Document: COD-3-68-14

Prescribed burning and overstory reduction as tools for restoration of ponderosa pine forests.

WIENK, C.L.* ¹, C.H.SIEG ² and G.R.MCPHERSON ¹

University of Arizona, Tucson, AZ, 85721, USA ¹
USDA Forest Service, Rocky Mountain Research Station, Rapid City, SD, 57701 ²

Abstract:
Disturbances such as fire have been absent from many forests for up to a century, with consequent impacts on ecosystem structure and function. In dense stands of Pinus ponderosa Laws. (ponderosa pine) in the Black Hills of South Dakota, understory vegetation has been replaced by a thick layer of pine needles. We experimentally addressed the main and interactive effects of prescribed burning (two levels) and overstory reduction (three levels) on understory vegetation. In addition, we examined the extent to which lack of a soil seed bank constrains understory recruitment in dense forests. Finally, stand history was examined by utilizing dendrochronological methods to determine fire history and stand age, and by researching historical documents to determine land use history. Dendrochronological results indicate that the stand is approximately 100 years old and has not burned for at least 100 years. Response of understory vegetation during the first growing season after application of treatments was very sparse, with no significant differences between treatments. Only 24 individual plants (representing 10-14 species of herbaceous dicots and 1-2 grass species) emerged from 1080 pretreatment soil samples. Paucity of viable seeds in the soil seed bank may constrain recruitment of understory vegetation in dense, undisturbed coniferous forests, such as ponderosa pine forests of South Dakota.

Keywords: Pinus ponderosa, fire ecology, soil seed bank, dendrochronology, timber harvest

This abstract is being presented at: 4:45 PM in session:
Oral Session #35: Fire Ecology.