that produced 

the SOM (Parton and others 1987). 

Soil phytolith content and composition can also be used to 

test the relative stability or longevity of grassy areas. Opal 

phytoliths are silicaceous formations produced in leaf 

material. Grasses produce large quantities of very 

distinctive, densely silicified, short-cell phytoliths. Trees 

and shrubs, on the other hand, produce significantly fewer, 

less densely silicified phytoliths in a variety of shapes that 

are more susceptible to breakage and dissolution. These 

differences are reflected in the soil phytolith content. Soils 

from stable grasslands have substantial1 y higher opal 

phytolith content than do woodland soils (Jones and Beavers 

1964). Soil phytolith content can be used to determine the 

dominance of grassy vegetation and the long-term stability 

of a grassy patch. 

The objective of this research was to determine the 

vegetative history of three Southern Appalachian ridge tops 

designated as balds. All three areas are within the Wine 
Spring Creek Ecosystem Management Area and are 

currently under different management regimes. The SOM 

W3C values were examined to dete~ne if a hlfC signal shift 

indicated major changes in vegetation, such as encroachent 

of grassy areas by woody vegetation or the presence of C, 

grasses. Changes in the values with depth in the soil 

profile were evaluated and compared with those in nearby 

forests. Soil chemical analysis was conducted to confirm 

that these sites had never been used for agriculture. Soil 

samples from balds and forests were analyzed for phytolith 

and charcoal content to estimate differences in grass 

populations and fire history. Soil samples from several 

depths on each bald were also 14C dated. 

Site Description 

The Wine Spring Creek Ecosystem Management Project 

Area in the Nantahala National Forest in western North 

Carolina contains three highelevation ridge locations 

hisl;srically known as balds. They are Goat Bald (GB), 

Jarrett Bald (JB), and Rocky Bald (RB). These areas are 

currently under different management regimes, but until 

1980 all were occupied by an oak/mixed-hardwood 

overstory with grassy herbaceous layers before management. 

The elevation at GB and JB is 1500 meters (m); RB is at 

1595 m. Sites are nearly level and occupied by soils in the 

Way& series--coarse-loamy, mixed, frigid Typic 

Haplumbrepts. 

Goat Bald has been managed as a wildlife opening since 

198 1. In 198 1 and 1986, prescribed burns were conducted 

to promote grass production. All woody vegetation, 

including stumps, was mechanically removed in 1987. 

Following clearing, land managers planted a mixture of cool 

season grasses. The site was burned again in 1990. In 1992, 

a Quercus rubra L. (red oak) stump was located adjacent to 

the bald, probably representing an individual that was 

dominant before the site was cleared. Ring counts showed it 

to have been approximately 180 years old when felled. 

Jmett Bald also is managed as a wildlife opening. In 1986, 

all woody vegetation was cut and left in place. Sprouting 

woody vegetation was periodically hand cut. Prescribed 

burns were conducted in 198 1 and in 1987. In 1992, crosssections from stumps of the apparent dominant and 

codominant Q. rubra were cut. Their ages when felled were 

210 and 98 years, respectively. Two Betula alleghaniensis 

Britton (yellow birch, a fire-intolerant species) stumps were 

also identified and cross-sectioned; they were about 40 years 

old when cut in 1987. 

Rocky Bald has not been disturbed by humans in recorded 

history. Q. rubra dominates the overstory. The ages of two 

dominant individuals were determined by coring and were 

found to be more than 100 years. Codorninant species were 

Betula lenta L. (black birch) and Acer rubrum L. (red 

maple) ranging from 45 to 50 years old. 

Reference forests used for comparison of 6°C values were at 

the Coweeta Hydrologic Laboratory, about 15 kilometers 

(km) from the Wine Spring Creek Project Area. The sites 

were three south-facing areas that, in side-slope, cove, and 

ridge landscape positions, represent three forest 

communities within the Coweeta basin. The mixed oakhardwood community, which is dominated by Q, prinus L. 

(chestnut oak), with Q. coccinea Muenchh. (scarlet oak), Q. 

alba L. (white oak), Q. velutina Lam. (black oak) plus A. 

rubrum and Carya spp. (hickory) present, is on the sideslope position. The cove-hardwood community, which 

includes Liriodendron tulipifera L. (yellow-poplar), A. 

rubrum, and Q. rubra, is found in mesic cove areas. The 

oak-pine community, dominated by Q. coccinea and Pinus. 

rigida Mill. (pitch pine), is on xeric, south-facing ridges. 

The slope and ridge sites had been undisturbed since the 

1920's, but the cove site was clear-cut harvested in 1977. 

All three community types were sampled at low and high 

elevations, approximately 870 m and 1 100 m, respectively. 

Soils on all sites are classified as either the Fannin series, a 

fine-loamy, micaceous, mesic Typic Hapludult; or the 

Chandler series, a coarse-loamy, micaceous, mesic Typic 

D y strochrept . 

Materials and Methods 

Sample Collection 

A transect extending from the elevational center of the bald 

toward the surrounding forest was established for soil and 

vegetation sampling on CB, JB, and RB. Transect 

establishment allowed examination of the possibility that 

hardwood vegetation had encroached on a completely grassy 

bald. Three or four 1-mquadrats along the transect were 

chosen to represent the vegetation occupying each bald. A 

complete vegetation inventory was conducted, and percent 

cover of each species was determined within each quadrat 

before sample collection. Vegetation inventory and samples 

were taken to characterize the quadrat from which soil 

samples were taken, not to confirm differences between 

balds. The plant materials collected from each quadrat were 

green graminoids (6); green forbs (F); litter, dead but 

identifiable plant material (L); and humus, unrecognizable 
organic material (H). All samples were dried and ground to 

pass a N-mesh sieve. 

Two soil cores were collected within each quadrat using a 

2.5-centimeters (cm) diameter, 60-cm-long core sampler 

with a slide hammer attachment. For each core, the soil 

profile was described; and the soil was sampled and 

compsited by horizon for each quadrat. Due to slight 

differences in horizon designations among quadrats, 

ANOVA testing was conducted on similar depthkorizon 

increments to determine differences among bald sites. Roots 

were removed from each soil horizon and sorted into two 

groups, 2 2 millimeters (mm) and I 2 mm in diameter. 

Roots and soils were treated with 1 N HC1 at room 

temperature and shaken to remove carbonates, which were 

occasionally present. Samples were then evacuated, 

centrifuged, and rinsed with deionized water before being 

ground. 

Reference forest soil samples were collected from soil pits. 

Two pits were dug for each community type in the reference 

forests, one at 870 m (low elevation) and one at 1 I00 m, 

bch soil pit was <1 m wide and up to 1 m deep. Soil 

profiles within the pits were described in two locations 1 m 

apart. Soil samples were collected from each horizon, one at 

each description point throughout the profile. Horizons 2 20 

cm deep were sampled in 10-cm increments. Leaf litter 

samples were collected from the dominant woody vegetation 

at each site: oak leaves (0) from the mixed oak site; oak 

leaves (0) and pine needles (P) from the xeric ridge site; and 

oak leaves (0), tulip poplar leaves (T), and black locust 

leaves (B) from the cove site. Forest floor samples were 

also collected and included the litter layer (L), fermentation 

layer (F), and humus layer (H). All samples were dried and 

ground to pass a 40-mesh sieve. 

Soil samples from each bald were composited by horizon for 

chemical characterization. Soil cation concentrations were 

detemined in dilute, double-acid extracts. Five grams of 

air-dried soil was shaken for 30 minutes with 25 milliliters 

(mL) 0.05 M H,SO, and 0.5 M HCl. Samples were then 

cenaifuged andsupematant analyzed for cation 

concentration using an atomic absorption spectrophotometer. Soil pH measurements were taken in a 1: 1 soil 

to 0.1 M CaCI, slurry, using a single pH electrode. 

Isotopic Analyses 

Vegetation and soil samples were analyzed for C and N by 

combustion ( 1.5 milligrams [mg] for vegetation, 5 to 20 mg 

for soil) on the Carlo Erba 1500 GN analyzer. Sample C0, 

from elemental analysis was then cryogenically purified anh 

analyzed for carbon isotope ratios on a VG SIRA 10 isotope 

ratio mass spctrometer (Tieszen and Fagre 1993). The 6°C 

values were calculated by the following standard equation: 

where 

Rs = ratio of ""C to I2C in the sample; 

Rp = ratio of 'T to I2C in PDB standard. 

The error associated with instrument precision, sample 

preparation, and analysis is 5 0.2%~. Quality control 

procedures included ruming periodic sample duplicates and 

an internal standard after every 10th sample. 

Soil samples from representative horizons of each bald were 

decarbonated and radiocarbon-dated at Geochron Inc. by 

conventional or Arnerican Meteorological Society counting 

met hods. 

Phytolith halyses 

Eight grams of air-dried soil were used for phytolith 

extraction, except where limited by sample size. Samples 

were treated with 20 mL HCl(37 percent) to oxidize 

carbonates, followed by repeated washing with distilled 

H,O. Sodium hexametaphosphate ((NaPO,),), 0.0 1 M, was 

used to deflocculate clays and oxidize colloidal organic 

material, which was removed by repeated settling and 

decanting. Then samples were treated with H,O, (30 

percent) in a boiling water bath to oxidize resibual organic 

material. Clay and colloidal materials released by this 

process were then decanted. Biogenic silicates were isolated 

from the soil mineral fraction by flotation with a ZnBr, 

solution at 2.35 specific gravity, repeated three times. he 

supernatant was filtered through a 5-pm pore membrane to 

ensure that no phytoliths were lost. The isolated fraction 

was washed, air-dried, and stored. The air-dried, extracted 

fraction (specific gravity 5 2.35) was weighed and expressed 

as a percentage of the original air-dried soil sample. 

Two or more slides per extracted sample were mounted 

using a glycerin solution. Glycerin allows the rotation of 

micro fossils under the cover-slip for more accurate 

classification. Slides were systematically scanned at 630X 

magnification using a Leitz Laborlux-S microscope. Rapid, 

point-count estimates were made for at least five fields of 

view. All objects greater than 5-pm were classified, 

including: ( 1) non-biogenic silicates, (2) irregular phytolith 

fragments, (3) large, dense arboreal phytolith forms, (4) 

grass short-cell phytolith foms, (5) other phytolith foms 
(elongate, bullifoms, trichomes, etc.), and (6) charcoal, So 

few large, dense arboreal phytolith foms were isolated that 

reladve frequencies could not be calculated. The percentage 

of grass short-cell fom, relative to the total phytolith sum, 

was calculated for each sample. Data reported are percent 

phytolith by weight recovered, and short-grass phytolich 

content as the percent total phytolith of each sample. 

Statistical analyses of bald 6°C values were conducted using 

NOVA procedures in SAS (SAS Institute 1985). A oneway ANOVA test was used to detennj;ne significant 

differences in among vegetation, litter. and soil 

horizons for each bald. A two-factor WOVA test was used 

to examine intemctions between bald and soil depthlhorizon. 

Matching soil horizons within the soil profile were analyzed 

using General Linear Models procedures (S AS Institute 

1985) to detemrine differences betvveen 6°C values for 

reference forest and bald soils. Significant differences 

betwwn means were detemined using Tukey's mean 

separation test (SAS Institute 1985). 

Neither SOM 8'" values, nor phytolith and j4"C data suggest 

that a major vegetation shift occurred on the three balds. 

There was no evidence that these sites ever included a 

sigPIificant C, grass component; however, RB showed an 

increase of 2 2%0 in SOM 6lT values within the soil profile, 

possibly due to some changes in vegetation composition. 

On the other hand, 613C data from the reference forests 

suggest that some major vegetation shifts may have 

occurred. As table 1 shows, the bald sites vary substantially 

in herbaceous plant species composition due to differences 

in management. 

Coat Bald was dominated by cool season grasses. Jarrett 

Bald was dominated by a variety of forbs and very few 

grminoids. Rocky Bald had Q. rabra and A. 

pennqlvanicum seedlings and an extensive cover of Carex 

pennsylvanica, which occasionally formed nearly pure 

swards beneath a closed tree canopy. Thirty percent of plant 

species found in the quadrat inventory were listed in 

histo~cal plant inventories conducted on balds in this area of 

the Blue Ridge province in the 1930's (table 1) (Wells 

1937). Current or historical plant inventories showed no 

evidence of C, plant species. The similar ages of dominant 

overstory trees, > 100 to 180 years, and fire sensitive 

understory trees, 40 to 50 years, suggest the three balds had 

a common history of woody plant occupation and fire 

frequency. 

ne relationship "oetween vegeation and SOM 6°C 

eompositim was similar among all qua&ats on all bald sites, 

dispelling the hypotf-nesis that they ever had a gassy center, 

lacked a forest component, or that trees are on the sire due to 

encrotlehment. Soil orgmic maner 5°C values were more 

psirive than the plant compartments (fig. 1). Soil and green 

vegetation differences were rnost marked on RB, where 

values for grmhoids and forbs were the rnost negative 

(-28.9%0)), and the soil from lower horizons was most 

positive (-23.4 760). The pattern at JB was inbemediate. 

BuUr root 6°C values were 1760 to 4%0 more negative than 

SOM at the same depth. 

Soil profiles in each quadrat along the transat from bald 

center to forest edge were similar on all three balds (table 2). 

There was no evidence that these areas had ever been used 

for agriculture, Distinct surface horizons were present on all 

bald sites. Lime application during grass establishment was 

evident in A hotizon soils on CB, where the pH is 5.8 and 

Ga and Mg levels are high. However, the effects of lime 

were evident only in the surface 12 em, suggesting that the 

area was never plowed. Soils from all balds were slightly 

acidic, with pH values ranging from 4.0 to 4.7 (table 2). 

Carbon content of the A horizon soils on all balds was quite 

high. Soil carbon was greatest at RB (1 1.0 percent) and 

significantly lower (7.7 and 6.6 percent, respectively) for 

GB and JB, (F = 10.847 and p = .008). Carbon-to-nitrogen 

(C:N) ratios ranged from 10 to 25 and differed significantly 

among balds but not with soil horizon. Soils from JB had 

the highest C:N ratios (mean = 21.4), compared with soils 

from GB (mean = 16.0) and RB (mean = 16.5). 

Vegetation 6°C values differed significantly among balds 

(F = 13.59, p = 0.0001) and plant components (F = 2.63, 

p = 0.018) (fig. I). Rocky Bald plant compartments were 

significantly more negative than the other balds at 2 -28%. 

This may have been due to increased assirnilation of soilrespired C02 because plants on RB were beneath a closed 

overstory canopy. Rocky Bald also showed a significant 

difference among plant compartments. The grminoid and 

forb 6°C values were more negative than values in the litter 

and humus layers, perhaps due to input from the overstory 

vegelation. WOVA testing showed that root 6I3C values 

did not change with soil depth on any of the bald sites. 

Reference forests showed the same pattern as bald sites, with 

SOM 6I3C values more positive than the plant components 

(fig. 2). Unlike the balds. differences in forest site 6°C 

values for plant components were not significant. Only oak 

leaf 6°C values were significantly more negative than other 

plant compnents, including the litter and humus layers. As 
Table 1-Average percent cover of each plant species present in the quadrant (1 mZ) sampied for 

vegetation. material and soil cores on Goat Bald, Jarrett Bald, and Rocky Bald 

Species 

Coat 

Bald 

Jarrett Rocky 

Bald Bald 

- 

---------- - - Average percent cover - - - - - - - - - - - - - 

Herbaceous 

Anemone quinqifolia 2 

Carex pennsylvanica 37 

Carex spp." 0.25 

Dactylis glomrata" 

Danthonia compressa" 

Diasporum lanuginosum 

Fern 

Festuca rubra 

Fragaria virginiana" 

Hedyotis crassifolia 

Hedyotis purpurea 

Honey sue kle 

Legume 

Luzula acuminata 

Lysimuchia quadnyolia" 

Monarda clinopodia" 

Panicum spp." 

Potentilla simplex 

Potentilla canadensis" 

Prenanthes trifoliata 

Ranunculus hispidus 

Smilax herbacea 

Solidugo argutaa 

Thelypten's novoboracensis 

Tiarella cordilfolia 

Woody 

Acer pensylvanicum 

Quercus alba 

Quercus rubra" 

Rhdodendron calendulaceum 

Rubus spp." 

a Included on a species list for balds in what is now the Wine Spring Ecosystem Management Area as described by Wells (I 937). 

Table &Soil profile description and chemical characterization for soils from Goat Bald, Jarrett Bald, 

and Rocky Bald 

Goat Bald 

A (4 cm) 

A2 (9 cm) 

AB (12cm) 

BA (20 cm) 

Bw 1 (33 cm) 

Bw2 (44 cm) 

BC (44 cmld 

Jarrett Bald 

A (7 cm) 

A2 (17 cm) 

A3 (19 cm) 

AB 1 (24 cm) 

AB2 (27 cm) 

BA (31 cm) 

B1 (42cm) 

B2 (54 cm) 

Rocky Bald 

A 1 (5 cm) 

A2 (15 cm) 

A3 (20 cm) 

AB (24 cm) 

BA (30cm) 

B 1 (35 cm) 

B2 (43 cm) 

Percent Ratio 

" Horizon designations are presented with average (n = 3 for CB and RB n = 4 for JB) bottom depth in parentheses. 

Percent C and C:N ratios presented with standard errors in parentheses, sample numbers as "a." 

"'Soil Ph, Ca, Mg, K, and P determinations were made on one cornposited sample per horizon for each bald. 

dn = 1. 
Flgwe 2. Mean (bar* = S.E.) carbon isotope values (6°C) for SOM (*) and roots (. ) at each sample point through the profile and mean isotopic values for plant companments on reference forest 

\ites. S~tes presented include mixed oak (A), xeric ridge (B), and mesic cove (C). Plant components: mixed oak, oak leaves (0); xeric ridge, oak leaves (0); pine needles (P); mesic cove, oak leaves 

(O), tul~p poplar leaves (T). black locust leaves (8). Organic horizon components: L (litter) = Oi. F (fermentation layer) = Oe, and H (humus) = Oa. Soil horizon designations represent a general 

profile descript~on and average depth for each community type. 
on the baids, reference forest root 6I3C values did not vary 

witfiin the soil profile. However, differences between root 

and S0M 6°C were much greater in the forests than on the 

bdd sites, rexhing up to 6%0 in the BC horizon on the xeric 

ridge site, 

Soil organic matter 6°C values differed significantly among 

sites and soil horizons on balds and reference forest sites 

(table 3)- Most showed a significant decrase in SOM 6°C 

with depth in the profile (figs. 1 and 2). The exceptions 

were GB and the cove site, where horizon effect p-values 

were 0.74 and 0.09, respectively. Rocky Bald soils showed 

the greatest enrichment with depth of the bald sites, with an 

increase of 2 2560 within the profile. Soil organic matter 

6°C increases, relative to profile depth, were greater in 

reference forests than on the balds, ranging from 2% for the 

cove site to 5760 for the xeric ridge. Changes in &I3C of this 

magnitude suggest that some vegetative changes have taken 

place. C, plant species may have been present on the xeric 

ridge and mixed-oak site, both south-facing slopes, resulting 

in less negative SOM 6°C values. 

Some "C enric krnent of SOM though the profile can be: 

accounted for by the incorporation of anthropogenically 

depleted 13C into SOM pools. Fossil fuel use, agricultural 

practices, and deforestation have released "C-depleted 

carbon into the atmosphere. This has resulted in 

atmospheric 6l" values that are about 1.5% more negative 

than they were a century ago. Von Fischer and Tieszen 

(1995) studied a Puerto Rican forest system and found that 

reeentfy fixed carbon, e.g., green vegetation and litter, is 

ifzeoprated into SOM pools wi& rapid 

nose SOM gmls afiat turn over more slowly bve 6°C 

vdues that korne more positive deeper in the profile, 

Many reseahers smdying forest soils have found increases 

of 1.4 to 2.m0 &tween the Iitter layer, sdace soils, and 

subsurface horizons deep ;in the profile (Goh and others 

1976; Melillo and others Z"d9; Nadelhoffer and Fry 1988; 

Schleser and others 198 1). Under deciduous forests in New 

aaltmd, Coh and others (1976) found a 1.4 to 1.5%~ 

eMchment between the surface and soils at a 75 ern depth. 

Sc hleser and others ( 198 1) studied some Geman forests 

where deeper soils were enriched 2% relative to surface 

soils. North American forests also have exhibited 

edchment within the soil profile. Soils under oak forests in 

Wisconsin were ewiched by 1.6960 between the top 10 cm of 

mineral soil and the deeper soils (Nadellroffer and Fry 

1988). A pine forest soil in Massachuselts was e~ched 

1.6%~ between the forest floor and SOM at 45 cm (Melillo 

and others 1989). 

Tieszen and Pfau ( 1995) exmined chnges in vegetation 

over time using chmges in S13C values with soil depth. They 

documented woodland intrusions on grasslands with a 

substantial C, component in loess hill areas of the grasslandforest transition zone. In this study, the SOM 6°C values on 

the bald sites did not lead to firm conclusions concerning the 

balds' vegebtive history. This is largely due to the absence 

of C, grasses. However, RB and the reference forest soils 

show greater enrichment with depth than can be accounted 

Table &Two-factor ANOVA for soil organic matter carbon isotcl-pe value as a function of bald or forest 

and horizon as described in the soil profileu 

Source d f Sum of squares F-value Rob >F 

Bald 2 

Horizon 5 

Bald X horizon 8 

Error 43 

Forest 2 

Horizon 8 

Forest X horizon 8 

Error 43 

"This table presents the analysis of all soil profile designations across all balds or reference forests. 

9 
for by anthropgenic edehment, suggesting that a 

vegetative shift took place on these sites sometime in the 

past. Balesdent and others (1987) showed that the C, signal 

of forest SOM was completely replaced by the C, signal of 

maize after 23 yeass of cultivation. However, this took place 

only in the surface soil. The C, signal was still evident at 

greater depths in the profile. SOM turnover rates decreased 

with depth in the profile due to lower biological activity and 

increased clay content. This is typical in soil profiles that 

have a Bt horizon, which is the case with most soils sampled 

in this study. 

The incorporation of recently fixed or modern C in the SOM 

on the bald sites is evident in the '4C data presented in table 

4. These data showed that modern C was >50 percent at all 

depths sampled. Many samples possessed substantial bomb 

radiocarbon; for example, the GB A-horizon soils, where the 

modem C was >lo0 percent. The samples from JB illustrate 

a profile where "C age increased with depth, and even the 

surface carbon was premodern. Radiocarbon dating showed 

the deepest soil sample, from between 37 and 48 cm, to be 

4,945 years B.P. Carbon at RB, however, was more recent 

than at JB and GB. This may reflect recent C input at 

greater depth by trees on the site. 

Total phytolith content of surface soils suggested no 

significant difference between bald and reference forest soils 

(table 5). However, the morphological compsitjon of 

phytolith assemblages suggested a slight difference between 

bald and forest soils. Upper soil horizons from balds had a 

slightly greater percentage of grass phytoliths than do forest 

soils, but the difference was not sigmificant. A significant 

decline in total phytolith content occurred with depth in most 

of the bald soil profiles. Deeper soil horizons from the balds 

had a greater percentage of grass phytoliths. This could 

have resulted from the long-term grass component present 

on the bald sites and the dissolution and decay of less hardy 

arboreal morphotypes over time. The dissolution of arboreal 

phytoliths was supported by the overall decrease in phytolith 

content with depth. Counts showed substantial amounts of 

charcoal in the bald soils at depths down to 20 cm in the 

profile. This supported the tree-age data, suggesting that 

bald sites had the same fire and vegetative histories. 

Conclusions 

Examination of SOM 6I3C values through the profile on 

three balds in the Southern Appalachians suggested a slight 

vegetative shift may have occurred on Rocky Bald. These 

data and the ages of dominant and codominant trees suggest 

the sites probably had the same fire history. There was no 

evidence that any of the bald sites were ever grassy without a 

woody vegetation component, or that woody vegetation 

Table 4-Carbon-14 dates for selected soil horizons from one sample for each baldu 

Site-horizon Carbon Age (S .E.) Modem (S .E.) Method 

RB-A 1 

RB-AB 1 

W-B A 

RB-B2 

JB-A1 

JB-AB 1 

JB-BA 

JB-B2 

GB-A1 

GB-B 1 

Percent 

Modem 

Modem 

365 (310) 

Modem 

Modem 

128 (398) 

Percent 

Conventional 

Conventiond 

Conventional 

Conventional 

Conventional 

Conventional 

Conventional 

AMS 

Conventional 

Conventional 

RB = Rocky Bald; JB = Sane% Bald; CB = Goat Bald; S.E. = Standard Errors. 

a Data presented include percent C, age of C, percent C that is mdern, and method of determination. Values in 

parenthesis for age and percent mGdern are standard errors. 
Table &Total percent phytolith (g phytolith x g soif-'x100), percent grass short cell 

phytolith (g grass phytolith x g phytolith-'~100) content, and relative abundance of 

charcoal for bald and reference forest soils (all values presented are means of all samples 

analyzed) 

Soil harizondepth 

CharcoalbPh ytolithsa Grass phytoliths abundance 

- - - - - - - - - - Percent - - - - - - - - - - 

Balds 

Alc (0-10 em) 0.94 (. 14) 3.52 (.90) 5 

A~/AB~ ( 10-20 cm) .63 (.06) 5.58 (.51) 3 

Forest 

A 1 (0-10 cm) 

"Standard errors in parentheses. 

Presented as mean of ranked values where 1 = absent; 5 = abundant. 

A l horizon n = 6. 

A2/AB horizon includes all soils above the B horizon n = 14. 

encroached on a grassy bald center. Neither modern nor 

older SOM 6'" data suggest these sites ever had a 

substantial C, grass component. Phytolith and charcoal 

analyses showed that the bald sites had both a greater grass 

component and higher charcoal content than reference 

forests. Changes in 6I3C with depth in the soil profile 

differed between bald and reference forest sites. 

Interestingly, SOM 6'" data from two of three reference 

sites indicated that a major vegetative shift had occurred. 

Acknowledgment 

This research was supported by the U.S. Department of 

Agriculture, Forest Service, Southeastern Forest Experiment 

Station (now Southern Research Station), through 

cooperative agreements 29- 1067 and 29-798. We thank 

Wayne Swank for supporting study in this area, Steven 

McNulty and David Wedin for their helpful reviews of this 

manuscript, Chad McMurtry and Michael Pfau for field 

assistance, Joe von Fischer and Donovan DeJong for early 

data analysis, Mike Chapman for the isotopic analyses, and 

Lee Reynolds for plant identification and logistic support. 

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Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 

12 p. 

The history of Southern Appalachian grassy balds has long been a topic of speculation. Two types have 

been identified: those completely covered by grass and those occupied by a mixed-hardwood overstory 

with a grassy herbaceous layer. Three areas historically known as balds were identified in the Wine 

Spring Ecosystem Project Area. Each is currently under a different management regime. The objective 

of this assessment was to determine the vegetative history of these balds through soil organic matter 

(SOM) analysis. Soil was collected from each horizon through the profile on the bald sites using a 

nearby forest for reference. The 6°C values were determined for the green vegetation, litter, and soils 

of the bald sites and reference forests. Samples were selected for determination of phytolith and 

charcoal content and for '4C dating. The 6°C value of plant tissues varies with photosynthetic pathway 

and plant type, providing a distinctive signature in SOM. Significant shifts in SOM 6°C values with 

depth in the profile would suggest changes in site vegetation. Organic matter analysis indicated that two 

of the bald sites were never completely covered by grass without a woody component. The third bald 

may have undergone a vegetative shift in more recent times. Data also suggest that a vegetative shift 

may have occurred on two of the reference forest sites. 

Keywords: Carbon dating, grassy bald, hardwood, prescribed burn, soil organic matter, Southern 

Appalachians. 
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