Author

Shaoyang Yang

Advisor

Renninger, Heidi J.

Committee Member

Ezell, Andrew W.

Committee Member

Fan, Zhaofei

Committee Member

Grado, Stephen C.

Date of Degree

8-1-2019

Original embargo terms

Visible MSU Only 1 Year||8/15/2020

Document Type

Dissertation - Open Access

Abstract

The coastal plain of the southeastern United States is historically wet pine savannahs, prairie, and hardwoods. However, many exotic species have invaded this area and become a serious threat to native forest ecosystems. Among those exotic species, Chinese tallow (Triadica sebifera) has become one of the most pervasive tree species in the southern coastal states, including Alabama, Mississippi, Louisiana, and Texas. Therefore, to understand the distribution and spread mechanisms has become important in the management and control of Chinese tallow in the southeastern United States. In this research, distribution and spread mechanisms of Chinese tallow were studied at multiple spatial scales, including regional, landscape, and stand. Effects of predisposing (community and landscape features) and inciting (natural disturbance and human activities) factors on Chinese tallow invasion had been evaluated by using a comprehensive data set (field data and Forest Inventory and Analysis data) and spatial statistical models. Results indicated that propagule pressure of Chinese tallow is the main force driving tallow dispersal at different spatial scales. Predisposing and inciting factors such as natural disturbances, anthropogenic disturbances, forest types, forestland ownerships, and landscape features are significantly related to the spread of Chinese tallow at different spatial scales. Regionally, Chinese tallow initially started to spread from southern Texas and Louisiana to the northeastern portion of the Gulf Coastal area. At landscape and stand scales, Chinese tallow has commonly invaded from edges of forests and habitats such as roads and firebreaks. Inciting factors, including hurricanes/storms and prescribed fires, could accelerate the spread of Chinese tallow at different spatial scales, especially in habitats that have previously been invaded. Compared to pine forests, it is easier for Chinese tallow to invade bottomland hardwood forests at the regional scale. The efficient dispersal distance of tallow seeds is 250-300 m, and its distribution is affected by the microtopography in forest stands. Management of Chinese tallow invasion should be focused at selected scales, such as landscape and stand levels, because of variations of site conditions.

URI

https://hdl.handle.net/11668/14506

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