Improving Productivity, Profitability and Sustainability of Degraded Grasslands Through Tree-Based Land Use Systems in the Philippines - Smallholder Tree Growing for Rural Development and Environmental Services - page 278

phosphorus content. These changes depend on various plant and soil processes tak-
ing place for each land use system.
Data from research trials and literature surveys were used in calibrating
SCUAF. The major inputs or parameters in the model include soil profile/charac-
teristics, soil erosion, plant growth, plant composition, removals (harvests), and
transfer (pruning). SCUAF determines plant growth and soil changes on a per
hectare basis. Hence, the systems under study are modeled on a hectare of land-
holding. Land use systems were specified in the SCUAF model and the simulation
outputs 1 served as the basis for the analysis of economic and environmental out-
comes. The associated economic model was implemented through the extended
benefit-cost analysis (BCA) framework.

14.2.1 Sampling and Data Collection

The study was conducted in four villages in Claveria, Misamis Oriental, the
Philippines. The criteria for village selection included the presence of mixed land
use systems and accessibility. In each village, respondents of households with
farms contiguous to each other were selected for the household survey. A total of
192 farmers were interviewed, among who tree-based farming systems adopters
and non-adopters were identified. The identification was based on their current land
use and particularly on whether or not they had planted trees on their farms. This
method of classifying respondents served as the basis in the data analysis.
This study utilized both primary and secondary data. Primary data such as socio-
economic and farm characteristics were collected through a survey using a pre-tested
structured interview schedule and a key-informant interview. Other primary data
collected include landholding, land use patterns, and other relevant information.

14.2.2 The Study Site

Claveria, Misamis Oriental was chosen to be the study site to calibrate the model
for the following reasons: (i) it is considered as a representative Imperata - dominated
grassland area in the Philippines, which meets the centre of interest of this study;
(ii) the area has been subjected to long-term government and non-government inter-
ventions relating to soil conservation practices; (iii) there is significant adoption of
soil conservation practices and transformation of Imperata grassland into tree-
based land use systems; and (iv) availability of biophysical and economic data for
model parameterization.

1 Changes in soil carbon, nitrogen and phosphorus contents resulting from soil erosion, recycling
of plant materials and mineral uptake in a specified land use system within a given environment.