Sociometabolic analysis of a traditional Mediterranean agroecosystem. Historical transition and Biocultural Heritage. (Les Oluges, Catalonia, c.1860-1959-1999)

Abstract

[eng] ith the spread of the Green Revolution from the mid-20th century, large part of the agricultural systems in the world experienced a series of transformations that have ultimately led to important sustainability problems. Acknowledging the sustainability problems of modern industrial agriculture, this PhD thesis analyses the historical transition of a Mediterranean agroecosystem from a traditional organic management to an industrialised functioning. Understanding how this transformation affected the sustainability of the agroecosystem, changing its structure and functioning, provides useful knowledge for improving the sustainability of future agricultural systems. The theoretical perspective that grounds this thesis is formed by the interconnection of different approaches: Ecological Economics, Social Metabolism, Environmental History, Agroecology, Biocultural Landscapes and Biocultural Heritage, and Peasant Economy theories. Thus, a biophysical analysis of the historical transformation of the agroecosystem of Les Oluges (from the county of La Segarra in Lleida, Catalonia) is built for three points in time: i) c.1860, when the agroecosystem was functioning under a traditional organic management; ii) 1959, when the traditional management was mixed with the introduction of the first industrial technologies from the Green Revolution; iii) 1999, when the agroecosystem was under a completely industrialized functioning. Firstly, the analysis of the energy balances of Les Oluges agroecosystem is presented (Chapter 2). The results obtained for 1860 show an agroecosystem with a relatively low energy efficiency due to the need to reinvest large part of the energy produced in order to maintain the productive capacity of its funds. In 1959, the introduction of the first external inputs from industrial origin reduced the pressure on the local resources. The combination of industrial and traditional-organic management in 1959 improved the energy efficiency of the agroecosystem not only from a human perspective, but also for the maintenance of associated biodiversity and provision of ecosystem services. However, in 1999 the complete industrialization of the agroecosystem led to a decline of its energy efficiency that eroded its sustainability. The nutrient balances (Chapter 3) deepen and complement the previous energy balances analysis. At the aggregated scale, the results show a great enlargement of the volume of nutrients cycling in the agroecosystem in 1999; however, while in 1860 and 1959 the nutrient balances were relatively equilibrated, in 1999 there were important nutrient surpluses that reflect an over-fertilization inefficiency. The nutrient balances at the crop system scale show the different fertilization managements that were applied in cereals, woody crops and associated crop systems. Finally, this PhD thesis analyses some of the biocultural heritage from Les Oluges (Chapter 4): the intercropping system in which cereals were grown in between the lines of woody crops (mainly vines, but also olive and almond trees). The presence of this crop system in Les Oluges until de mid-20th century, as well as in other Mediterranean regions, indicate the existence of an important traditional ecological knowledge linked to this polyculture. In order to determine the possible advantages of this alley-cropping system I developed a multidimensional analysis that assesses agroecological and socioeconomic aspects. From the agroecological point of view, the results show that the intercropping system did not have a productive disadvantage. This can be explained by the weak competition among crops and the possible existence of mutual facilitation processes. Additionally, from the socioeconomic perspective the alley-cropping system provided savings in human and animal workforce, which were of great importance in the context of traditional-organic management in Les Oluges. The analysis of the traditional intercropping system in Les Oluges shows as well the adaptation of the agroecosystem’s management to a logic of peasant economy that seeks to balance multiple elements rather than maximize only one.