Water Table Depth, Surface Saturation, and Drought Response in Bog Turtle (Glyptemys muhlenbergii) Wetlands

Abstract

The bog turtle (Glyptemys muhlenbergii) is known to select wetland areas that are near water with deep mud, but water table dynamics in their habitats have not been well described. We installed and monitored shallow groundwater wells to evaluate hydrology over a continuous 28-month period on six wetlands known to be frequently used by bog turtles and six similar wetlands not known to be used. Overall, water tables remained high, with mean monthly depth to the water table for all 12 wetlands varying between −1 cm and −35 cm below the soil surface. Wetlands frequently used by bog turtles had higher mean water tables and surface saturation than wetlands not known to be used, particularly during summer months. Differences in mean water table (17 cm) and saturation (25 %) were greatest during southwestern Virginia's 2008 drought. A differential remained after the resumption of normal rainfall, demonstrating the importance of groundwater recharge to bog turtle wetlands. Relatively small differences in water table hydrology have the potential to affect bog turtle biology and wetland use because bog turtles primarily use the top 15 cm of the soil and select saturated locations even when the availability of saturated soil is limited.

A hydrologic and land cover‐based habitat model for use in bog turtle (Glyptemys muhlenbergii) conservation

“…Lower organic matter soils associated with large floodplains are not typical of occupied habitats (Feaga et al, 2013). Flooding in the seepage areas of the occupied wetlands is not a common occurrence even during large rains, although it can occur (Feaga et al, 2012). Hydrology sources on floodplains are typically overbank flooding while hydrology on lower order streams is associated with groundwater sources (Brinson, 1993).…”

“…Bog turtles are found in and near soils of nearly continuous water saturation (Carter et al, 1999;Chase et al, 1989;Feaga et al, 2012Feaga et al, , 2013Pittman & Dorcas, 2009;Pitts, 1978). As a result, previous efforts modelling potential bog turtle habitat consistently incorporate published data from the National Wetlands Inventory (NWI), the National Hydrography Dataset (NHD) and Soil Survey maps for identification of landscape hydrologic features (Buhlmann et al, 1997;Myers & Gibbs, 2013).…”

Landscape-level Factors Influencing Bog Turtle Persistence and Distribution in Southeastern New York State

“…This heterogeneity may also offer more options to bog turtles across variable environmental conditions. For example, Feaga et al (2012) reported that bog turtles in Virginia shifted their movements in response to droughts. Finally, larger wetlands may be more resistant to vegetative changes from nutrient runoff.…”

“…Greater upstream area typically acts to attenuate flood pulses, moderating the intensity of downstream flood events. Feaga et al (2012) found evidence that bog turtles occur in wetlands with low flood frequency, which he attributed to reduced flood-caused erosion of organic soils and destructive inundation of bog turtle nests. Indeed, the short-term impacts of beaver flooding are known to be destructive to nearby bog turtle sites in Massachusetts (Sirois 2011).…”