soil solution and sugar maple response to nh4no3 additions in a base-poor northern hardwood forest...

Environ Monit Assess (2009) 155:177190DOI 10.1007/s10661-008-0427-y

Soil solution and sugar maple response to NH4NO3additions in a base-poor northern hardwood forestof Qubec, Canada

Jean-David Moore Daniel Houle

Received: 4 December 2007 / Accepted: 3 June 2008 / Published online: 12 August 2008 Springer Science + Business Media B.V. 2008

Abstract Nitrogen additions (NH4NO3) at ratesof three- and ten-fold ambient atmospheric de-position (8.5 kg ha1 year1) were realised in anacid- and base-poor northern hardwood forest ofQubec, Canada. Soil solution chemistry, foliarchemistry, crown dieback and basal area growthof sugar maple (Acer saccharum Marsh.) weremeasured. Except for a transitory increase of NO3and NH4 concentrations, there was no persistentincrease in their level in soil solution 3 years afterN treatments, with the exception of one plot out ofthree, that received the highest N addition, begin-ning to show persistent and high NO3 concentra-tions after 2 years of N additions. Three years of Nadditions have significantly increased the N DRISindex of sugar maple but not N foliar concentra-tion. Potassium, Ca and Mn foliar concentrations,as well as P and Ca DRIS indices, decreased intreated plots after 3 years. No treatment effectwas observed for basal area growth and diebackrate. One unexpected result was the significantdecrease in foliar Ca even in the treated plotsthat received low N rates, despite the absenceof significant NO3-induced leaching of Ca. Themechanism responsible for the decrease in foliar

J.-D. Moore D. Houle (B)Direction de la recherche forestire, Fort Qubec,min. des Ressources naturelles et de la Faune,2700 rue Einstein, Sainte-Foy, QC, G1P 3W8, Canadae-mail: [email protected]

Ca is not known. Our results, however, clearlydemonstrate that increased N deposition at siteswith low base saturation may affect Ca nutritioneven when clear signs of N saturation are notobserved.

Keywords Sugar maple Nitrogen saturation Nitrogen fertilization Soil solution Dieback

Introduction

In the early 1980s, sugar maple (Acer saccharumMarsh.) dieback was a major concern in south-eastern Canada and northeastern United States,where it is a highly valued species. Although im-provement has been observed in the last decade,sugar maple dieback is still seen in poorly bufferedsoils of Pennsylvania (Horsley et al. 2000, 2002)and Vermont (Wilmot et al. 1995, 1996) in theUnited States, and those of Qubec (Duchesneet al. 2002; Moore and Ouimet 2006) and Ontario(McLaughlin 1998) in Canada. Many years afterthe appearance of this phenomenon, the cause ofthe decline is still debated (Driscoll et al. 2001,2002; Horsley et al. 2000, 2002; Sharpe 2002).Insect defoliation, extreme climatic events, andpathogenic factors (Bernier et al. 1989; Ct andOuimet 1996; Payette et al. 1996; Auclair et al.1997; Horsley et al. 2000, 2002) are among thecauses that have been proposed for sugar maple

178 Environ Monit Assess (2009) 155:177190

decline. Other studies concluded that acid rain re-mains an important agent of sugar maple dieback(Ryan et al. 1994; Ouimet et al. 2001; Duchesneet al. 2002; Sharpe 2002).

SO4 and NO3 are the major components of aciddeposition. Although S emissions have been de-creasing, particularly in recent decades (Driscollet al. 2001; NADP 1998; Houle et al. 2004),agricultural and industrial intensification have ledto large increases in the production of airbornereactive nitrogen (Galloway 1995; Asner et al.2001). In recent years, a growing number of forestsin the USA have showed signs of N saturation(Fenn et al. 1998), including sugar maple forestsin New York (Driscoll and Van Dreason 1993;Mitchell et al. 1996; Lovett et al. 2000) andVirginia (Gilliam et al. 1996; Peterjohn et al. 1996;Adams et al. 1997). However, few studies havenoted symptoms of N saturation in Canada ex-cept for the Turkey Lakes Watershed in Ontario(Foster et al. 1989; Moayeri et al. 2001). One ofthe major symptoms of N saturation is an elevatedloss of NO3 to ground and surface waters (Aberet al. 1989; Stoddard 1994; Fenn et al. 1998). Othersymptoms are an increasing N concentrations anda higher N:nutrient ratios in foliage. Increase inNO3 leaching may lead to several undesirableeffects on soils, including higher leaching lossesof base cations (Aber et al. 1989; Stoddard 1994;Likens et al. 1996; Adams et al. 1997; Fenn et al.1998), increased Al mobility and soil acidification(Johnson et al. 1991). These changes may leadto nutritional imbalances (Schulze 1989), includ-ing Ca foliar depletion (Schaberg et al. 2001),decreases in tree growth and productivity (Aberet al. 1995; McNulty et al. 1996), and eventuallyto forest dieback (e.g., Aber et al. 1989; Schulze1989; Skeffington and Wilson 1988).

Chronic N additions have been done to sim-ulate high atmospheric N deposition in sugarmaple-dominated stands in Maine (Elvir et al.2003, 2006), Michigan (Pregitzer et al. 2004; Zaket al. 2004), New York (Mitchell et al. 2003), andVermont (Ellsworth 1999). However, the standsstudied in the northeastern USA generally hadricher soils in terms of base cations as comparedto most maple stands in eastern Canada that growon soils developed from the granitic rock of the

Canadian Shield (Duchesne et al. 2002). To date,the effects of adding N to sugar maple standsgrowing on poor and acidic soils in Canada is notknown.

The objective of this study was to determine theeffect of N additions (three- and ten-fold currentatmospheric N deposition levels), as NH4NO3,on soil solution chemistry, and on sugar maplefoliar status, crown dieback and growth for a sugarmaple stand (Lake Clair Watershed, LCW) grow-ing on poorly buffered soils with low Ca avail-ability (Houle et al. 1997; Duchesne et al. 2002).We hypothesize that (1) N additions will resultin a persistent increase of inorganic N species inthe soil solution of treated plots because of thepoor health status of the forest, which would limitits potential to accumulate the added N, and (2)the leaching of NO3 should increase Ca leachingand potentially affect Ca nutrition, which maynegatively affect foliar chemistry, crown diebackand growth of sugar maple.

Methods

Study sites

The LCW (226 ha (Lake = 36 ha), 4657N,7140W, 270390 m above see level) is locatedapproximately 50 km northwest of Qubec City,Qubec, Canada. The mean slope is approxi-mately 10%. Mean annual temperature is 3.4Cand annual precipitation is 1300 mm. The for-est in this area is uneven aged and composedof sugar maple in association with yellow birch(Betula alleghaniensis Britt.) and American beech(Fagus grandifolia Ehrh.). Soils (Table 1) are clas-sified as Orthic FerroHumic Podzol (Canada SoilSurvey Committee 1998), or Typic Haplorthod(Soil Survey Staff 1998). The humus is a mor-moder type and the surface deposit is a very acidand stony glacial till derived from granitic gneissbedrock.

N addition trial

At the border of the LCW, a representative areaof the whole watershed in terms of tree ages,stand density and composition was selected for the

Environ Monit Assess (2009) 155:177190 179

Table 1 Summary ofbasic soil characteristicsat the studied site(adapted from Houleet al. 1997)

nd Not determined

Thickness (cm) pH (CaCl2) Base saturation (%) Carbon (%) N (%) C/N

LFH 8.9 3.14 48.3 39.1 1.7 23.1Ae 3.2 3.26 21.4 5.0 0.2 29.2Bhf 21 4.03 10.7 6.64 0.27 24.2Bf 17.2 4.31 12.5 3.18 0.12 27.5BC 16.3 4.47 nd 0.28 nd nd

fertilization trial. In this selected area, 12 experi-mental units of 15 15 m were chosen, but onlynine were used for this experiment. Experimentalunits had to be at least 10 m apart from eachother, but were often more than 15 m apart. Treat-ments were randomly assigned to three replicateblocks. NH4NO3 was diluted in 20 L of deionizedwater. Application rates of N were three- andten-fold the annual precipitation of N at this site(Low N(LN) = 26, High N(HN) = 85 kg N ha1year1). The additions were done in four passeswith a Solo backpack sprayer. From 2001 to2003, fertilizer was applied monthly, five timesa year from June to October. Before treatment,sugar maple trees on the nine experimental plotshad a mean diameter at breast height of 26.1 8.3 cm and a low mean basal area growth of 6.0 1.1 cm2 year1, presumably because of poorsoil conditions (Houle et al. 1997; Duchesne et al.2002).

Field sampling

Soil solution chemistry

Two soil tension lysimeters (Soil Moisture Equip-ment Corp., Model 1911) were installed at depthsof 30 and 60 cm in October 2000 in the center ofeach of the nine experimental units. Soil solutionwas then sampled weekly from May to October in2001, 2002 and 2003.

Vegetation

In each experimental unit, five dominant orcodominant sugar maple trees were selected andnumbered in October 2000, for a total of 45 trees.Approximately 40 leaves from each tree were col-lected at mid-crown, on two opposite branches, inAugust 2001, 2002 and 2003. This period of the

year corresponds to stable foliar concentrationsin sugar maple, i.e., preceding foliar coloration(Duchesne 1998). In addition to absolute ele-ment concentrations in leaves, the Diagnosis andRecommendation Integrated System (DRIS) wasused to evaluate the nutritive foliar status of sugarmaple (Lozano and Huynh 1989). This approach,previously developed by Beaufils (1973) and de-scribed by Walworth and Sumner (1987), takesinto account the relationships between differentnutrient concentrations. The index values calcu-lated from these ratios can vary from negativeto positive, but the sum is always equal to zero.The ideal balance is when the DRIS index for allnutrients and the sum of their absolute values, theso-called nutrient disequilibrium index (NDI),is close to zero (Walworth and Sumner 1987).

Two increment cores were taken in May 2004 tomeasure radial growth on the same trees used forfoliar sampling. Annual ring measurements weredone using WinDendro version 6.1D software(Rgent Instruments Inc. 1998) and validated withsignature rings. Ring values were converted tobasal area increment (BAI) using the followingequation:

BAIt(cm2) = (R2t R2t1)where R is the tree radius (cm) and t is the year

of tree ring formation.Dieback was evaluated in summer 2005 by es-

timating the percentage of missing crown foliage(5% class intervals).

Chemical analyses

All soil solutions were filtered (0.45 m, Nucleo-pore) and analysed for basic cations (K, Ca, Mg,Na) by plasma emission spectrometry, while SO4and NO3 were analysed by ion chromatography.


Analyses for NH4 were done by colourimetry(Technicon AA2).

Foliar tissues were dried at 65C and groundto 250 m. Nitrogen content was determined fol-lowing Kjeldahl digestion (Kjeltec Tecator 1030).For P, K, Ca, Mg and Mn contents, 500 mg offoliage was digested with H2SO4. Following di-gestion, element concentrations were measuredby atomic emission spectroscopy (Perkin ElmerPlasma Model 40).

Statistical analyses

Soil solution

The chi-square test was used to determine theeffects of N fertilization (95% confidence interval)on NO3 and NH4 concentrations in soil water foreach treatment and at each depth (30 and 60 cm).Each event that exhibited a concentration of NO3and NH4 greater than 1.00 and 0.05 mgL1, re-spectively, was recorded. The frequency of theseevents was then compared between treatmentswithin contingency tables using the chi-squaretest. The correlations between temporal variationof pH, NO3 and Ca concentrations in soil waterwere determined using Kendals Tau (95% con-fidence interval). This non-parametric correlationis based on the number of pairs of matched andmismatched observations, and uses a correctionfactor for pairs of observations with the samevalue.

Foliar, dieback and growth data

ANOVAs were performed on foliage variablesusing treatments and years as independent factors,and individual trees or sampling sub-plots as sub-jects in the repeated statement. Dieback ratewas analysed for 2005 only. For basal area growth,the pre-treatment measures of 19982000 wereused as covariables. Parallelism and heterogeneitytests were performed. Polynomial contrasts werebuilt to assess the effect of N additions. All analy-ses were performed using the SAS mixed proce-dure (SAS Software Inc. 2000).

Results

Soil solution

Absolute inorganic N concentrations in the con-trol plots of both sites were low, and exhibitedvery small temporal variations (Figs. 1a and 2a).There were many punctual increases of NO3 and,to a lesser extent, of NH4 concentrations in thetreated plots (LN and HN) of both sites for bothdepths (Figs. 1 and 2). The timing of the increasesappeared to coincide with the combination in thetiming of N additions and precipitation events(not shown). The increases were generally tran-sitory in nature with the exception of one plotout of three in the HN treatment that began toshow persistently high NO3 concentrations at bothdepths in 2002 (60 cm) and 2003 (30 and 60 cm).For both sites, the chi-square tests showed a sig-nificant treatment effect, with a higher probabilityof observing NO3 and NH4 concentrations abovethe fixed threshold in treated plots (Table 2).

The increases in inorganic N species, partic-ularly NO3, were generally accompanied by in-creases in H and base cations concentrations, asillustrated by the significant correlations betweenNO3, pH and Ca (Table 3) in the treated plotsof both sites. However, the correlations coeffi-cients were rather weak, and episodic NO3 leach-ing did not result in significant leaching of Caor other base cations. Significant correlations be-tween NO3 and Mg were also observed but are notdiscussed (data not shown).

Foliar concentrations and DRIS indices

According to the range of foliar nutrient valuespresumably associated with healthy sugar mapletrees, as reported by Kolb and McCormick (1993),and with the DRIS indices calculated in this study,the nutritional status of Ca and Mg was low in thecontrol plots, while N was high (Table 4). Follow-ing N addition, significant year-to-year variations

Fig. 1 Temporal variations of NO3 concentration in thelysimeters located at 30 and 60 cm in the control, the lowN and the high N fertilization treatments. Note the differ-ences in the Y axis range between treatments


06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

0

1

2

3

4

5

2001

0,0

0,5

1,0

1,5

0

1

2

3

4

5

6

7

2001

0

10

20

30

0

10

20

30

40

2001

0

3

6

9

12

15

18

2002

2002

2002

2003

2003

2003

30 cm

60 cm

30 cm

60 cm

60 cm

30 cm

(a) Control

(b) Low N

(c) High N

mg L

-1

mg

L-1

mg

L-1


0,00

0,05

0,10

0,15

0,20

2001

0,00

0,05

0,10

0,15

0,20

0,00

0,05

0,10

0,15

0,20

0,25

2001

0,0

0,5

1,0

1,5

2,0

2,5

5,0

6,0

0,0

0,5

1,02,0

2,5

3,0

2001

0,0

0,5

1,02,0

2,5

2002

2002

2002

2003

2003

2003

30 cm

60 cm

30 cm

60 cm

60 cm

30 cm

(a) Control

(b) Low N

(c) High N

06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

06 07 08 09 10 11 06 07 08 09 10 11 06 07 08 09 10 11

mg L

-1

mg L-

1m

g L

-1


Fig. 2 Temporal variations of NH4 concentration in thelysimeters located at 30 and 60 cm in the control, the lowN and the high N fertilization treatments. Note the differ-ences in the Y axis range between treatments

in foliar concentrations were observed for P, Kand Ca, and for every element included in theDRIS indices calculation, with the exception ofMg (Table 5). Decreasing trends were detected forK, Ca and Mn foliar concentrations following Namendment (Tables 4 and 5). The effect was moremarked in 2003, with K, Ca and Mn decreasingby 19%, 30%, and 50%, respectively, in the HNtreatment as compared to the control. No signif-icant treatment effect was observed for N, P andMg foliar concentrations (Tables 4 and 5), with theexception of N which was significantly higher inthe HN treatment in 2003 as compared to the LNtreatment and controls.

The nitrogen DRIS index was affected by Naddition after the second (2002) and third years(2003), with N DRIS values increasing linearlywith the N addition rate (Tables 4 and 5). Treat-ment effect was greater in 2003, with respectiveincreases of 81 and 111% of N DRIS indicesin LN and HN treatments, as compared to con-trols. DRIS index of P also increased with the Naddition rate (Tables 4 and 5). Over the 3-yearperiod, Ca DRIS index decreased linearly withan increasing N addition rate, reaching low valuesof 68 (5) and 59 (5) in HN and LN treat-ments, respectively. NDI DRIS indices increasedlinearly with N addition rate (Tables 4 and 5).

The more evident effects were observed in 2003,with an increase of 29 and 66% in LN and HNtreatments, respectively, as compared to controlplots. No effect was observed on K and MgDRIS indices.

Crown dieback and basal area growth

The dieback rate of sugar maple, 5 years aftertreatments (Control: 28 17%; LN: 39 16%;HN: 36 14%), although it was not significant(P = 0.6367), was 39% and 29% higher in LN andHN treated plots, respectively, as compared withcontrol plots. No treatment effect was observedfor basal area growth (Fig. 3; P = 0.3944).

Discussion

Soil solution chemistry

One indicator of N saturation of forest soils ishigh concentrations of inorganic N in soil solution,inorganic N losses in N-limited ecosystems beingvery low (Perakis and Hedin 2002). Concentra-tions of NO3 and NH4 in the soil solution ofcontrol plots at 30 and 60 cm were stable andlow (Figs. 1 and 2), suggesting that this site isnot N saturated at the current level of ambientatmospheric deposition. This agrees well with theprevious observation of high N retention withinthe terrestrial part of the watershed (Houle et al.

Table 2 Results of chi-square testing of the differences for NO3 and NH4 concentrations between treatments for eachlysimeter depth

Lysimeter depth NO3 NH4High N Low N C High N Low LN C

30 cmPositive 39 13 4 56 2 = 39.2 12 45 2 59 2 = 67.6Negative 116 129 155 400 p < 0.0001 141 94 153 388 p < 0.0001Total 155 142 159 456 153 139 155 447

60 cmPositive 29 22 2 53 2 = 27.3 3 15 2 20 2 = 17.8Negative 136 139 177 452 p < 0.0001 156 144 176 476 p < 0.0001Total 165 161 179 505 159 159 178 496

Every occurrence of an NO3 and NH4 concentration higher than 1.00 and 0.05 mg L1, respectively, was considered as anevent (positive), while the values below were considered as an absence of event (negative)


Table 3 Values of Kendalls Tau coefficients for the soil solution sampled at two different soil depths

Treatment Soil solution variable 30 cm 60 cm

NO3 Ca NO3 Ca

High N pH 0.24 ns 0.29 0.28***NO3 0.49*** 0.31***

Low N pH ns 0.33*** ns 0.35***NO3 0.31*** 0.43***

Control pH ns 0.42*** 0.15** 0.42***NO3 ns

N varies between 142 and 179 depending on treatment and depthns Not significant*p < 0.05**p < 0.01***p < 0.0001

1997). Low inorganic N concentrations and highatmospheric N retention were also observed inhardwood forests of the Adirondack Mountains(Mitchell et al. 2003) and Massachusetts (Magillet al. 2000).

Treated plots, particularly for the high rate ofN application, clearly responded to fertilization.Indeed, a significantly higher number of increasesin NO3 and NH4 concentrations in soil solutionwere observed at both lysimeter depths (Figs. 2and 3) in treated plots, as compared to controls(Table 2). Contrary to our expectations, the ob-served changes were often transitory, except forone plot out of three in the HN treatment, wherehigh NO3 (but not NH4) concentrations persistedin 2002 (60 cm) and 2003 (30 and 60 cm). The tem-poral variations in NO3 and NH4 concentrationsincreases seem to depend on when the fertilizerwas applied and on the timing of rainfall eventswith respect to N application. Generally, N con-centrations returned to the very low levels typicalof the control plots. The removal of N from thesoil solution was probably the result of root and/ormicrobial absorption. There is also a possibilitythat a part of NH4 could have been retained byadsorption on negative charged sites.

An estimation of N exports below 60 cm, doneby multiplying modelled monthly soil water fluxesfrom the FORHYM model (Houle et al. 2002)times inorganic N concentrations in soil solution,showed that N retention was over 95% in treatedplots (data not shown).

The response of forests to N addition varieswidely between sites. Some other studies also re-ported high N retention following various rates ofN addition (Wright and Tietema 1995; Christ et al.1995; Gundersen et al. 1998; Magill et al. 2000),while others reported considerable NO3 leaching(Mitchell et al. 1994; Pregitzer et al. 2004). Thelarge array of responses among sites is not surpris-ing, considering the differences in site histories, Nfoliar status, soil C:N ratio and tree species.

There was good synchronicity in the concen-tration increases of NO3 and NH4 in the soilsolution of treated plots. However, NO3 con-centration generally was an order of magnitudehigher than NH4. Since the solution used to add Nis composed of equal quantities of NO3 and NH4(NO3NH4) on a molar basis, the lower NH4 con-centration observed in the soil solution of treatedplots must be explained either by preferential up-take of NH4 by roots and soil microbes and/orby nitrification of the added NH4. The fine rootsof sugar maple have a much higher affinity forNH4 than for NO3 (Rothstein et al. 1996). Themarked decreases in pH observed concomitantlywith high NO3 concentrations suggest, however,that nitrification might have been responsible forthe high NO3:NH4 ratio in soil solution. Thepresence of nitrification at low pH may appear un-usual, because net nitrification is generally inhib-ited at a pH lower than 4.5 (Laverman et al. 2000;Persson and Wirn 1995; Rudebeck and Persson1998; Ste-Marie and Par 1999). Heterotrophic


Tab

le4

Adj

uste

dm

eans

offo

liar

conc

entr

atio

ns(m

gkg

1 )an

dD

RIS

indi

ces

for

cont

rola

ndN

-fer

tiliz

edpl

ots

atD

uche

snay

from

2001

to20

03(s

tand

ard

erro

rsar

egi

ven

inpa

rent

hese

s)

Yea

rsT

reat

men

tF

olia

rco

ncen

trat

ions

DR

ISin

dice

s

NP

KC

aM

gM

nN

PK

Ca

Mg

ND

I

2001

Con

trol

2000

6(7

30)

1338

(51)

8292

(431

)49

05(3

26)

870

(67)

708

(65)

26.3

(2.7

)9.

3(1

.8)

6.8

(3.5

)3

9.1

(4.6

)3

.6(3

.3)

94.6

(10.

4)L

owN

1918

0(7

30)

1270

(51)

7600

(431

)44

79(3

27)

849

(67)

582

(65)

29.3

(2.7

)9.

8(1

.9)

3.7

(3.5

)4

2.8

(4.6

)0.

0(3

.3)

102.

3(1

0.4)

Hig

hN

1940

0(7

30)

1320

(51)

7600

(431

)41

15(3

27)

799

(67)

474

(65)

31.9

(2.7

)14

.1(1

.9)

5.7

(3.5

)4

8.8

(4.6

)3

.0(3

.3)

114.

3(1

0.4)

2002

Con

trol

1907

6(7

65)

1296

(50)

8555

(429

)49

54(2

82)

910

(63)

709

(59)

22.3

(2.5

)6.

5(1

.6)

9.3

(2.8

)3

7.3

(4.6

)0

.8(2

.9)

85.9

(9.4

)L

owN

1906

7(7

57)

1207

(49)

8160

(426

)42

86(2

79)

841

(62)

564

(59)

28.3

(2.5

)7.

5(1

.5)

10.1

(2.8

)4

5.7

(4.6

)0.

2(2

.9)

99.8

(9.3

)H

igh

N20

360

(757

)11

91(4

9)76

73(4

26)

3845

(279

)77

7(6

2)42

3(5

9)36

.3(2

.5)

10.2

(1.5

)6.

5(2

.8)

52.

6(4

.6)

0.4

(2.9

)11

4.2

(9.3

)20

03C

ontr

ol19

307

(794

)12

02(5

8)79

03(4

26)

4655

(314

)86

0(6

6)75

6(7

1)26

.8(3

.3)

6.7

(1.9

)8.

0(3

.2)

39.

4(4

.6)

1.7

(2.9

)93

.9(1

0.9)

Low

N19

473

(798

)10

90(5

9)73

13(4

26)

3615

(321

)77

8(6

7)51

3(7

4)39

.4(3

.3)

8.8

(1.9

)7.

5(3

.3)

59.

0(4

.6)

3.3

(2.9

)12

3.4

(11.

2)H

igh

N22

247

(798

)11

19(5

9)63

87(4

26)

3238

(321

)67

9(6

7)37

8(7

4)57

.1(3

.2)

14.6

(1.9

)3

.8(3

.3)

67.

9(4

.6)

0.0

(2.9

)15

8.1

(11.

2)

Tab

le5

Stat

isti

cala

naly

sis

for

folia

rco

ncen

trat

ions

and

DR

ISin

dice

s

Yea

rs(Y

)T

rait

(T)

Y

TT

linT

lin20

01T

lin20

02T

lin20

03T

quad

Tqu

ad20

01T

quad

2002

Tqu

ad20

03

Fol

iar

conc

entr

atio

nsN

0.31

210.

1118

0.22

490.

1822

0.49

020.

3301

0.03

760.

0988

0.66

650.

3520

0.07

56P

0.00

260.

1923

0.88

820.

1160

0.65

480.

1298

0.24

570.

3587

0.39

690.

8134

0.47

93K

0.01

930.

0785

0.74

560.

0282

0.22

600.

1791

0.02

870.

6724

0.70

610.

6832

0.39

00C

a0.

0302

0.00

740.

7929

0.00

200.

1095

0.01

200.

0042

0.82

290.

7619

0.76

070.

9072

Mg

0.28

120.

1716

0.92

020.

0746

0.49

660.

1590

0.07

970.

5846

0.73

940.

7679

0.60

00M

n0.

6615

0.00

240.

7117

0.00

070.

0218

0.00

360.

0015

0.56

250.

6501

0.46

720.

8159

DR

ISin

dice

sN

>0.

0001

>0.

0001

0.00

31>

0.00

010.

1665

0.00

15>

0.00

010.

0985

0.79

380.

2442

0.05

08P

0.01

700.

0438

0.50

450.

0305

0.12

130.

1408

0.01

650.

1756

0.23

670.

4194

0.16

90K

0.03

230.

3177

0.14

110.

2088

0.73

450.

6038

0.03

960.

3987

0.59

700.

4346

0.07

28C

a0.

0014

0.00

730.

1227

0.00

210.

1735

0.03

150.

0003

0.67

100.

5996

0.69

460.

9515

Mg

0.39

770.

6385

0.87

960.

6449

0.75

660.

9176

0.50

320.

4133

0.44

440.

9205

0.30

61IN

D0.

0076

0.00

760.

2190

0.00

280.

2202

0.05

100.

0009

0.33

790.

6469

0.61

720.

2858


nitrification and/or acid-tolerant autotrophic ni-trification (De Boer and Kowalchuk 2001) maythus potentially be responsible for the nitrificationobserved at the LCW.

Foliar chemistry

Nitrogen foliar concentrations (2%) and DRISindices (2227) were relatively high in controlplots. The relatively high N deposition observedin the past at LCW (Houle et al. 1997) and theabsence of recent disturbances may explain thefavourable N status of this site.

According to N DRIS indices, treatments ac-centuated N imbalances in sugar maple in 2002and 2003 (Tables 4 and 5). Also, N foliar con-centrations were higher in HN treatments ascompared to controls in 2003 (Table 4), butthis difference was not statistically significant(Table 5). This is in contrast with reports of higherN foliar concentrations for various tree speciesfollowing chronic N application (Hutchinson et al.1998; Ellsworth 1999; White et al. 1999; Zaket al. 2004; Elvir et al. 2006). Although dilutionin a larger leaf biomass could possibly explainthe absence of effects for N foliar concentrations(Ellsworth 1999), leaf size did not differ amongthe treatments (P = 0.638). The absence of an Nfoliar response could be attributed to the initialfavorable N foliar status at LCW (foliar N con-centrations 2%, cf. Moore et al. 2000; Mooreand Ouimet 2006). Previous work by Carmeanand Watt (1975) also showed that sugar maplewith foliar N concentrations of about 2% do notrespond to increased N additions. Positive foliarconcentration response of sugar maple to singleor chronic N additions seemed to be associatedwith N foliar concentrations below 2% beforetreatment (Hutchinson et al. 1998; Ellsworth 1999;Zak et al. 2004; Elvir et al. 2006).

The foliar mean Ca (4,6554,954 mgkg1) andMg (860910 mgkg1) concentrations in the con-trol plots over the 3-year study period were amongthe lowest reported in the literature for sugarmaple (cf. Bernier and Brazeau 1988; Kolb andMcCormick 1993; Wilmot et al. 1995; Long et al.1997; Horsley et al. 2000; Moore et al. 2000; Mooreand Ouimet 2006) and are well below the foliarconcentration threshold established for healthy

sugar maple (Hendershot 1991; Ct et al. 1993;Kolb and McCormick 1993). This could be ex-plained by the low level of exchangeable soil Caand Mg (Houle et al. 1997) at LCW. In agreementwith these observations, sugar maple growth hasbeen shown to increase significantly following CaMg amendments (Moore et al. 2000; Moore andOuimet 2006) at the LCW. Nitrogen fertilizationshave decreased Ca concentrations to values as lowas 3,615 and 3,238 mg kg1 in 2003, for the LN andHN treatments, respectively (Tables 4 and 5). TheN addition effect on foliar Ca after only 3 yearsof treatment, even at a low rate of N addition(three times the atmospheric N deposition), wastotally unexpected. This result strongly contrastswith Hutchinson et al. (1998) in Ontario, who re-ported no treatment effect on sugar maple Ca fo-liar concentration after adding N, as (NH4)2SO4,at a much higher rate than in our study (up to212 kg N ha1 year1), for 2 and 3 years at twodifferent sites. In Maine, 14 years of (NH4)2SO4chronic additions (25.2 kg N ha1 year1) had noeffect on sugar maple foliar Ca (Elvir et al. 2006).While increased Ca losses from soils are expectedat N-saturated sites because of high NO3 leaching(Aber et al. 1989; Stoddard 1994; Likens et al.1996; Adams et al. 1997; Fenn et al. 1998), theeffect on foliar Ca at the LCW occurred despitethe absence of significant NO3 (and Ca) leaching.The results strongly suggest that high atmosphericdeposition of N may affect Ca nutrition on low-base soils, although the mechanism behind thisphenomenon remains unclear.

Similarly, the decreases of foliar Mn concen-trations observed following N additions was alsounexpected (Tables 4 and 5). This is in con-trast with other studies that reported an increase(Hutchinson et al.1998) or no change (Elvir et al.2006) in Mn foliar concentration following(NH4)2SO4 addition in sugar maple stands.

Crown dieback and basal area growth

Despite the significant decreases in foliar Ca,there was no significant change in sugar maplecrown dieback and basal area growth (Fig. 3). Sim-ilar results for sugar maple crown dieback werenoted in Ontario, 3 years following application of


0

2

4

6

8

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

Basal are

a incre

ment

(cm

2)

Control Low N High N

N treated

period

Fig. 3 BAI means (non adjusted) of sugar maple at LCW before (19902000) and during (20012003) N additions

(NH4)2SO4 in two sugar maple-dominated hard-wood forests (Hutchinson et al. 1998). Previousexperiments have produced contrasting results re-garding tree growth. In a 10-year experiment inMaine, where N was added at a rate of 119 kg ha1year1 as (NH4)2SO4, Elvir et al. (2003) foundthat sugar maple BAI was significantly higherin the N-treated area, while no growth responsewas observed in other studies with single N addi-tions ranging from 112 to 672 kg ha1 (Leaf andBickelhaupt 1975; Stone 1980; Ellis 1979; Stanturfet al. 1989). In our study, although foliar chemistrychanged with treatments, it is possible that crowndieback and growth response may take a longertime to develop and will appear after a longertreatment duration.

Conclusion

Three years of N addition had no significanteffects on maple growth and crown dieback, al-though the foliar N DRIS was significantly in-creased. However, given the poor health andgrowth status of sugar maple at this site

(Duchesne et al. 2002; Moore and Ouimet 2006),the limited NO3 leaching observed in the soilsolution (except for one plot among the threereceiving the highest N treatment) is somehowsurprising. It suggests that a large proportion ofthe added N was retained within the soil organicmatter. A previous study realised at the LCW siteshowed that soil microorganisms rapidly cycle Ninorganic species, leading to residence times inthe soil exchangeable complex lower than one day(Ste-Marie and Houle 2006).

The significant decrease of foliar Ca concentra-tions in treated plots is a major concern, consid-ering that this site was initially Ca (and possiblyMg) limited, and had among the lowest foliarCa concentrations reported for sugar maple. Thisresult suggests that sites with low levels of ex-changeable base cations are more at risk of beingnegatively affected by high levels of N depositioneven when a situation of N saturation (high basecation losses associated with high NO3 leaching)does not develop.

Acknowledgements This research was co-supported bythe Ministre des Ressources naturelles et de la Faune du


Qubec (project no. 0200 3056) and by the Centre Saint-Laurent of Environment Canada. We would like to thankB. Toussaint, J. Martineau, J. Gagn and M. Saint-Germainfor field assistance and L. Blais for statistical advice.

References

Aber, J. D., Magill, A., McNulty, S. G., Boone, R. D.,Nadelhoffer, K. J., Downs, M., et al. (1995). Forestbiogeochemistry and primary production altered bynitrogen saturation. Water, Air, and Soil Pollution, 85,16651670. doi:10.1007/BF00477219.

Aber, J. D., Nadelhoffer, K. J., Steudler, P., & Melillo, J. M.(1989). Nitrogen saturation in northern forest ecosys-tems. Bioscience, 39, 378386. doi:10.2307/1311067.

Adams, M. B., Angradi, T. R., & Kochenderfer, J. N.(1997). Stream water and soil solution responses to5 years of nitrogen and sulfur additions at the Fernowexperimental forest, West Virginia. Forest Ecologyand Management, 95, 7991. doi:10.1016/S0378-1127(96)03990-4.

Asner, G. P., Townsend, A. R., Riley, W. J., Matson, P. A.,Neff, J. C., & Cleveland, C. C. (2001). Physical andbiogeochemical controls over terrestrial ecosystem re-sponses to nitrogen deposition. Biogeochemistry, 54,139. doi:10.1023/A:1010653913530.

Auclair, A. N. D., Eglinton, P. D., & Minnemeyer, S. L.(1997). Principal forest dieback episodes in northernhardwoods: Development of numeric indices of arealextent and severity. Water, Air, and Soil Pollution, 93,175198.

Beaufils, E. R. (1973). Diagnosis and Recommandation In-tegrated System (DRIS). Soil Sci. Bul. 1, University ofNatal, Petermaritsburg, South Africa.

Bernier, B., & Brazeau, M. (1988). Foliar nutrient statusin relation to sugar maple dieback and decline in theQuebec Appalachians. Canadian Journal of Forest Re-search, 18, 754761. doi:10.1139/x88-115.

Bernier, B., Par, D., & Brazeau, M. (1989). Naturalstresses, nutrient imbalances and forest decline insoutheastern Quebec. Water, Air, and Soil Pollution,48, 239250. doi:10.1007/BF00282381.

Canada Soil Survey Committee (1998). The Canadian sys-tem of soil classification, Publ. 1646, 3rd edn. Ottawa,Ontario.

Carmean, W. H., & Watt, R. F. (1975). Response of a pole-size maple stand to fertilization. In B. Bernier, & C. H.Winget (Eds.), Forest soils and forest land management(pp. 417433). Quebec: Les Presses de lUniversiteLaval.

Christ, M., Zhang, Y., Likens, G. E., & Driscoll, C. T.(1995). Nitrogen retention capacity of a northernhardwood forest soil under ammonium sulfate ad-ditions. Ecological Applications, 5, 802812. doi:10.2307/1941988.

Ct, B., Hendershot, W., & OHalloran, I. (1993). Re-sponse of sugar maple to seven types of fertilization in

southern Quebec: Growth and nutrient status. In R. F.Huettl, & D. Mueller-Dombois (Eds.), Forest declinein the Atlantic and Pacific region (pp. 162174). Berlin:Springer.

Ct, B., & Ouimet, R. (1996). Decline of the maple-dominated forest in southern Quebec: Impact of nat-ural stresses and forest management. EnvironmentalReview, 4, 133148.

De Boer, W., & Kowalchuk, G. A. (2001). Nitrificationin acid soils: Micro-organisms and mechanisms. SoilBiology & Biochemistry, 33, 853866. doi:10.1016/S0038-0717(00)00247-9.

Driscoll, C. T., Lawrence, G. B., Bulger, A. T., Butler, T. J.,Cronan, C. S., Eagar, C., et al. (2001). Acidic de-position in the Northeastern United States: Sources,inputs, ecosystem effects and management strategies.Bioscience, 51, 180198. doi:10.1641/0006-3568(2001)051[0180:ADITNU]2.0.CO;2.

Driscoll, C. T., Lawrence, G. B., Bulger, A. T., Butler, T. J.,Cronan, C. S., Eagar, C., et al. (2002). Response toW. Sharpes Acid deposition explains sugar mapledecline in the East.. Bioscience, 52, 56. doi:10.1641/0006-3568(2002)052[0006:RFDAC]2.0.CO;2.

Driscoll, C. T., & Van Dreason, R. (1993). Seasonaland long-term temporal patterns in the chemistry ofAdirondack Lakes. Water, Air, and Soil Pollution, 67,319344. doi:10.1007/BF00478152.

Duchesne, L. (1998). Cycle biochimique des lmentsnutritifs majeurs au bassin versant du lac Clair,Duchesnay. M. Sc. Thesis, Fac. For. Gom., Univ.Laval, Qubec.

Duchesne, L., Ouimet, R., & Houle, D. (2002). Basal areagrowth of sugar maple in relation to acid deposition,stand health, and soil nutrients. Journal of Environ-mental Quality, 31, 16761683.

Ellis, R. C. (1979). Response of crop trees of sugar maple,white ash, and black cherry to release and fertiliza-tion. Canadian Journal of Forest Research, 9, 179188.doi:10.1139/x79-032.

Ellsworth, D. S. (1999). Nitrogen addition affects leaf nu-trition and photosynthesis in sugar maple in a nutrient-poor northern Vermont forest. In S. B. Horsley &R. P. Long (Eds.), Sugar maple ecology and health(pp. 98105). Proceedings, U.S.D.A. Forest ServiceGeneral Technical Report NE-261, Northeastern Res.Stn, Radnor, PA.

Elvir, J. A., Wiersma, G. B., Day, M. E., Greenwood, M. S.,& Fernandez, I. J. (2006). Effects of enhanced nitro-gen deposition on foliar chemistry and physiologicalprocesses of forest trees at the Bear Brook water-shed in Maine. Forest Ecology and Management, 221,207214.

Elvir, J. A., Wiersma, G. B., White, A. S., & Fernandez,I. J. (2003). Effects of chronic ammonium sulfatetreatment on basal area increment in red spruce andsugar maple at the Bear Brook watershed in Maine.Canadian Journal of Forest Research, 33, 862869.doi:10.1139/x03-016.

Fenn, M. E., Poth, M. A., Aber, J. D., Baron, J. S.,Bormann, B. T., Johnson, D. W., et al. (1998). Nitro-gen excess in North American ecosystems: Predis-


posing factors, ecosystem responses, and managementstrategies. Ecological Applications, 8, 706733. doi:10.1890/1051-0761(1998)008[0706:NEINAE]2.0.CO;2.

Foster, N. W., Nicolson, J. A., & Hazlett, P. W. (1989).Temporal variation in nitrate and nutrient cationsfrom drainage waters from a deciduous forest. Journalof Environmental Quality, 18, 238244.

Galloway, J. N. (1995). Acid deposition: Perspectives intime and space. Water, Air, and Soil Pollution, 85, 1524. doi:10.1007/BF00483685.

Gilliam, F. S., Adams, M. B., & Yurish, B. M. (1996).Ecosystem nutrient responses to chronic nitrogen in-puts at Fernow experimental forest, west Virginia.Canadian Journal of Forest Research, 26, 196205.

Gundersen, P., Emmett, B. A., Kjonaas, O. J., Koopmans,C. J., & Tietema, A. (1998). Impact of nitrogen de-position on nitrogen cycling in forests: A synthesis ofNITREX data. Forest Ecology and Management, 101,3755. doi:10.1016/S0378-1127(97)00124-2.

Hendershot, W. H. (1991). Fertilization of sugarmaple showing dieback symptoms in the QuebecAppalachians, Canada. Fertilizer Research, 27, 6370.doi:10.1007/BF01048609.

Horsley, S. B., Long, R. P., Bailey, S. W., Hallett, R. A., &Hall, T. J. (2000). Factors associated with the declinedisease of sugar maple on the Allegheny Plateau.Canadian Journal of Forest Research, 30, 13651378.doi:10.1139/cjfr-30-9-1365.

Horsley, S. B., Long, R. P., Bailey, S. W., Hallett, R.A., & Wargo, P. M. (2002). Health of eastern NorthAmerican sugar maple forests and factors affectingdecline. North. J. Appl. For, 19, 3444.

Houle, D., Duschesne, L., Ouimet, R., Paquin, R., Arp,P. A., & Meng, F. R. (2002). Evaluation of theFORHYM2 model for prediction of hydrologic fluxesand soil temperature at the Lake Clair Watershed(Duchesnay, Quebec). Forest Ecology and Manage-ment, 159, 249260.

Houle, D., Gagnon, C., Couture, S., & Kemp, A. (2004).Recent recovery of lake water quality in southernQuebec following reductions in sulfur emissions. Wa-ter Air and Soil Pollution, 4, 247261.

Houle, D., Paquin, R., Camir, C., Ouimet, R., &Duchesne, L. (1997). Response of the Lake Clairwatershed (Duchesnay, Quebec) to change in pre-cipitation chemistry (19881994). Canadian Journalof Forest Research, 27, 18131821. doi:10.1139/cjfr-27-11-1813.

Hutchinson, T. C., Watmough, S. A., Sager, E. P. S., &Karagatzides, J. D. (1998). Effects of excess nitro-gen deposition and soil acidification on sugar maple(Acer saccharum) in Ontario, Canada: An experimen-tal study. Canadian Journal of Forest Research, 28,299310. doi:10.1139/cjfr-28-2-299.

Johnson, D. W., Van Miegroet, H., Lindberg, S. E.,Harrison, R. B., & Todd, D. E. (1991). Nutrientcycling in red spruce forests of the Great Smokymountains. Canadian Journal of Forest Research, 21,769787. doi:10.1139/x91-110.

Kolb, T. E., & McCormick, L. H. (1993). Etiology ofsugar maple decline in four Pennsylvania stands.

Canadian Journal of Forest Research, 23, 23952402.doi:10.1139/x93-296.

Laverman, A. M., Zoomer, H. R., van Verseveld, H. W.,& Verhoef, H. A. (2000). Temporal and spatial vari-ation of nitrogen transformations in a coniferous for-est soil. Soil Biology & Biochemistry, 32, 16611670.doi:10.1016/S0038-0717(00)00082-1.

Leaf, A. L., & Bickelhaupt, D. H. (1975). Possible mu-tual prediction between black cherry and sugar maplefoliar analysis data. Soil Science Society of AmericanProceedings, 39, 983985.

Likens, G. E., Driscoll, C. T., & Buso, D. C. (1996). Long-term effects of acid rain: Response and recovery of aforest ecosystem. Nature, 272, 244246.

Long, P. L., Horsley, S. B., & Lilja, P. R. (1997). Impactof forest liming on growth and crown vigor of sugarmaple and associated hardwoods. Canadian Journalof Forest Research, 27, 15601573. doi:10.1139/cjfr-27-10-1560.

Lovett, G. M., Weathers, K. C., & Sobczak, W. V. (2000).Nitrogen saturation and retention in forested water-sheds of the Catskill mountains, New York. Eco-logical Applications, 10, 7384. doi:10.1890/1051-0761(2000)010[0073:NSARIF]2.0.CO;2.

Lozano, F. C., & Huynh, K. D. (1989). Foliar diagnosis ofsugar maple decline by DRIS. Communications in SoilScience and Plant Analysis, 20, 18951914.

Magill, A. H., Aber, J. D., Berntson, G. M., McDowell,W. H., Nadelhoffer, K. J., Mellilo, J. M., et al. (2000).Long-term nitrogen additions and nitrogen satura-tion in two temperate forests. Ecosystems (New York,N.Y.), 3, 238253. doi:10.1007/s100210000023.

McLaughlin, D. (1998). A decade of forest tree monitoringin Canada: Evidence of air pollution effects. Environ-mental Review, 6, 151171.doi:10.1139/er-6-3-4-151.

McNulty, S. G., Aber, J. D., & Newman, S. D. (1996).Nitrogen saturation in a high elevation sprucefirstand. Forest Ecology and Management, 84, 109121.doi:10.1016/0378-1127(96)03742-5.

Mitchell, M. J., Driscoll, C. T., Inamdar, S., McGee, G. G.,Mbila, M. O., & Raynal, D. J. (2003). Nitrogenbiogeochemistry in the Adirondack mountains ofNew York: Hardwood ecosystems and associatedsurface waters. Environmental Pollution, 123, 355364.doi:10.1016/S0269-7491(03)00026-5.

Mitchell, M. J., Driscoll, C. T., Porter, J. H., Raynal,D. J., Schaefer, D., & White, E. H. (1994). TheAdirondack Manipulation and Modeling Project(AMMP): Design and preliminary results. ForestEcology and Management, 68, 87100. doi:10.1016/0378-1127(94)90140-6.

Mitchell, M. J., Driscoll, C. T., & Raynal, D. J. (1996).Biogeochemistry of a forested watershed in the centralAdirondack mountains: Temporal changes and massbalances. Water, Air, and Soil Pollution, 88, 355369.doi:10.1007/BF00294111.

Moayeri, M., Simpson, B., Arp, P., & Foster, N. (2001).Evaluating critical soil acidification loads and ex-ceedances for tolerant hardwood stands at TurkeyLakes, Ontario. Ecosystems (New York, N.Y.), 4, 555567. doi:10.1007/s10021-001-0029-9.


Moore, J.-D., Camire, C., & Ouimet, R. (2000). Effectsof liming on the nutrition, vigor and growth of sugarmaple at the Lake Clair watershed, Quebec, Canada.Canadian Journal of Forest Research, 30, 725732.doi:10.1139/cjfr-30-5-725.

Moore, J.-D., & Ouimet, R. (2006). Ten-year effect ofdolomitic lime on the nutrition, crown vigor andgrowth of sugar maple. Canadian Journal of ForestResearch, 36, 18341841. doi:10.1139/X06-081.

NADP (1998). National Atmospheric Deposition Programannual summaries. Available from http://nadp.sws.uiuc.edu (accessed December 2006).

Ouimet, R., Duchesne, L., Houle, D., & Arp, P. A. (2001).Critical loads of atmospheric S and N deposition andcurrent exceedances for northern temperate and bo-real forests in Quebec. Water Air and Soil PollutionFocus, 1(1/2), 119134. doi:10.1023/A:1011544325004.

Payette, S., Fortin, M. J., & Morneau, C. (1996). The recentsugar maple decline in southern Quebec: Probablecauses deduced from tree rings. Canadian Journal ofForest Research, 26, 10691078. doi:10.1139/x26-118.

Perakis, S. S., & Hedin, L. O. (2002). Nitrogen lossfrom unpolluted South American forest mainly viadissolved organic compounds. Nature, 415, 416419.doi:10.1038/415416a.

Persson, T., & Wirn, A. (1995). Nitrogen mineraliza-tion and potential nitrification at different depthsin acid forest soils. Plant and Soil, 168169, 5565.doi:10.1007/BF00029313

Peterjohn, W. T., Adams, M. B., & Gilliam, F. S. (1996).Symptoms of nitrogen saturation in two centralAppalachian hardwood forest ecosystems. Biogeo-chemistry, 35, 507522. doi:10.1007/BF02183038.

Pregitzer, K. S., Zak, D. R., Burton, A. J., & Ashby, J. A.(2004). Chronic nitrate additions dramatically in-crease the export of carbon and nitrogen in north-ern hardwood forests. Biogeochemistry, 68, 179197.doi:10.1023/B:BIOG.0000025737.29546.fd.

Rgent Instruments Inc. (1998). WinDendro version 6.3.Universit du Qubec Chicoutimi. Chicoutimi,Qubec, Canada.

Rothstein, D. E., Zak, D. R., & Pregitzer, K. S. (1996).Nitrate deposition in northern hardwood forests andthe nitrogen metabolism of Acer Saccharum Marsh.Oecologia, 108, 338344.

Rudebeck, A., & Persson, T. (1998). Nitrification in or-ganic and mineral soil layers in coniferous forestsin response to acidity. Environmental Pollution, 103,377383. doi:10.1016/S0269-7491(98)80057-2.

Ryan, D. A. J., Allen, O. B., McLaughlin, D. L., & Gordon,A. M. (1994). Interpretation of sugar maple (Acersaccharum) ring chronologies from central and south-ern Ontario using a mixed linear model. CanadianJournal of Forest Research, 24, 568575. doi:10.1139/x94-075.

SAS Software Inc. (2000). SAS/STAT users guide, version8. Cary, NC: SAS.

Schaberg, P. G., deHayes, D. H., & Hawley, G. J. (2001).Anthropogenic calcium depletion: A unique threat toforest ecosystem health? Ecosystem Health, 7, 214228. doi:10.1046/j.1526-0992.2001.01046.x.

Schulze, E. D. (1989). Air pollution and forest decline ina spruce (Picea abies) forest. Science, 244, 776783.doi:10.1126/science.244.4906.776.

Sharpe, W. E. (2002). Acid deposition explains sugar mapledecline in the east. Bioscience, 52, 45. doi:10.1641/0006-3568(2002)052[0005:ADESMD]2.0.CO;2

Skeffington, R. A., & Wilson, E. J. (1988). Excess ni-trogen deposition: Issues for consideration. Environ-mental Pollution, 54, 159184. doi:10.1016/0269-7491(88)90110-8.

Soil Survey Staff (1998). Keys to Soil Taxonomy, 8thedn. USDA. Natural Resources Conservation Service,Washington, DC.

Stanturf, J. A., Stone, E. L., Jr, & McKittrick, R. C. (1989).Effects of added nitrogen on growth of hardwoodtrees in southern New York. Canadian Journal of For-est Research, 19, 279284. doi:10.1139/x89-041.

Ste-Marie, C., & Houle, D. (2006). Forest floor gross andnet nitrogen mineralization in three forest types inQuebec, Canada. Soil Biology & Biochemistry, 38,21352143. doi:10.1016/j.soilbio.2006.01.017.

Ste-Marie, C., & Par, D. (1999). Soil, pH and N availabi-lity effects on net nitrification in the forest floors of arange of boreal forest stands. Soil Biology&Biochemis-try, 31, 15791589. doi:10.1016/S0038-0717(99)00086-3.

Stoddard, J. L. (1994). Long-term changes in watershedretention of nitrogen: Its causes and aquatic conse-quences. In L. A. Baker (Ed.), Environmental chem-istry of lakes and reservoirs. Advances in chemistryseries number 237 (pp. 223284). Washington, D.C.,USA: American Chemical Society.

Stone, D. M. (1980). Fertilization of a pole-sized maplestand: 10-year results. Canadian Journal of Forest Re-search, 10, 158163.

Walworth, J. L., & Sumner, M. E. (1987). The diagnosisand recommendations integrated system (DRIS). Ad-vances in Soil Science, 6, 149188.

White, G., Fernandez, I., & Wiersma, G. (1999). Impacts ofammonium sulfate treatment on the foliar chemistryof forest trees at the bear brook watershed in Maine.Environmental Monitoring and Assessment, 55, 235250. doi:10.1023/A:1006186105021.

Wilmot, T. R., Ellsworth, D. S., & Tyree, M. T. (1995).Relationships among crown condition, growth, andstand nutrition in seven northern Vermont sugar-bushes. Canadian Journal of Forest Research, 25, 386397. doi:10.1139/x95-043.

Wilmot, T. R., Ellsworth, D. S., & Tyree, M. T. (1996).Base cation fertilization and liming effects on nutritionand growth of Vermont sugar maple stands. ForestEcology and Management, 84, 123134. doi:10.1016/0378-1127(96)03743-7.

Wright, R. F., & Tietema, A. (1995). Ecosystem responseto 9 years of nitrogen addition at Sogndal, Norway.Forest Ecology and Management, 71, 133142. doi:10.1016/0378-1127(94)06090-6.

Zak, D. R., Pregitzer, K. S., Holmes, W. E., Burton, A. J.,& Zogg, G. P. (2004). Anthropogenic N depositionand the fate of 15 nitrate in a northern hardwoodecosystem. Biogeochemistry, 69, 143157. doi:10.1023/B:BIOG.0000031045.24377.99.

Soil solution and sugar maple response to NH4NO3 additions in a base-poor northern hardwood forest of Qubec, CanadaAbstractIntroductionMethodsStudy sitesN addition trialField samplingSoil solution chemistryVegetation

Chemical analysesStatistical analysesSoil solutionFoliar, dieback and growth data

ResultsSoil solutionFoliar concentrations and DRIS indicesCrown dieback and basal area growth

DiscussionSoil solution chemistryFoliar chemistryCrown dieback and basal area growth

ConclusionReferences

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soil solution and sugar maple response to nh4no3 additions in a base-poor northern hardwood forest...

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