A presentation by Dr. Anne Akol: A study of soil biota of the Mabira forest ecosystem, Uganda

1. 5/27/2010
Anthropogenic disturbance in the
Mabira forest ecosystem
Relating BGBD to soil quality
along an agricultural land use Deforestation (for wood, settlement and farming)
Consequently, several land use types exist in the area
gradient
A study of soil biota of the Mabira forest ecosystem, Uganda Fires (grassland areas & sugarcane fields)
Presented at the global closing conference of the CSM-BGBD Project
CSM-
May 18th, 2010; Nairobi
Application of agrochemicals (sugarcane
A. M. Akol, B.E. Isabirye, C. Nkwiine, S.A. Okurut, M.S. fields)
Rwakaikara, M.J.N. Okwakol
Land use types and agricultural
intensification
nsification
o Forest
How do soil biota respond to
o Fallows
habitat disturbance?
Increasing inten
o Grassland
o Mixed cropping
o Tea
o Sugarcane
Ants Ants
Land use types Land use types
18
800
16 F5,90 = 5.623; P<0.001
2 700
R = 0.238 Kobs = 18.366; df=5; P<0.01
14
600
12
a 500
richn ess
undance
10 ab
8 bc 400
abu
6 c c bc 300
c
4 200 bc
2 abc
100 a a
ab
0
Forest Fallow Grassland MCS Sugarcane Tea 0
Forest Fallow Grassland MCS Sugarcane Tea
Reduced abundance of ants with conversion from forest
Conversion from forest to other land use to other land use forms
forms results in reduced richness of ants
1

2. 5/27/2010
Variation in earthworm density across land use types
Response of termites to land use conversions
a
300
30.00
250 a a 25.00
P<0.05
B ms ( m )
2
200 20.00
i asg -
mean#/m2
150 15.00
o
100 ab 10.00
b b
50 5.00
0 0.00
Forest Fallow Mixed Tea Grassland Sugarcane
Forest Fallow Tea MCS Grassland Sugarcane LUTs
land-use type
2000.0
Variation in earthworm biomass across land-use type
bna c ( ds q )
A a d n ein v / s m
1500.0
140 a
1000.0
120 a P<0.05
ab
100
500.0
2
gm/m
80
60 0.0
40 abc
e
d
d
bc
w
st
ea
an
e
n
e
lo
c
la
ix
T
20
or
rc
M
al
ss
-500.0
F
F
a
ra
ug
0
G
S
Forest Fallow Tea MCS Grassland Sugarcane LUT
land-use type
Ants Ants
Land use intensification Land use intensification
18 800
16 F2,93 = 11.447; P<0.001 700 Kobs = 11.173; df=2; P<0.01
2
14 R = 0.198
600
12
a 500
rich n ess
10
abundance
e
e
400
8
b b 300
6 b
200
4
a
100
2 a
0 0
high low medium high low medium
Increasing intensification results in reduced
Reduced richness of ant genera with intensification numerical strength
Earthworm abundance declines with intensification
Abundance of E/worms y = -9.2092x + 220.74
P< 0.007
Assessing soil quality
1200
1000
A bundance
800
Is belowground biodiversity relevant?
600
400
200
0
0 5 10 15 20
LUI
2

3. 5/27/2010
Separation of LUTs by BGBD sub-indicator Separation of LUTs by AGBD sub-indicator
1 1.2
a a
0.9 a
a
1
0.8 a
0.7 b
0.8 b
0.6 b b c
b
BGBD
AGBD
0.5 0.6
bc
0.4
0.4
0.3
0.2
0.2
0.1
0
Grassland MCS
Fallow Forest MCS Sugarcane Tea 0
Fallow Forest Grassland Sugarcane Tea
1 a
How does soil
0.9
0.8
quality in the 0.7 b
bc
LUTs compare by 0.6 bc
G ISQ
cd d
sub-indicator?
0.5
0.4
An intensification value computed for @ of the 96 points. 0.3
Values used to derive 5 sub-indicators of soil quality: 0.2
AGBD, BGBD, Organic, Chemical, Physical
0.1
Grassland Tea
0 MCS Sugarcane
Fallow Forest
y = 0.0002x + 0.5338
Physical VS LUI
R2 = 3E-05 y = -0.0094x + 0.6148
BGBD Vs LUI
Which sub-indicators are
P < 0.961 R2 = 0.1137
1.2
P < 0.001
1 sensitive to intensification? 1.2
0.8 1
P hy s ic a l
0.8
B GB D
0.6
0.6 y = -0.0308x + 0.7945
0.4 GISQ Vs LUI
0.4 R2 = 0.6254
0.2 0.2 P<0.0001
y = -0.0098x + 0.4997 1.2
0 Organic Vs LUI 2
0
R = 0.092
0 5 10 15 20 0 5 10 15 20 1
P < 0.003
LUI 1 LUI 0.8
G IS Q
0.8 0.6
O rg a n ic
0.6 0.4
0.4 0.2
y = -0.0351x + 0.9343
AGBD Vs LUI
0.2
2
R = 0.6675 0
P < 0.0001 0 5 10 15 20
y = 0.0009x + 0.2357 0 1.2
Chemical Vs LUI LUI
R2 = 0.0018 0 5 10 15 20 1
P < 0.684 0.8
1.2 LUI
A GB D
1 0.6
C h e m ic a l
0.8
0.6
0.4
Increasing
Organic parameters (soil intensification
0.2
0.4
0
0.2
0
carbon/organic matter) 0 5 10 15 20 associated with decline
0 5 10 15 20 correlated with LUI LUI in soil quality defined by
LUI AGBD, BGBD, GISQ
1.2 1 1 1.2
F C B R2 = 0.58, P<0.0001 A
R2 = 0.04, P>0.05 R2 = 0.18, P<0.0001
0.9 0.9
R2 = 0.003, P>0.05
1 1 a
0.8
0.8
AGBD Sub-Indicator
a
Chemical Sub-Indicator
BGBD Sub-Indicator
Physical Sub-Indicator
0.7
0.7 0.8
0.8 ab b
0.6 b
0.6 bc
0.6
0.5 c
0.6 0.5 c
0.4
0.4
0.4
0.3
0.4
0.3 0.2
0.2
0.2 0.1
0.2 Multiple Past Tree
Multiple Past Tree 0
Grazing Monoculture Cropping Cutting
0.1 0
Grazing Monoculture Cropping Cutting
Multiple Past Tree Monocultur Multiple Past Tree
0 0
Grazing Monoculture Cropping Cutting Grazing e Cropping Cutting
1
0.9 E
D
R2 = 0.18, P<0.0001
0.9 R2 = 0.58, P<0.0001 a Which sub-indicator
Which sub- Organic sub-
0.8
can discriminate
0.8
indicator can
0.7
ab a
indicator
Organic SubIndicator
broad categories of
0.7
discriminate
0.6
was able to 0.6
b
separate the
bc b
disturbance?
GIEQ
0.5
broad 0.5 c
0.4
land use
categories of
b 0.4
0.3
forms based
disturbance?
0.3
0.2
on 0.2
0.1
Multiple Past Tree
disturbance 0.1
0
Grazing MonocultureCropping Cutting Multiple Past Tree
0
Grazing MonocultureCropping Cutting
3

4. 5/27/2010
Key conclusions Acknowledgements
Above-
Above- and Below-ground biodiversity are
Below- GEF-
GEF-UNEP, TSBF-CIAT
TSBF-
sensitive to disturbance
Fellow colleagues
Combining these parameters with physical
and chemical parameters g
p gives a more Mabira forest authorities &
robust indicator of soil quality communities
iti
Restricting assessments of soil quality to
chemical or physical parameters may not
give a true picture of the impacts of
disturbance on ecosystems
4