Long term after-effects of forest management practices PI : Pierre Montpied (UMR 1137 Joint Research Unit for Forest Ecology and Ecophysiology – EEF) Co-applicants : BEF, (UL EA 7304 LOTERR) Collaboration :  B. Zeller (BEF), X. Rochel (LOTERR),J.-L. Dupouey (EEF) ____________________________ Context — The long-term effects of a former agricultural land use on the current state of forest ecosystems after forest recolonisation are relatively well documented. The long-term after-effects of forest management are much less known whereas it is important to assess its consequences on soils, productivity or biodiversity in the context of the current incentives to increase extraction of biomass from forests. Significant changes in forest management occurred during the nineteenth century in relation to industrial revolution, which resulted in a decrease in the timber extraction on some forests that were previously assigned to intensive production of fuelwood. If the immediate effects of this overexploitation have been widely studied, the long-term resilience of forest ecosystems to these practices remains widely unknown Objective — The objective of the study is to test the hypothesis that intensification of wood extraction from forest would in the long term impair future productivity and biodiversity through soil and floristic impoverishment. Approach —  We compared formerly over-exploited forests with neighboring less exploited forests to study the long-term impacts of high harvest levels on soil and vegetation of forest ecosystems.. Tree inventories, floristic surveys and soil analysis, including innovative NIRS-MIRS methods, were carried out for this purpose. Two annual surveys were carried out, the first (2014) compared the former “quarts en réserve” and “coupes affouagères” or allocation from the affouage in the municipal forests of the Lorraine Plateau, the second (2015) studied forests formerly devoted to fuel wood production for the “Salines de Lorraine”. Key results —

• Low long-term impact of the past management intensity on the vegetation and the studied soil parameters;
• Some species showed a preference for the formerly over-exploited forests or conversely less intensely exploited;
• The NIRS-MIRS soil analysis revealed differences in spectrum between the two former levels of exploitation intensity, which will need to be interpreted in terms of physicochemical parameters.

Main findings — Reported low long-term impacts of former management modes used in Lorraine forests does not necessarily indicate harmlessness of these modes of management given that certain uncertainties existed up to the beginning of the XIXth century, regarding recommendations we found in archives. It is very possible that he extraction of fuel wood was as strong in the “protected” forests than in the others and that, consequently,  overexploitation was generalized. Future perspectives — As the latest soil analyses have not yet been received, full data analysis, particularly that which relates to infrared reflectance spectra, will be continued and further explored.