Impacts of colonization and establishment of Chinese tallow (Triadica sebifera) on ecosystem resilience of native forest under different stand conditions

Background/Question/Methods: Chinese tallow has become a serious ecological threat at south coastal area of the United States, especially for the resilience of fire-regulated longleaf-slash pine ecosystems. Therefore, understanding Chinese tallow invasive pattern and its impacts on ecosystem resilience at stand level are important for coastal ecosystem management and restoration. In this paper, the mechanisms of Chinese tallow invasion and its impacts on ecosystem resilience can be studied through analyzing abundance, age structures, biodiversity, seedlings, and seed bank of Chinese tallow trees and disturbance records in 3 longleaf-slash pine stands of Mississippi Sandhill Crane Wildlife Refuge.

Results/Conclusions: The results indicate that fire disturbance could increase the density of Chinese tallow at burned year and periodic burn (3-6 years) tends to favor tallow invasion and establishment which will decrease the resilience of native forest ecosystems, especially when there are tallow seed trees. The area where Chinese tallow trees have established and occupied has lower biodiversity compared to uninvaded area because once Chinese tallow established it would create an exclusion zone in native forest stands. The Poisson regression indicates that Chinese tallow seedlings have significant negative relationship with understory vegetation coverage which means low understory coverage could have higher probability to find Chinese tallow seedlings. Moreover, when the understory vegetation type is grass this relationship will be more significant. Therefore, once Chinese tallow trees have established in native forest stands, fire disturbances would decrease resilience of native forest ecosystems. Increasing of Chinese tallow trees in native forest stands could decrease biodiversity of native forest ecosystems.