Floristic inventory and floristic quality assessment of the LSL tract, Straits of Mackinac, Emmet County, Michigan.

Abstract

The 55 ha Emmet County LSL tract was obtained in 1990 by Emmet County as an addition to their adjacent Cecil Bay Park. The perimeter of the preserve consists of disturbed roadside and a two-track clearing to the north and a power line in the southwest corner. Though the LSL tract is surrounded by paved road and residential properties, the central core of the site remains fairly untouched. The majority of the site consists of a Thuja forest (37 ha) that surrounds relict beach pools and their surrounding marshes (12 ha). Our objective was to conduct a botanical inventory and floristic quality assessment (FQA) of the LSL Tract to establish a baseline of botanical knowledge that may inform future management of the site. We surveyed the property on four separate occasions in June and July of 2013. We collected every new species we encountered within focal habitats. The inventory consisted of 199 species, 165 of which (83%) were native. Coefficients of conservatism and wetness were calculated for every species identified. The entire tract had an FQA of 66.6, the roadsides 24.0, the power line 14.9, the two-track 34.7, the Thuja forest 37.6, and the beach pool marshes 44.1. The majority of the native plants with high conservation value were located in the beach pool marshes. However, two federally threatened, Great Lakes endemic species (Iris lacustris and Solidago houghtonii) were found in the two-track clearing at the northern end of the property. Some invasive species found in the site that may be able to colonize inner parts of the preserve if trails are established. Of these, Cirsium palustre (swamp thistle) and Fallopia japonica (Japanese knotweed) need to be carefully monitored. Here, we provide suggestions for the protection of the valuable native flora of the LSL Tract, a property that is a noteworthy representation of a Straits of Mackinac native forest and wetland complex.