Diez, JeffEaston, Anna2024-08-302024-08-302024https://hdl.handle.net/1794/2992039 pagesWhile it's known that warming influences species' reproduction, the interactive effects of warming with other abiotic and biotic factors are less clear. Successful reproduction in annual plants hinges on the production of viable seeds, yet few studies account for variation in seed quality by focusing on seed quantity. In this study, we explore how warming impacts seed and seedling traits across space and stages of fruit phenology. Understanding these traits is crucial for grasping the broader implications of warming on the dynamics of populations and communities, especially in annual plants. We conducted a warming experiment at eight sites distributed across an elevational gradient to ask how warming affects seed characteristics across space. We studied two species of Willamette Valley prairie annuals, Clarkia purpurea and Collinsia grandiflora, and placed open-top warming chambers on half the plots at each site to simulate future environmental conditions. Mature fruits were collected from plots on two dates to examine the interaction of fruiting phenology and warming. We measured mean seed mass and number of seeds per fruit, followed by sowing the seeds in a greenhouse study to measure germination success and speed, and seedling dry root:shoot ratio and total dry mass. We found that the timing of fruit collection had the most impact on seed and seedling traits overall and that warming effects were site specific. For both species, fruits collected later in 3 the season produced fewer and lighter seeds, while germination responses were species-specific. Seedlings from these seeds had decreased dry mass while showing opposing root:shoot ratio responses. Warming exacerbated the difference between early and late seeds for some traits and warming effects varied in magnitude and direction by site for all traits. These findings emphasize the high variability of seed traits among populations and their nuanced sensitivity to shifts in climate. Although there were few consistent effects of warming on seeds, there was significant variability across sites and warming exaggerated the effects of timing of fruit production, indicating that subtle environmental differences could notably impact how these populations respond to climate change. Our findings highlight that predicting population dynamics under future climate conditions will necessitate a detailed understanding of plant functional traits across variable environments.en-USCC BY-NC-ND 4.0EcologyNative plantsSeedsClimate changeBiologyThesis/Dissertation