Background
LCCS-based land cover
databases contain information that can be used to derive indices
representing spatial relations within different land cover/land use
types.
The Field Area Ratio is derived from the ratio between:
areas classified "with dominance of Large-Medium sized fields (> 2 ha)"
areas classified "with dominance of Small sized fields (< 2 ha)".
and represents a value of areas characterized from lower probability of
mechanization to areas with higher probability of mechanization.
The Advanced Database Gateway (ADG)
software was used to calculate the index distribution. The output files in
raster or vector form can be downloaded and imported in any GIS system.
Otherwise a map layout can be downloaded and printed in a4 format.
Methodology
The agricultural codes were re-classified based on the field size
attributes. An ADG legend was created separating polygons characterized
by the agricultural classifier B1 (Large-Medium sized fields) from B2
(Small sized fields). The classifier were selected in the LCCS Group 1
(Cultivated Terrestrial Areas) and Group 3 (Cultivated aquatic or Regularly
Flooded areas)
For each cell, Large-medium (LM) and Small (S) classified polygons were
summarized and used to extract the ratio. Only single and mixed units (see section
in the LCCS manual for more)
were included. Area factors were adopted to differentiate the area
calculation in single and mixed units:
| polygon type | factor |
| Single code: | 1.0 | - | - |
| Mixed 1st code: | - | 0.6 | 0.5 |
| Mixed 2nd code: | - | 0.4 | 0.3 |
| Mixed 3rd code: | - | - | 0.2 |
The output file shows a continuum of values: lower values indicate
dominance of S sized fields and/or absence of LM fields, higher values
shows a dominance of LM fields. These areas are considered as having
a higher probability of mechanization.
The mapping of this data set was conducted applying a graduated values
classification with 10 classes (see legend below). Only cells where the agricultural
cover was more than 10% were included in the calculation of the index.
| % ON AGRICULTURAL AREA | Mechanization Index | |
| RANGE VALUES LM FIELDS |
RANGE VALUES S FIELDS |
INDEX RANGE |
CLASS DESCRIPTION |
CLASS |
| 0.1-19 | 81-99.9 | >0-0.25 | MAINLY SMALL FIELDS | 1 |
| 19-33 | 67-81 | 0.25-0.5 | DOMINANT SMALL FIELDS WITH PRESENCE OF LARGE-MEDIUM FIELDS | 2 |
| 33-43 | 57-67 | 0.5-0.75 | PREVALENT SMALL FIELDS WITH SUBSTANTIAL PRESENCE OF LARGE-MEDIUM FIELDS | 3 |
| 43-47 | 53-57 | 0.75-0.9 | PRINCIPAL SMALL FIELDS | 4 |
| 47-53 | 47-53 | 0.9-1.1 | SMALL/LARGE FIELDS ALMOST EQUAL | 5 |
| 53-67 | 33-47 | 1.1-2 | PRINCIPAL LARGE-MEDIUM FIELDS | 6 |
| 67-81 | 19-33 | 2-4 | PREVALENT LARGE-MEDIUM FIELDS WITH SUBSTANTIAL PRESENCE OF SMALL FIELDS | 7 |
| 81-86 | 14-19 | 4-6 | DOMINANT LARGE-MEDIUM FIELDS WITH PRESENCE OF SMALL FIELDS | 8 |
| 86-99.9 | 0.1-14 | >6 | MAINLY LARGE-MEDIUM FIELDS | 9 |
| NO DATA: AGRICULTURAL AREA BELOW THE THRESHOLD OF 10% OF CELL AREA | 0 |
The percentages on the first three columns are related to the agricultural
areas in a single cell.
Taking that the sum of LM and S areas within the cell is 100%, the first
two columns show the relative percentage of large/medium fields respect
to small fields. The third column is the ratio of the first two. Note that
all cells with agricultural areas less than 10% of the entire cell have been
excluded from the calculation of the index.
However, the attributes table of the digital data set (MI_presenc and
MI_pres_LG columns) contains the % of area covered by agricultural
fields within the cell in 10 value ranges (0-10%, 10-20% up to 90-100%).
With these data, the user can subset the MI data and work with different
area threshold.
Data
First example of calculation of this index is the 10 countries of the
Africover land
cover mapping initiative.
Land cover data were analysed at 3 levels:
- Regional level: the ratio was run over the whole 10 countries;
a 2 km cell size was adopted.
- National level: run on a 1 km cell size.
- Sub-National level: 0.5 km cell size. For each country, the
first Administrative level was used.
National and sub-national data can be displayed by clicking on the map
or selecting the links below.
| id | extent | map (JPG) | dataset (SHP) |
|---|
|
| 0. | REGION |
show |
download [ 7.54 MB] |
| 1. | Burundi |
show |
download [ 0.61 MB] |
| 2. | DR of Congo |
show |
download [19.93 MB] |
| 3. | Egypt |
show |
download [ 1.55 MB] |
| 4. | Eritrea |
show |
download [ 1.22 MB] |
| 5. | Kenya |
show |
download [ 3.96 MB] |
| 6. | Rwanda |
show |
download [ 0.69 MB] |
| 7. | Somalia |
show |
download [ 4.48 MB] |
| 8. | Sudan |
show |
download [11.06 MB] |
| 9. | United Republic of Tanzania |
show |
download [13.00 MB] |
| 10. | Uganda |
show |
download [ 4.29 MB] |
