10.4.2 Study Area
The study was conducted in the village of Ban Put in Chieng Khoi commune, which
is located in Son La province in the north-west of Vietnam. The village
encompasses a total area of 558 ha and has a population of 467 people of Black
Thai ethnicity. The land use systems studied comprised secondary forest (375 ha),
upland cropping dominated by maize, cassava and mango (77 ha) and lowland
paddy fields (11 ha) (Chieng Khoi Commune 2007).
10.4.2.1 The Forest, Agroforest, Low-value Landscape or Wasteland?
(FALLOW) Model
FALLOW is a spatially explicit land use and land cover change model with a yearly
time-step (van Noordwijk et al. 2008). In this study, FALLOW version 1.0 was
employed, having been encoded using the PCRaster Environmental Modeling
software language (http://pcraster.geo.uu.nl/). The model used here assumed
farmers to be the main agents of land cover and land use change, based on a
multi-criteria analysis of: (1) plot attractiveness – to expand a land use type as a
function of soil fertility, accessibility, attainable yield, and potential costs arising
from transportation and land clearing, (2) the allocation of labor and land to
available options of investment, and (3) the diminishing and increasingly marginal
returns on soil fertility and land productivity. The annual simulation loop for
FALLOW was built on the ‘Trenbath’ soil fertility approach (Trenbath 1989),
under which soil fertility at the plot-level proportionally declines during cropping
periods by a specific soil fertility depletion rate and increases during fallow periods
with a characteristic half-recovery time. Fertilizer application affected soil fertility
and yields by reducing the depletion rate, while crop yield was a function of a crop
specific conversion factor and existing soil fertility levels at the plot-level. Overall
crop productivity at the landscape level contributed to food security, together with
revenues gained from other economic activities (such as forest resource utilization
activities or tree plantations). The consequences of these landscape dynamics were
assessed by output indicators, that is, annual land use and soil fertility maps
(Suyamto et al. 2009).
10.4.2.2 Participative Focus Group Discussions
The employed participatory assessment approach was built on conceptual ideas drawn
from Soft-System-Methodology by Checkland (2000) and Participatory Rural
Appraisal by Chambers (1994). The assessment was carried out in two stages. Firstly,
a reconnaissance survey was carried out drawing on field visits and semi-structured
interviews with local stakeholders such as farmers, villagers and government officials,
to obtain an overview of the study area. Secondly, focus group discussions were
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
391
The study was conducted in the village of Ban Put in Chieng Khoi commune, which
is located in Son La province in the north-west of Vietnam. The village
encompasses a total area of 558 ha and has a population of 467 people of Black
Thai ethnicity. The land use systems studied comprised secondary forest (375 ha),
upland cropping dominated by maize, cassava and mango (77 ha) and lowland
paddy fields (11 ha) (Chieng Khoi Commune 2007).
10.4.2.1 The Forest, Agroforest, Low-value Landscape or Wasteland?
(FALLOW) Model
FALLOW is a spatially explicit land use and land cover change model with a yearly
time-step (van Noordwijk et al. 2008). In this study, FALLOW version 1.0 was
employed, having been encoded using the PCRaster Environmental Modeling
software language (http://pcraster.geo.uu.nl/). The model used here assumed
farmers to be the main agents of land cover and land use change, based on a
multi-criteria analysis of: (1) plot attractiveness – to expand a land use type as a
function of soil fertility, accessibility, attainable yield, and potential costs arising
from transportation and land clearing, (2) the allocation of labor and land to
available options of investment, and (3) the diminishing and increasingly marginal
returns on soil fertility and land productivity. The annual simulation loop for
FALLOW was built on the ‘Trenbath’ soil fertility approach (Trenbath 1989),
under which soil fertility at the plot-level proportionally declines during cropping
periods by a specific soil fertility depletion rate and increases during fallow periods
with a characteristic half-recovery time. Fertilizer application affected soil fertility
and yields by reducing the depletion rate, while crop yield was a function of a crop
specific conversion factor and existing soil fertility levels at the plot-level. Overall
crop productivity at the landscape level contributed to food security, together with
revenues gained from other economic activities (such as forest resource utilization
activities or tree plantations). The consequences of these landscape dynamics were
assessed by output indicators, that is, annual land use and soil fertility maps
(Suyamto et al. 2009).
10.4.2.2 Participative Focus Group Discussions
The employed participatory assessment approach was built on conceptual ideas drawn
from Soft-System-Methodology by Checkland (2000) and Participatory Rural
Appraisal by Chambers (1994). The assessment was carried out in two stages. Firstly,
a reconnaissance survey was carried out drawing on field visits and semi-structured
interviews with local stakeholders such as farmers, villagers and government officials,
to obtain an overview of the study area. Secondly, focus group discussions were
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
391