PhD defence: Incorporation of Trees in Smallholder Land Use System: Farm Characteristics, Rates of Return and Policy Issues Influencing Farmer Adoption

PhD defence

Syed Ajijur Rahman


The main cause of tropical deforestation is conversion to agriculture, which is continuously increasing as a dominant land cover in the tropics. The loss of forests greatly affects biodiversity and ecosystem services. Tree-based farming, in a range of agroforestry systems, have been proposed as a mechanism for sustaining both biodiversity and its associated ecosystem services in agricultural areas, by increasing tree cover, while maintaining agricultural production. This thesis aims to assess the rates of return resulting from incorporating trees into food-crop-based smallholder agricultural systems, in order to assess the economic and social potential of agroforestry systems, and the barriers to their widespread adoption in the study sites in eastern Bangladesh and West Java, Indonesia.

The four papers included in the thesis specifically address the types of agroforestry, in order to characterize their differences in basic structure, management and associated crop plant diversity; the economic and social potential of agroforestry systems and the barriers to their widespread adoption, as a land use alternative to swidden cultivation, which may potentially help protect local forest; the trade-offs between income and tree cover when incorporating trees into food-crop-based smallholder agricultural systems; and the challenges of local land use and the factors that could facilitate smallholder tree farming. Data were collected through rapid rural appraisal, focus group discussions, field observation, semi-structured interviews of farm households and key informant interviews of state agricultural officers. Data have been analyzed through narrative qualitative methods, and through quantitative methods such as descriptive statistics, analysis of variance, and cost-benefit analysis.

Five main agroforestry systems (homegarden, fruit tree, timber tree, mixed fruit-timber, and cropping in the forest understory) exist in the Java study area, and can be categorized into two main types, i) integral, rotational and ii) integral, permanent, both of which exhibit a noticeable diversity in terms of both species composition and utilization. In both Java and Bangladesh the inclusion of tree crops in seasonal agriculture improved the systems’ overall economic performance (NPV), even when it reduced understorey crop production. Tree ownership was associated with more permanent rights to farmland and was prestigious in the community, which also helped strengthen social cohesion when the products (fruit, vegetables, etc.) were shared with neighbors. Agroforestry farmers were less involved in forest clearing and forest products collection indicating that agroforestry may contribute positively to conservation of local forests. However, seasonal agriculture has a higher income per unit of land area used for crop cultivation compared with the tree establishment and development phase of agroforestry farms. There is thus a trade-off between short-term loss of agricultural income and longer-term economic gain from planting trees in farmland. Various conditions can facilitate tree farming as some farmers are reluctant to implement agroforestry. Therefore there is a need for a carefully designed landscape approach supported by coherent local communities and competent government policies. In land-use classifications agroforestry systems are not recognized as forestry, but like forests they provide tree products and services. Classification will always be problematic if a binary system is applied, thus a more sophisticated approach should be adopted that incorporates the economic and environmental characteristics of a wider range of systems.


Jette Bredahl Jacobsen, Professor, Department of Food and Resource Economics, University of Copenhagen, Denmark

Assesment Committee

Carsten Smith-Hall, Professor, Department of Food and Resource Economics, University of Copenhagen, Denmark

Kate Schreckenberg, Lecturer, Centre for Environmental Science, University of Southampton, United Kingdom

Jürgen Pretzsch, Professor, Institute of International Forestry and Forest Products, Technische Universität Dresden, Germany

If you are interested in a full copy of the thesis, you can contact the PhD student or one of the supervisors.