In their ambitious experiment, Joshua J. Tewksbury of the University of Florida and his colleagues created eight similar landscapes in the Savannah River Site in South Carolina, a federally protected research area. Each of the locations featured five patches of logged and burned ground cover surrounded by mature forest (see image for an overhead view). To test the interactions between patches, the team planted male holly bushes in the middle site and female holly bushes in the four surrounding sites, one of which was connected to the central patch. Holly is not naturally present in the forest, and the female plants cannot bear fruit unless they are pollinated. Compared with plants in unconnected patches, significantly more of those in the field linked to the central patch by a corridor bore fruit: the proportion of flowers that produced berries was 69 percent higher.
The researchers also tested the effect corridors had on seed dispersal by birds. After marking thousands of seeds in the central patch with a sticky powder visible under fluorescent light, the scientists analyzed bird droppings containing ingested seeds to track the animals' travels. According to the report, nearly 20 percent more fluorescent fecal samples were collected in connected patches than in isolated ones, indicating that the corridors facilitate the birds' movement. Says Tewksbury: "Our study suggests that these corridors do help in connecting populations, and theoretically, they should help sustain networks of populations existing in increasingly fragmented landscapes."