An exploration of sustainability versus productivity and ecological stability in planted and natural forests in Sichuan, China

Implementation of the Natural Forest Protection Project and Grain-for-Green Program in China has promoted forest restoration, increased productivity, and enhanced carbon stocks. However, few studies have characterized temporal and spatial variation in productivity and ecological stability in planted and natural forests and evaluated the factors driving such variation. In this study, we used 1399 permanent forest plots to identify change patterns in the productivity and temporal stability of above-ground biomass (AGB), and evaluate the factors driving these changes in planted and natural forests in Sichuan Province, China. The mean temporal stability of AGB was higher for natural forests than for planted forests from 1979 to 2017; While the productivity of planted forests was higher. The stability decreased at a rate of -0.013 yr(-1) in entire natural forests and -0.011 yr(-1) in planted forests, and the productivity of natural forests decreased significantly over time, with a slope of -0.0065 Mg ha(-1) yr(-1). Altitude, latitude, annual precipitation, and stand age dominated variability in the productivity and AGB stability of natural forests. Richness, tree density, and stand age were the determinants of productivity and stability in the planted forest. Our results suggest that selective thinning, enriching species richness, and forest stand age can effectively balance the productivity and biomass temporal stability of planted forests. Due to climate change, older natural forests should be strictly protected.