THE EFFECT OF FIRE ON DRY DIPTEROCARP FOREST SOIL...

Karma DorjiKarma DorjiSchool of Biology, Institute of Science,

Suranaree University of Technology

THE EFFECT OF FIRE ON DRY DIPTEROCARP FOREST SOIL

SPIRATION AT SAKAERAT ENVIRONMENTAL RESEARCH

STATION, NAKHON RATCHASIMA

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� Soils are the largest carbon pool in terrestrial ecosystems and

soil respiration is the major pathway of carbon transfer from

soil to atmosphere

� Soil respiration releases about 11 times more CO2 than

current fossil fuel combustion (Peng et al., 2009)

Soil respirationSoil respiration

Root respirationRoot respiration

Microbial decomposition

(litter soil organic matter)

Microbial decomposition

(litter soil organic matter)

Fauna respirationFauna respiration

Temp. in

degree F

CO2

in parts

per

million

C0

2(p

pm

)te

mp

erat

ure

ch

ang

ed (

F)

(Manchester Knowledge Capital, 2009)

Carbon dioxide and global temperature since 1880

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What is the role

of forest fire on

DDF soil

respiration?

(Photography.nationalgeographic.com/photography)

Materials and method

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Sakaerat Environmental Research Station

(Sakaerat Environmental Research Station 2009) 6

SERS（79.6km2）

Longitude 101°50‘～102°00’

Latitude 14°25‘～14°35’

・The hillside around Korat Plateau

・Dominant Vetetation

Dry Evergreen Forest(DEF)

Dry Dipterocarp Forest(DDF)

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Forest types at SERS

DDF

Area (km²) %

Dry evergreen forest 46.82 59.96

Dry dipterocarp forest 14.51 18.58

Forest plantation 14.46 18.52

Grassland 0.93 1.19

Bamboo 1.12 1.43

Buildinng 0.25 0.32

78.08 100

(Sakaerat Environmental Research Station 2009)

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Fired area Fire protected area

Study sites (DDF, SERS)

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StudyStudy

Feild studyFeild study Laboratory incubation experimentsLaboratory incubation experiments

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�Field Soil Respiration measurement:

Line transect 100 m (at 10m interval)

EGM-4 (PP-systems)

�Soil moisture (Delta Probe type ML2x

(Delta-T Devices)

�Soil temperature (CT-430WP)

Field study

10m

100m

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1. 3 soil samples from 40m line transect (20 m apart)

2. Sieve through 2mm mesh

3. Incubation treatments:

� Temperature: 25 and 30°C

� Water : 75% WHC

4. Soil analysis (C, N, pH)

Incubation experiment

40m

20m

Soils sampling

Incubation procedures

SR measured using LI-820 CO2 Gas

Analyzer on day 1, 2, 3, 6, 9, 12.

SR measured using LI-820 CO2 Gas

Analyzer on day 1, 2, 3, 6, 9, 12.

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� Conical flasks (500ml)

� 50 g Soil samples

� Parafilm sheet

� Incubation chamberTemperature: 25, 30°C

Laboratory equipment set-up

LI-820 CO2 analyzer

�Water content:

75% WHC

Data analysis

� Pearson’s correlation coefficient: relationship between

the soil respirations and environmental factors.

� Statistical analysis :using SPSS 16.0 for windows

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� t-test: compare soil respiration between fired and no fire

soils of a DDF.

� ANOVA : compare soil respiration among temperature

different treatments

Results and Discussion

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Field results

Fired Fire protected p-value

Respiration rate

(µmol CO₂m¯² s¯²) 1.39 2.3 0.013

Water content (%) 0.9 1.92 0.000

Organic C (%) 2.43 1.83 0.005

Total N (%) 0.19 0.15 0.000

pH 5.2 5.3 0.742

soil temperature (°C) 28.4 27.8 0.100

Soil respiration rates and soil factors of fired and fire-protected areas at DDF

The last column shows the significance value of t-test

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Field results

The soil water content of soils were positively correlated with

soil respiration rates at p<0.01

The soil water content of soils were positively correlated with

soil respiration rates at p<0.01

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Mean soil respiration rates of fired and fire-protected

areas with response to different treatments (n=18)

ab

c

b

The letters a, b and c shows the results of post hoc Duncan tests

Laboratory incubation results

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Ecosystem Fire No fire p-value

Organic C (%) 2.291 2.142 0.000

Total N (%) 0.187 0.174 0.035

Table The mean values of soil respiration rates and other

controlling factors of fired and fire-protected soils (n=3)

The last column shows the significant value of t-test

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The mean soil respiration rates of two ecosystems at different

incubation days (N=3).

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� Field SR of fire protected soil was significantly higher than fired

areas with 2.299 and 1.792 µmol CO2 m-2 s-1 (significant higher

soil water content)

� On incubation (25°Cand 30°C and water content of 75% WHC)

fired area soils had significantly higher SR than non-fire soils

(p<0.05)

� Significantly higher soil organic carbon in fired soils might have

accelerated the SR

� Results suggest that forest fire in DDF could enhance SR if there

is a rainfall after the fire

Conclusion

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Recommendation

More detail study needed: The effect of fire on soil respiration

� SR measurements: before and after the fire.

� fire and non-fire site should be close to each

other.

�To fully understand the carbon (C) cycle impacts of forest

fires,

both C emissions during the fire and post-disturbance fluxes

need to be considered

THANK YOU FOR

YOUR

KIND ATTENTION

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