Optimal tree canopy cover during ecological restoration: A case study of possible ecological thresholds in Changting, China

Abstract

Tree planting is a powerful ecological restoration method that is frequently used around the world. However, the optimal tree canopy cover to promote ecosystem sustainability during ecological restoration is not yet known. To provide some guidance, we monitored 24 artificial restoration (afforestation) plots from 1999 to 2014 and 30 natural restoration plots from 1984 to 2014 in Changting County, Southern China. We found that some ecological parameters stabilized when the tree canopy cover was as low as 48.5% in the afforestation plots. The effects of this ecological threshold appeared approximately 10 years after plantation establishment. This stability was not detected or occurred after a much longer time in the natural restoration plots. The time lag before the stability appears may have prevented previous afforestation researchers from detecting such consequences, which would not appear in short-Term research. Therefore, long-Term research is needed to monitor the effects of ecological restoration activities.