Plants and soil microbiota play an active role in rock weathering. Here we show that the coupling between erosion and weathering might be established by nutrients that are taken up by trees, are not recycled from plant litter and are missing in the dissolved river flux due to forest re-growth after clear cutting or due to erosion as coarse woody debris. To track this nutrient pathway we used magnesium stable isotopes in combination with innovative metrics over annual and millennial timescales.