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Trends and patterns of DON and DOC/DON in deposition and soil solution in Flanders, Northern

Belgium

Arne Verstraeten

Meeting of the ICP Forests Expert Panel on Deposition23 April 2015, Göttingen, Germany

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Introduction

Hypotheses

Results- DON trends and patterns- DOC/DON trends and patterns- Dependence of DOC/DON on variables:

forest typesoil texturehydrological conditionsNO3

- concentrationN stocksoil C/N ratio

Conclusions

Overview

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Acidifying depositions (N and S) decreased (1994–2010)

Soil solution concentrations (NO3-, SO4

2-, Al, Ca2+, K+, Mg2+) and ionic strength decreased, pH increased (1994–2010)

DOC concentrations and fluxes increased in soil solution (2002–2012)

(Verstraeten et al. 2012, 2014)

Introduction

Knowledge gapDo concentrations and fluxes of DON follow trends and patterns of DOC?

We analyzed data trends and patterns of DON and DOC/DON (2005–2013) collected at the 5 Level II plots in Flanders

National data evaluation

Initial recovery in five Level II plots in Flanders

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1) DON concentrations and fluxes increased (like DOC)

2) DOC/DON remained stable

3) Soil solution DOC/DON depended on the forest type, soil texture, soil C/N, soil organic N stock, soil solution NO3

– concentration and

hydrological conditions

Hypotheses

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ResultsPlot Deptha Water fluxes DON concentrations DON fluxes DOC/DON

(cm) Mean Slope Mean P10 P90 Slope Mean Slope Mean Slope Cor

Open field precipitation RAV 935a ns 0.48a 0.09 0.84 ns 3.9a ns 6.9a ns ns

BRA 947a ns 0.40a 0.07 0.80 ns 3.3a ns 7.1a ns *

WIJ 947a ns 0.46a 0.09 0.86 ns 3.8a ns 6.8a -0.47* ns

GON 855a ns 0.41a 0.09 0.81 ns 3.0a ns 7.2a ns ns

HOE 959a ns 0.40a 0.10 0.72 ns 3.4a ns 6.6a ns *

Stand precipitation

RAV 667a ns 1.37b 0.32 2.29 +0.08*** 8.3b ns 15.8bc -0.92** ns

BRA 755a ns 1.08ab 0.28 2.09 +0.04* 7.0ab ns 17.6c ns **

WIJ 727a ns 1.05ab 0.31 1.92 +0.04* 5.6a ns 9.7a -0.48* **

GON 622a ns 1.41b 0.34 2.42 +0.08** 6.3a +0.34** 11.6ab -0.81** ns

HOE 764a ns 0.95a 0.17 1.87 +0.07*** 5.9a +0.46*** 9.1a -0.54** ***

O horizon

RAV 536a ns 2.23ab 0.96 3.79 +0.19*** 10.7a +0.63** 27.0a -1.99*** ***

BRA 569ab -30* 2.22ab 0.71 4.53 +0.18*** 10.7a ns 27.1a -1.87** ***

WIJ 708b ns 1.98a 0.59 3.41 +0.25*** 12.3a +0.81*** 22.9a -1.47*** ns

GON 435a ns 2.58b 1.00 4.66 +0.23*** 10.1a +0.45* 19.4a -1.32*** **

HOE 584ab ns 2.15ab 0.98 3.59 +0.13*** 11.1a +0.73** 23.5a -1.66*** **

A horizon

RAV 10-25 427a ns 1.92c 0.84 3.06 +0.09** 7.9c +0.36* 34.8b -2.45*** ns

BRA 15-25 330a ns 1.82bc 0.84 2.97 +0.13*** 5.6ac +0.21* 30.2b -1.80** ns

WIJ 10-20 330a ns 1.48ab 0.45 2.28 +0.11*** 4.3ab ns 33.4b -1.85* *

GON 10-20 334a ns 2.08c 0.87 2.95 +0.04* 6.5bc ns 16.5a -0.47* ns

HOE 10-15 359a ns 1.23a 0.31 1.97 +0.07*** 4.0a +0.15* 28.0b -1.42* ***

B horizon

RAV 30-45 350a ns 1.65b 0.67 2.71 ns 5.5c +0.24* 37.8b ns ***

BRA 30-55 249a ns 1.43b 0.67 2.24 +0.08*** 3.4ab ns 27.2ab -1.05* ***

WIJ 45-70 257a ns 0.86a 0.16 1.41 ns 2.1a ns 29.3b ns ***

GON 25-40 303a ns 1.45b 0.54 2.19 +0.05* 4.2bc ns 19.0a ns ***

HOE 20-30 359a ns 0.71a 0.06 1.29 +0.05** 2.5a +0.12* 16.4ab ns ***

C horizon

RAV 70-95 333b ns 1.28b 0.36 2.01 ns 3.7c ns 23.2b ns **

BRA 70-90 220a ns 1.20b 0.51 1.91 +0.05** 2.5b ns 24.0ab ns **

WIJ 75-110 181a ns 0.70a 0.22 1.18 ns 1.2a ns 21.4ab ns ***

GON 45-55 197a ns 1.18b 0.49 1.93 ns 2.3b ns 14.8a ns **

HOE 35-55 344b ns 0.66a 0.06 1.31 +0.06*** 2.1b +0.16** 21.6b ns ***

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Results

Open field precipitation- moderate to high levels- slightly higher during the growing seasonStand precipitationconspicuous peak in May in deciduous plots=> bud burst + bud scales, water brown coloreffect of the forest typespring > autumn phenology

Soil solutionpeak was mirrored, butlater towards the season

DON concentrations(Seasonal) patterns

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Results

open field precipitationsimilar to concentrationsstand precipitationconiferous > deciduous

Soil solution- highest in organic layer- decline with depth- 1.2–3.7 kg ha–1 yr–1 leaching (<0.1% of N stock)- higher peak during winter(more abundant rainfall)

DON fluxes(Seasonal) patterns

Precipitation

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Results

Open field precipitation- 6.6–7.2 (quite low)- higher during the growing seasonStand precipitation- coniferous > deciduous 15.8–17.6 9.1–11.6- higher during the autumn

Soil solution- higher during the autumn- silty–loamy < sandy soilseffect of soil texture(sorption capacity)

DOC/DON(Seasonal) patterns

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Plot Soil type Depth Morpho-Genetic

C/N pH(CaCl2) CEC BS Clay Silt Sand

cm Horizon

cmolc kg-1 % 0–2 µm 2–63 µm >63 µm

RAV Endogleyic Folic Brunic -6.6 – -0.8 OF 33 2.5 23 36

Albic Arenosol (Dystric) -0.8 – 0 OH 35 2.3 26 16

0 – 5 Ap/E 27 2.9 4.6 11 2.3 10.2 87.5

5 – 10 Ap/E 27 3.0 3.8 7.6 0.9 12.6 86.5

10 – 20 Ap/E 23 3.1 3.6 7.4 0.7 11.9 87.4

20 – 40 Bhs 21 3.4 3.3 8.2 3.0 12.0 85.0

40 – 80 B, Bg1 - 4.1 1.7 15 1.4 12.3 86.3

BRA Endogleyic Brunic -5.2 – 0 OFH 30 2.7 25 42

Albic Hypoluvic 0 – 5 Ap1 18 3.1 2.2 18 2.0 7.0 91.0

Arenosol (Dystric) 5 – 10 Ap1 18 3.2 1.8 15 1.9 4.7 93.4

10 – 20 Ap1 15 3.3 1.7 16 1.8 5.9 92.3

20 – 40 Ap1, Ap2 14 3.4 1.6 17 1.0 6.1 92.8

40 – 80 E, Bg1, Bg2 - 3.6 1.5 18 1.6 5.3 93.1

WIJ Endogleyic Folic Umbrisol -8.0 – -2.1 OF 25 2.7 31 42

(Brunic, Humic, Alumic, -2.1 – 0 OH 22 2.7 25 23

Hyperdystric, Arenic) 0 – 5 A1 21 2.5 7.3 32 - - -

5 – 10 A2 19 2.7 4.2 14 3.3 24.7 72.0

10 – 20 A2 16 3.0 3.5 11 3.8 23.8 72.5

20 – 40 A3 18 3.3 3.1 10 3.6 21.5 74.9

40 – 80 Bhg, Cgc 10 3.6 3.0 11 5.9 21.9 72.2

GON Luvic Folic Planosol -6.2 – 0 OFH 25 3.6 - -

(Albic, Ruptic, Dystric, 0 – 5 A 20 2.9 17 23 - - -

Siltic, Clayic) 5 – 10 B 17 2.9 15 20 9.5 50.6 39.9

10 – 20 B, 2B 17 3.0 12 15 11.0 48.2 40.8

20 – 40 2B, 2Bg 12 3.3 14 21 24.5 46.0 29.5

40 – 80 2Bg, 3Bg 7.8 3.5 23 61 47.5 36.6 15.9

HOE Albic Cutanic Alisol -3.0 – 0 OFH 23 3.1 24 81

(Fragic, Abruptic, Alumic, 0 – 5 A 17 3.3 6.3 16 10.6 85.9 3.6

Hyperdystric, Siltic) 5 – 10 Bh 17 3.5 4.3 13 5.3 90.7 4.0

10 – 20 E 14 3.8 3.8 11 14.4 81.8 3.8

20 – 40 Bt 10 3.8 4.6 8.9 13.5 81.3 5.2

40 – 80 Btmx1 5.4 3.8 5.2 16 19.1 76.9 4.0

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Soil type, depth, genetic horizons, C/N, pH, CEC, base saturation (BS) and texture

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ResultsTrends

DON concentrations

Open field precipitationstableStand precipitationincrease

Soil solution- increase, particularly inO and A horizon- downward peak in 2007,increase (peak) in 2008,then more or less stable

ns(5) +(2)++(1)+++(2)

+++(5) +(1)++(1)+++(3)

ns(2)+(1)++(1)+++(1)

ns(3)++(1)+++(1)

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ResultsTrendsDON fluxes

Similar as concentrations, but less significant(variability water fluxes)

ns(5) ns(3)++(1)+++(1)

ns(1)+(1)++(2)+++(1)

ns(2)+(3)

ns(3)+(2)

ns(4)++(1)

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ResultsTrendsDOC/DON

Open field precipitationstableStand precipitationdecrease

Soil solution- decrease in O and A horizon, stable in B and C horizon- conspicuous peak in 2007,downward peak in 2008,then more or less stable=> effect drying and rewettingApril–May 2007: drought (36–37d no rain)June–August: up to 400 mmrain

ns(4)-(1)

ns(1)-(1)- -(3)

- -(1)- - - (4)

-(3)- -(1)- - - (1)

ns(4)-(1)

ns(5)

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DOC/DON was positively related to NO3– concentration in the

A horizon (p<0.05), but not in the O, B and C horizon

In the O horizon, DOC/DON was negatively correlated with litter input rate (g m–2 d–1) (p<0.05), suggesting an effect of the forest type

DOC/DON showed no relationship with soil C/N ratio or soil organic N stock

ResultsDependence of DOC/DON on other factors

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Conclusions• DON increased (2005–2013), particularly in stand deposition,

O and A horizons

• DOC/DON decreased in stand deposition, O and A horizons, because DON increased faster than DOC

• DOC/DON depended on the forest type, soil texture and hydrological conditions, but not on soil C/N ratio and soil organic N stock, while results were inconclusive with regard to NO3

– concentration

• It would be interesting to check whether results are valid on a European scale, using aggregated data from deposition and soil solution

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Thank you for your attention!

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Precipitation

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Quality control water fluxes

Fig. Residuals of lm(cumulative water flux ~ time) in function of timeClear correlation for deposition and soil solution.Overestimation when storms bring high amount of Na+ landward