History and spatial complexity of deforestation and logging in small private forests

Abstract

Despite awareness of the importance of taking historical factors into account to understand drivers of present biodiversity, few studies have considered long-term forest historical data because of the difficulty involved in reconstructing forest management history. Our aim was to trace the management history of small private forests, which are the most frequent type of woodlands in France, as they play a major ecological role. We analyzed forest continuity and logging history of a group of small private forests that formed a continuous forest before 1771. Thanks to two old maps (Cassini's map – dating from around 1771 – and Napoleon's cadastral map – from around 1825) and aerial photographs (1942–2006), we were able to reconstruct forest continuity for 235 years and logging history after 1942 at a fine scale by adapting a regressive photo interpretation method in a GIS. Between 1771 and 1942, we detected both fragmentation and a decrease in total forest area following the conversion of forest land into agricultural land. However, the selection criteria of deforested areas changed over time. After 1942, the situation was reversed due to rural depopulation. Traditional logging activities continued after 1942, resulting in a complex mosaic of stands with different logging histories. The only change in logging modalities was a decrease in the quantity of wood harvested (smaller cuttings) after the 1980s. We discuss how such temporally and spatially complex management modalities could affect plant biodiversity in these farm forests.