The Significance and Sustainability of Charcoal Production in the ...

1991b) were used during the field work for orientation. The digital map mosaic was converted
from WGS-84 to follow the parameters described in Table 1 in ERDAS IMAGINE.
Soil data comprises of two sources: KSS and ISRIC compiled 1:1M geo-referenced Soil and
Terrain Database for Kenya (kenSOTER) (ISRIC 2010); and IPCC Default Soil Classes
derived from the Harmonized World Soil Data Base (HWDB) (Ver 1.1) from Carbon Benefit
Project and ISRIC (Batjes 2010). KenSOTER is compiled in 1995 in accordance with the
SOTER methodology, for national and local agricultural planning purposes (ITC 2010; ISRIC
2010). It comprises of soil geographical and attribute data; the previous contains data of
location, extent and topology of each SOTER unit while the latter holds information on the
characteristics of spatial unit and includes information on both area data and point data
(Batjes & Gicheru 2004: 5). Data regarding the clay content in soils was derived from IPCC
soil classification scheme that is derived from the HWSD. The IPCC clustering scheme
generalize the over 60 soil units defined by HWSD (derived from FAO) into seven broad
classes that define the soil suitability for agriculture: high activity (HAC), low activity (LAC),
sandy (SAN), spodic (POD), volcanic (VOL), wetlands (WET) and organic (ORC) (Batjes
2010: 2). The parameter convertion from WGS-84 to parameter described in Table 1 was
conducted to the kenSOTER file that was Spatially Adjusted with affine transformation
method in ArcMap to gain the right coordinate system, Arc1960 37S. KenSOTER
geographical database class NEWSUID was linked with NEWSUID class from attribute data
soilparameters.dbf file. Mu_Global class from GBC_globalIPCCsoilclasses.mdb (inner
CBP_IPCCsolclas file from Batjes 2010) was joined with adjusted kenSOTER file in order to
be able to visualize the IPCC clay activity data. KenSOTER is the data source for HWSD,
consequently the soil mapping unit boarders coincide even if the HWSD-IPCC data is in
raster and kenSOTER data in vector form.
Shapefiles of existing road network of easily accessible roads were done based on the scanned
topographic maps, satellite image and field observations. Water bodies, important towns in
the area, five important eco-tourism sites among others were digitalized on shapefiles, too.
Tree DBH, that is outside bark diameter at breast height, was used to measure the maturity of
trees in the randomly chosen 17 test plots of 30x30 meters each. Breast height is defined as
4.5 feet (1.37 meters) above the forest floor on the uphill side of the tree (FORESTRY 2011).
Bila and Lindgren (1998: 122) define a mature Brachystegia spiciformis to be of 0.4 to 0.6
meters on DBH. However, trees � 0.15 meters in DBH were classified as mature in this study
as this size of trees are commonly used for charcoal production in the area.
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