Resumen de Efecte de les pràctiques agricoles i del paisatge sobre la flora segetal dels secans mediterranis. Implicacions per a la conservació = Effect of farming practices and landscape on the segetal species of Mediterranean dry land arable fields. Implications for conservation
ABSTRACT OF THE THESIS Effect of farming practices and landscape on the segetal species of Mediterranean dry land arable fields. Implications for conservation Roser Rotchés Ribalta Many arable plant species that inhabit almost exclusively in cereal fields have undergone severe population declines owing to agricultural intensification. These species, indicators of sustainability in agricultural systems, should be considered in conservation programs, but their conservation must be based on the maintenance of cropping activities. Unfortunately, in the Mediterranean region characteristic arable species have attracted relatively little the attention of researchers and conservationists. This thesis deepens our knowledge on the characteristic arable species of winter cereal fields, and assesses the reasons why some of these species have become rare in these habitats. We assessed which farming practices and landscape characteristics favour the presence of these species, both common and rare, at the edges of a large number of organically managed fields in the Central Catalan Depression. We also evaluated experimentally the effects that particular farming practices (herbicide application and fertilization) have on the fitness of certain segetal species. Characteristic and rare arable species correlate better with the factors operating at the field scale than with the factors that depend on the farm or with the landscape characteristics. The intensification of organic farming practices is highly variable. Therefore, specific farming practices such as autumn-sowing of cereal crop varieties, non-inversion tillage and the adjustment of the fertilization should be promoted to benefit the presence of characteristic arable species at the field level, whose effects scale up at the farm level. The high specificity of the segetal species to the dry land cereal habitats and the continued pressure from the application of herbicides and the high inputs of mineral fertilizers in the conventional farming systems have affected negatively their populations. Indeed, these farming practices cause significant effects on the growth and reproduction of the segetal species. However, the particularly low frequency of some of these species does not correlate with the differential effects of these practices. Thus, the rarity degree of these species is likely to be the consequence of several factors, or probably the interaction of some of them, whose effects may vary from one species to another.
