Date of Award

Spring 5-7-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy - Forestry

Department

Forestry

First Advisor

Jeremy Stovall

Second Advisor

Brian Oswald

Third Advisor

Kathryn R. Kidd

Fourth Advisor

Yuhui Weng

Fifth Advisor

James Van Kley

Abstract

Non-native, invasive species disrupt ecological processes and functions, posing a serious threat to natural ecosystems. By examining the growth metrics of the non-native, invasive tree, Chinese tallow (Triadica sebifera [L.] Roxb.), hereafter tallow, across different flooding and light regimes, I investigated how restructuring native communities with valuable native species will prevent the reestablishment of tallow. I studied the changes in morphological and physiological traits of tallow when growing with water tupelo (Nyssa aquatica L.), sugarberry (Celtis occidentalis L.), and green ash (Fraxinus pennsylvanica Marshall). I found that in the non-flooded and high irradiance treatments, tallow's growth metrics were highest when growing with sugarberry and water tupelo, but decreased when competing with green ash. I concluded that tallow may be less competitive with certain native species and underplanting may be a possible opportunity for improving the success rates of native trees species establishment in areas prone to tallow invasion.

I also investigated the interactive effect of light, flooding, and community types on the growth, dominance, and competitive ability of tallow and water tupelo, sugarberry, green ash, and baldcypress (Taxodium distichum[L.] Rich). I found that mixed community depressed the dominance of tallow in the flooded and low irradiance treatment, however, leaf area and leaf biomass of tallow increased in the mixed community in the non-flooded and high irradiance treatment. I concluded that establishing an appropriate native community in flooded and low irradiance environments may reduce future dominance of tallow.

I additionally tested the competitive ability of tallow, water tupelo, sugarberry, green ash, and baldcypress using the relative interaction index, taking into account the competition of native taxa growing with tallow (effect of natives as competitors) and competition of tallow growing with native taxa (effect of competition on natives). I concluded that with the exception of water tupelo, tallow had no significant impact on the biomass of the native species studied.

Finally, I investigated the growth and survival of water tupelo, baldcypress, water oak (Quercus nigra L.), and loblolly pine (Pinus taeda L.) across the Green Bayou Wetland Mitigation Bank (GBWMB) in Harris County, TX. I found that baldcypress had the highest survival rates that baldcypress and water tupelo had greater tree heights than loblolly pine, and that only loblolly pine and water tupelo had significant increases in tree heights between establishment and final measurements. I concluded that baldcypress is better adapted to the microenvironmental conditions across GBWMB. Overall, the results show that restructuring a native community by planting valuable native hardwood species can be a potential means of reducing future dominance of tallow.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Thursday, April 27, 2023

Share

COinS

Tell us how this article helped you.