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C Content and C Changes in Soils of the Forestry Sector of Mexico J. Etchevers 1 ; C. Balbontín 1 ; F. Paz 1 ; Ben de Jong 2 ; O. Masera 3 1 Colegio de Postgraduados; 2 ECOSUR; 3 CIECO-UNAM e-mail: [email protected]. Materials and Methods. - PowerPoint PPT Presentation
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Acknowledgements
INEGI, CONAFOR, SEMARNAT, CONABIO, and INE for providing national maps and forest inventory data. Also, we thank CONACYT-SEMARNAT and UNDP for their financial support.
Figure 1. Mexico soil map (INEGI, 2003) and samples places.
Results and Discussion
SOC in vegetation units
C Content and C Changes in Soils of the C Content and C Changes in Soils of the Forestry Sector of MexicoForestry Sector of Mexico
J. EtcheversJ. Etchevers11; C. Balbontín; C. Balbontín11; F. Paz; F. Paz11; ; Ben de JongBen de Jong22; O. Masera; O. Masera33
11 Colegio de Postgraduados; Colegio de Postgraduados; 22 ECOSUR; ECOSUR; 33 CIECO-UNAMCIECO-UNAMe-mail: [email protected]: [email protected]
Soil units Sampling sites
IPCC Unit Soils
SOC *(Mg ha-1)
HAC 91.35LAC 70.36
Sandy 41.64Volcanic 93.70
Wetland (non-Histos) 49.43
Mean 75.45
Balance of SOC in the different soil uses and total emissions
Annual balance between emission-captures of CO2 and annual total emissions
Table 1. SOC for IPCC soil unit
43,334
-35,077
8,257
-40,000
-30,000
-20,000
-10,000
0
10,000
20,000
30,000
40,000
50,000
Emission Capture Net Emissions
SO
C (
Gg
year-
1)
74,317
-250,000
-200,000
-150,000
-100,000
-50,000
0
50,000
100,000
Bro
adle
af F
ore
st –
sec
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atio
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ical
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Hig
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med
ium
Tro
pic
al F
ore
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sec.
veg
.
Lo
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rop
ical
Fo
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Hig
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ium
Tro
pic
al F
ore
st
Nat
ura
l g
rass
lan
d
Nee
dle
leaf
Fo
rest ND
Sh
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s -
sec.
veg
.
Man
gro
ve
Wet
lan
d
Oth
ers
Nee
dle
leaf
Fo
rest
-se
c. v
eg.
Bro
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af F
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dle
leaf
an
d
Bro
adle
af F
ore
st
IAP
F
Gen
eral
To
tal
SO
C f
low
(G
g)
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.180
Man
gro
ve
Hig
h a
nd
med
ium
Tro
pic
al F
ore
st
Hig
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ary
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eco
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ion
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Fo
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IAP
F1
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rop
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Sec
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dar
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atio
n.
SO
C (G
g ha
-1)
Introduction
The highest increases of atmospheric CO2 over the last two centuries in the planet have been attributed mainly to two human activities: the indicriminate use of fossil fuels (5.5 ± 0.5 Pg C yr-1) and the land use change or LULUC (1.6 ± 1.0 Pg C yr-1) (Lal et al., 1998). The C content change quantification in soils due to LULUC allows to make a balance between CO2 captures and net emissions from this source (IPCC, 1996). Recent soil C (SOC) changes between 1993-2002 due to LULUC in the forestry sector (LULUCF) in Mexico's soils are analyzed.
A standardized database (4422 samples of SOC, 0-30cm depth, adjusted bulk density, Figure 1) built from available sources was used. Soil organic carbon (SOC) data were first spatialized on a soil unit map 1: 250,000 (FAO 68, INEGI, series II, Fig. 1), then expressed in terms of IPPC soil units (Table 1), and finally spatialized again on a soil use unit map (Fig. 2). This exercise yielded the SOC per IPPC soil unit and vegetation units. The comparison (1993-2002) of each soil/vegetation surface unit was used as a criterion for SOC change (Table 2).
Figure 2. 1993 and 2002 Land-Cover maps using to determinate the major Land-Cover changes.
2002
Table 2. Land-cover change matrix (in Kha)
KhaMontane Forests
Montane Forests sec
Tropical Forests
Tropical Forests sec
Scrublands Grass & Agriculture
Other land covers
Total 2002
Montane Forests 24,396 1,964 9 669 3 27,040 Montane Forests sec 473 6,524 5 519 3 7,524
Tropical Forests 20,361 1,927 233 1,417 33 23,972 Tropical Forests sec 2,048 8,570 37 1,550 22 12,227
Scrublands 6 18 353 50 51,822 879 54 53,183 Grass & Agriculture 354 362 605 662 210 60,419 224 62,836
Other land covers 1 1 16 12 28 223 7,593 7,874
Total 1993 25,230 8,868 23,384 11,222 52,345 65,676 7,931 194,656
1993
* 0 to 30 cm
Low activity clay (LAC) showed lower SOC values (70.4 Mg ha-1) than High Activity Clay soils (HAC) and Volcanic (91.3 and 93.7 Mg ha-1, respectively) but higher than Sandy and Wetlands (49.4 and 41.6 Mg ha-1). Soil unit and climate conditions determine SOC accumulations. Mangroves and temperate and tropical forests accumulated the highest SOC quantities (80 a 160 Mg ha-1), while the low tropical forest on LAC accumulated the lowest (less than 70 Mg ha-1). In Mexico soil C emissions and capture due to LULUCF in the period 1993-2000 were 74,317 and 35,077 Gg C respectively, i.e. a net emission of 8,257 Gg C per year or 30, 277 Gg of CO2 equivalent.
Conclusions
The Mexican forest soils are net emitters of CO2 (8,257 Gg de C or 30,277 Gg of CO2 per year).
Materials and Methods
