The research is about how tropical deforestation had impacted soil function in Kapuas Hulu, West Kalimantan, Indonesia. Deforestation had reduced soil nutrients, infiltration rate and carbon stocks. This study suggests and confirms that logging should be banned from hilly and mountainous landscape in order to sustain soil functions.

1. THINKING beyond the canopy
Soil dynamics in tropical forest transition:
a case study from Borneo, Indonesia
[Imam Basuki and Yves Laumonier]
[July, 22nd 2014 – Cairns, Australia]

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Few studies had been conducted in
SEA on deforestation’s impact on soils.
The research hypothesized that
deforestation and forest degradation
have decreased performance of soil
function such as fertility, water
regulation and sequestration of GHG.
Introduction

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Concept of local LUC

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Methods
 Site selection considered: slope ≥ 40%, slope position (up,
mid, bottom), and distance to primary forests  33 sites.
 Soil samples were collected from 5 LUs, i.e., the primary
forest and the adjacent logged over forests, rice field,
fallow, and rubber garden.
 Lab. analyses on soil physical and chemical properties.

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Research site

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Results

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Status of soil surface characteristics
by land types
-------------------------------- Land type (N) -----------------------------------
Soil
characteristics
Primary Forest
(12)
Logged Forest
(8)
Upland rice
(5)
Fallow
(4)
Rubber
(4)
CEC (me/100g) L - M VL - L L VL VL
Base Saturation
(%) VL VL VL - L L L
P2O5 (ppm) VL - M VL VL VL VL
K2O (ppm) M - VH L - VH M - VH VH M - VH
C (%) L - VH VL - M VL - H VL - H VL - L
N (%) L - M VL - L VL - M VL - M VL - L
C/N M - H M M M L - M
K+ (me/100g) VL - L VL - L VL - M L - M VL - L
Na+ (me/100g) VL - L VL - L VL - L VL - L VL
Mg2+ (me/100g) VL VL VL - L VL VL
Ca2+ (me/100g) VL VL VL VL VL
Al3+ (me/100g) VL VL VL VL VL

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Stock changes on mean carbon and
exchangeable cations in the soil surface
Land-use Soil
layer
Change in stocks of soil carbon and exchangeable cations (kg/ha)
C N P2O5 Ca2+ Mg2+ K+ Na+ Al3+
Primary forest
(PF)
1 *45422.88 *3370.96 *9.06 *101.51 *44.74 *72.95 *30.94 *668.45
2 *15560.84 *1266.95 *4.26 *121.39 *35.83 *32.45 *26.70 *448.93
Logged over
forest (LF) 1 -18884.48 -1300.42 -2.74 +20.40 -1.20 -14.33 +4.46 -104.84
2 +1606.46 +100.98 +1.11 +31.61 +0.51 +2.79 -0.88 +87.50
Upland rice
(UR)
1 -6000.09 -186.54 -1.70 +66.83 +15.22 +22.75 +9.04 -111.91
2 +898.69 +130.13 -0.11 +63.05 +12.87 +19.91 +5.19 -121.46
Fallow
(FL)
1 -20256.88 -1035.46 -6.02 +27.36 +9.91 +26.11 +6.37 -381.69
2 +6828.16 +760.55 -1.71 +10.20 +9.72 +31.32 -10.43 -265.36
Rubber
(RB)
1 -29969.38 -1910.96 -5.97 +69.57 +12.44 -2.98 -13.99 -405.33
2 +13550.66 +1353.55 -1.96 +79.68 +11.39 +37.34 -6.92 -130.29
(*) : original stock (-) : lost stock; (+) : gained stock

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Soil fertility and water
availability
 Logging activities and forest conversion
to agriculture land decreased soil
fertility in the research area.
 Forest conversion into upland rice,
fallow and rubber garden had increased
the infiltration rate of surface soil and
percentage of macro pores.
 Logging activities had increased soil
bulk density and decreased the soil
macro porosity as well as infiltration
rate.

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Carbon and Nitrogen loss
 Soil organic carbon stock had
decreased from primary to logged
over forests, upland rice, fallow and
rubber garden by -18.8 Mg/ha (-
42%), -6.0 Mg/ha (-13%), -20.3
Mg/ha (-54%) and -30.0 Mg/ha (-
66%) respectively.
 Soil nitrogen had also decreased by
-1.3 Mg/ha (-39%) in LF, -0.2 Mg/ha
(-6%) in UR, -1.0 Mg/ha (-31%) in FL
and -1.9 Mg/ha (-57%) in RB.

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Deforestation deplete soil-Al3+
Al3+(cmol/kg)
a. Clay (%) b. P2O5 (ppm)

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Conclusion
 Logging activities and forest conversion
to agriculture-land decrease soil fertility
in the research area.
 Moreover, those activities can increase
runoff, soil erosion and further released
the carbon and nitrogen stocks from
soils.
 Logging should be totally banned on the
steep slopes and soil conservation
techniques are needed to sustain a
more productive and responsible
agriculture.

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Acknowledgement
 Authors would like to express gratitude to research partners
particularly Riak Bumi foundation that provided logistical and
technical supports during the research.
 We appreciate all the helps and trusts from local people in
Keluin longhouse and local government in Kapuas Hulu
District, West Kalimantan, Indonesia.
 We also express sincere thanks to the Europian Union for
funding this research, and to CIFOR CRP-6 Component 3 for
financial supports.

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www.cifor.cgiar.orgThank you!