Afforestation with Non-native Pinus nigra in the Karstic Areas of Southwestern Slovenia Since the Mid-Nineteenth Century: Environmental Implications

The paper deals with the afforestation project and the creation of monocultural forest stands of non-native black pine (Pinus nigra) in southwestern Slovenia, mainly on the Kras Plateau and in the Vipava Valley since the middle of the nineteenth century, and its social and environmental implications. It is based on the archival sources kept in the state, regional, and local institutions involved in the afforestation project at various levels and over the time span of three different state entities with their distinctive social orders that shaped the territory under consideration in the twentieth century. The paper analyses the reasons for the afforestation and the consequences of this human intervention in the environment, which has completely changed the characteristics of the landscape and, consequently, the economic situation of the local inhabitants. The paper outlines the various environmental impacts caused by afforestation, such as changes in the soil, vegetation, and microclimate, while focusing primarily on the infestation of the non-native processionary moth (Thaumetopoea pityocampa), which, due to the specific characteristics of the Slovenian karstic region and local climatic conditions, spread rapidly even in the forested areas up to 1200 m above sea level. It describes the methods of controlling this pest, which were initially mechanical, while after WWII, the pest was also aggressively controlled with chemical agents, contaminating the groundwater in the karst areas and the entire local environment.