Anthropogenic habitat disturbance and alteration pose serious threats to the persistence and diversity of bird communities throughout the world. Current ecological research and conservation planning efforts largely focus on understanding the relative influence of habitat composition (e.g. how much) and habitat configuration (e.g. the spatial arrangement) on species occurrence across a landscape. Despite this intensive focus, there is little consensus regarding to what degree fragmentation affects biodiversity, either positively or negatively. Research methods used to assess the impacts of habitat fragmentation on species richness (the number of species in a given area) often rely on generalized, vegetation categories that are based on human-classified land-cover data. However, using such coarsely classified vegetation data as a proxy for actual habitat may be a problematic oversimplification leading to inconsistent results, especially when studying multiple species.
In a new publication selected as “editor’s choice” in the journal Landscape Ecology, researchers from Oregon State University’s Department of Forest Ecosystems and Society and Klamath Bird Observatory tested a novel species-centered technique for quantifying the influence of habitat amount and fragmentation on a community of 48 common bird species in Oregon’s Rogue Basin, including 25 oak-woodland specialists. Rather than using human-classified land-cover data, the species-centered technique uses stacked species-distribution models to quantify habitat amount and configuration. The results suggest that using this species-centered approach to define habitat for entire bird communities reveals relationships between fragmentation and bird diversity that would otherwise be obscured by the use of classified land-cover.
First, the researchers combined unclassified satellite-based land-cover images with bird survey data from over 2,700 locations across the Rogue Basin of southern Oregon to create species distribution models that predict where each bird is likely to occur across the landscape. They used these models to create predicted habitat maps for each of the 48 bird species. These maps were then stacked to provide a community-level habitat prediction for all 48 species. Finally, metrics that quantify habitat amount and fragmentation were calculated using the stacked maps. These metrics were compared to habitat amount and fragmentation metrics developed using classified land-cover to see which best explained bird species richness.
In their paper, the researchers demonstrate that the novel species-centered habitat metrics provided a more statistically robust approach to describe the effects of habitat amount and fragmentation on species richness than were derived using traditional land-cover classifications. Their results support the “landscape fragmentation hypothesis” which posits that species richness declines linearly with increased fragmentation. Lead author Kate Halstead suggests that, “while complex, our species-centered methodology may provide a more accurate picture of the relationship between habitat composition and configuration and species richness. The power of our methods lies in their embrace of the complexity inherent in natural systems, providing insight into theoretical and applied questions alike in a way that is not possible using the generic land-cover based approach. From investigating the drivers of biodiversity, to exploring how edge specialists might respond to landscape change predicted under changing climate scenarios, this approach has broad potential utility across systems and taxa.”
The paper, titled Using a Species-centered Approach to Predict Bird Community Responses to Habitat Fragmentation, was published in Landscape Ecology in July 2019.
This research was completed in collaboration with the American Bird Conservancy and the Klamath Siskiyou Oak Network. This work was funded in part by the Neotropical Migratory Bird Conservation Act as part of the Quercus and Aves Program, and by the National Science Foundation.
The Department of Forest Ecosystems and Society at Oregon State is world renowned for its education, outreach, and research in the areas of forest science, natural resources, and tourism, recreation and adventure leadership. Students and faculty study and work in Corvallis, at OSU-Cascades in Bend and around the state, nation and world. The Department’s research impacts policy and land management decisions worldwide and outreach programs benefit communities throughout Oregon.
The Forest Biodiversity Research Network is rooted at Oregon State University and conducts collaborative research throughout the world’s forest ecosystems to foster a global awareness of biodiversity, facilitate science-based solutions to ecological crises and support a sustainable future for both nature and society.
The Klamath Bird Observatory (KBO) is a non-profit organization that advance bird and habitat conservation through science, education, and partnerships. Working in the Pacific Northwest and throughout the ranges of migratory birds KBO emphasizes high-caliber science and the role of birds as indicators to inform and improve natural resource management. KBO also nurtures an environmental ethic through community outreach and education.