The Wrenn Road Wastewater Treatment Facility in Garner, North Carolina is an ecosystem that uses tree plantations to treat, recycle, and reuse municipal wastewaters. A series of risers set between rows of trees at each stand sprays treated wastewater for an hour per stand. The site has a mixture of planted novel or natural stands, where natural stands are not irrigated by wastewater. This novel system is poorly described with respect to vegetation diversity and wildlife use.
We sought to determine what wildlife and vegetation used the wastewater tree plantation. Through this information, we wanted to describe the ecosystem services of this novel system and compare it to a natural system.
Of the nine stands observed, three contained planted green ash, three had planted mixed pine and green ash, and three were naturally occurring. Each stand held a central camera trap except one green ash, one mixed pine/ash, and one natural stand that instead held two cameras; at the stand center and edge. The cameras were placed using eMammal protocol and surveyed large and medium sized mammals. We used Carolina vegetation survey protocol to determine plant diversity in each stand and took hemispherical photographs to determine canopy cover.
Results/Conclusions Through the camera trap data, we found the majority of wildlife using the site are white-tailed deer. We also captured photos of multiple coyotes, raccoons, red-shouldered hawks, and an opossum. The vegetation surveys revealed a low diversity of vegetation in the non-natural stands as they are dominated by microstegium, a highly invasive exotic grass, and lack midstory vegetation. Microstegium accounted for 80-96% of the cover in novel stands and only 14% of the cover in natural stands. The natural stands had appearingly less microstegium, 2.5 times more plant species than the novel stands, and contained a developing midstory. The wastewater irrigation plantation does not look like anything in nature. It contains very limited diversity of vegetation; however, we have found it is providing ecosystem services to the North Carolina fauna while also allowing the introduction of treated wastewater back into the environment.