Comolli suolo

R. Comolli Earth and Environmental Sciences Dept.

Milan Bicocca University Milan

SOIL MONITORING PRELIMINARY RESULTS IN ITALY

MILAN, 17 JUNE 2014

LIFE+ 10 ENV/IT/399

Final conference FORESTE URBANE – IL RESPIRO DELLE CITTÀ

Soils and forests

Natural forest (Bosco Fontana) UPF (Bosco di Maristella)

Aims

• Characterization of UPF soils • Soil modifications owing to UPF

implantation • Evaluation of UPF soils (chemical

and biological fertility, water retention, etc.)

• Soil-vegetation relationships

Soil

Soilscapes of the study plots

1. Parco Nord Milano: coarse LGM fluvioglacial deposits

2. Boscoincittà: hydromorphic LGM fluvioglacial deposits

3. Bosco di Maristella: LGM fluvial deposits 4. Bosco Fontana: fluvial terraces 5. Foresta di Carpaneta: hydromorphic LGM

fluvioglacial deposits

Soil types

Plot Soil type (WRB 2006) Parco Nord Milano 23B Haplic Luvisol (Humic, Endoskeletic, Chromic)

Parco Nord Milano 2A_nd Luvic Phaeozem (Endoskeletic)

Parco Nord Milano 18C Haplic Luvisol (Humic, Epidystric, Endoskeletic)

Parco Nord Milano 25A Haplic Luvisol (Humic, Epidystric)

Parco Nord Milano 2A Cutanic Luvisol (Humic, Epidystric, Endoskeletic)

Parco Nord Milano 9A Luvic Phaeozem (Endoskeletic, Endoarenic)

Parco Nord Milano 1D Haplic Luvisol (Humic, Endoskeletic, Chromic)

Parco Nord Milano 28C Haplic Luvisol (Humic, Epidystric, Endoskeletic, Chromic)

Parco Nord Milano 1A Haplic Luvisol (Humic, Endoskeletic, Chromic)

Parco Nord Milano 14A Haplic Luvisol (Humic, Epidystric, Endoskeletic)

Boscoincittà Haplic Umbrisol (Humic, Endoeutric)

Foresta della Carpaneta Endopetric Hypocalcic Vertic Calcisol

Bosco di Maristella Haplic Cambisol (Humic, Hypereutric, Siltic)

Bosco Fontana Petric Luvic Calcisol (Skeletic, Endoarenic, Chromic)

Soil types

Plot Soil type (WRB 2006) Parco Nord Milano Luvisol (Phaeozem)

Humic, Epidystric, Endoskeletic, Chromic Boscoincittà Umbrisol

Humic, Endoeutric Foresta della Carpaneta Calcisol

Endopetric Hypocalcic Vertic Bosco di Maristella Cambisol

Humic, Hypereutric, Siltic Bosco Fontana Calcisol

Petric, Luvic, Skeletic, Endoarenic, Chromic

Soil types

Parco Nord Milano

The soils are about 1.5 m deep, moderately acid, have generally sandy loam texture, and some of them have compacted subsurface horizons. The main pedogenetic process is clay illuviation.

Soil types

Bosco Fontana

The soils have thick organic surface horizons, are strongly acid in the topsoil, but alkaline in the subsoil, with hard petrocalcic horizons and a large amount of rock fragments. The main pedogenetic processes are clay

illuviation and calcification.

Soil spatial variability

Examples of topsoil and subsoil pH maps (referred to 1A study area in Parco Nord Milano): for both of them, it can be noted a positive pH gradient from north-west to south-east.

pH maps

For each plot, topsoil and subsoil pH maps were obtained by applying geostatistic procedures: pH reveals strong variability in some plots, but greater uniformity in others.

Organic surface horizons

Organic horizons

Dry weight of the soil organic horizons (litter)

related to the forest type of each study area.

Soil biological quality index (QBS)

QBS-ar is based on microarthropod groups present in a soil sample. Each biological form found in the

sample receives a score from 1 to 20 (EcoMorphological Index, EMI), according to its

adaptation to soil environment. QBS method is based on the assumption that there

is a direct correlation between soil quality and microarthropod groups well adapted to edaphic life.

Soil samples for QBS calculation were taken from the surface layer, up to 10 cm depth, using a known volume sampler, to determine also soil bulk density and water content.

Determination of biological forms and calculation of QBS Index

Berlese-Tullgren extractor

Bait-lamina test

The feeding activity of soil animals was determined by the Bait-lamina Test, through insertion into the ground of drilled strips, filled with an

organic bait, and their subsequent extraction after 14 days: the biological activity, at different depths, was expressed as percentage of empty holes

on the total of the holes.

Forest and meadow soils

To assess the soil changes as a result of land use change (from arable or meadow to forest), we

studied soils that retained the land use preceding the planting

of the wood. In these comparison soils, field observations with auger were

executed, together with topsoil and subsoil sampling.

forest soil meadow soil for comparison

Biological indices

The edaphic community of the woods shows a greater diversification compared to that of

the meadows.

The Bait-lamina Test proves that the biological activity is greater in the meadow (22% of organic bait consumed) than in the wood

(16%), contrary to what happens with QBS values, generally greater in the wood.

QBS Index vs Bait-lamina Test

Tests were taken both in the forest areas and in adjacent soils maintained with the former land use (arable or meadow).

Soil modifications

pH H2O

Aree Confronto Boschi0

1

2

3

4

5

6

pH

Mean: 5.84 ± 0.09 5.62 ± 0.04 Mean: 56.22 ± 4.08 25.77 ± 2.23 P value: 0.0360* P value: <0.0001***

Tasso Saturazione in Basi

Aree Confronto Boschi0

10

20

30

40

50

60

70

TSB

pH H2O Base Saturation

UPFs Comparison plots UPFs Comparison plots

BS

(%)

pH

Soil modifications

Soil pH (H2O) vs. Forest age

Age of the forest (years)

Topsoil R2=0.0836

0-10 cm layers R2=0.296

A horizons R2=0.566

Soil modifications

Carbonio organico

Aree confronto Boschi0.00

0.25

0.50

0.75

1.00

1.25

C %

Capacità di Scambio Cationico

Aree confronto Boschi0

10

20

CS

C (c

mol

(+)/k

g)

Soil Organic Carbon Cation Exchange Capacity

Mean: 1.05 ± 0.16 0.98 ± 0.08 Mean: 12.10 ± 1.27 15.53 ± 0.72 P value: 0.6987 P value: 0.0165*

UPFs Comparison plots UPFs Comparison plots

SOC

(%

)

CEC

(cm

ol (+

) kg-1

)

Soil modifications

Soil Organic Carbon vs. Forest age

Topsoil R2 = 0.111

0-10 cm layers R2 = 0.400

A horizons R2 = 0.656

Age of the forest (years)

Soil

Org

anic

Car

bo

n (

%)

Soil monographs

Photographs of the soil profile

The soil of each study area was described in a specific monograph.

Soil monographs

Horizon Depth Description

Ah 0 - 7 cm dry; matrix color 10YR 3/2; silty loam; very little few rock fragments, not weathered; large granular structure, strongly

developed; abundant roots, from very fine to medium; no effervescence to HCl; abrupt wavy lower boundary

A1 7 - 25 cm dry; matrix color 10YR 3/3; loam; common rock fragments, fine and very fine, not to low weathered; large subangular blocky

structure, moderatately developed; common roots, from very fine to medium; no effervescence to HCl; little brick fragments;

gradual smooth lower boundary

A2 25 - 40 cm dry; matrix color 10YR 3/3.5; silty loam; common rock fragments, fine and very fine, not to low weathered; large subangular

blocky structure, moderately developed; moderately compacted; common roots, from very fine to medium; no effervescence

to HCl; little brick and plastic fragments; clear smooth lower boundary

Btd 40 - 58 cm slightly moist; matrix color 7.5YR 3/4; sandy loam; abundant rock fragments, fine and very fine, medium weathered; fine

angular blocky structure, slightly developed, tending to massive; heavy compaction (possibly plow sole); few roots, from very

fine to medium; no effervescence to HCl; clear wavy lower boundary

Bt 58 - 80 cm slightly moist; matrix color 7.5YR 3/4; sandy loam; abundant rock fragments, fine and very fine, medium weathered; medium

subangular blocky structure, moderately developed; few roots, from very fine to medium; no effervescence to HCl; clear wavy

lower boundary

Description of the soil profile (by horizons)

Etc.

Soil monographs

Analytical data of the soil profile (by horizons)

Horizon Depth

pH H2O pH KCl tot. CaCO3 % org. C tot. N

C:N avail. P mg

kg-1 cm % %

Ah 0 - 7 6,5 5,7 0,00 4,254 0,262 16,21 18,23

A1 7 - 25 5,3 4,3 N.D. 1,138 0,084 13,49 21,87

A2 25 - 40 5,4 4,2 N.D. 0,988 0,092 10,73 23,09

Btd 40 - 58 5,4 4,1 N.D. 0,520 0,060 8,65 10,69

Bt 58 - 80 5,3 4,0 N.D. 0,409 0,043 9,56

BC 80 - 95 5,9 5,1 N.D. 0,269 0,033 8,25

CB 95 - 130 7,9 7,1 1,62 0,289 0,030 9,58

C 130 - 160 8,3 7,8 26,23 0,124 < 0,001 -

Horizon Depth Cation exchange complex (cmol(+) kg-1) BS

cm CEC Ca2+ Mg2+ Na+ K+ %

Ah 0 - 7 20,53 13,70 2,53 0,02 0,32 80,73

A1 7 - 25 15,83 2,58 0,53 0,07 0,08 20,59

A2 25 - 40 14,03 2,46 0,42 0,05 0,06 21,31

Btd 40 - 58 15,44 4,18 0,71 0,07 0,15 33,10

Bt 58 - 80 11,56 3,41 0,52 0,06 0,14 35,74

BC 80 - 95 12,29 5,20 0,72 0,09 0,07 49,46

CB 95 - 130 9,90 7,52 0,56 0,00 0,02 81,79

C 130 - 160 6,63 6,23 0,46 0,05 0,01 100,00

Soil monographs

Vertical trend of pH, organic C and C:N

ratio in the soil profile

Soil monographs

Soil classification Diagnostic horizons (WRB, 2007):

• umbric = 0-40 cm • argic = 40-80 cm

WRB (2007) classification:

Haplic Luvisol (Humic, Epidystric, Endoskeletic) Soil Taxonomy (2010) classification:

Typic Hapludalf, loamy-skeletal, mixed, mesic Réferéntiel Pédologique (2008) classification:

NÉOLUVISOL oligosaturé, compacté Topsoil depth: 0-40 cm Subsoil depth: 40-80 cm

Soil monographs

Point Horizon Depth

(cm)

Rock

fragments

(class)

Effervescence

to HCl

(class)

Color Notes

T1 A

AB

B

0-12

12-45

45-83

0

1

1

0

0

0

10YR 3/3

10YR 3/3,5

10YR 3/6

T2 A

AB

Bt1

Bt2

0-11

11-35

35-59

59-80

0

0

0

0

10YR 3/3

10YR 3/3,5

9YR 3/4

9YR 3/4

40 cm: brick

fragments

T3 A

AB

Bt1

Bt2

0-11

11-38

38-60

60-80

1

1

1

1

0

0

0

0

10YR 3/3

10YR 3/3,5

7,5YR 3/4

7,5YR 3/4

50 cm: brick

fragments

T4 A

AB

BA

B

0-11

11-25

25-38

38-57

1

1

2

3

0

0

0

0

10YR 3/3

10YR 3/4

10YR 3/4

10YR 3/6

T5 A

AB

BA

C?

0-12

12-25

25-35

35-59

3-4 0

0

0

0

10YR 3/3

10YR 3/3,5

10YR 3/3,5

7,5YR 3/4

brick fragments

Etc.: T6-T15

Description of the observations with soil

auger

Soil monographs

Analytical data (pH in H2O and KCl)

for topsoil and subsoil samples collected from the observations

with auger

pH in H2O pH in KCl

Punto Topsoil Subsoil Punto Topsoil Subsoil

T3 5,1 5,3 T3 4,1 4,2

T4 5,2 5,3 T4 4,2 4,3

T5 5,6 5,5 T5 4,5 4,3

T6 5,2 5,4 T6 4,2 4,3

T7 5,4 5,4 T7 4,2 4,2

T8 5,0 5,3 T8 3,9 4,1

T9 5,1 5,0 T9 4,0 3,9

T10 5,0 5,3 T10 4,0 4,1

T11 5,0 5,3 T11 4,0 4,2

T12 5,2 5,3 T12 4,1 4,2

T13 4,9 5,1 T13 4,0 4,1

T14 5,1 5,3 T14 4,0 4,2

T15 5,0 5,2 T15 4,0 4,2

P 5,5 5,3 P 4,5 4,0

Mean 5,09 5,27 Mean 4,08 4,16

St. dev. 0,22 0,12 St. dev. 0,17 0,11

min. 4,8 5,0 min. 3,9 3,9

max. 5,6 5,5 max. 4,5 4,3

Soil monographs

Maps of pH H2O of the plot

Soil monographs

Layer Depth

pH H2O pH KCl tot. CaCO3 % org. C tot. N

C:N av_P

mg kg-1 cm % %

Topsoil 0 - 40 5,3 4,2 0,0 1,22 0,10 12,12 22,69

Subsoil 40 - 80 5,5 4,3 0,0 0,59 0,06 9,11 17,23

Layer Depth Cation exchange complex (cmol(+) kg-1) BS

cm CEC Ca2+ Mg2+ Na+ K+ %

Topsoil 0 - 40 15,31 1,50 0,26 0,08 0,09 12,61

Subsoil 40 - 80 12,88 2,37 0,37 0,06 0,09 22,43

Layer

Depth Particle size % Text. class

USDA cm Coarse

sand Fine sand

Total

sand Coarse silt Fine silt Total silt Clay

Topsoil 0 - 40 29,3 12,3 41,6 17,4 31,7 49,1 9,3 Loam

Subsoil 40 - 80 26,0 14,6 40,6 14,1 28,0 42,1 17,3 Loam

Analytical data for topsoil and subsoil (mixed samples)

Principal Component Analysis (PCA)

Relationships between topsoil parameters of the 14 study plots: • there are strong relationships between

exchangeable bases (Ca, Mg, Na, K) and pH;

• bulk density and soil organic matter are opposite;

• bulk density and age of the wood are opposite;

• the litter weight and the age of the wood are related;

• the organic C content is related to the age of the wood.

PCA for topsoil parameters (with the addition of the plot age)

PCA for topsoil cases (study plots)

Principal Component Analysis (PCA)

• There is great similarity between the soils of the Parco Nord Milano (except the plot 9A)

• Bosco Fontana soils and Bosco di Carpaneta soils are very different from each other and from Parco Nord Milano soils

Correlations

pH

H2O

pH

KCl CaCO3 SOC Tot N C:N Av P CEC Ca Mg K BS Clay Sand Litter QBS BD Age

pH H2O 1,00

pH KCl 0,98 1,00

CaCO3 0,81 0,85 1,00

SOC -0,35 -0,23 -0,16 1,00

Tot N -0,24 -0,12 -0,04 0,98 1,00

C:N -0,65 -0,55 -0,59 0,68 0,53 1,00

Av P -0,10 -0,21 -0,28 -0,22 -0,17 -0,18 1,00

CEC 0,50 0,59 0,69 0,46 0,59 -0,26 -0,19 1,00

Ca 0,91 0,94 0,88 -0,05 0,08 -0,57 -0,25 0,76 1,00

Mg 0,86 0,88 0,83 -0,04 0,12 -0,57 -0,07 0,75 0,97 1,00

K 0,72 0,70 0,72 0,04 0,22 -0,61 -0,08 0,76 0,85 0,87 1,00

BS 0,91 0,90 0,73 -0,17 -0,06 -0,55 -0,17 0,53 0,93 0,92 0,78 1,00

Clay 0,76 0,72 0,81 -0,49 -0,34 -0,90 0,09 0,52 0,73 0,72 0,70 0,61 1,00

Sand -0,57 -0,47 -0,50 0,76 0,64 0,87 -0,25 -0,10 -0,43 -0,43 -0,41 -0,42 -0,78 1,00

Litter -0,38 -0,30 -0,29 0,58 0,48 0,49 -0,39 0,16 -0,18 -0,25 -0,21 -0,25 -0,36 0,54 1,00

QBS 0,43 0,54 0,60 0,46 0,49 0,11 -0,45 0,72 0,63 0,56 0,47 0,46 0,23 0,10 0,36 1,00

BD 0,40 0,25 0,16 -0,93 -0,88 -0,72 0,21 -0,37 0,10 0,06 0,10 0,23 0,51 -0,82 -0,52 -0,40 1,00

Age -0,65 -0,55 -0,33 0,72 0,64 0,67 -0,42 0,03 -0,38 -0,39 -0,23 -0,46 -0,60 0,83 0,52 0,13 -0,76 1,00

Statistical correlations between parameters of the topsoil samples

Marked correlations are significant at p < 0,050 - N=14

Future monitoring

Sample plot Confidence interval

75% 85% 95%

Parco Nord Milano – 23B 2 2 4

Parco Nord Milano – 1A 10 15 27

Parco Nord Milano – 1D 2 3 5


Parco Nord Milano – 2A_nd 7 11 19



Parco Nord Milano – 18C 2 2 4

Parco Nord Milano – 28C 1 1 2


Boscoincittà 2 3 5

Bosco di Maristella 1 1 1

Foresta di Carpaneta 1 1 1

Bosco Fontana 1 1 2

Number of samples for future soil monitoring

It was calculated the minimum number of soil subsamples to be collected for each plot in a future monitoring program in order to apply significantly sound statistics oriented to highlight a defined change in soil pH.

The table shows the number of future samplings necessary to highlight, in a few years, a possible variation of ± 0.3 pH points, according to the confidence interval. The minimum number of future soil subsamples (n) to be collected in different areas was obtained using the following equation:

• Фα is the critical value at the probability level α • s2 is the observed variance • D is the defined change in soil pH

2 2

2

s

D

n =

s2

where:

Conclusions

The 14 studied plots have soil well differentiated from each other. In some plots, pH has a great spatial variability, while it’s rather homogeneous in

others. Soil parameters: there is strong correlation between the age of the UPF and some

soil parameters (pH, SOC, total N, bulk density). The number of future soil samplings is in inverse relation to the variance of the

parameter: therefore, plots with a higher variability will require a greater number of samplings than more uniform areas.

The QBS Index has higher values in forest soils, intermediate values in meadow soils and lower values in arable soils; the biological quality tends to increase with the age of the forest.

Soil properties are modified by the UPF implantation, at first in the topsoil: the main processes are acidification and SOM accumulation. Their intensity is directly correlated with the age of the UPF.

Thank you for your attention!