Geomorphological and meteorological drivers of ephemeral pond hydrology in the Canadian shield forest

Abstract

AbstractEphemeral ponds in cold and humid forested regions are often vulnerable because of their small size and ephemeral nature. The aim of this study was to identify the geomorphological and meteorological drivers of ephemeral pond hydrology in the forests of cold and humid climates. A multi‐year study of 40 ponds was conducted in the Kenauk forest located in the Canadian Shield of the Outaouais region (Quebec, Canada). Pond bathymetry, mineral and organic sediment thickness, watershed area, slope, canopy cover and maximum depth were measured in‐situ. The spring hydroperiod (the period during which there is water in the ponds between April and October) as well as the surface and groundwater recession rates were measured throughout the study period, from 2016 to 2020. Data from this study show that ponds located at lower altitudes in the landscape are larger, receive water from a larger area, and have longer hydroperiods than ponds located at higher altitudes. The results demonstrated a connection between the ponds and the surrounding aquifer. Spring and early summer precipitation was shown to affect hydroperiods the most, while summer precipitation influenced the presence of water in the ponds from April to October. Winter precipitation appear determinant for pond recession rates. Simple multiple regression models were able to simulate hydroperiods and hydroperiod indices relatively well, but pond recession rates were not well represented by the models. This study brings original multi‐year and multi‐site data identifying parameters and variables that determine ephemeral pond hydrology in cold and humid climates. The results provide new insights into their resilience on the landscape and bring new arguments for their long‐term protection.