Suppemental material to the manuscript: The effect of mid-19th century forest use practices on carbon stocks of mountain forests in the Alps.

Abstract

Historical forest use practices included the removal of large quantities of organic material from forests. The material served as animal bedding and subsequently, mixed with animals’ urine and faeces, as organic fertilizer for agriculture. This changed forests ecosystem properties, and the consequences of these century-long interventions may affect forest functions and services until today.

Taking stand history into account can improveforest management strategies with respect to climate change adaptation and biodiversity. However, therefore it's necessary to develop a more profound understanding of historical forest use practices and their ecological consequences. Litter raking experiments, mimicking the historical practice, were conducted on four experimental plots located in spruce-dominated mountain forests in Tyrol.

Analysis of archival data from 1840 enabled the quantification of historical forest use practices. By combining experiments, laboratory analyses and archival data, it was possible to gain detailed insights into historical carbon storage and flows. Our one-time litter raking experiments removed 2.4 to 3.5 kg m-2 of organic carbon, which is 17 to 26% of the total organic carbon stored in organic layers and mineral soil at the respective sites.

The analyses of archive data revealed that an area-weighted mean of 119 kg C ha-1 yr-1 of forest bedding material was removed annually around 1840 in the research area, whereas intense used areas showed removal rates of 321 to 537 kg C ha-1 yr-1. The results improve our understanding of the current state of forest ecosystems and helps us to assess legacy effects of historical forest use practices on carbon stocks, productivity, soil health and biodiversity.