Browsing by Subject "Agricultural diversification"

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Comparative advantage of Vietnam's rice sector under different liberalisation scenarios: a policy analysis matrix (PAM) study
(2004) Nguyen, Manh Hai; Heidhues, Franz
The rapidly changing global economic environment and domestic economic reforms in Viet-nam have brought the issue of comparative advantage of the rice sector to the forefront. In recent years, Vietnam has had to compete in an increasingly competitive rice export market. This paper examines the fluctuations in the comparative advantage of Vietnamese rice production based on different scenarios of trade liberalisation and economic reform in Viet-nam. To do this, a Policy Analysis Matrix (PAM) was used in conjunction with an econo-metric model. The study involved simulation of a large number of scenarios of trade liberalisation and macroeconomic reform, using variations in a single factor and in a group of factors such as product price and input costs, i.e., the price of imported fertilisers, land, water and labour costs, etc. The empirical results show that in 1998 (the baseline scenario), the comparative advantage in rice was relatively high and that the use of domestic resources ? i.e., land, labour and water ? was efficient in economic terms. The estimated DRC elasticities in respect of the world rice price and the shadow exchange rate in 1998 showed a considerably improved com-parative advantage. The estimated DRC elasticities for land rent, the social costs of labour, the import price of fertilisers and irrigation water charges were small in absolute values indi-cating small and negative impacts on comparative advantage with a rise in these prices. The results of sensitivity analyses revealed that the comparative advantage of rice is very sensitive to changes in its export price. In addition, the exchange rate and land rent are also important determinants of the rice sector?s comparative advantage in Vietnam. Other empirical results show that Vietnam is still likely to retain its comparative advantage in rice production in the next decade; however, its comparative advantage might be seriously affected or even dis-appear entirely if Vietnam is exposed to a number of unfavourable economic conditions simultaneously. The major recommendation of this paper is that production should be diversified, with appropriate agricultural policy support, within a broader framework of macroeconomic transformation and trade liberalisation.
Insect conservation in agricultural landscapes needs both high crop heterogeneity and semi-natural habitats
(2024) Tassoni, Sara; Becker, David; Kasten, Marit Kinga; Moriníere, Jérôme; Grass, Ingo
Identifying landscapes that are suitable for both biodiversity conservation and agricultural production is a major challenge. Traditionally, much research has focused on biodiversity conservation outside of agricultural production areas, e.g., in semi-natural habitats. In contrast, recent research has mainly focused on the potential of crop heterogeneity. This includes both compositional (crop diversity) and configurational heterogeneity (field border density). However, if and how crop heterogeneity, and semi-natural habitats interact to shape insect diversity in agricultural landscapes remains poorly understood. Here we investigated the combined effects of crop diversity, field border density, and semi-natural habitats (i.e., grassland proportion, hedge density) on insect diversity. We sampled insect communities from 14 – 17 June 2021 with pan traps in 27 study landscapes (500 m x 500 m) covering independent gradients of these landscape variables and identified a total of 587 insect species with DNA metabarcoding. We found that field border density mediated the effects of crop diversity, grassland proportion, and hedge density on insect richness. At low levels of field border density (i.e., landscapes with mostly large fields), effects were either neutral (crop diversity), negative (grassland proportion) or weakly positive (hedge density). By contrast, at high levels of field border density, crop diversity, grassland proportion, and hedge density all exerted positive effects on insect richness. Responses to crop heterogeneity and semi-natural habitat differed among trophic groups of insects (decomposers, herbivores, parasitoids, predators). While variation in richness of herbivorous insects followed the patterns of the overall richness, decomposer richness was not related to any of the investigated variables. Predator richness increased with hedge density in landscapes, whereas parasitoid richness increased when high levels of field border density and grassland proportion coincided. Our study shows that increasing crop heterogeneity is a viable strategy for promoting insect diversity in agricultural landscapes. However, the effects of the amount of remaining semi-natural habitats, such as grassland or hedges, are mediated by configurational heterogeneity, and vary between trophic groups. Efforts to conserve insects in agricultural landscapes must therefore focus on both increasing the heterogeneity of the crop matrix by promoting crop diversity and increasing the density of field borders, while also maintaining or restoring semi-natural habitats as important source habitats for insect species.