Interactions between white-tailed deer density and the composition of forest understories in the northern United States

Abstract

Woodall, Christopher W.; Potter, Kevin M.; Walters, Brian F.; Domke, Grant M.; and Oswalt, Christopher M., "Interactions between white-tailed deer density and the composition of forest understories in the northern United States" (2017 a b s t r a c tForest understories across the northern United States (US) are a complex of tree seedlings, endemic forbs, herbs, shrubs, and introduced plant species within a forest structure defined by tree and forest floor attributes. The substantial increase in white-tailed deer (Odocoileus virginianus Zimmerman) populations over the past decades has resulted in heavy browse pressure in many of these forests. To gain an objective assessment of the role of deer in forested ecosystems, a region-wide forest inventory across the northern US was examined in concert with white-tailed deer density information compiled at broad scales. Results indicate that deer density may be an additional driver of tree seedling abundance when analyzed along with stand attributes such as aboveground biomass, relative density, and stand age. Tree seedling abundance generally decreased as deer density increased above 5.8 deer km 2 for all forest type groups with the exception of oak-dominated forests. Findings indicate that introduced plant species, of which 393 were recorded in this study, increased in areas with higher deer density. The abundance of whitetailed deer is just as important as forest stand and site attributes in the development of forest understories. Given the complexity of forest and land use dynamics across the northern US, this study provides directions for future research as more data linking forest-dependent wildlife and forest dynamics at regional and national scales become available.

Compounding human stressors cause major regeneration debt in over half of eastern US forests

“…Nonetheless, regeneration debt is usually inevitable where the current regeneration trajectory differs from the adult community. In the near term, regional patterns of consistently low-regeneration density or suboptimal composition can reveal concerns about the long-term viability and adaptive capacity of a given forest biome (Bradshaw & Waller, 2016;Russell et al, 2017).…”

“…Although the regeneration niche has been extensively studied, we are aware of few macroecological studies that examine the influence of multiple stressors on regeneration abundance and composition. For example, Russell et al (2017) documented strong associations between stressors and low-seedling densities covering a large area of the eastern US forest. However, they did not consider regeneration mismatch (composition) and their analysis was not spatially explicit.…”

Estimating aboveground live understory vegetation carbon in the United States

“…Understory vegetation (UVEG) plays a key role in ecosystem function and the terrestrial carbon cycle (Hou et al 2015, Saitoh et al 2014. The composition of shrubs, forbs, graminoids and seedlings interact with and influence plant diversity, forest productivity and nutrient cycling (Yarie 1980, Mallik 2003, Gilliam 2007, Moore et al 2007, and wildlife diversity and abundance (Pardini et al 2005, Russell et al 2017. Despite the importance of UVEG, relatively few measurements of UVEG characteristics are available compared to the overstory.…”

A reconceptualization of open oak and pine ecosystems of eastern North America using a forest structure spectrum

“…Other factors, such as drought and soil limitations, may cause enough tree mortality to produce persistent open forests at smaller spatial and temporal scales, but will not favor only fire-tolerant oak and pine species throughout large regions. As for large herbivores, white-tailed deer (Odocoileus virginianus) densities are at or above historical highs, but while they may be selectively affecting certain tree species, deer are not browsing forests sufficiently to prevent some type of closed forests from developing (Rooney and Waller 2003, Bradshaw and Waller 2016, Russell et al 2017).…”