Agriculture Reference
In-Depth Information
table 4.1
a comparison of the number of concepts and Relationships in cognitive maps
drawn by six communities in Kiambu district, Kenya, depicting community
Perceptions of factors Influencing agroecosystem Health and sustainability
number of concepts
number of arcs
% with
negative effect
Village
total
Problems
outputs
states
Institutions
total
Githima
34
8
4
15
7
63
63.5
Gitangu
31
11
4
15
1
59
64.4
Kiawamagira
37
10
4
16
7
66
69.7
Mahindi
38
6
3
28
1
59
71.2
Gikabu
33
10
3
13
7
57
66.7
Thiririka
31
10
3
15
3
48
70.8
The impacts of Githima community's goals, based on a geometric analysis of
their cognitive map of factors influencing agroecosystem health and sustainability, are
shown in Table 4.2. Roads, knowledge, and illiteracy had indeterminate impacts on
most vertices. These result from two imbalanced paths from vertex 6 (agrochemical
use) to vertex 13 (income). All goals had negative impacts on agrochemical use. This
is because it is a negative vertex but with positive impact on farm productivity.
All goals except roads had a negative impact on vertex 30 (school committee),
caused by the positive-impact negative-feedback loop linking it to the negative vertex
28 (ignorance). All goals except artificial insemination (AI) and security had indeter-
minate impacts on vertex 12 (soil erosion and infertility). The indeterminate impacts
of roads, knowledge, and literacy on the soil vertex were due to the path imbalance
between vertices 6 and 13. The indeterminate impacts of health and health care on
the soil vertex resulted from path imbalance between vertices 13 and 12 (the positive
path passes through vertex 16, while the negative one passes through vertex 27).
When arc [6, 9] is negative or absent, the overall positive impacts of commu-
nity goals increase to 154 with only 16 negative impacts. This results mostly from
an increase in the positive impacts of roads and literacy. Removing the arc [8, 6]
increases the overall impact of community goals to 134 while reducing negative
impacts to 8. Setting arc [13, 24] to either negative or zero reduces positive impacts
of community goals to 45 and 73, respectively, while increasing the negative impacts
to 60 and 16, respectively. Similarly, inverting or removing the arc [24, 31] results in
reduced positive impacts (50 and 78, respectively). Inverting the arc increases nega-
tive impacts to 55, but removing the arc reduces negative impacts to 10.
The digraph consists of 25 feedback loops, only 4 of which are negative feed-
back. The longest of all the feedback loops are of length nine. There are two strong
components. The first has two vertices (tea production and tea centers) in a positive-
feedback loop. The other strong component includes all the other vertices except AI
services, dairy production, roads, electricity committee, security, population, ter-
rain, health care, lifestyle, and birth rate.
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