Impacts of forest management on medicinal herbs in the Missouri Ozarks

Abstract

As agroforestry becomes more accepted in the Midwestern US, understanding how non-timber forest product growth is impacted by forest management practice becomes increasingly important. Timber harvest and prescribed fires are common forest management practices in the Central Hardwoods Region, and canopy gaps commonly result from these practices. Three studies were conducted in central and southern Missouri to assess the impacts of forest management. One of the studies focused on the effects of discrete canopy gaps on the height, reproduction and mortality of transplanted Actaea racemosa L., Allium tricoccum Aiton, Collinsonia canadensis L. and Hydrastis canadensis L. This study was replicated at the Horticulture and Agroforestry Research Center in New Franklin, MO as well as the Doug Allen Project Site in Gravois Mills, Missouri. Results indicate that small canopy gaps may prove beneficial for increasing rates of photosynthesis, as well as the height and sexual reproduction of the study species. Using ground flora cover data from the Missouri Ozark Forest Ecosystem Project, a second study was conducted on the relationships (P less than 0.05) between size and abundance of eleven herb species with ecological site types and the following timber harvest types: clearcutting, group selection, single-tree selection and intermediate thinning timber and no harvest (control). The goals were to ascertain whether ecological site descriptions can be used in conjunction with silvicultural management to select and manage sites for forest farming.Study species included Actaea racemosa L., Apocynum cannabinum L., Aristolochia serpentaria L., Dioscorea quaternata J.F. Gmel., Echinacea simulata R.L. McGregor, Geranium maculatum L., Hydrastis canadensis L., Parthenium integrifolium L., Podophyllum peltatum L., Sanguinaria canadensis L. and Tephrosia virginiana (L.) Pers. Uneven-aged management harvest types were significantly positively related to the percent cover and/or frequency of A. racemosa, E. simulata, G. maculatum, H. canadensis, P. peltatum and S. canadensis. Percent covers and/or frequencies of A. racemosa, A. cannabinum and A. serpentaria were significantly , positively related to mesic ESDs only, while the percent covers and/or frequencies of D. quaternata, G. maculatum and P. integrifolium were significantly , positively related to specific mesic and specific xeric ESDs A third study was conducted using the ground flora cover data from The Nature Conservancy's Chilton Creek Management Area, to assess significant (P less than 0.05) relationships between size and abundance of eight herb species with different ecological site descriptions under prescribed fire management. Goals for the study included identifying forest farming sites and planning prescribed fire management that, paired together, might stimulate growth of these plants. Study species included Actaea racemosa L., Apocynum cannabinum L., Aristolochia serpentaria L., Dioscorea quaternata J.F. Gmel., Geranium maculatum L., Parthenium integrifolium L., Sanguinaria canadensis L. and Tephrosia virginiana (L.) Pers. Percent cover values for the following species were positively related to time since beginning of experiment: A. racmosa, A. serpentaria, A. cannabinum, D. quaternata and T. virginiana, and frequency of A. cannabinum and D. quaternata was positively related to time since beginning of experiment. Representatives of these species significantly increased in percent cover over time and in the latter subset, had higher frequency over the course of prescribed fire management. Small canopy gaps may be beneficial to non-timber forest product species in oak hickory forests. Knowledge of how these species perform on particular ecological site descriptions can influence forest farming site selections. Additionally, decisions about which overstory management activities will be conducted, whether these be timber stand improvement activities involving canopy-gap creation, unevenaged management timber harvest types, and prescribed fire, can be used to determine whether forest farming operations can be synergistic with the existing silvicultural management plan.