United States 

Department of 

Agriculture 

Forest Service 

Pacific Southwest 

Research Station 

Research Paper 

PSW-200 

Content of Chemical Elements in Tree Rings 

of Lodgepole Pine and Whitebark Pine 

from a Subalpine Sierra Nevada Forest 

David L. Peterson Darren R. Anderson 
Peterson, David L; Anderson, DarrenR. 1990. Content of chemical elements In tree rings 

of lodppde pine and whitebark pine from a subalpine Sierra Nevada for&. Res. 

Paper PSW-20. Berkeley, CA: Pacific Southwest Research Station, Forest Service, 

U.S. Depamnent of Agriculture; 9 p. 

The wood of lodgepole pines and whitebark pines fran a high elevation site in the eastcentral Sierra Nevada of California was analyzed for chemical content to determine whether 

there were any temporal patterns of chemical distribution in tree rings. Cores were taken 

from 10 trees of each species and divided into 5-year increments for chemical analysis. Correlation analysis indicated that calcium and magnesium, both of which have divalent cations, 

were strongly correlated for both species. The elements copper, iron, cobalt, nickel, 

molybdenum, chromium, tin, and arsenic were all significantly correlated with one another 

in lodgepole pine but not in whitebark pine. Concentrations of calcium and magnesium 

decreased over time for both species, while that of boron increased dramatically. None of 

the other elements showed sigdicant trends. Most elements had higher concentrations in 

the youngest wood, which probably reflects greater mobility of soluble foms of elements 

in and adjacent to living vascular tissue. Chemical concentrations in the wood of trees from 

this study are presumably free of the effects of substantial input from humans. This data set 

therefore provides valuable information an wood chemistry with which to evaluate disturbed or polluted stands with similar characteristics. 

Retrieval Terms: dendmeeology, tree growth, wood chemistry 

The Authors: 

DAVID L. PETERSON was formerly supervisoty ecologist with the Station's Atmospheric Deposition Research Unit at Riverside, California. He is now an associate professor 

of forestry, University of Washington, Seattle and a research biologist, U.S. National Park 

Se~ce. DARREN R. ANDERSON is a computer programmer with the Unit. 

Acknowledgments: 

We are grateful to Gloria Vasquez for assistance with preparation of samples and to Phil 

Rundel for assistance with chemical analysis. Michael Arbaugh assisted with statistical 

analysis. Helpful review comments on the manuscript were provided by Nancy Grulke, 

James McClenahen, Mark Poth, Martin Rose, and Hulm Wood. We appreciate the 

cooperation of the Inyo National Forest. This study was partially supported by Southern 

California Edison and the University of California, Riverside. 

Pacific Southwest Research Station 

P.O. Box 245, Berkeley, California 94701 

June 1990 
Content of Chemical Elements in Tree Rings 

of Lodgepole Pine and Whitebark Pine 

from a Subalpine Sierra Nevada Forest 

David L . Peterson Darren R . Anderson 

CONTENTS 

.. lo Brief ..................................................................a 

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

Methods ..................................................................................................................................... 1 

Results and Discussion ............................................................................................................. 2 

Conelation Analysis ............................................................................................................ 2 

Temporal Trends in Element Concentration ....................................................................... 3 

Phosphorus (fig . I) ....................................................................................................... 4 

Potassium (fig . 2) ........................................................................................................ 4 

Calcium @g . 3) ............................................................................................................ 5 

Magnesium (fig . 4) ....................................................................................................... 5 

Sodium (fig . 5) ............................................................................................................. 6 

Bomn (fig . 6) ................................................................................................................ 6 

Iron (fig . 7) ................................................................................................................... 7 

Copper (fig . 8) .............................................................................................................. 7 

Manganese (fig . 9) ....................................................................................................... 8 

Zinc (fig . 10) ................................................................................................................ 8 

Lead. Tin. Barium. Swntium ...................................................................................... 8 

. . Aluminum. Sll~con ....................................................................................................... 9 

Other Elements ............................................................................................................. 9 

References ................................................................................................................................. 9 
IN BRIEF.. . 

Peterson, David L.; Anderson, Damn R. 1990. Content of analyzed for chemical content to determine whether there were 

chemical elements in tree rings of lodgepole pine and any temporal patterns of chemical distribution in tree rings. 

whitebark pine from a subalpine Sierra Nevada forest. Trees were sampled above 3000 m near timberline in the Sierra 

Res. Paper PSW-200. Berkeley, CA: Pacific Southwest Re- Nevada of California, at a location that is assumed to have 

search Station, Forest Service, U.S. Depwent of Agricul- minimal humandismbanceorimpactfromairpoUutants. Trees 

ture; 9 p. of a wide range of sizes and ages of both species were sampled. 

Calciumandmagnesium (bothdivalentcations) werestrongly 

Retrieval Term: dendroecology, nee growth, wood chemishy correlated with each other in both species. Copper, iron, cobalt, 

Little i~ known about the ecology of highelevation forests in 

the Sierra Nevada of California. Tree species located near 

timberline grow slowly and may be sensitive to small environmental changes. The effects of atmospheric deposition on 

California forests are of particular concern because of the presence of phytotoxic levels of ozone and elevated levels of nitrogen deposition at some montane locations. In addition, some 

high elevation sites are poorly buffered against potential increases in the acidity of precipitation and snowmelt 

Some studies have indicated that the chemical content of 

wood can be used to detect changes in the atmospheric environmentandother facDrs over time. Chemical analysis of cores has 

been particularly useful in studies of sees located adjacent to 

smelters and indusuial operations, but has been less successful 

in identifying chemical markers in trees exposed to nonpoint 

sources of pollution. 

In this study, cores oflodgepolepineand whitebarkpine were 

nickel, molybdenum, chromium, tin, and arsenic wereall corm 

lated with each other in lodgepole pine but not whitebark pine. 

The clearest trends in the data were decreases in calcium and 

magnesium over time, and a dramatic increase in boron. These 

trends were found in both species. In addition, most elements 

had higher concentrations in the youngest wwd, which probably indicates greater mobility of soluble forms of elements 

adjacent to living vascular tissue. There was a high degree of 

variance in chemical concentration data. 

This data set provides information on wood chemistry from a 

site without the influence of human disturbance or elevated 

levels of pollutants. The data can therefore be compared with 

those from similar sites that may be affected by pollutants, in 

order to determine whether a chemical marker related to air 

pollution can be detected. The data can also serve as a bench 

mark for future evaluations of tree growth and chemical content 

of wood at the study site. 

USDA Faat Savicc Rcs. Papr PSW-200.1990. 
INTRODUCTION METHODS 

W igh-elevation forest ecosystems of the Sierra Nevada The study site was located in the Eastern BmkLakes water- 

-- of California may be sensitive to small environmental shed at 118'44' W. longitude, 37'26' N. latitude in the Inyo 

changes. Treesat highelevatiws grow slowly, and speciesnear 

timberline are at the limit of their existence due to low temperahues and desiccation. Subalpine forests may be affected by 

atmospheric deposition as well as by changes in atmospheric 

CO, (Bazzaz and others 1985, Oechel and Strain 1985). It is 

impossibleto&tminewhethertherearechangesin theecosystem, however, without a record through time. The expected 

range of variability in ecosystem response to environmental 

variables must also be known. 

Lodgepole pine (Pinus contorta var. murrayana) and whitebark pine (Pinus dbicaulis) are common species in the subalpine forests of the Siena Nevada. Research has been conducted on the ecology and silviculture of lodgepole pine (e.g., 

Lotan and Perry 1983), although there is little information on 

this species in California There have been a few studies on the 

ecology of whitebark pine (Arno and Hoff 1989, Forcella and 

Weaver 1977, Peterson and Arbaugh 1990, Weaver and Dale 

1974). including recent work on its physiology (Armstrong and 

others 1988) and leaf area (Peterson andothers 1989). Previous 

ecological studies of high elevation forests in California have 

focused on red fir (Abies magnifica) (Oosting andBillings 1943, 

Westman 1987). 

Previous dendroecological studies have indicated that chemical content of wood can be used in some cases to identify 

changes in the atmospheric environment over time (Brilker 

and others 1985, Lepp 1975). A number of studies have identified changes in the concentration of some elements over time 

that are related to differing exposures to pollutants from industrial processes (Arp and Manasc 1988, Bees and McLaughlin 

1984, Guyeaeand McGinnes 1987) or to siteand soil chteristics (McClenahen and others 1987,1989). It has been considerably more difficult to associate chemical distribution in tree 

rings with regional effects of aunospheric deposition (Berish 

and Ragsdale 1985, Frelich and others 1989, Legge and others 

1984). A reliable baseline is needed to compare trees with 

potential effects of chemical changes. Analyses of chemical 

content of wood from areas free of pollution may help to 

determine whether there have been chemical changes in trees at 

similar sites. 

This paper reports the results of a study to analyze the 

chemical content of lodgepole pine and whitebark pine cores 

from a subalpine Sierra Nevada forest, to determine whether 

there wereany temporal patterns of chemicaldistribution in tree 

rings. 

National Forest, Inyo C&ty. California. This high-elevation 

forest is relatively free of air poUutants and has no history of 

largescale humandisturbance. The250-ha watershedis located 

between 3170and 3780melevationandcontainslodgepolepine 

andwhitebarkpineforest, alpinemeadows,willows(Salixspp.), 

and scattered shrubs. A large portion of the watershed consists 

of alake, several streams, granite cliffs, and talus slopes. There 

is little evidence of fire in the watershed. Frequent avalanches 

appear to be the major form of disturbance. Soils within the 

sample area are of a glacii origin and derived from granitic 

material. They areclassified asTypic Crycchrepts, and depth to 

bedrock is less than 100 cm (B. Smith unpublished data). 

The sampling area was composed of mixed lodgepole pine 

and whitebark pine (Petemon and Arbaugh 1990, Peterson and 

others 1989). Slope was less than 10 percent in this area, with 

little variation in slopeorothersitecharacteristics. Density was 

3050 stemsh, and basal area was 18.2 mama (Peterson and 

others 1989). Ten aees of each species (table 1) were sampled 

along a msect usingthepoint-centeredquarter method (Peterson and Arbaugh 1990). All aees exceeded 10 cm in diameter 

without major crown or stem defects. Trees were cored with an 

Table 14lrmmav of choraclerll*s d-Ie IreI Ccnno. I D.bh.' I Hciaht I BCE&&IR yur 

1 md~a pine I I 

USDA Forest Ssnict Rca. Paptr PSW-200. 1990. 
incrementborer, withonecorebeing takenfrom oneof thecrossslope positions of each tree. Cores were stored in paper smws 

and transported back to the laboratory for analysis. 

Cores were sanded as necessary so that individual rings were 

clearly visible. They were then crossdated (Fritts 1976) so that 

individual rings could be associated with specific years. Tree 

cores were then sectioned into 5-year increments for chemical 

analysis. Each 5-yearincrementwasplacedinaseparate sample 

vial and submittedfor laboratory analysis. Wood samples were 

analyzed by thechemical analysis laboratory of the Department 

of Biological Science at the University of California, Los 

Angeles, by using inductively coupled plasma emission spectroscopy afterashmganddis~~lvingsampl~id Total 

concenmtion of the following elements was determined: phosphorus (P), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), 

Correlation analysis (Pearson product-moment correlation 

coefficient) was initially conducted to determine the relationship between pairs of elements. The entire time series of all 

cores for each species were used to calculate correlation coefficients. Concentration of elementsovertime wasplonedforeach 

element of each txe core. These graphs were aggregated for 

display purposes. 

RESULTS AND DISCUSSION 

boron @),silicon (Si), titanium (Ti),vanadium (~icobalt (co), 

nickel mi), molybdenum (MO), chromium (cI), strontium (sI), Correlation Analysis 

barium- (Ba), silver (~g); ti (Sn), lead (Pb), arsenic (As), 

cadmium (Cd), beryllium (Be), lithium (Li). Distributions of chemical elements in the wood of lodgepole 

pine and whitebarkpinevaried widely, and trends were difficult 

Table ZMem of Pwsonprducf-mmnf corrr~ion coefficirur for elrmrnLr in 10 lodgepole pinr cores. Corrrlafim corficienrr ore for allfh segmnfs 

of oil cores (n=). Valw greater lhan 05DDO are vndcrscorcdfo askt the reader in lowling lnrgc values. 

2 USDA Farst Service Res. Paper PSW-200. 1990. 
Tsble3-Mcon ofPcorsonpraiucr-~M~uN conclarion corffuhm for rlrmrNs L! I0 whilrhkpinrcoru. Conrlarioncorfiirm 

ore fa all fLN ~e~mm ofall COT- fn=J. VaIu~8r~aferlh OJOOO we vndrrscaedfo cmirr fhe redr in locoling lorgr volus. 

to interpret in some cases. Unfortunately this is typical in most 

studies of this type because natural variation is high and the 

relationship between element concentration and the environment of sees is complex. 

Correlation analysis indicated correlations among certain 

groups of elements (tables 2,3). Statistical significance is not 

indicated in the tables, although correlation coefficient values 

greater than 0.5 and less than -0.5 have been underscored. One 

of the strongest average correlations for both species was be 

tweenCaandMg. Bothelementsarerelatively abundantinmost 

soils, are critical for plant nuhition, and are divalent cations in 

solution. Both Ca and Mg are also correlated with the divalent 

cationsBaandSrin bothspecies. BaandSrare highly correlated 

with each other in both species, and are both correlated with K. 

Zn, Mn, and Al in whitebark pine but not in lodgepole pine. Al 

and Si, both common elements in the structure of clay minerals, 

were correlated in both species. 

Correlations among some of themetals were found for lodgepolepinebut not for whitebarkpine. Cu, Fe, Co, Ni, Mo. Cr, Sn, 

and As were all correlated with one another (table 3). In 

addition, all eight elements were correlated with P. 

Someof thecorrelations wereexpected on the basis of simple 

chemicalprinciples(t&les2,3). For example,onemightexpect 

CaandMgto have directly proportionalconcentrations in wood 

because they are both relatively common divalent cations. 

Conelations of these elements with their chemical analogs, Ba 

and Sr, are also to beexpected. Correlations among some of the 

metals are reasonable because they have similar adsorption and 

aansport mechanisms in plants (Lepp 1975). It is not clear, 

however, why there was such a large discrepancy between tree 

species. 

Temporal Trends in Element 

Concentration 

The time series of chemical concentrations in the wood of 

whitebark pine and lodgepole pine must be interpreted in the 

context of radial growth patterns of the trees. Basal area trends 

for the Eastern Brook Lakes study site were described in a 

previous study (Petersonand Arbaugh 1990). whichdetermined 

that basal area growth increased over time for all age classes of 

both species. This is an unusual pattern of growth for most 

USDA Fauit Scrvicc Rcs. Paper PSW-UM. 1990. 3 
conifers, which normally have aplateau or reduction in annual 

basal area increment after 50-100 years. 

Figures 1-10, which depict temporal trends, present data for 

all cores. The figures are rather "noisy," but are valuable 

because they display the entire range of element concentrations 

for trees of different ages. There are several high or low values 

for some elements, pmbably due to ertors in chemical analysis, 

values outside the detection limits of the instrument used for 

analysis, or samplecontamination. Theoverall wendof element 

coucentrations should be observed, rather than these outliers. 

Phosphorus (fig. 1) 

P concentration for half of the whitebark pines increased 

slightly, especially since 1950. Except for a recent increase in 

some trees, no apparent trend was found in lodgepole pine. The 

data contained a high degree of variance. Similar studies of red 

spruce (Picea rubens) (Arp and Manasc 1988). Eastern white 

pine (Pinus slrobus), and sugar maple (Acer saccharurn) (Relich and others 1989) showed no increase in P concentration 

over time, except in the youngest wood. 

Phosphorus is an important structural component of many 

plant compounds, especially nucleic acids and phospholipids, 

and plays a critical role in energy metabolism (Bidwell 1974). 

The high levels of P found in the youngest wood in this and other 

, . , , ism ,A roio Ik- Y.., 

Figure l-Concentrationof P (ppm) overtime forlodgepde pine (A)and 

whitebark pine (8). Each line represents a separate bee core. Color6 

and type of line were randomly assigned to each tree, and are consistent 

among all figures (for example, the same me is represented by a solid 

red line in figs. 1-10). 

studies is pmbably related to the process of wcod formation, 

which leaves substantial concenmtions of P in newly formed 

xylem. Concentrations may be reducedin subsequent years by 

the radial flow of sap through the stems (Arp andManasc 1988). 

Potassium (fig. 2) 

No trend in K concentration was found for either species, 

although concentration was much higher during themost recent 

10 years of growth. The concentration for the youngest increment of wood was twice that of wood that was 10 years older in 

both species. Variancein concentration was generally higher in 

whitebark pine than in lodgepole pine. This pattern was similar 

to that foundinother treespecies (ArpandManasc 1988,Frelich 

and others 1989, Matusiewicz and Barnes 1985). 

Potassium has no structural role in plants, but serves in a 

number of catalytic roles. It is apparently involved in enzyme 

activity. especially for protein synthesis (Bidwell 1974). It also 

servesas an osmotic agent in theopening andclosing of stomata 

(KramerandKozlowski 1979). It is highly mobile in plants and 

is easily translocated among different tissue types in trees 

(Peterson and Rolfe 1982). The high concentrations of K found 

in the youngestwoodarepmbably related totheprocessofwood 

formation, with reduction in subsequent years by radial sap 

movement (Arp and Manasc 1988). 

Flgure 24oncsntrahn of K(ppm) over lime for lodgepole pine (A) and 

whitebark pine (B). Each line represents a separate me core. 

USDA F-I SEnicc Rcs. Pnpcr PSW-2W. 1990. 
Calcium (flg. 3) 

Concentration of Ca decreased through time for both species, 

inolderas well as youngertrees. Concenwtionsduring themost 

recent 5 years were high for whitebark pine and slightly higher 

than the previous 5-year increment in lodgepole pine. Concentrationsofcainthe 1970'swasabouthalfthatof theoldestwood 

in many cores of both species. The pattern of decreasing Ca 

through time is similar to that found in other species (Arp and 

Manasc 1988,Frelichandothers 1989,Meischandothers 1986), 

although the high concentration in the youngest wood is different. Although Ca concentration decreased over time, the absolute amount of Ca fixed in the wood may be relatively constant 

because of the concurrent increase in basal area increment 

(petemn and Arbaugh 1990). 

Calcium is a critical element in plants and is found in high 

concenwtions in most plants and soils. It is important in the 

synthesisofpectinin themiddlelamellaof cell walls, isinvolved 

in the metabolism of the nucleus and mitochondria pidwell 

1974). is an enzyme activator, and is involved in nitrogen 

metabolism (Kramer and Kozlowski 1979). Calcium is generally regardedasanimmobileelementbecauseitisfixedinxylem 

cell walls and incorporated into woody tissue. However, the 

high concentrations of Ca in the youngest wood of the trees in 

out study suggest that there must be some mobility in order to 

reduce these concentrations as the wood ages. 

Magnesium (flg. 4) 

The overall trend of Mg concentrations paralleled that of Ca 

for younger and older trees of both species. Concentrations in 

the 1970's were half that of the oldest wood in the core for 

lodgepole pine and 20-30 percent of the oldest wood in some 

whitebark pine cores. Concentrations during the most recent 5 

years were several times higher than the previod5-year increment for whitebark pine. and slightly higher in most lodgepole 

pines. The generally decreasing trend in Mg again paralleled 

that of other species (Arp and Manasc 1988, Frelich and others 

1989, Matusiewicz and Barnes 1985). but the high concentrations in the youngest wood was a major difference. 

Magnesium is critical for several plant functions. It is a 

constituent of the chlomphyll molecule, is involved in the 

phosphate nansfer reaction of several enzyme systems, and is 

involved in maintaining the integrity of ribosomes (Kramer and 

Kozlowski 1979). Magnesium is highly soluble and readily 

@ansported within plants, and concenwtions tend to be high in 

xylem sap (Starkandothers 1984). These factors may account 

for the high concentdon of Mg found in this study and the 

reduction in concenwtion as the wood ages. 

Figure 3--Concentration of Ca (ppm) over time for lodgapole pine Rgure 4-Concenbation of Mg (ppm) over time for lodgepole pine 

(A) and whitebark pine (B). Each line represents a separate tree (A) and whitebark pine (8). Ed line represents a separate bee 

core. 

USDA Fae~ Swiw Rc* PFI PSW-200.1990. 
Sodlum (flg. 5) 

Concen~ons of Na tended to increase in about 1930 and 

decrease in 1950 for about half of the lodgepole pinecores. We 

found no apparent trend for whitebark pine. The pattern was 

quite different fmm the general decreasing trend found in red 

spruce (Matusiewicz and Barnes 1985). Sodium hasno apparent 

function in plants other than halophytes, and the patterns found 

in this study are difficult to explain. The temporary increase 

found in this study may be related to increased availability ofNa 

in the soils due to drying. Sodium concentrations pmbably 

contain little information about nutrition in conifers, although 

they can reflect changes in uptake paaerns. 

Boron (flg. 6) 

Concentrations of B increasedover time for both species, and 

concentration of the youngest wood was several times higher 

than that ofthe oldest wood in several cores. This increase was 

especially prominent since 1960, with highest values during the 

most recent time period. Concentrations were quite similar for 

both species. The increase in B, coupled with the temporal 

increase in basal area increment for most cores, indicates that 

there was a substantid increase in the amount of B fixed in the 

wood over time. 

Bomn is essential in small quantities for plant growth, although its mle in plant metabolism is prly understood. It 

appears to be involved in the translocation and absorption of 

sugars in plants (Bidwell 1974). Cmifers tend to be more 

tolerant than angiosperms of lower concentrations of B, and I 

normalty have specific requirements for less than 15 ppm 

(Kramer and Kozlowski 1979). Many of the sees in this study 

accumulated concentrations higher than 15 ppm. We could not 

find similar studies of B distribution in wood in the literature. 

The increasing concentration of B over time is difficult to 

explain, although it is possible that salts conlaining B increased 

in the soilover time because of dryiig and became increasingly 

available for uptake. 

""I m 

Flgure 5-Concentration of Na (ppm) over time for lodgepole pine (A) Flgure6-Soncenbationof B(ppm)overtimeforhdgepdepine (A)and 

and whitebark pine (B). Each line represents a separate tree core. whitebark pine (0). Each line represents a separate traa core. 

6 USDA Forest Service Rcs. Paper PSW-200. 1990. 
Iron (fig. 7) 

The trend in Fe concentration was weak, although some 

whitebark pines appeared to have a slightly increasing trend in 

Fe concentration since 1960. This generally agrees with the 

results of other studies (Frelich and others 1989), although red 

spruce had a much longer period of concentration increase (Arp 

and Manasc 1988, Matusiewicz and Barnes 1985). 

More iron is required in plants than are other micronutrients, 

probably because of its low solubility. Fe is part of the catalytic 

site of important oxidation-reduction enzymes, and is essential 

for chlorophyll synthesis (Bidwell 1974). The higher recent 

concentrations of Fe in some trees indicate that there is some 

mobility of this element in wood despite its low solubility. 

copper (fig. 8) 

No trendin Cuconcenhations foreither species was detected. 

Concentrations tended to be higher and more variable in lodgepole pine than in whitebark pine. The low concentrations and 

lack of trend agree with studies of other species from nonplluted sites (Arp and Manasc 1988, Berish and Ragsdale 1985, 

Matusiewicz and Barnes 1985, Robitaille 1981):' 

Copper is generally found in small quantities in both soils and 

plants. It plays a catalytic role in plants as part of a number of 

important enzymes, and is present in plastocyanin in chloroplasts (Bidwell 1974). Concenhations measured in this study 

were low and far below the range considered to be indicative of 

contamination from industrial processes (ArpandMmsc 1988. 

Robitaille 1981). 

Flgure 74oncentration of Fe (ppm) over time for lodgepole pine (A) Flgura 8--Concentration of Cu (ppm) over time for lodgepole pine (A) 

end whitebark pine (B). Each line represents a separate tree mre. and whitebaik pine (B). Each line represents a separate tree mre. 

USDA Porest Service Rea. Pap PSW-200. 1990. 
Manganese (fig. 9) 

No trendin Mnconcentrationsforeitherspecies wasdetected. 

Some of the whitebark pine cores had a large increase in Mn 

concentration during the most recent 5-year increment. Previous studies that evaluated Mn concentration also found no 

temporal trends at unpolluted sites (Arp and Manax: 1988, 

Berish and Ragsdale 1985, Matusiewicz and Barnes 1985). but 

none of these studies had the high concentations found in the 

mostrecentwhitebark pinewood. Younger!n%sofboth species 

tcnded to have higher Mn concentrations, which agrees with 

previous results for red spruce (Arp and Manasc 1988). 

Manganese is widely involved in catalytic mles in plants. It 

is an important enzyme activator in the Krebs cycle and is 

required in other respiratory processes, nitrogen metabolism, 

and photosynthesis. It may also have ashuctural role in chloroplasts (Bidwell 1974) and affect the availability of Fe (Kramer 

and Kozlowski 1979). The lack of trend in this study indicates 

that there has probably been no unusual deposition of Mn in the 

watershed. 

Zinc (fig. 10) 

No mnd in conceneations for either species was detected. 

Most of the whitebarlr pines and half ofthe lodgepole pines had 

alarge increase during the mostment 5-year increment There 

1988, Robitaille 1981). increasing trend (Berish and Ragsdale 

1985), and no trend (Frelich and others 1989, Matusiewicz and 

Barnes 1985). None of these studies found the high Zn concennations that we observed in the youngest wood of whitebark 

pine. 

Zinc is involved in the synthesis of indoleacetic acid and is 

therefore related to the form and growth habit of plants. Zinc is 

also an activator of several important enzymes, and is involved 

in protein synthesis (Bidwell 1974). The lack of trend in Zn 

concentrationsuggests thatthismetaldidnotcauseany contamination at the study site. 

Lead, Tln, Barlum, Strontium 

Concenaations of Pb,Ba, andsrdecreasedin mostlodgepole 

pine cores since 1940 and Sn decreased since 1950. Similar 

trends were found in whitebarkpine. Noneof theseelements has 

a known function in plants, but are discussed here because they 

displayed some trends in the concentration data. Lead is of 

particular interest because it is a common pollutant associated 

with gasoline and is phytotoxic. Concentrations measured in 

this study were too low to reflect the possible effect ofautomobide emissions (Rolfe 1974) or a change From the use of leaded 

was a range of results for previous studiesof Zn concentrations to unleaded fuel. The only ker studht examined Ba and Sr 

in trees, including decreasing temporal trend (Arp and Manasc 

Figure S-Concenlrahn of Mn (ppm) over time for lodgepole pine (A) Flgura 10--Concenlrahn of Zn (ppm) over time for lodgepde pine (A) 

and whitebark pine (8). Each line represents a separate bee mre. and whitebark pine (8). Each line represents a sepmte bee core. 

8 USDA Pores Setvie Rcs. Paptr PSW-200.1990. 

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