Soil Properties And Carbon Stocks
“Best bet” Land-use Systems
Thematic reports
Impact of different land uses on biodiversity
An Intensive Biodiversity Baseline Study in Jambi Province,Central Sumatra, Indonesia
Unique id: 10
Source file: D:\Projects\ASB\ASB Country and Thematic reports\Above ground biodiversity assessmet WG\C-Sec-10.xml
Authors: Kurniatun Hairiah, Meine van Noordwijk
--------------------------------------------------------------------------
10.1. Introduction:
The integrated biodiversity survey compared a
range of land-use practices in the Bungo-Tebo district in the lowland peneplain
of Jambi. The landscape consists of an undulating plain, formed as marine
sediment in the tertiary period (Van Noordwijk et al., 1995, 1997b). Most of the land in the interfluves is
covered by highly leached oxisols/ultisols, with more recent sediment and
generally higher fertility near the rivers where inceptisols and entisols
dominate. The survey was intended to highlight the effects of land use on
biodiversity, so variation in soil types would be minimized in the selection of
sample points. As older human settlements, and hence an important land use type
in the form of extensive rubber agroforest, are usually found close to the
streams and rivers, not all sampling points could be located in the
oxisol/ultisol complex.
Data on conservative soil properties such as texture, pH and exchangeable cations were collected to check the extent to which all variation in biodiversity can be attributed to land use and management, rather than to a priori differences in soil and vegetation. Soil organic matter content and bulk density are likely to be influenced by land use, and may themselves become factors influencing development of vegetation and ecosystem function. The above-ground biodiversity sampling protocol (Gillison et al., this volume) includes an estimate of woody plant basal area. For the full characterization of terrestrial carbon stocks the ASB project has developed a protocol quantifying biomass in trees, understorey vegetation, surface litter and dead wood, and soil carbon in the top 30 cm of the profile. Data were collected with this protocol to help calibrate the simpler assessment of woody plant basal area.
Decline of soil organic carbon content of (former) forest soils after
forest conversion is a major concern, both for the on-site fertility of such
soils and for estimating the impacts of land-use change on the global C balance
in the context of climate change. Effects of land-use change on soil organic
carbon (Corg), may be difficult to quantify from limited datasets,
as generally no historical data are available of Corg before forest
conversion, and one normally has to rely on 'paired' datasets of sites still
under forest and those now under other land uses. Even moderate differences in
soil texture and/or pH, however, can lead to changes in Corg of
similar magnitude as those of the land use change. Van Noordwijk et al. (1999) proposed to use a ratio of
the measured Corg and a reference Corg value for forest
(top) soils of the same texture and pH as a 'sustainability indicator'. A
substantial dataset of soils on Sumatra (
10.2. Methods:
Methods for quantifying carbon stocks were used as specified in the ASB protocol (Palm et al., 1994). For the vegetation and soil macrofauna, the sampling area was based on the 40 x 5 m2 transect, as before. All tree diameters above 5 cm in the forest plots were measured by the BIOTROP team and data were converted into aboveground biomass with an allometric equation modified from Brown (1997) on the basis of additional data collected in the Jambi area (Ketterings et al., in prep.):
Y (kg tree-1) = 0.092 Diam 2.60
where tree diameter (Diam) is measured in cm.
Understorey and herbaceous layer vegetation was measured in eight 0.25 m2 quadrat samples (or four 1-m2 samples for non-forest plots); total fresh weight was measured, and subsamples were collected for determining dry matter content. Diameter and length of dead wood (> 5 cm diameter) were measured within the 40 x 5 m2 transect and converted to volume on the basis of a cylindrical form; three apparent density classes were used and ring samples were taken to assess the dry weight bulk density (g cm-3) of the partly decayed wood . Surface litter (including wood < 5 cm diameter) was collected down to the surface of the mineral soil in eight 0.25 m2 samples. To remove mineral soil particles, the litter samples were washed and sundried; subsamples were taken for dry matter content.
Soil bulk density was measured for the 0-5 cm top soil layer (8 replicates per sampling point) by carefully inserting a 165 cm3 ring from the mineral soil surface, just below the litter layer.
Soil samples were collected (composited from 8 sample
points per 200 m2 sampling area) for the 0-5, 5-10, 10-20, 20-30 cm
depth zone below the litter layer, passed through a 2 mm sieve and air-dried
for analysis of texture (sand, silt, clay), pH (1N KCl), pH(H2O), P BrayII,
Corg (Walkey and Black), Ntot (Kjeldahl), exchangeable K,
Ca, Mg, Na, Al and H, and effective cation exchange capacity (ECEC) by
summation. All these routine soil measurements were done on air-dried, sieved
soil in the soils laboratory of
10.3.
Field notes on sampling points:
Primary forest (BS 1,2) - two samples behind the permanent forest plots of BIOTROP but in the 25 ha reserve; the plots are on two sides of a small stream. Logged-over forest (BS 3,4,5) - three samples: no. 3 close to the second primary forest plot, on a ridge with logging track overgrown by ferns, secondary forest regrowth and patches of undisturbed forest; no. 4 and 5 in the logged-over forest (1983) where BIOTROP has permanent plots; no. 4 includes a recent tree fall, no. 5 appears to be little affected by the logging. Industrial timber plantation(HTI) (BS 6,7)- 5-year old Paraserianthes falcataria plantation; no. 6 close to the road and forest edge, no. 7 in the centre of the HTI area; (the Paraserianthes still seemed to be affected by a moth). Rubber plantation (BS 8,9) - 8-year old intensively managed rubber established by slash-and-burn from logged-over forest, along the main logging road in Pasir Mayang; both plots are part of a 18 ha farm established by a former employee of PT IFA, and currently partly operated by share-tappers; the plantation was established from seedlings obtained from the plantation project across the river (GT1 ?) and was managed in plantation-style (but without legume cover crops). Jungle rubber (BS 10,11) - a 45 (?) year old rubber agroforest in Dusun Tuo (across the Batang Hari river from Pasir Mayang), in a landscape with a lot of newly planted rubber (mostly seedlings). Imperata grassland (BS 12,13) - in Kuamang Kuning, close to the Imperata plots sampled in 1996. Cassava (BS 14,15) - in Kuamang Kuning, close to Imperata plots; part of the fields was opened by tractor, apparently for planting oil palm. Chromolaena fallow (BS 16) - in Dusun Tuo, close to the jungle rubber (10 and 11); a 3 (?) year old fallow, about to be re-opened for planting rice.
10.4. Results and Discussion:
Soil characteristics are summarized in Table
10.1. Soil texture data show that the sampling points belong to essentially
three groups:
soils with less than 20% clay in the top 5 cm (sampling points BS 1, 2 ,4, 5 and 6),
soils with 20-40% clay in the top 5 cm (BS 3, 7, 10, 11, 12, 13, 14, 15 & 16),
soils with more than 40% clay in the top 5 cm (sampling points BS 8 and 9).
These differences are probably a priori and not caused by current land use. The location of the rubber plantation (8&9) on a soil of higher clay content is probably typical for the position of rubber in the landscape. Comparisons between sites in different classes have to take these soil differences into account.
All sites were acid, with the highest pH (H2O) values found in the Imperata and Cassava sites around the transmigration village, possibly indicative of past lime applications (note that pH(KCl) values show less variation) and the Chromolaena fallow plot.
Soil organic carbon (Corg)
and total N (Ntot) showed a strong decrease with depth, justifying
the separation of the 0-5 and 5-10 cm depth layer. Available soil phosphorus
levels were very low in sample 8, and relatively high in 10 and 11. The
effective cation exchange capacity was low (< 12 cmole kg-1)
in all soils. Al saturation was high in all soils, but lowest in sites 12 and
13. Overall, a weak buyt statistically significant relationship was found
between Al-saturation and pH(H20):
Al-sat = 104.0 – 12.5 * pH(H2O) [n
= 63, r2 = 0.23, P < 0.001]
Al-sat = 99.2 – 14.8 * pH(KCl [n
= 63, r2 = 0.05, P = 0.045]
Bulk density measurements (Table 10.2) showed substantial differences between the plots; tracks in the logged over forest, the young industrial timber plantation and the Cassava and Imperata plots had a bulk density substantially higher than that of natural forest; the logged over forests outside the skidding track had a high coefficient of variation in bulk density, indicating patch-wise soil compaction
The differences between Corg of the topsoil between the sampling points probably reflect differences in soil texture as well as land use. When the Corg/Cref ratio is compared, the data appear to reflect land use effects more clearly (compare Figure 10.1A and 10.1C). The size/density fractionation data (Figure 10.1C) failed to differentiate clearly between the land uses.
Table 10.1.Measured soil parameters
|
No. |
LUT |
Depth |
Texture |
pH_H2O |
pH_KCl |
C_org |
N_tot |
C/N ratio |
P_brayII |
Exchangeable cations |
ECEC |
Al_sat |
|||||||
|
Sand |
Silt |
Clay |
K |
Na |
Ca |
Mg |
Al |
H |
|||||||||||
|
|
|
cm |
% |
|
|
% |
% |
|
mg kg-1 |
cmole kg-1 |
|
% |
|||||||
|
1 |
NF |
0_5 |
62 |
24 |
14 |
4.0 |
3.5 |
4.01 |
0.28 |
14.3 |
10.2 |
0.16 |
0.34 |
1.65 |
0.41 |
4.19 |
1.16 |
7.91 |
53.0 |
|
1 |
NF |
5_10 |
62 |
20 |
18 |
4.7 |
3.8 |
1.86 |
0.14 |
13.3 |
4.19 |
0.09 |
0.24 |
1.54 |
0.51 |
4.19 |
0.85 |
7.42 |
56.5 |
|
1 |
NF |
10_20 |
62 |
20 |
18 |
4.9 |
3.9 |
1.20 |
0.09 |
13.3 |
2.09 |
0.08 |
0.22 |
1.54 |
0.10 |
3.59 |
0.89 |
6.42 |
55.9 |
|
1 |
NF |
20_30 |
64 |
18 |
18 |
4.9 |
4.0 |
0.80 |
0.06 |
13.3 |
1.69 |
0.06 |
0.22 |
1.03 |
0.07 |
3.53 |
0.83 |
5.74 |
61.5 |
|
2 |
NF |
0_5 |
67 |
22 |
11 |
4.2 |
3.5 |
3.21 |
0.19 |
16.9 |
9.19 |
0.19 |
0.31 |
1.54 |
0.62 |
3.71 |
1.27 |
7.64 |
48.6 |
|
2 |
NF |
5_10 |
69 |
19 |
12 |
4.7 |
3.8 |
2.01 |
0.13 |
15.5 |
6.69 |
0.11 |
0.24 |
1.54 |
0.10 |
3.53 |
0.83 |
6.35 |
55.6 |
|
2 |
NF |
10_20 |
66 |
17 |
17 |
4.8 |
3.7 |
1.61 |
0.12 |
13.4 |
2.69 |
0.11 |
0.23 |
3.61 |
1.03 |
3.17 |
0.93 |
9.08 |
34.9 |
|
2 |
NF |
20_30 |
67 |
17 |
16 |
4.8 |
4.0 |
0.96 |
0.07 |
13.7 |
1.69 |
0.09 |
0.20 |
1.54 |
0.1 |
2.99 |
1.06 |
5.98 |
50.0 |
|
3 |
LOF |
0_5 |
54 |
8 |
38 |
4.5 |
3.7 |
1.85 |
0.13 |
14.2 |
2.69 |
0.12 |
0.25 |
1.55 |
0.51 |
2.93 |
0.8 |
6.16 |
47.6 |
|
3 |
LOF |
5_10 |
81 |
10 |
9 |
5.2 |
3.8 |
1.53 |
0.12 |
12.8 |
5.19 |
0.10 |
0.29 |
2.06 |
0.21 |
2.69 |
0.24 |
5.59 |
48.1 |
|
3 |
LOF |
10_20 |
67 |
13 |
20 |
5.0 |
4.0 |
1.36 |
0.11 |
12.4 |
4.69 |
0.08 |
0.20 |
1.03 |
0.51 |
2.69 |
0.74 |
5.25 |
51.2 |
|
3 |
LOF |
20_30 |
65 |
13 |
22 |
4.8 |
4.0 |
1.20 |
0.08 |
15.0 |
3.16 |
0.06 |
0.18 |
1.02 |
0.51 |
3.02 |
0.99 |
5.78 |
52.2 |
|
4 |
LOF |
0_5 |
81 |
11 |
8 |
4.5 |
3.6 |
4.66 |
0.28 |
16.6 |
18.0 |
0.15 |
0.25 |
1.12 |
1.02 |
4.15 |
1.09 |
7.78 |
53.3 |
|
4 |
LOF |
5_10 |
79 |
10 |
11 |
4.0 |
3.5 |
3.13 |
0.18 |
17.4 |
5.19 |
0.11 |
0.25 |
1.55 |
1.34 |
3.29 |
1.38 |
7.92 |
41.5 |
|
4 |
LOF |
10_20 |
77 |
10 |
13 |
4.6 |
3.7 |
2.09 |
0.12 |
17.4 |
3.69 |
0.09 |
0.25 |
2.57 |
0.41 |
3.29 |
1.38 |
7.99 |
41.2 |
|
4 |
LOF |
20_30 |
74 |
10 |
16 |
4.7 |
3.7 |
1.85 |
0.12 |
15.4 |
2.69 |
0.08 |
0.28 |
2.37 |
0.21 |
3.41 |
0.95 |
7.30 |
46.7 |
|
5 |
LOF |
0_5 |
79 |
13 |
8 |
4.2 |
3.3 |
4.41 |
0.28 |
15.8 |
6.19 |
0.20 |
0.39 |
2.06 |
0.31 |
2.69 |
1.65 |
7.30 |
36.8 |
|
5 |
LOF |
5_10 |
79 |
13 |
8 |
4.5 |
3.8 |
1.91 |
0.12 |
15.9 |
6.13 |
0.10 |
0.28 |
1.12 |
1.22 |
2.97 |
0.97 |
6.66 |
44.6 |
|
5 |
LOF |
10_20 |
76 |
11 |
13 |
4.8 |
3.9 |
1.61 |
0.10 |
16.1 |
4.65 |
0.07 |
0.22 |
1.33 |
0.41 |
2.97 |
0.73 |
5.73 |
51.8 |
|
5 |
LOF |
20_30 |
75 |
15 |
10 |
4.8 |
4.0 |
1.27 |
0.10 |
12.7 |
4.15 |
0.07 |
0.16 |
1.22 |
0.61 |
2.67 |
0.66 |
5.39 |
49.5 |
|
6 |
HTI |
0_5 |
84 |
8 |
8 |
4.4 |
3.9 |
2.78 |
0.17 |
16.4 |
18.5 |
0.18 |
0.38 |
2.04 |
0.61 |
2.61 |
0.47 |
6.29 |
41.5 |
|
6 |
HTI |
5_10 |
82 |
10 |
8 |
4.3 |
3.9 |
2.15 |
0.13 |
16.5 |
9.10 |
0.06 |
0.19 |
1.33 |
1.22 |
2.67 |
0.72 |
6.19 |
43.1 |
|
6 |
HTI |
10_20 |
79 |
8 |
13 |
4.8 |
4.0 |
1.67 |
0.10 |
16.7 |
5.64 |
0.06 |
0.14 |
1.54 |
1.02 |
2.31 |
0.77 |
5.84 |
39.6 |
|
6 |
HTI |
20_30 |
74 |
10 |
16 |
4.8 |
4.1 |
0.50 |
0.05 |
10.0 |
2.66 |
0.04 |
0.13 |
1.22 |
0.31 |
2.55 |
0.60 |
4.85 |
52.6 |
|
Table 10.1.Measured soil parameters |
|||||||||||||||||||
|
No. |
LUT |
Depth |
Texture |
pH_H2O |
pH_KCl |
C_org |
N_tot |
C/N ratio |
P_brayII |
Exchangeable cations |
|
Al sat |
|||||||
|
Sand |
Silt |
Clay |
K |
Na |
Ca |
Mg |
Al |
H |
ECEC |
|
|||||||||
|
|
|
cm |
% |
|
|
% |
% |
|
mg kg-1 |
cmole kg-1 |
% |
||||||||
|
7 |
HTI |
0_5 |
46 |
28 |
26 |
5.2 |
3.8 |
4.21 |
0.28 |
15.0 |
8.78 |
0.41 |
0.62 |
4.68 |
1.56 |
1.33 |
0.87 |
9.47 |
14.0 |
|
7 |
HTI |
5_10 |
45 |
19 |
36 |
5.2 |
3.9 |
2.11 |
0.16 |
13.2 |
1.20 |
0.21 |
0.45 |
4.16 |
1.14 |
1.89 |
0.21 |
8.06 |
23.4 |
|
7 |
HTI |
10_20 |
43 |
22 |
35 |
4.8 |
3.6 |
1.78 |
0.14 |
12.7 |
0.69 |
0.19 |
0.43 |
3.12 |
1.04 |
4.23 |
0.80 |
9.81 |
43.1 |
|
7 |
HTI |
20_30 |
43 |
22 |
35 |
4.8 |
3.6 |
1.62 |
0.11 |
14.7 |
0.19 |
0.12 |
0.38 |
1.87 |
1.25 |
5.14 |
0.90 |
9.66 |
53.2 |
|
8 |
RUB_P |
0_5 |
14 |
27 |
59 |
4.6 |
3.5 |
5.97 |
0.38 |
15.7 |
1.20 |
0.19 |
0.36 |
2.41 |
0.95 |
3.96 |
2.07 |
9.94 |
39.8 |
|
8 |
RUB_P |
5_10 |
14 |
11 |
75 |
4.5 |
3.7 |
2.95 |
0.18 |
16.4 |
0.19 |
0.12 |
0.29 |
2.10 |
0.31 |
2.81 |
1.25 |
6.88 |
40.8 |
|
8 |
RUB_P |
10_20 |
12 |
16 |
72 |
4.9 |
3.7 |
1.96 |
0.13 |
15.1 |
0.19 |
0.12 |
0.33 |
1.68 |
0.41 |
2.81 |
0.86 |
6.21 |
45.2 |
|
8 |
RUB_P |
20_30 |
11 |
13 |
76 |
4.9 |
3.8 |
1.86 |
0.12 |
15.5 |
0.19 |
0.1 |
0.32 |
1.52 |
0.94 |
1.63 |
0.71 |
5.22 |
31.2 |
|
9 |
RUB_P |
0_5 |
15 |
41 |
44 |
4.4 |
3.6 |
3.27 |
0.53 |
6.2 |
10.0 |
0.27 |
0.38 |
1.78 |
0.59 |
5.67 |
1.89 |
9.40 |
60.3 |
|
9 |
RUB_P |
5_10 |
13 |
15 |
72 |
4.8 |
3.7 |
2.41 |
0.31 |
7.8 |
7.50 |
0.13 |
0.36 |
1.62 |
0.42 |
3.23 |
1.21 |
7.65 |
42.2 |
|
9 |
RUB_P |
10_20 |
13 |
18 |
69 |
4.7 |
3.9 |
2.19 |
0.16 |
13.7 |
1.25 |
0.09 |
0.18 |
1.80 |
1.08 |
3.14 |
1.04 |
7.50 |
41.9 |
|
9 |
RUB_P |
20_30 |
12 |
23 |
65 |
4.5 |
3.9 |
2.13 |
0.14 |
15.2 |
0.18 |
0.05 |
0.17 |
1.57 |
0.63 |
3.36 |
1.08 |
6.82 |
49.3 |
|
10 |
J_RUB |
0_5 |
6 |
70 |
24 |
5.2 |
3.8 |
6.23 |
0.46 |
13.5 |
41.5 |
0.51 |
0.69 |
2.37 |
0.76 |
5.31 |
2.63 |
10.7 |
49.5 |
|
10 |
J_RUB |
5_10 |
7 |
58 |
35 |
5.1 |
3.8 |
3.97 |
0.28 |
14.2 |
17.2 |
0.23 |
0.63 |
2.12 |
0.42 |
5.05 |
1.49 |
11.1 |
45.6 |
|
10 |
J_RUB |
10_20 |
5 |
54 |
41 |
5.1 |
3.8 |
2.81 |
0.22 |
12.8 |
10.5 |
0.22 |
0.37 |
1.59 |
0.21 |
4.93 |
1.48 |
8.81 |
56.0 |
|
10 |
J_RUB |
20_30 |
5 |
46 |
49 |
5.1 |
3.8 |
2.13 |
0.19 |
11.2 |
4.78 |
0.13 |
0.31 |
1.26 |
0.31 |
4.88 |
1.15 |
8.37 |
58.3 |
|
11 |
J_RUB |
0_5 |
9 |
52 |
39 |
5.4 |
3.9 |
5.76 |
0.37 |
15.6 |
32.8 |
0.46 |
0.68 |
2.46 |
0.33 |
3.39 |
1.76 |
8.47 |
40.0 |
|
11 |
J_RUB |
5_10 |
9 |
50 |
41 |
5.3 |
3.9 |
3.20 |
0.27 |
11.9 |
10.2 |
0.25 |
0.45 |
1.71 |
0.23 |
3.98 |
1.53 |
8.38 |
47.5 |
|
11 |
J_RUB |
10_20 |
9 |
42 |
49 |
5.2 |
3.8 |
2.44 |
0.23 |
10.6 |
5.44 |
0.25 |
0.42 |
1.84 |
0.32 |
3.77 |
1.26 |
8.13 |
46.4 |
|
11 |
J_RUB |
20_30 |
7 |
33 |
60 |
5.1 |
3.8 |
2.11 |
0.20 |
10.6 |
1.30 |
0.27 |
0.52 |
1.72 |
0.34 |
3.10 |
1.02 |
7.21 |
43.0 |
|
12 |
IMP |
0_5 |
66 |
14 |
20 |
5.8 |
4.1 |
2.19 |
0.13 |
16.8 |
8.27 |
0.20 |
0.36 |
1.56 |
1.04 |
1.21 |
0.05 |
5.39 |
22.4 |
|
12 |
IMP |
5_10 |
67 |
11 |
22 |
5.5 |
4.2 |
2.03 |
0.12 |
16.9 |
6.25 |
0.12 |
0.37 |
1.35 |
0.41 |
1.03 |
0.61 |
3.33 |
30.9 |
|
12 |
IMP |
10_20 |
69 |
9 |
22 |
5.3 |
3.8 |
1.78 |
0.10 |
17.8 |
1.20 |
0.11 |
0.31 |
1.35 |
0.73 |
1.51 |
0.31 |
4.62 |
32.7 |
|
12 |
IMP |
20_30 |
61 |
13 |
26 |
5.2 |
3.9 |
1.22 |
0.09 |
13.6 |
1.20 |
0.05 |
0.22 |
1.56 |
0.52 |
2.00 |
0.39 |
4.66 |
42.9 |
|
13 |
IMP |
0_5 |
66 |
13 |
21 |
5.7 |
4.0 |
2.23 |
0.13 |
17.2 |
4.15 |
0.09 |
0.42 |
1.12 |
0.51 |
1.18 |
0.67 |
3.71 |
31.8 |
|
13 |
IMP |
5_10 |
67 |
5 |
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