Elizabeth Waring

Ph.D. Candidate, Texas Tech University

Field Travel Grant Type 1

Effects of climate change and nitrogen availability on photosynthetic processes of Phalaris arundinacea and Carex stricta

“My dissertation work will examine the relationship between invasive plants and non-point pollution in the form of excess N in soils. It has been well documented that many invasive species, including Pa, might be better adapted to deal with high N availability compared to native species. However, none of these previous studies have examined the physiological traits that allow the invasive species to deal with high resource availability. Furthermore, I will test to see if invasive species use N to enhance net carbon gain better than native species to offset damage from increased temperature and greater temperature variability. This will be done in a controlled growth chamber as well as open top mesocosms to gain a more thorough understanding of which variables influence P. arundinacea invasion.
I propose to determine whether temperature variability and increasing average temperature differentially affect leaf photosynthesis and respiration in C. stricta and P. arundinacea growing under different levels of N availability. Achievement of this objective will address how climate change will affect the ability of P. arundinacea to invade C. stricta, because P. arundinacea success appears to be tied to N availability and net carbon gain. The ability of P. arundinacea to keep leaf N at a constant level over the entire growing season and to delay leaf senescence could be a strategy of P. arundinacea to gain more carbon for the following spring, while C. stricta has senesced and moved its N to its roots for conservation. The ability to gain extra carbon in the autumn could assist P. arundinacea in being an aggressive invader. How soil N availability affects this potential strategy and that of C. stricta will be investigated.
Data from the field site will be used to make comparisons with the data from the mesocosm experiments. This will provide insight into how physiological processes are affected currently and under a changing climate. Increased knowledge on how invasion could change under climate change is important for directing management practices for P. arundinacea in the future. ”