Spatial analysis of communal grazing resources and their utilisation by sheep in the highlands of Mexico
Abstract
This thesis is concerned with analysing the interactions between smallholder sheep
farming systems and the sustained maintenance of communal grazing resources in
the temperate region of Mexico. The study was carried out in the parish of
Coajomulco, which is located in the mountainous region south of Mexico City.
Sheep production is a traditional agricultural activity in the region and extensive
grazing is practised in the parish's communal forest. In 1988 the area was decreed
as protected by the Ministry of Environment, and agricultural practices were highly
regulated. Although sheep flocks could still have access to the forest, the
establishment of an exclusion zone resulted in the inability of sheep farmers to make
use of 48 % of the communal grazing area. Thus, the objectives of this thesis were
concerned with finding a way of enhancing the development of the local
smallholder sheep farming whilst concomitantly protecting the forest ecology.
The ultimate objective of this thesis was to develop a spatial optimisation model for
the grazing management of the communal land. This model produced the optimal
distribution of flocks in time and space according to the characteristics of both the
grazing resources and the sheep population. Prior to the development of the
optimisation model, it was necessary to characterise the basic elements that affected
the supply and demand of forage. Thus, under a farming systems research
framework, the plant and animal elements of the farming system were
characterised. The managerial and biological influences that defined the sheep
grazing patterns were investigated and their resulting effects discussed.
Participatory techniques were included as the core of the characterisation
methodology. Findings derived from the characterisation were utilised to assist in
the development of a geographical information system (GIS) and the application of
biological simulation models. Two models, one that simulated flock dynamics and
another that simulated sheep performance, were used. Subsequently, a two-way
link was established between the simulation models, the GIS and the optimisation
model.