Date of Award
Master of Science
Ecology, Evolution, and Organismal Biology
Ecology and Evolutionary Biology
The overarching goal from each of the thesis chapters in this document is to provide information on survival, growth and germination responses of Schismus arabicus when exposed to multiple fertility island microhabitat conditions simultaneously. Data from these studies may help identify key interactions which help explain contradictory findings in the literature, facilitate or direct future research, or potentially be incorporated into conservation plans or fire models.
In the first study, three questions were addressed: in the absence of competition and possible allelopathy: (1) how does Schismus arabicus survival and growth respond to varied shade, moisture and soil-nitrogen treatments combinations? (2) Which microhabitat features (shade, moisture, soil-nitrogen) exert the greatest influence on S. arabicus survival and growth when experienced in combination? And (3) do the results support the assertion that competitive or allelopathic influences outweigh the potential benefits of fertility islands and drive Schismus distribution away from the shrub canopy at the Desert Flame project Mojave site, as proposed in Schafer et al. 2012? Results of generalized linear mixed effects models and visual interpretation of graphs indicated that many multilevel interactions influenced the survival and growth of Schismus arabicus. However, even in the absence of competition or allelopathy, survival and growth variables demonstrated a strong preference for dry open conditions similar to the shrub interspace.
The goal of the second study was to create a set of inexpensive, time efficient and effective methods for germinating Schismus from seedbank soil. Generalized linear mixed model analysis indicated that moisture was the primary driver of germination. As long as an optimal moisture threshold was met, shade and watering periodicity were only influential insomuch as they helped reach and maintain soil moisture levels within the optimal range. The simplest, cheapest and most time effective method for germinating Schismus arabicus from seed bank soil was to apply 9, 12 or 15 ml of water per 40 g of soil every other day in open shade conditions.
Sarah Elizabeth Emeterio
Emeterio, Sarah Elizabeth, "Germination, survivorship and growth of an invasive desert grass, Schismus arabicus, under varied shade, moisture and soil-nitrogen regimes" (2018). Graduate Theses and Dissertations. 16347.