study area - department of environment and science · 2013-04-12 · classification australian soil...
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Soil
Ind
icat
ors
of Q
uee
nsla
nd W
etla
nds Brown Lake
North Stradbroke Island
Study AreaBrown Lake is located approximately 4 km east of Dunwich on North Stradbroke Island, South-East Queensland.
Brown lake is a perched lake which form when an impermeable layer of sand become cemented. This cemented layer,known as coffee rock prevents rainwater from percolating through to the regional aquifer1.
This is an example of a coastal and sub-coastal non-floodplain sand lake (perched) in the South-East Queensland Bioregion.
Climate2
0
100
200
300
400
500
600
700
800
900
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonth
Rai
nfal
l-Eva
pora
tion
(mm
)
0
5
10
15
20
25
30
35
40
Tem
pera
ture
(Deg
.C)
Rain Evap
Temp (min) Temp (max)
The study area is situated within a subtropical climatic region with a wet and dry season. Rainfall exceeds evaporation in the majority of months. The average annual rainfall for the area is 1668 mm.
Landform and Inundation
Perched Lake
Permanent freshwater inundation from overland flow
Soils3 Podsdols and Organosols
Vegetation4 Swamps with Baumea spp., Juncus spp. and Lepironia articulata (RE 12.2.1�)12.2.1�)
Geology� Pleistocene beach ridge systems (quartz sand)
Disturbance Little to no disturbance
Soil
In
dic
ator
s of
Q
ue
ensl
and
W
etla
nd
s Location GDA94 • MGA Coordinates : �42618 E, 69�8�99 N, Zone �6 • Lat/Long : -27.49��7 S, 1�3.4314� E
Landscape Diagram
Brown Lake Site 117
Site 118Site 119
Site 120
Transition zone
Outer zone
Very shallow water table
1.2 m
140 m
Soil Profiles Site 117Site 118
0.2 m
P1
0.3� m
0.� m
P21
P22
A11
A12
A21e
0.2 m
0.4� m
1.0 m
Fibric loam textures, very high organic carbon content, dark colours and shallow water
table all indicate a permanently waterlogged environment
Sites 119 and 120 (not shown) similar to this profile
Low chroma values in the surface 0.3 m is the only wetland soil indicator observed
For soils dominated by sand textures, low chroma values alone are not considered good indicators of
wetland soils without additional indicators
such as organic materials, redox
features (like mottles) or ferruginous root channels and pore
linings6
Soil
In
dic
ator
s of
Q
ue
ensl
and
W
etla
nd
s Soil Indicators Present (within 0.3 m of surface)
Indicator7 Site 117 Site 118Organic materials and organic carbon (OC)*
No organic materials OC: 1.04%
Organic materials to 0.3 m OC: 34.6%
Matrix colour Greyish brown to dark grey Dark brown to black
Chroma (thickness of layer)**
Present (0.3 m) Present (0.3 m)
Mottles and Segregations
Not present Not present
Depth to groundwater Not present 0.1 m
Ferruginous root channel and pore linings
Not present Not present
pH*8 Very strongly acid Very strongly acid
Texture Sand Loam
Acid sulfate material Not present Not present
Electrical Conductivity (EC)8
Non saline Non saline
Indicator7 Site 119 Site 120 Organic materials and organic carbon*
Organic materials to 0.3 m OC: 2�%
Organic materials to 0.3 m OC: 36.3%
Matrix colour Black Black
Chroma (thickness of layer)**
Present (0.3 m) Present (0.3 m)
Mottles and Segregations
Not present Not present
Depth to groundwater 0.01 m 0.01 m
Ferruginous root channel and pore linings
Not present Not present
pH*8 Very strongly acid Very strongly acid
Texture Loam Loam
Acid sulfate material Not present Not present
Electrical Conductivity (EC)8
Non saline Non saline
*Organic carbon % (Dumas method) and pH taken from surface (0-0.1 m) **Chroma value is less than or equal to 2
Summary of Field Observations• The presence of swamp hummock microrelief is typical of a saturated environment
• Fibric and sapric materials indicative of a waterlogged environment (Figure 1)
• High water table with poor external drainage suggests a permanently inundated area
• No evidence of sulfidic materials
• Organic acids produced from organic materials create a very acidic environment (pH range from 3.� in the saturated zone to 4.� in the outer zone)
Figure 1: Fibrous mat of roots which sit on a shallow water table
Soil Indicators of Queensland WetlandsSo
il M
orph
olog
y
Site
117
Clas
sifi
cati
on
Aust
ralia
n So
il Cl
assi
fica
tion
Aq
uic
Podo
sol
Land
form
Ele
men
t D
unes
lope
Mor
phol
ogic
al T
ype
Low
er s
lope
Hor
izon
Dep
th (
m)
Boun
dary
Text
ure
Colo
urM
ottl
esCo
arse
Fr
agm
ents
Stru
ctur
eSe
greg
atio
nsCo
nsis
tenc
e
A11
0 to
.2
gra
dual
to
sand
very
dar
k gr
eyis
h br
own
(10Y
R32)
no
neno
nesi
ngle
gra
inno
neve
ry w
eak
dry
A12
.2 t
o .4
� c
lear
to
sand
dark
gre
y (1
0YR4
1)
none
none
sing
le g
rain
none
very
wea
k m
oder
atel
y m
oist
A21
e.4
� to
1 d
iffu
se t
osa
ndlig
ht b
row
nish
gre
y (1
0YR6
2)no
neno
nesi
ngle
gra
inno
neve
ry w
eak
mod
erat
ely
moi
st
A22
e1
to 1
.2 d
iffu
se t
osa
ndlig
ht b
row
nish
gre
y (1
0YR6
2)no
neno
nesi
ngle
gra
inno
neve
ry w
eak
moi
st
A23
e1.
2 to
1.3
�-
sand
light
gre
y (1
0YR7
2)
few
(2-
10%)
fine
(<
� m
m)
fain
t br
own
mot
tles
none
sing
le g
rain
none
very
wea
k w
et
Site
118
Clas
sifi
cati
on
Aust
ralia
n So
il Cl
assi
fica
tion
Re
golit
hic,
Aci
dic,
Sap
ric
Org
anos
olLa
ndfo
rm E
lem
ent
Swam
p M
orph
olog
ical
Typ
e Si
mpl
e sl
ope
Hor
izon
Dep
th (
m)
Boun
dary
Text
ure
Colo
urM
ottl
esCo
arse
Fr
agm
ents
Stru
ctur
eSe
greg
atio
nsCo
nsis
tenc
e
P10
to .
2 g
radu
al t
ofib
ric
loam
very
dar
k br
own
(10Y
R22
)no
neno
ne-
none
wea
k w
et
P21
.2 t
o .3
� g
radu
al t
osa
pric
loam
blac
k (1
0YR
21)
none
none
-no
new
eak
wet
P22
.3�
to .
�-
sapr
ic lo
ambl
ack
(10Y
R21
)no
neno
ne-
none
wea
k w
et
Site
119
Clas
sifi
cati
on
Aust
ralia
n So
il Cl
assi
fica
tion
Rego
lithi
c, A
cidi
c, H
emic
Org
anos
olLa
ndfo
rm E
lem
ent
Swam
pM
orph
olog
ical
Typ
e Fl
at
Hor
izon
Dep
th (
m)
Boun
dary
Text
ure
Colo
urM
ottl
esCo
arse
Fr
agm
ents
Stru
ctur
eSe
greg
atio
nsCo
nsis
tenc
e
P11
0 to
.1 g
radu
al t
ofib
ric
loam
blac
k (1
0YR
21)
none
none
-no
neve
ry w
eak
wet
P12
.1 t
o .3
-fib
ric
loam
blac
k (1
0YR
21)
none
none
-no
neve
ry w
eak
wet
Soil Indicators of Queensland WetlandsSi
te 1
20Cl
assi
fica
tion
Au
stra
lian
Soil
Clas
sifi
cati
on
Rego
lithi
c, A
cidi
c, H
emic
Org
anos
olLa
ndfo
rm E
lem
ent
Swam
pM
orph
olog
ical
Typ
e Fl
at
Hor
izon
Dep
th (
m)
Boun
dary
Text
ure
Colo
urM
ottl
esCo
arse
Fr
agm
ents
Stru
ctur
eSe
greg
atio
nsCo
nsis
tenc
e
P11
0 to
.1-
fibri
c lo
ambl
ack
(10Y
R21
) no
neno
ne-
none
very
wea
k w
et
P12
.1 t
o .2
-fib
ric
loam
blac
k (1
0YR
21)
none
none
-no
neve
ry w
eak
wet
Soil
Chem
istr
y
Site
Dep
th (
m)
pH*
EC (
dS/m
)Cl
(m
g/kg
)N
O3-
N (
mg/
kg)
TC%
**TN
%**
117
0.00
-0.1
04.
80.
01<2
0<1
1.04
<0.0
3
0.20
-0.3
04.
60.
0122
<10.
6�<0
.03
0.40
-0.�
04.
90.
01<2
0<1
0.12
<0.0
3
118
0.00
-0.1
03.
60.
7�2
6<1
34.6
1.04
0.20
-0.3
03.
40.
4730
91
3�1.
47
0.40
-0.�
03.
40.
3622
3<1
32.2
1.29
119
0.00
-0.1
03.
60.
221�
0<1
2�0.
93
0.20
-0.3
03.
70.
2620
81
26.7
1.23
120
0.00
-0.1
03.
60.
�239
82
36.3
1.29
0.10
-0.2
03.
60.
282�
4�
31.4
1.36
*Aqu
eous
1:�
**To
tal c
arbo
n an
d to
tal n
itro
gen
Refe
renc
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QW
P (2
008)
. W
etla
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abit
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ypol
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lust
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d.
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oret
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iner
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etla
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oils
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ilson
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urge
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ueen
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etla
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ueen
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3