Grays Lake coring in February 1997

GRAYS LAKE NATIONAL WILDLIFE REFUGE, SOUTHEASTERN IDAHO, U.S.A.

The marshes that cover the floor of a former large Pleistocene lake comprise the Grays Lake National Wildlife Refuge, one of the largest in the United States and lying just outside the northeastern margin of the Great Basin. This stop along the flyway is rich in resources that serve the needs of its many visitors. The role of fire in enhancing the marsh ecosystem is an issue that has repercussions for the management of the marsh. A set of cores spanning the last 11,000 years provides the potential for a very detailed Holocene vegetation and climate record. Organic carbon percentage of samples spanning the last 1,000 years reflects productivity in the marsh, that is, greater organic content equals greater marsh productivity. Although short-term responses (increased productivity) of the marsh to fire might have occurred, the only clear relationship is that between lowered water table and fire when the marsh dried out in response to drought. Cat-tail and rush charcoal was used as evidence that fires were occurring in the marsh and not just in the area surrounding the marsh. Appearance of distinctive plant leaf-hairs and changes in pollen types from plants of deeper or fresher (e.g., Ceratophyllum leaf-hairs) to shallower or more brackish (e.g., cat-tail and sedge pollen) water plant species was used as evidence of changes in water depth in the marsh.