The Invasion of Erigeron canadensis L. (Asteraceae: Astereae): A Substantial Threat to Plant Diversity and Community Stability in Naturally Restored Secondary Bare Lands

The ecosystem of naturally recovered secondary bare land (NRSBL) is highly vulnerable to external interference. Alien invasive plants can exert notable impacts on the restoration of indigenous plant communities. This study aimed to investigate the effects of a global alien invasive plant of Erigeron canadensis L. at different degrees of invasion (including uninvaded condition, the low invaded with the relative abundance of E. canadensis <35%, and high invaded with the relative abundance of E. canadensis >75%) on the indigenous plant communities in NRSBL in the subtropical monsoon climate zone of Zhenxiong, Zhaotong, Yunnan, China. The results showed that E. canadensis invasion significantly decreased plant species diversity and community stability, with a highly significant negative correlation between E. canadensis relative abundance and these two types of indices. Low invasion of E. canadensis caused mild disturbance on the species diversity and no significant disruption (even potential promotion) on the community stability, while high invasion of E. canadensis induced moderate to severe disturbances on the two indices. This study provides a strong theoretical support for the early warning and control of invasive plants in NRSBL.