Complex sentence: The preserve in Manitoba was only discovered in the late 1980s by botanists of the Manitoba Naturalist Society who were cataloging native plant species in the area and discovered that a significant portion of the tallgrass prairie remained despite the belief it had been wiped out.
Split into simpler sentences: The preserve in Manitoba was only discovered in the late 1980s by botanists of the Manitoba Naturalist Society who were cataloging native plant species in the area. They discovered that a significant portion of the tallgrass prairie remained despite the belief it had been wiped out.