Since the late 1950s, China's forests have experienced several periods of significant deforestation, which contributed to related environmental disasters such as the Yangtze River flood in 1998. In response, the Central Government has attempted to restore forest cover by investing upwards of 1 trillion RMB into six forest conservation programs, the most significant of which include Grain to Green (1999–2016) and the Natural Forest Protection Program (NFPP) (1998–2020). These programs combine afforestation efforts (primarily in northern China) and timber harvesting bans or limits to restore forest cover.