Protecting small forests fails to protect bird biodiversity

February 20, 2019, Rutgers University

Simply protecting small forests will not maintain the diversity of the birds they support over the long run, a Rutgers-led study says. Forests need to be carefully monitored and managed to maintain their ecological integrity.

A major focus in conservation is acquiring forests—often at great expense—to expand the network of thousands of protected areas around the world. But conservationists cannot simply designate an area as "protected" and assume all species within the area will remain there, according to the study in Biodiversity and Conservation, which focused on a small Rutgers-owned old growth forest within William L. Hutcheson Memorial Forest in central New Jersey.

Though the forest could be considered ideal for many bird species because of its old growth status, nine species no longer nest there, the study says. These species, including the ovenbird (Seiurus aurocapilla) and American redstart (Setophaga ruticlla), were once common sights in the forest. Many other species have lower populations than would be expected.

"We argue that there must be a greater emphasis on monitoring and managing protected areas to achieve conservation goals," said lead author Jeffrey Brown, a doctoral student and member of the Lockwood Lab in the Department of Ecology, Evolution, and Natural Resources at Rutgers University-New Brunswick.

Previous research has shown that invasive plants have increased dramatically in the old growth forest, resulting in a generally open forest floor—except for a few dominant invasive plants such as Japanese stiltgrass—compared with the previously thickly carpeted floor. The population of white-tailed deer has also grown, leading to over-grazing of plants beneath the forest canopy and likely creating less suitable habitat conditions for ground-nesting and migratory birds that have largely disappeared.

Surprisingly little is known about the effectiveness of protected areas in preventing species extinction. Almost nothing is known about biodiversity over the long-term in smaller protected forests in temperate areas like New Jersey, the study says.

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