GROUNDWATER AND NATIVE ORCHIDS IN ALBERTA: IS THERE A LINK?

Many people are surprised to learn that there are approximately 28 species of native orchids (Family Orchidaceae) found in the Province of Alberta, Canada. These plants range from rare to locally abundant, and are hosted in a diverse range of ecosystems from all across the Province. Field observations of the type, and abundance, of native orchid populations revealed a striking (albeit qualitative) correlation to groundwater flow systems. There appears to be a correlation between orchid species and the ecosystem position within the “Unit Basin” of regional groundwater flow systems. A fourfold “classification” groundwater scheme for the native orchids of Alberta has been devised: those found in discharge; recharge; and midline areas; and a group that shows no general preference.

Recognition that there is a link between the groundwater regime and native orchids is significant, for a number of reasons. First, for locating orchid populations it is often useful to make use of the relationship between topography and flow systems: if one can predict from the topography the position in the groundwater flow regime, it can be very helpful in locating previously unknown populations of plants. Second, for understanding habitat function, knowledge of the hydrogeology and hydrology of the ecosystem is of prime importance. Third, for habitat protection and/or restoration it is critically important to understand the source of the groundwater flow system to ensure adequate protection of the entire flow system supporting the orchid population. For example, orchid populations near a spring might be protected at the actual point of groundwater discharge, however the recharge area feeding the spring often remains unprotected and open to disturbance. Thus, knowledge of the linkage between groundwater flow systems and native orchids can be important.