I OFT
ORNL P
3067

EEEFEEEE
FEEE
1
www
MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963
AXY
ORNU. 3067
Conf. 6405052-97
HASTE

UN 1 3 1967
2. NICIS
--------.. , NICUS
CYCLING OF 4CA BY LAWOOD TREES
William A. Thomas
10:3.00, mw.66
Radiation Ecology Section, Health Physics Divis.01,
Oak Ridge National Laboratory, Oak Ridge, Tennessee
ABSTRACT
Twelve flowering dogwood (Cornus florida L.) trees were store
inoculated with ca in early May and studied until lear aoseission.
six months later. At the end of the experiment only 27 + 3 01 1r.-
oculum was in woody tissues (stem ii, branches 15, roots 2). Losses
(as percentage of inoculum) were by leaf fall (64), Poliar leaching
(6), stemflow («< 1), and insect damage (3). Rapid turnover of in-
oculated calcium (73% + 3) by these trees within a single' growing
season is further evidence that this species may be a nutritionally
beneficial component of forest communities.

Work performed while author was an Oak Ridge Graduate Fellow from
the University of Minnesota under appointment from Oak Ridge Associated.
Universities.

<Operated for the U. S. Atomic Energy Commission by Union Carbide
Corporation.
LEGAL NOTICE
The report was prepared a aa account of Government sponsored worte. Matches the United
Status, nor the Commarlou, nor any person notas ou batalla the Counterton:
A. Make any warranty or representation, proud or implied, with respect to the Moon-
racy, complet , or watelnous of the laboration contained the report, or that the mes
of my la formation, apparaat, method, or procum dieslonud ta the report may not mortuga“
primtal omad richtes or ....
B. Anions may labutine with repost to the un of, or for dummon routtes from the
As wood, to the above, pornoa notte a ball of the Contacto" trobudur .
ploys or contractor of the Comminahon, or aployho o mal contractor, the action that
nk employee or contractor of the Communion, or opploys of mod contractor prepare
dannatates, or provides noceno to, aby Information present to Me ploy or continos
with the Commission, or Me employment with a doutrmotor,
DISTRIBUTION OF THIS DOCUMENT, IS, UNLIMITED
UCN.MRA?...
A.
I
.
N
.
.
....
1,1-
1
,
y
ANINI
i
.
**
Ly..
INTRODUCTION
Flowering dogwood (Cornus florida L.) has been cited us a nutricionally
beneficial understory tree due to accumi lation of calciura in its leaves
(coile 1940; Metz 1952), thus keeping this essential elerent in circuisition
in upper soil layers. Resulto reported here are from one exçerirent in a
comprehensive investigation of the accumulation and cycling of calcium by
this species.
This experiment was performed to ascertain the distribution or calcune
in the tree-soil system during the growing season in which it entered the
tree. Although stable calcium analysis was sufficient to answer several
questions concerning the function of dogwood as a calcium "pump", use of
radiocalcium was necessary to fulfill this objective.
METHODS

Experimental Site
Dogwood trees were studied in a loblolly pine (Pinuo taeda L.) planta.
18 tion on the Oak Ridge Reservation, Roane County, Tennessee. Soil was e col-
19 luvial member of the Minvale series with exchangeable calcium concentration
20 (meq/100 g oven-dry) in the upper 20 cm of 1.35 + 0.05 (N = 4).
21 Calcium-45 Determination
Plant and litter material was oven-dried at 105 C for 48 hours and ashed
23 overnight in a muffle furnace at 575 C. Ashed samples were dissolved in
4 N HC1, filtered, and diluted to known volume. Radiocalcium was extracted
from soil by shaking samples overnight in an excess of 1 N HCI. A 4 ml aliquot
26 was evaporated in a planchet and counted with a Beckman Instruments, Inc.,
.
-
-
: YC60%
UCN-6.7
mome'.
mon.....
.
......

Widebeta II plar.cviet counting system for 20 minutes or 10° counts. Giurcaras
.
2 were prepared with identical volume and density ci sarples. Counting di üs
3 were corrected for machine efficiency, backcround radioactivity in cor.trci
samples, and radiological decay. Sample counting data were sot considerii
significant unless they exceeded background rate at the 0.05 level (Jarrett
| 1946). Coefficient of variation of 20 replicate analyses of "sca in leaves
was 1.8%, indicating exceptional reproducibility. Average values are pre-
8 | sented as the mean plus or minus one standard error of the mzan.
9 Tree Inoculation
Twelve dogwood trees were selected to represent the range of tree sizes 1
11 in the understory stratum. They ranged in diameter at grouni level from 4.4
12 to 7.1 cm and in height from 3,3 to 5.2 m. Tree weight (roots plus top wita-
13 out leaves) was estimated with a regression equation based oa data from prior
14 tree harvests. Inoculum (0.67 to 2.51 millicuries of Caci, in ici, adjusted
15 to pH 5 with NaOH) was proportional to estimated tree weight (i rci per 2500
8 oven-dry). Troughs, with volume from 20 to 40 cc, were constructed I am
17 above ground; they were filled with water, and chicol cuts (5 mm wide; 5 menit
deep) were made into the xylem at 1 cm intervals around the stem circumference
before isotope was added. Trees were tagged on 4 May 1966 between 1130 and
1300 hours; soil was moist, air temperature in the stand was 27 C, and the
sky was cloudless. All troughs had emptied once within 20 minutes; they
22 were refilled with water three times and removed after all water entered the
transpiration stream. Troughs were then soaked overnight in 1 N HCl; an
24 aliquot was taken to estimate ca retention on troughs.
Throughĩall and Steraf low collection
Three rain gauges were placed under cach crown and rura..071.6266 silveri
times during the experiment. Trees were stratifica inio iour estimated
weight classes, and one from each class was randomly selected for steron
collections. A trough was constructed 3 dm above ground to intercept store
flow which was collected in polyethylene bottles. Throughfall ard stemnion
fron tagged trees and a control tree were sampled after every period of con-
tinuous precipitation.
-
Lear Collection
A monthly sample of fifty leaves from each tagged tree was collected
by removing two leaves from each of 25 branches; the same branches were used
for all collections and represented the entire crown.
Total number of leaves on each tree was estimated with a regression
equation which related number of leaves in September to branch dia.ceter.
Since new leaves were produced during the growing season and some leaves fell
due to drought and insect damage, these estimates were corrected monthly wita
data obtained by counting the leaves on .12 branches when tagged leaf collec-
tions were made (a small correction was also made for leaves removed in pre-
vious samples). Estimated *Sca in fallen leaves was summed for the season
(with appropriate decay corrections) to estimate amount of radiocalcium lost
from the tree by leat fall. . : i . .
Insect damage
On each leaf-sampling date, 400 leaves were za ndomly selected from ad-
jacent untagged trees. Leaf area was estimated with a regression equation
26 based on the product of leaf length arid width. . Area of holes caused by
-
-
-
1 insects was measured with a transparent grid. Where a portio, oi ti.c Ico
margin was missing, the margin was drawn, and missing area was eclinatea.
3 Almost all insect damage was in intervein area. Radiocalciur. 106s was cal.
culated with data for "sca content per cm? of intervein area.
Tree harvesting
On 4 November, six months after inoculation, the eight trees not uscá 20:
stemt low collection were harvested, and "sca was determined in each of four
compouents (sten, branches, roots > 4 cm diameter, roots < 4 cm diazeter).
All leaves had fallen when trees, were harvested.
RESULTS
Radiocalcium Distribution in Tree-Soil System
Essentially all inoculum entered the transpiration stream (only 0.1%
is 10.02 of inoculum was retained by the trough).
On 5 June, one month after inoculation, 73% + 6 of total inoculum was in
17 leaves. Calcium-45 concentrations (absolute amount or percentage of total)
steadily decreased during the remainder of the season due to physical decay,
rollar leaching, and leaf fall. Radiocalcium lost from the tree by leaf fall
20 was 64% + 1 of total inoculum.
21. Newly-formed leaves in late September contained 4ca, indicating that
22 radiocalcium was still present in the transpiration stream since calcium is
23 not transferred from older to younger leaves (Nason and McElroy 1963).
24 This was confirmed by presence of "sca in samples of solution removed from
25 xylem of small twigs with a vacuum pump.
-
-
-
-
"
..
.
..
.
.
.
..
.
-
.
..
Radiocalcium loss due to insect damage was last of maximum "Cik Cance
-
-
-
-
-
although only 1.8% of leaf area had been recoved by insects throuch Cocooor.
This loss represented 3% of total inoculuru.
All samples of throughfall and sterflow, collected 2 tj moes during tre
-
-
-
radiocalcium in foliage that was removed by precipitation sir.ce leaf samples
were not collected immediately prior to every period of precipitation. The
equivalent or 8% of maximum radiocalcium in Poliage (June) was removed by
precipitation during the entire experiment. This arounted to 6% 1 1 of
10 total inoculum.
11 . Although stemf low volume was appreciable (usually from 100 to 3500 ml
· 12 depending upon the tree and amount of precipitation), it accounted for only
13 0.20% + 0.01 of total volume and 0.17% + 0.02 (N = 60) of total 4%ca which
14 reached the forest floor under trees. Radiocelcium in stemf low was only
15 0.01% + 0.01 of total inoculum. .
Two litter and soil samples were collected under each tree on 12 October
Soll samples were taken to a depth of 6 cm (8011 at greator depths did not
contain Sca). Of total 45ca found, 89% + 1 (N = 24) was in litter. Radio-
calcium was found in aboveground portious of ground vegetation: trumpet-
creeper (Campsis radicans L.), honeysuckle (Lonicera japonica Thunb.), and
greenbrier (Smilax sp.). This transfer of 45ca represented a negligible
22 amount of the inoculum due to paucity of ground vegetation under the trees.
of radiocalcium remaining in nonfoliar organs of the eight harvested
! 24 trees on 4 November, 97% + 2 was in aboveground tissues. ·· Xylem accounted for
93% + 1 of 45ca in the stem.
.
.
....

i i vean concentration of radiocalcium (uci/c oven-dry) in stem. Egmontö
within 2 cm or site of inoculation was 5.8 times that in the remainder of
the stem; however, this was only 0.08% of total inoculur.
Radiological Dose Absorbed by Apical veristems
Taylor (1966) predicted, based on interphase cr.romocome volume, trat cos-
wood meristems were most sensitive to radiation in June, the mont: they proo-
ably contained the greatest amount of ca (0.20 $ 0.041C1/6 on 5 June).
A dose of 74 15 rads during the entire experiment was estimated with
equation 92a in Loevinger, Holt, and Hine (1956), corrected for deta particle
energy not absorbed by cylindrical tissues (Parmley, Jenson, and Mays 1962).
This dose (<rad/day) is about two orders of magnitude less than that re-
quired to cause slight growth inhibition in a species with the seasonal inter-
phase chromosome volume of dogwood (Sparrow 1964).
DISCUSSION AND CONCLUSIONS
:
1. Estimated amount of ca accounted for at the end of the experiment
18 (106% + 5 of inoculum remaining after physical decay) was well within limits
19 lof sampling error for a weak beta emitter in a tree-soil system for six
months.
.::. Sample data and known pathways of calcium transfer were used to pre-
pare a diagrammatic summary of the results (Fig. 1). Stem and branches re-
tained 26% of the inoculum, most of which was pribably bound an exchange sites
in xylem (Bell and Biddulph 1963). The large percentago of total “sca which
reached foliage (73%) was due to rapid uptake of inoculum and polarity of
26 calcium in plants, which limits calcium to acropetal movement (Tukey, Wittwer,

UCN8867
i and Bukovac 1962). Since calciun is not returned to worry tissues iero
? Leat abscission, as are several other elements (Stenlia 1958), E 12: fccucci
of Poliar calcium was lost from the troc in lear iall.
The appreciable role of precipitaticn in renoviri caiclu. C.
5 rollage is to be expected (Attiwill 1966), while the role or ster.figu wind
normally be minimal due to its small contribution to total precipitacio..
7 reaching the forest floor under trees (He Ivey and Patric 1965). Rudiocalciu.
loss from foliage by insects was less thor, anticipated since insects have cee.
9 reported to remove from 3 to 15% of leaf area during the season (Bray 15ól,
10 1964; Rothacher, Blow, and Potts 1954).
1 Much of the ca in litter will be subsequently transferred to so:1
12 due to leaf decomposition and leaching by precipitation although a sizable
13 fraction of it will probably remain in the litter layer due to abundance of
14 exchange sites on dead pine needles.
L . It is not clear how ca entered roots, but it probably descended
16' from the stem since the amount of radiocalcium in roots greater than 4 cm
aiameter was 4.4 times that in roots less than 4 cm diameter and since there
was so little radiocalcium available for rcot absorption in soil. This does
not refute the concept of polarity for calcium movement since trees were
inoculated so close to the roots that some radiocalcium could have diffused
downward 10 bark (as opposed to translocation).
Rapid turnover of inoculated calcium by these trees is further evi-
dence that dogwoods are beneficial in keeping calcium in circulation in the
upper layers of soil, thus keeping it available for use by other species by
limiting its downward movement.
.
5.

2
.
Although this study emphasizes nutritional uprecis ci calc . CCCC.
Wowledge or ca circulation may also be of interest (1.) attor riuc Icar cc Tois-
tions (James and Flening 1966), (2) since calcium und strontiwa ochovu
similarly in forests (Aleksakhin and Ravikovich 1966), and (3) in forest
rertilization research (Mustanoja and Lear 1965).
.
-
.
- -
- -
..
-
-
...
.
.
.
.
..
...
.
..
.
.

LINZIVIDUR CITUD
Aleksamin, R.Y., and M. X. Ravi kovich. 1966. Corüain putiiorro . this
behavior of alkaline corth elements (ca, VS, Sr) in foresit bicocco.com
Soviet Soil Sci. 1966: 414-421.
5 Attiwill, P. M. 1966. The chemical composition of rainwater in zoietic. to
1 cycling of nutrients in mature eucalyptus forest. Plant and Soil
24: 380-406.
Bell, C. W., and o. Biddulph. 1963. Translocation of calcium: Exchange ca
!
10 Bray, J. R. 1961. Measurement of leur utilization as an index of minimum
1 level of primary consumption. Oikos 12: 70-74.
12 Bray, J. R. 1964. Primary consumption in three forest canopies. Ecology
45: 265-267. .
14 Coile, T. S. 1940. Soil changes associated with loololly pine succession on
abandoned agricultural land of the Piedmont Plateau. Duke Univ. School
Forestry Bull. 5. 85 p.
Helvey, J. D., and J. H. Patric. 1965. Canopy and litter interception :
rainfall by hardwoods of eastern United States. Water Resources Res.
1: 193-206.
James, R. A., and E. H. Fleming, Jr. 1966. Relative significance index of
radionuclides for canal studies. Univ. Calif. Lawrence Radiation Lab.
22. · Rep. UCRI-50050-1. 10 p.
Jarrett, A. A. 1946. Statistical methods used in the measurement of radio-
24 activity with some useful graphs and nomographs. 'U. S. Atomic Energy
Comm. Rep. ADCU-262. 43 p.
-
UCN.*567
.
5.:.
L
.
Loeveinger, R., J. G. Holt, and G. J. Hine. 1956. Internally administered
T radioisotopes, p. 801-873. In G. J. Hine and G. L. Brownell (ed.)
Radiation dosimetry. Academic Press, New York.
4 Metz, L. J. 1952. Weight and nitrogen and calciua content cf the annual
litter fa 11 of forests in the South Carolina Piedmont. Soil Sci. Soc.
Amer. Proc. 16: 38-41.
:7 Mustanoja, K. J., and A. L. Leat. 1965. Forest fertilization research, 1957-
| 1964. Bot. Rev. 31: 151-246.
9 Nason, A., and W. D. McElroy: 1963. Modes of action of the essential mineral
elements, p. 451 - 536. In F. C. Steward (ed.) Plant physiology, &
treatise. Vol. III. Academic Press, New York.
15
Parmley, W. W., J. B. Jenson, and C. W. Mays. 1962. Skeletal self-absorption
of beta-particle energy, p. 437-451. In T.7. Daugherty, W. S. S. Lee,
C. W. Mays, and Betsy J. Stover (ed.) Some aspects of internal irradiation.
Pergamon Press, New York.
17 Rotacher, J. S., F. E. Blow, and Sara M. Potts. . 1954. Estimating the
quantity of tree foliage in oak stands in the Tennessee Valley.
19
J. Forest. 52: 169–273.
Forest Ho.
20 Sparrow, A. H. 1964. Comparisons of the tolerances of higher plant species
to acute and chronic exposures of lon izing radiation. Jep: j. Genet.
40 (Suppl.): 12-37.
Stenlid, G. 1958. Salt losses and redistribution of salts in higher plants.
Encycā. Plant Physiol. 4: 625-637.
L
Taylor, F. G., Jr. 1966. Predicted seasonal radiosensitivity of southeastern
tree species. Radiat. Bot. 6: 307-311.
Tukey, H. B., S. H. Wittwer, and M. J. Bukovac. 1962. The uptake ará loss
of materials by leaves and other above-ground plant parts with special
reference to plant nutrition. Agrochimica 7: 1-28.
-
-
-

nino
Figure 1. Distribution of
Ca after stem-inoculation of doe,wood trces.
Numbers in parentheses are percentages of inoculuni found after
.
leal abscission. Numbers not in parentheses represent maximum
percentages of inoculum in components during the growing season.
der...
Trees were tagged on 4 May and harvested on 4 November 1966.
..
.
.
-.... ..
ORNL-DWG 66-12555
73
88
BRANCHES
(15)
INSECT
DAMAGE
LEAVES
(3)
100
STEM
C 64
LEAF FALL
STEMFLOW
LEACHATE
.
ROOTS
70
LITTER
(69)
-

SOIL
(0)
.
::
.
..
END

.
.
.
.
.
-
ma
..
.
.
"
...
SY
.
!
DATE FILMED
8 / 15 /67