Recent vegetation changes linked to forestry legislation inferred from pollen and sedimentological analyses in northwest Spain

Abstract

The decline of forest cover in the northwestern Iberian Peninsula during the recent centuries, driven by anthropogenic activities, has necessitated the establishment of a set of laws and regulations to ensure stricter control of the use of natural forest resources. However, the assessment of the effects of such legislation on plant populations is inaccurate and lacks a longer-term perspective. The present study aims to assess the impact of the most important forestry policies of the last centuries on past plant population dynamics using high-resolution pollen analysis of three sedimentary sequences extracted from the inner zone of the Ría of Ferrol, Galicia, northwest Spain. Pollen evidence suggests that plant populations are strongly influenced by the different reforestation and afforestation activities carried out during the last centuries. A substantial change in the regional vegetation is evident during the latter half of the 20th century, mainly attributed to the reforestation activities of Patrimonio Forestal del Estado (State Forestry Heritage), established in 1941, alongside changes in the socioeconomic dynamics of the region. Pollen signals preserved in the sediments along with changes in particle size, were driven by sedimentary processes associated with urban infrastructure development and changes in the erosive rate likely related to the removal of the tree cover by increasing silvicultural activity. The high-resolution of the radiometric chronologies obtained allows to detect changes in plant populations that can be correlated with specific historical events, thereby reinforcing the efficacy of high-resolution pollen analysis as a valuable tool for science-based forest management assessment.