1) Land cover (preferably in time series);

(including Reserves and protected areas, Potential vegetation)

2) Climate data (monthly precipitation, monthly max and min air temperatures);

3) Initial soil organic matter content;

4) Soil texture (% sand, % clay,% silt)

5) Drainage/water holding capacity;

GIS Data for Carbon Simulation

1) Crop yield or net primary productivity;

2) Land use (fertilization, cultivation, tree or crop species; Rotation probability; Harvesting practices, Fertilization; Irrigation; Grazing; Organic matter addition, Land fire; Cultivation....); times of inputs and occurrences

1) C:N ratios of plant tissues and SOC pools;

2) Soil erosion and deposition.

GIS or Tabular Data for Carbon Simulation

Objectives

1. Adapt GEMS (general ensemble biogeochemical modeling system) for Africa

2. Quantify carbon dynamics in the Department of Velingara from 1900 to 2100

3. Assess the impacts of land use and climate change on carbon dynamics

4. Discuss carbon management options

Field Measurements of Carbon Stocks

 

Cover Biomass   SOC (0-40 cm)   SOC (0 – 20 cm) Bulk

  Mean Range   Mean Range   Mean Range Den.

Cropland 1.9 09-4.0   29.9 15.0-56.0   19.2 9.6-35.9 1.57

Fallow 29.9 6.2-49.5   22.2 20.2-25.5   14.2 12.9-16.3 1.58

Forest 53.3 19.1-134.0   41.3 25.8-57.4   26.5 16.5-36.7 1.52

Parkland 20.0 19.4-20.5   18.8 17.0-19.8   12.0 10.9-12.7 1.42

Savanna 26.1 14.7-43.1   37.7 29.7-50.1   24.2 19.0-32.1 1.57

 

Data were collected around six villages in five land cover classes.Unit: MgC ha-1

SOC contents in the top 0 – 20 cm layer were estimated from those in the 0 – 40 cm layer according to Jobbagy and Jackson (2000).

Spatially-Explicit Biogeochemical Modeling

The General Ensemble biogeochemical Modeling System (GEMS) is developed to simulate carbon dynamics over large areas. It consists of

Encapsulated ecosystem biogeochemical model(s).

Data assimilation system

Input/output processor

User-friendly GUI

Time

Spatial and Temporal Changes of Land Cover, Carbon Stock in Vegetation and Soils

EcosystemBiogeochemical

Model

Input Files

Data AssimilationSystem

JFD Table

DatabasesJFD Cover

OverlayOperation

OutputFiles

Land Cover

Land Use Info UnitsClimateSoils

GIS Coverages

Structure of ENSEMBLE

land cover Soil

climateLand use

N deposition.......

Spatial and Temporal C Dynamics and Uncertainties

Major Components of GEMS

JFD Grid/Table

Meaning of Each Column

in the JFD Table

Number of Simulations

for Each Cohort, n

Read a Cohort

Copy Default Input Files From Library

Update Default Input Files

Run CENTURY

Write Output

Stop

K = 0

K = k + 1

yes

no

yes

no

End of JFD Table?

K>n?

Diagram of information flow linking the CENTURY model with GIS data to produce estimates of regional emissions in GEMS

jfd_vlg.xtr JFD filevar_order_vlg.xtr variable order in the JFD file/edcsnw64/data/sliu/velingara/edc100files default century 100 filesstatus0.bin file name specifying the starting status of simulations; use NONE if no file2 previous status based on potential vegetation types (=1), or JFD cases (=2)status1.bin file name specifying the ending status of simulations; use NONE if no file0 spinning up run under potential vegetation (=1), otherwise (=0)0 MONTE_CARLO (yes = 1; no=0)5 Number of runs for each unique JFD case2 Land cover choice (1 --- ag census data; 2 --- GIS grid Time Series; 3 --- both) 6 total number of LC datasets9 max number of years that remote sensing can pick up clearcutting activities1900 Init_landcov1973 lc01978 lc11984 lc21990 lc31999 lc4soil.data soil data base soil_dr_vlg.data soil drainage dataprec_tab.txt monthly precipitationMinTemp.txt monthly min temperature maxTemp.txt monthly max temperaturecroprotat.data crop trasition probability generated from NRIn_depo.txt atmospheric deposition data baselc2cent.map land cover codes and default site filecrop_comp.data crop composition datafallow.data fallow infomanager.data data on fire, forest harvest, grazing etc.

Modeling Environment Specifications

lc_Code colInComp Trends_classtype abgc_rank Deflt_site_fCENTTREECENTCROPCrp_Harv fert irri FIRE graz OMAD cult trem133 101 14 0 0 barren.100 CZERO CZERO NONE NONE NONE NONE NONE NONE NONE NONE233 102 15 0 0 barren.100 CZERO CZERO NONE NONE NONE NONE NONE NONE NONE NONE300 100 30 3 1 vlg_fallow.100DDWD TKNZ NONE NONE NONE BSH1 VLG NONE NONE 2603 201 3 3 5 vlg_savwd.100DDWD TKNZ NONE NONE NONE BSH2 VLG NONE NONE 4613 202 4 3 3 vlg_bush.100DDWD TKNZ NONE NONE NONE BSH1 VLG NONE NONE 2623 203 5 3 8 vlg_dsavwd.100DDWD TKNZ NONE NONE NONE BSH2 VLG NONE NONE 4633 204 6 3 7 vlg_dsavwdb.100DDWD TKNZ NONE NONE NONE BSH2 VLG NONE NONE 4643 205 8 3 8 vlg_ddecw.100DDWD TKNZ NONE NONE NONE BSH3 VLG NONE NONE 4653 206 9 3 10 vlg_evergr.100GALA TKNZ NONE NONE NONE BSH4 VLG NONE NONE 2663 207 12 3 10 vlg_evergr.100GALA TKNZ NONE NONE NONE BSH4 VLG NONE NONE 2673 208 13 3 2 vlg_shrsav.100DDWD TKNZ NONE NONE NONE BSH1 VLG NONE NONE 2933 209 10 0 0 barren.100 CZERO CZERO NONE NONE NONE NONE NONE NONE NONE NONE810 1 1 2 0 vlg_ag.100 CZERO MLT VLG_G NONE NONE NONE NONE VLG3 AT NONE820 2 1 2 0 vlg_ag.100 CZERO SRGM VLG_G NONE NONE NONE NONE VLG3 AT NONE830 3 1 2 0 vlg_ag.100 CZERO COT COTG N1 NONE NONE NONE VLG3 AT NONE840 4 1 2 0 vlg_ag.100 CZERO GNUT GN_L NONE NONE NONE NONE VLG3 AT NONE850 5 1 2 0 vlg_ag.100 CZERO MZUN VLG_G NONE NONE NONE NONE VLG3 AT NONE890 6 1 2 0 vlg_ag.100 CZERO RICE RIWS N1 A95 NONE NONE NONE HT NONE810 1 2 2 0 vlg_ag.100 CZERO MLT VLG_G NONE NONE NONE NONE VLG1 AT NONE820 2 2 2 0 vlg_ag.100 CZERO SRGM VLG_G NONE NONE NONE NONE VLG1 AT NONE830 3 2 2 0 vlg_ag.100 CZERO COT COTG N1 NONE NONE NONE VLG1 AT NONE840 4 2 2 0 vlg_ag.100 CZERO GNUT GN_L NONE NONE NONE NONE VLG1 AT NONE850 5 2 2 0 vlg_ag.100 CZERO MZUN VLG_G NONE NONE NONE NONE VLG1 AT NONE

Mapping Land Cover to CENTURY

Default site fileTree or crop speciesRotation probabilityHarvesting practicesFertilizationIrrigationGrazingOrganic matter additionLand fireCultivation

 

 

1973 18.3 2.7 28.9 35.1 9.2 5.8

1978 26.2 8.8 16.1 25.4 12.0 11.4

1984 11.3 17.4 32.0 15.6 16.3 7.3

1990 9.5 21.6 14.7 15.9 27.2 11.1

         

Year MilletSorgh

umCotto

nGround-nuts Maize Rice

1999 7.1 26.7 12.1 29.0 18.2 6.9

Crop Composition (%) and its Temporal Change

 

Two Fallow Scenarios

 

Probability of Land in Fallow

minimum maximum minimum maximumBusiness as usual

Intensive Agriculture 4 8 0 2 0.14Extensive Agriculture 3 6 3 6 0.50Bushland, old fields 0 0 6 15 1.00

Agricultural Intensification ScenationIntensive Agriculture 4 8 0 1 0.08Extensive Agriculture 3 6 1 2 0.25Bushland, old fields 3 6 3 10 0.59

Time in Fallow (Years)Land Cover Time In Crop(years)

Crop Rotation Probability

 

COT FAL GN MA MIL RI SOCOT 0.31 0.08 0.33 0 0.28 0 0FAL 0.16 0.5 0.06 0 0.28 0 0GN 0.34 0.06 0.38 0 0.22 0 0MA 0 0 0 0.52 0 0 0.48MIL 0.26 0.1 0.34 0 0.3 0 0RI 0 0 0 0 0 1 0SO 0 0 0 0.45 0 0 0.55

Land Cover Change

 

 

Dense Savanna Woodland 30 29 26 25 21

Dry Deciduous Woodland 23 21 18 17 16

Dense Savanna Woodland with bowe 15 14 14 14 14

Extensive Ag land with some fallow (1-3 years) 9 11 8 9 13

Bushland, Old Fields 0 0 5 3 13

Intensive Ag land with few fallow (0-1 year) 6 8 14 17 8

Savanna Woodland 8 8 6 6 5

Moist semi-evergreen woodland, gallery forest 4 4 3 3 3

Riparian forest 3 3 3 3 2

    Year    

Land Cover Class 1973 1978 1984 1990 1999

Shrub Savanna 2 2 2 2 2

1 324 7 1 12 13 13 13 13 13 372 57 7 1 12 11 11 11 11 11 373 2442 17 1 12 13 13 13 13 13 374 459 17 1 12 11 11 11 11 11 375 799 17 1 12 5 5 5 5 5 376 1499 17 1 8 5 5 5 5 5 677 7 17 1 12 13 13 13 13 13 678 117 16 1 12 13 13 13 13 13 379 486 17 1 10 10 10 10 10 10 3710 54 17 1 10 10 10 10 10 10 6711 36 16 1 12 13 13 13 13 13 9512 3 16 1 12 5 5 5 5 5 3713 28 16 1 8 5 5 5 5 5 95

Index

Frequency

Climate

Reserve

Land CoversSoil

Joint Frequency Distribution Table

ClimateDatabase

Reserved?

Land Covers Soil Database

Data Assimilation System

1 324 7 1 12 13 13 13 13 13 372 57 7 1 12 11 11 11 11 11 37

ManagementPractices, etc.

Weather fileSite fileSchedule fileEtc.

CENTURY input files

Temporal Change of Spatial Patterns

0

0.05

0.1

0.15

0.2

0.25

0.3

1800 1850 1900 1950 2000 2050 2100

Year

Gra

in Y

ield

(M

gC/h

a/y)

HCCS, more CUT

LCCS, more CUT

NCCS, more CUT

HCCS, less CUT

NCCS, less CUT

LCCS, less CUT

Grain Yield

1. It was assumed that agricultural will not expand in 21st century2. High Climate Change Scenario (HCCS) poses a great threat to food

security

Net Primary Productivity

1. NPP varies between 3 and 4 MgC/ha/y.2. Large inter-annual variability caused by precipitation fluctuation.3. NPP decreases under HCCS (i.e., large climate change)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1800 1850 1900 1950 2000 2050 2100

Year

NP

P (

MgC

/ha/

y) HCCS, more CUT

LCCS, more CUT

NCCS, more CUT

HCCS, less CUT

NCCS, less CUT

LCCS, less CUT

Carbon in Live Biomass

1. C stock in undisturbed dry and moist tropical forest is 88 and 135 MgC/ha, respectively

2. C stock has decreased by 46% from 1900 to 2000 in Velingara3. Woodfuel production has a larger impact than climate change

0

20

40

60

80

100

120

1800 1850 1900 1950 2000 2050 2100

Year

Liv

e B

iom

ass

(MgC

/ha)

HCCS, more CUT

LCCS, more CUT

NCCS, more CUT

HCCS, less CUT

NCCS, less CUT

LCCS, less CUT

0

5

10

15

20

25

30

35

1800 1850 1900 1950 2000 2050 2100

Year

SO

C (

MgC

/ha) HCCS, more CUT

LCCS, more CUT

NCCS, more CUT

HCCS, less CUT

NCCS, less CUT

LCCS, less CUT

Soil Organic Carbon

1. SOC stock in undisturbed dry and moist tropical forest is 29 and 35 MgC/ha, respectively

2. SOC stock has decreased by 9% from 1900 to 2000 in Velingara3. The max difference caused by management and climate change

options is about 5 MgC/ha in 2100

Total C Stock in Vegetation and Soil

1. Total C stock has decreased 37% from 1900 to 20002. Live biomass reduction accounts for 88% of the total C loss3. Selective logging has a significant impact4. Large climate change (HCCS) reduces C stock

0

20

40

60

80

100

120

140

160

1800 1850 1900 1950 2000 2050 2100

Year

Tot

al C

(M

gC/h

a) HCCS, more CUT

LCCS, more CUT

NCCS, more CUT

HCCS, less CUT

NCCS, less CUT

LCCS, less CUT