Effects of resources and herbivory on leaf morphology and physiology of Chinese tallow (Sapium sebiferum) tree seedlings

Chinese tallow (Sapium sebiferum) is a major woody invader in a variety of ecosystems throughout the southeastern United States. This study was conduc ted to examine the effects of different levels of resources and herbivory o n the growth and physiology of Chinese tallow leaves. Chinese tallow tree s eedlings were grown outdoors in pots for fifteen weeks under experimental c ombinations of shade, nitrogen and simulated herbivory. All of the seedling s survived and grew vigorously under a variety of shade, nitrogen and herbi vory conditions. Shade and nitrogen manipulations had the greatest effects on leaf growth and physiology. Stomatal conductance: was significantly decr eased by increasing levels of shade and tended to decrease with added nitro gen. Leaf area and number of new leaves were greater in shaded conditions t han in full sunlight. increased amounts of nitrogen increased average leaf area, leaf number, and leaf mass. Petiole lengths also significantly increa sed with higher levels of nitrogen and shade. Surprisingly, simulated herbi vory did not significantly affect any of the leaf parameters measured. This study has demonstrated that Chinese tallow is capable of thriving under a number of environmental conditions and, in addition to previous research sh owing resistance to most native herbivores, that it is extremely tolerant o f herbivory leaf damage. Combined, these factors increase the success of Ch inese tallow as an invasive species and will complicate the development of an effective management strategy.