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Document Type

Peer-Review Article

Abstract

Alvars are rare grassland communities found in the North American Great Lakes Region consisting of thin mineral soil over limestone bedrock and act as refugia for many unique and threatened endemic species. Few studies have catalogued Hemiptera species present in the alvars of the Maxton Plains on Drummond Island, MI. We aimed to add to these species lists, compare species diversity between alvar sites with varying levels of exposed bedrock, and test if an unpaved limestone road running through our sample sites influenced Hemipteran populations. We collected several prairie endemic species of Cicadellidae (Hemiptera), including a new record for the island, Laevicephalus unicoloratus. We found that pavement alvars, those with large portions of exposed bedrock, had higher species diversity on both of our collection dates despite having less overall vegetation when compared to grassland alvars with continuous soil coverage (H’ – Date 1: pavement = 0.649, grassland = 0.471; H’ – Date 2: pavement = 0.982, grassland = 0.855). We observed that distance relative to the unpaved limestone road affected the population densities of our target Hemiptera groups (Cicadellidae, Aphrophoridae, and Delphacidae), likely due to dust arising from dry conditions and road use. Our results, and the results of others, indicate the biological uniqueness of the alvars. Alvars face threats from off-road vehicle use, individual disregard for their conservation, and a changing climate. The continued monitoring, maintenance and protection of remaining alvars is imperative if their existence is to be continued beyond our lifetime.

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