Rare plants are often an indicator of uncommon or disappearing habitats. When you think of these rare habitats, you often think of a fragile type of an environment that requires special care and management. A beach is such an area.
Beaches are very dynamic. Annual fluctuations in Great Lakes water levels and even one severe storm can wipe out a population of plants or bring in new seeds or roots to establish new plant communities. A process known as littoral drift is the process by which waves on Lake Erie move sand eastward along the south shore and westward along the north shore. When we construct shoreline protection we affect the natural littoral drift. To the west of the protection, sand is built up; to the east, the beach is starved for sand.
Fringed gentian
Beach plants have been surveyed for a number of years at Lakeshore Reservation in North Perry. As the lake levels have risen and fallen over the years, so have the number of beach plants present. During a period of high water in 1997, only two individual beach plants were found. As lake waters dropped and more habitat was exposed, the population rose to 5,371 individual plants in 2005. A slight rise in lake levels dropped that number to 3,960 in 2010. This ever-changing environment makes it necessary to conduct annual surveys.
Two of the eight rare plants found at Lake Erie Bluffs, fringed gentian and golden-fruited sedge, occur on the slumps above the beach. Slumps are a natural process where the bank occasionally slips and exposes bare soil. The upper layer of soil is porous and the lower layer is not, which causes water to flow over the non-porous layer resulting in occasional slides. If it were not for occasional landslides, trees and shrubs would crowd out rare species.
Golden-fruited sedge
Three of the rare plants are actually of maritime origin. These plants are inland beach-pea, inland sea-rocket and seaside spurge. How they arrived on our beaches is an amazing story (see Ice Age Beach Plants below). These plants actually thrive on natural disturbance. However, disturbances from man (i.e. constructing shoreline protection and clearing beaches and slopes) destroy the habitat for these rare plants. Lake Metroparks’ goal is to allow this area to maintain itself naturally.
Inland sea-rocket
Approximately 13,000 years ago, much of North America was covered by a glacier. The weight of the glacier caused the ground below to compress. As the glacier retreated, the compressed area was below sea level and flooded by glacial melt water and salt water from the Atlantic Ocean. This large brackish lake was known as the Champlain Sea. This sea actually contained marine species like Beluga whales and Atlantic cod (bones of whales have been found well inland).
This period is likely when various beach plants moved into what is now the Great Lakes basin. The sea remained until approximately 10,000 years ago when the ground started slowly rebounding as the weight of the glacier was removed. As the land rose above sea level, fresh water eventually replaced salt water. Amazingly, the ground around the Great Lakes continues to rebound to this day as evidenced by GPS satellite data (this rise is only a few inches every century.)
Inland beach-pea
Seaside spurge