Historically, Manitoba supported one-third of the world’s tall-grass prairie ecosystem. It now has less than one per cent of the tall-grass prairie it once had and the remnants are small, threatened patches that can’t be completely revived but can be sustained, a new study says.
In a paper published in this month’s Biological Conservation, Nicola Koper, a University of Manitoba ecologist, studied the extent of tall-grass prairie ecosystems in Manitoba, comparing present data to studies done in the 1980s.
Prairies are the most endangered terrestrial ecosystem in the world and they are the least protected; northern tall grass-prairies are the most endangered, having lost more than 97.5 per cent of their historical extent world-wide. Manitoba, which contains almost all of Canada’s tall-grass prairie, has lost more of this rare feature than any other state or province.
The 1980s survey revealed gloomy prospects for species dependent on this ecosystem of up to 8-foot-tall grass, and since then, Koper found, conditions have deteriorated. A further 37 per cent of prairies were lost since the late 1980s. Prairie quality also declined. Koper found that 21 hectares (ha) seems to be a threshold of sorts: patches smaller than that either disappeared or decayed to an unrevivable state, but those larger than 21 ha grew in size although not necessarily in quality since many alien species now seem set to thrive in them.
The larger patches, the study notes, may have increased in size because of restorative treatments brought about by conservation groups. Therein lies the hope. “However, it remains of great concern that most remnant tall-grass prairies in Manitoba fall below the critical threshold of 21 ha, and are therefore at risk,” the study says.
For more information contact Sean Moore, public affairs, University of Manitoba, 204-474-7963 (firstname.lastname@example.org).