PARENT SESSION
Poster Session 10: Restoration and Adaptive Management
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Understory composition with varying light intensity in managed and unmanaged oak openings.
Stanton, Michael *,1, Wolf, Joy2, 1 University of Wisconsin - Parkside, Kenosha, WI, USA2 University of Wisconsin, Kenosha, WI, USA
ABSTRACT- Light intensity was quantified to determine if levels of shadiness in unmanaged and managed bur oak (Quercus macrocarpa) openings affect species composition, shade tolerance, and species richness in the understory. By superimposing a grid over each oak opening to mark 5m x 5m adjacent plots, species composition and shade intensity were recorded in 57 randomly located plots. In each plot, visible light was measured with a light meter with a range of -10 to +6. Our results show that managed sites had overall less canopy cover (51%) and a higher mean light reading (+3.72) than the unmanaged site (97%) (canopy, F = 11.57, P<0.01), where the visible light was significantly lower with a mean reading of -2.06 (light, F = 24.75, P<0.01). The data show that light partitioning affected species composition development. Understory species composition shifted with changes in light availability. As the percent canopy decreased, species richness increased. In the managed site, overall species richness was higher compared the unmanaged site (16 versus 10 species). Depending on light availability, species composition favored shade-tolerant or shade intolerant species. Echinecea and Solidago species were more abundant in sites with less canopy cover, but were out competed by Thalictrum thalictriodes, Geranium maculatum and other shade-tolerant species in higher canopy cover. More woody-stemmed species, such as Rhanmus cathartica and Rubus species replaced shade intolerant grass and forb species. Some species, such as Cornus racemosa, Vitis riparia, and Hypochaeris radicata, with a wide light tolerance range, could exist in full shade or full sun. These generalist species may play an important role in altering species composition and facilitating biological invasion. Future restoration of overgrown oak openings should consider light partitioning and species tolerance to maintain the highest quality of native understory species richness. David, please put this poster (along with Joy Wolf's other poster) on either Wednesday or Thursday evening, per your phone conversation with Joy Wolf regarding schedule conflict with another conference. Or they could go in Friday's poster session, if that works better. Thank you.
Key words: light tolerance, savanna understory, oak canopy cover