Hannah Pfaff, “Timing and Duration of Spring Leaf-Out of Trees and Shrubs in an Urban Woodland”
Mentor: Alison Donnelly, Geography, Letters & Science (College of)
Oral Presentation: 10:45am Union E260
As the climate in Wisconsin changes, the timing and duration of growth-stages in shrubs and trees is changing, in response. For example, budburst and leaf-out are getting earlier as spring temperature increases. Some studies have shown that non-native shrubs leaf-out earlier than native species giving them a significant advantage in their spread and colonization, while other studies have shown the opposite. This study is based on observations taken of different growth-stages (budburst and leaf-out) of a suite of native and nonnative shrubs, and native trees in a temperate deciduous woodland, twice per week. The goal: to determine whether or not non-native shrub species begin growth in spring before native shrubs and trees at our site. The results will help address how native trees, and native and nonnative shrubs are adapting to earlier, milder springs, and how changes in the timing of budburst and leaf-out are influencing their survival, summer growth, and interactions with herbivores and pollinators. Our data collection is part of ongoing research, which suggests that shrub growth-stages are responding faster than tree growth-stages, with some interesting repercussions. Consequences of changing leaf-out timing and duration include native species losing out to competitive nonnative species, earlier pollen seasons, desynchronization with caterpillar and bee populations (which has significant impacts on the food web), and potentially increased annual carbon dioxide absorption, possibly mediating some effects of climate change.