PARENT SESSION
Wednesday, August 9, 8:00-11:30 am
COS 58 - Temperate deciduous forest ecology
Sultana, Mezzanine Level, Cook Convention Center
Presiders: G Wang

Understory vegetation recovery from the seed bank following herbicide application in northern hardwood forests.

Ristau, Todd^*,1, ¹ USDA Forest Service, Northern Research Station, Warren, PA

ABSTRACT- Dense layers of interfering plants can prevent establishment of diverse tree species following forest overstory removal. Herbicide application is an effective method for reducing competition with tree species establishment when done with fencing and partial cutting. Understory plants are temporarily reduced in coverage by herbicide. We tested the role of the seed bank in vegetation recovery after herbicide application at three 13 ha sites on the Susquehannock State Forest in Pennsylvania. Glyphosate (3.5 l/ha) and sulfometuron methyl (146 ml/ha.) herbicides with 0, 73, or 146 ml/ha imazapyr were mixed in 234 l/ha of water and applied in July or August of 2004 (7 treatments including a control). Understory vegetation was surveyed before and after treatment. Seedling emergence was monitored in a greenhouse using soil cores (10 cm diameter, 5 cm deep). Carex spp., Danthonia compressa, Dryopteris intermedia, Huperzia lucidula, Maianthemum canadense, Oxalis acetosella, Viola mackloskeyi and Viola rotundifolia dominated the herbaceous layer before treatment. Acer pensylvanicum, Fagus grandifolia, Prunus serotina, and Acer rubrum dominated the woody vegetation. The seed bank consisted primarily of Carex spp., Rubus allegheniensis, Danthonia compressa, Prunus pensylvanica, (43, 20, 16, and 10 percent respectively) with several other species making up the other 11 percent. Vegetation after treatment consisted primarily of seed bank species and plants that were able to survive herbicide treatment. Danthonia compressa, Carex spp., Rubus allegheniensis, and Viola spp. dominated plants germinating in the field. No differences among treatments were observed in this early stage after treatment. Very few tree seedlings germinated following treatment.

Key words: northern hardwood forest, seed bank, herbaceous plants