FALLOW is a landscape-dynamics model, which comprises the following main annual dynamic processes: (1) plot-level soil fertility dynamics in crop and fallow phases affecting agricultural crop production; (2) food storage, use and sale at the village level, with options along the spectrum from ‘full dependence on local food production' to ‘fully market integrated' economy; (3) farmer decisions on increase or decrease of the area cropped, depending on labour availability and expected profitability of various land use options, as they have learnt from past experiences within the simulation; (4) spatial implementation of choices for clearing land, choosing among the options available; and (5) impact assessment of how the resultant mosaic of land cover types and successional processes will affect watershed functions (annual water yield, base flow, net sediment loss), biodiversity indicators and carbon stocks.
Initially developed as a Stella model, FALLOW has now been re-implemented in the spatially explicit modelling environment of PCRaster, making it possible to apply the model to larger landscapes with real spatial data sets. FALLOW can be used for impact assessment and scenario studies, assisting the negotiation process between stakeholders in a changing landscape by visualizing possible/likely consequences of factors such as changes in prices, population density and human migration, availability of new technology, spatial zoning of land use, pest and disease pressure or climate.
Example on FALLOW application
Reconstruct historical pathway of land-use/cover change
In this example, simulation was initialized from totally forested landscape, which was occupied by 5 inhabitants/km2 of people who had a relatively adaptive learning style. Human population increased according to natural growth and migration that were determined by food sufficiency and returns to labour respectively. Shifting cultivation was the first livelihood recognised in the area, which fallow duration was affected directly by food need. Market had been introduced at this early stage. People then adopted coffee agroforestry and NTFP gathering activities as alternative livelihoods. Later, agroforestry development led to tenure recognition and land privatisation, through which people had the power to exchange their lands, which might lead to increase land-holding size to start adopting more modern type of production system, which was monoculture coffee plantation. In more profit-oriented type of people, market dynamics could trigger people to alter tree-based production systems into horticultural production systems, which was more promising in term of profit that could be earned in relatively shorter time. And the results of simulation for 100 years are:
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