Assessing Differences in Insect Diversity between Pastures, Restored Sites and Flatwoods

By Cherice Smithers

Things are buzzin’ for the botany team! FWRI’s Upland Habitat team is collaborating on an insect diversity study with Dr. David Kaplan and his PhD student Kevin Henson, who are members of the Environmental Engineering Sciences Department at the University of Florida. The study is investigating how differences in plant species composition between pastures, restored sites and native flatwoods communities translate to differences in insect species composition. Insects are a key puzzle piece missing from our understanding of how to achieve functional restoration of former agricultural and pasture land, and this study will help us fill that critical knowledge gap. The findings could be used to assess habitat quality as it relates to insect assemblages, which in turn could influence management decisions seeking to restore and conserve habitat for insect taxa that fill important roles within ecosystems.

We are focusing our assessment of insect diversity on two key functional groups thought to play a central role in ecosystem processes at different trophic levels: pollinators and predatory beetles. Native pollinators, including bees, wasps, moths, butterflies, and flies, sustain many of the plant species of natural communities and serve a critical role in food webs. Beetles of the family Carabidae fill a functional role as ground predators, with diets consisting primarily of herbivorous insects and other herbivorous arthropods. Since many herbivorous insects have co-evolutionary relationships with specific plant species, by extension Carabid beetles are also indirectly linked to particular plant species assemblages.

Our field sites are located at Triple N Ranch Wildlife Management Area (WMA), Half Moon WMA, and Caravelle WMA. At each WMA, we selected a bahiagrass-dominated pasture site (representing low plant diversity), a Native Groundcover Restoration (NGCR) site (representing medium plant diversity), and a reference flatwood site (representing high plant diversity). The NGCR sites are part of an ongoing restoration effort undertaken by the Division of Habitat and Species Conservation’s Wildlife and Habitat Management Section to restore formerly agricultural and pasture land to historic native flatwoods communities. As such, the NGCR sites represent the “middle phase” of an induced succession from pasture lands to flatwoods, and are regularly monitored by the Upland Habitat team.

The Upland Habitat team collected data on the understory species occurring at each of the study sites. In addition, we have collected data on the bloom phenology at each site to help understand pollinator species abundance cycles and feeding preferences. To sample for pollinators, we have set up a vane trap filled with propylene glycol at each point . In addition, a pitfall trap filled with formalin has been set up at each point to collect carabid beetles . Upon collection, insects are stored in ethyl alcohol until they are pinned and identified. The sampling is conducted for a period of one week per month from April through September.

We have collected a wide variety of insects to date, which are currently being identified with the help of Dr. Josh Campbell at the University of Florida Entomology Department. We are hopeful that the results of this study will shed light on ways that natural areas can be managed for the conservation of insect communities and the critical ecological roles they fill.