Transició socioecològica dels agroecosistemes a Mallorca. Canvi d'usos del sòl, ecologia del paisatge i balanços energètics (1860-2012)

Abstract

This Doctoral Thesis analyses the socio-ecological transition of the agroecosystems of Mallorca, and the driving forces of change, through the historical reconstruction of energy balances and land uses. The research is based on a long-term contextualization, reinterpreting the socio-ecological ruptures that took place. They began with the Catalan colonization and the establishment of an agrarian class structure based on large estates and the subjugation of the peasantry, which determined the entry into agrarian capitalism of the modern times. Later, the change caused by the bankruptcy of large property and the advance of small peasant property between the end of the 19th century and the middle of the 20th is studied. From that peasant turn onwards, with the arrival of mass tourism, a process of marginalization of the agricultural sector took place on the island that has led to its dismemberment, but paradoxically it has also allowed the preservation of a biocultural heritage that is facilitating the conversion towards organic farming. Once the main stages of the socio-ecological transition of Mallorcan agriculture have been established, the research continues to delve into the analysis of agroecosystems from two complementary perspectives for three time cuts representative of three different agricultural systems: the predominance of large property in the middle of the 19th century (1850-1860), the peasant family farming of the mid-20th century (1956), and lastly, the conventional agriculture of the beginning of the 21st century (2012). The study continues with the cartographic survey of the land covers and land uses at three scales -regional, local and landscape-, and the application of landscape metrics, with the aim of exploring the evolution of its structure and ecological functionality. This part of the doctoral thesis demonstrates the usefulness of transferring the concept of intermediate disturbance-complexity to Mediterranean cultural landscapes, and how traditional agriculture generates a heterogeneous agroforestry mosaic of great interest for nature conservation. The last part of the research reconstructs the energy balances of the agroecosystems of the Manacor municipality, a territory that can be considered representative of the entire island due to its extension and biogeographic diversity, through the quantification of energy flows and multi-EROI indicators (Energy Return on Investment) from a circular biophysical perspective. The results confirm how the ownership structures have conditioned the management of land and other resources, and how the transition from an organic-based agriculture to a fossil-based one has reduced the energy returns of the agroecosystem, putting the reproduction of their funds at risk. However, and unlike other territories, the partial adoption of conventional agriculture techniques has led to the (precarious) permanence of a biocultural heritage that can be an important resource for the present and the future.