Smallholder agricultural systems in Northwest Vietnam face a number of significant economic and ecological challenges. The move from shifting cultivation to more static farming methods, particularly maize farming, in this mountainous region has resulted in high levels of soil erosion. Agroforestry offers a potential mechanism to both stabilise these systems and to diversify production. The four chapters presented in this PhD thesis develop an integrated framework to scale up agroforestry options in Northwest Vietnam. Given the cultural and biophysical heterogeneity of this area it was assumed that there were no “one-size-fit-all” agroforestry solution. The concept of developing options that fitted, and were appropriate, to local contexts was used as a guiding principle. The framework was developed by mapping the extent and prevalence of soil degradation across the agricultural landscape and associating that with biophysical suitability mapping for different agroforestry options. Next the impact of social factors, including ethnicity and gender, were evaluated in terms of how they influence adoption of different agroforestry options. Finally the impact of social factors including ethnicity and gender affect adoption of different agroforestry options were assessed. Finally, shaded coffee agroforestry, an example of existing agroforestry system with potential for expansion, was explored as a case study to capture farmers’ existing knowledge of the costs and benefits of integration of trees on farmland to identify opportunities for knowledge exchange.
The study provides the first systematic evaluation of soil erosion in the Northwest – showing that the area of cropland on erosion prone slopes has been underestimated (and is almost double the area identified by officially reported data). Agroforestry systems are an appropriate response option to this degradation as they have well established soil stabilisation benefits, particularly in contour planting patterns. Biophysical suitability analysis of different agroforestry options showed that 85 % of study site areas was viable for such agroforestry systems using high value tree species.
The study found that farmers’ preferences for agroforestry adoption were highly influenced by social norms associated with different ethnic minorities who make up the majority of the farming population in this area (this study focused on the Kinh, Thai and H'mong groups). A case study looking at gender in H'mong communities found that H'mong men and women had very differentiated roles within the current agricultural systems and were subject to different constraints and interests in relation to agroforestry adoption opportunities. These social norms currently limit H'mong women’s full participation in agroforestry expansion.
In terms of design, tree selection for agroforestry was significantly influenced by the economic value to the tree (either as timber or fruit) and accessibility to market. Detailed analysis of farmers’ understanding of the benefits of different trees in coffee systems explained why there were fewer native species in the areas with better road accessibility despite the farmers’ own valuations of non-native tree species limited ecological benefits to coffee trees. The native leguminous tree Leucaena leucocephala and fruit tree Dimocarpus longan were identified by farmers as providing the broadest range of environmental benefits to coffee systems. However, Leucaena leucocephala had limited economic value and was primarily found only in the areas far away from roads and market. On the contrary, Dimocarpus longan had high market value, was found in more than 50% of surveyed farms, mostly near and medium distance to market. These results help local extension institutions understand current selection criteria of the ‘right’ tree species according to the local context
An integrated framework for scaling out agroforestry adoption is proposed and discussed in the synthesis chapter. It is tailored to a Vietnamese context through provision of greater detail on the context, options and actors involved in potential agroforestry systems in Northwest Vietnam.