Design and Implementation of an Adaptive, Integrated Approach to Health and Sustainability in a Smallholder-Dominated Agroecosystem - Integrated Assessment of Health and Sustainability of Agroecosystems - page 36

2.3.1 h of l A r C h i C A l s C A l e s
The biophysical holarchy is best described in terms of five layers (Figure 2.4).
The innermost or smallest layer—the field—was defined mostly by management
characteristics. The layer after the field was the farm. Farms were defined mostly
by land-use characteristics and were perceived as nested within catchments (a term
commonly used by soil conservation officers in the district). The latter were defined
mostly by topographical (valley, ridge, plain, etc.) characteristics. Catchments cor-
responded, in many instances, to the villages defined in the human activity holarchy.
Catchments were seen as nested within agroecozones as described by Jaetzold and
Schmidt (1983). Agricultural potential, vegetation, and geologic and climatic factors
defined the boundaries of agroecozones. Kiambu is within the central highlands
geoclimatic zone and comprises four major agroecozones (Figure 2.4).
The human activity holarchy was confluent with the administrative zoning of
Kiambu district. The district is divided into six administrative zones called divi-
sions (Limuru, Kikuyu, Lari, Tigoni, Githunguri, and Kiambaa). Each division is
further subdivided into several locations, which are in turn divided into sublocations
(Figure 2.4). The latter is the lowest formal administrative unit. According to the
key informants and administrative officials, each sublocation may consist of one to
four villages with informal boundaries, but consisting of groups of people who work

BIOPHYSICAL SYSTEM HUMAN ACTIVITY SYSTEM

POLICY
AND
MANAGEMENT HOLARCHY BOUNDARIES TYPES HOLARCHY

GOK NATION

-ARID AND SEMI-ARID
-CENTRAL HIGHLANDS
-COASTAL REGION
-LAKE BASIN

PROVINCIAL
ADMIN.

PROVINCE

GEO-CLIMATIC
ZONE

GEOGRAPHIC
AND CLIMATIC
FEATURES

DISTRICT
ADMIN.

DISTRICT

AGROECOZONE

-GEOLOGY
-CLIMATE
-VEGETATION
-AGRIC. POTENTIAL

-FOREST ZONE
-TEA-DAIRY ZONE
-COFFEE-TEA ZONE
-MARGINAL ZONE

DIVISIONAL
OFFICE

DIVISION

CHIEF LOCATION

SUBCHIEF SUBLOCATION

HEADMAN VILLAGE

CATCHMENT

FARM
FIELD

LAND USE
MANAGEMENT

FARMER FARM

fIGuRe 2.4 An illustration of the holarchical structure of the Kiambu agroecosystem from
both the biophysical and the human activity perspectives. GOK, Government of Kenya. See
CD for color image.