Abstract Detail

Ecology

Limbird, Eric [1], Walck, Jeffrey [2], Phillips, Nathan [3], Hidayati, Siti [4].

Using open top chambers to test winter conditions in redcedar woodlands of middle Tennessee.

Winters in middle Tennessee, and throughout most of southeastern United States, are mild with warm spells lasting a few days that are interrupted by cold snaps when soils freeze. While studying exotic woody plants, which are dominant in forests of middle Tennessee, we have found that: (1) their seeds are less dormant, (2) a few seeds germinate during winter warm spells in the field, (3) peak germination in the field occurs earlier (late winter to early spring) than native plants, and (4) seed viability can be greatly reduced with simulated warm spells. Although exotic seedlings tolerate freezing to -10°C, those that germinate during mid-winter do not survive late winter freezes but those that germinate in late winter do survive. Thus, we hypothesized that under simulated future conditions of warmer winters: (1) peak germination will shift to mid-winter for exotics, (2) seedlings of exotics that emerge during mid-winter will survive, and (3) seed viability will not be reduced with a warm spell. We used open top chambers (OTCs), which function as miniature greenhouses, to simulate milder winter conditions within a mostly redcedar (Juniperus virginiana) woodland in middle Tennessee. We sowed seeds into trays placed in the middle of OTCs and placed outside of OTCs (control) from four species that contrast in their seed ecologies: Euonymus fortunei (exotic, seeds are dormant and susceptible to freezes), Lonicera maackii (exotic, seeds mostly non-dormant and readily germinate), Celtis laevigata (native, seeds are dormant and germinate late), and Juniperus virginiana (native, seeds moderately dormant and germinate early). In addition, we placed seeds into nylon mesh bags and interrupted the ambient winter condition by placing them at 20/10°C for 3 days in an incubator. Although mean temperatures inside our OTCs did not differ from ambient (control) temperatures, maximum temperatures in the OTCs were higher than the ambient particularly when sunlight filtered through the redcedar canopy. Seed germination and viability of the four species did not differ between the OTCs and control. However, viability of the native, but not exotic, species was greatly reduced with a warm spell interruption during winter. The failure of our OTCs to warm above ambient conditions was probably due to the mostly shaded conditions of the woodland.

1 - Middle Tennessee State University, 1500 Greenland Ave., Murfreesboro, TN, 37132, USA
2 - Middle Tennessee State University, 1301 East Main St, PO Box 60, Murfreesboro, TN, 37132, USA
3 - Middle Tennessee State University, Agriscience and Agribusiness, 1500 Greenland Ave., Murfreesboro, TN, 37132, USA
4 - Middle Tennessee State University, Biology, 1301 East Main St, PO Box 60, Murfreesboro, TN, 37132, USA

Keywords:
none specified

Presentation Type: Poster
Session: P, Ecology Section Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEC026
Abstract ID:665
Candidate for Awards:None