Woodland herbs account for a significant amount of the biodiversity found in temperate deciduous forests. Although they sometimes appear as solitary plants, usually they are found in patches that are not uniformly distributed. Most herbs seem to be found in sites that are a little wetter or have a little more light, such as in canopy gaps.
The responses of woodland herbs to treefall gaps are complex. We found, for example, that few individuals of Bellwort (Uvularia perfoliata) produce flowers in the deep shade of the forest, and flowering was more common in gaps. Plants which grew in areas associated with past or present treefalls had much higher genetic diversity compared to patches in undisturbed areas of the forest. This high genetic diversity suggested that some patches of plants may be very old and that the high genetic diversity may reflect a series of different treefall gaps that occurred over many decades.
Wild comfrey is a woodland herb that occurs in older forests at SERC. We marked individual plants in three populations and followed their fate over several years. A large percentage of individuals flowered in one of the populations shortly after a treefall gap was created. Seed production was also higher in the gap population. However the benefits gained by this short-term flowering response have been few, only two seedlings produced during the gap formation survived. All individuals that flowered and produced seeds decreased in size. Only 1 individual reflowered, suggesting that the initial high rate of flowering and successful seed production, associated with the creation of the gap, may have resulted in the utlization of stored nutrients. Gaps may only be beneficial for Wild Comfrey if seeds are dispersed outside the gap area or if seeds can remain dormant in the soil until conditions are more suitable for seedling survival.
This long-term study on Wild Comfrey (Cynoglossum virginianum) demonstrated that even though gaps may benefit understory herbs, these benefits may not be clear cut or long-term.
Our interest in the ecology of woodland herbs has been wide-ranging and we refer you to our publications to learn more.