COS 274-2 - Effects of linear disturbance on biodiversity across multiple taxonomic groups

Abstract: Linear disturbances such as roads, paths, and railways, are an increasingly common feature of many landscapes. These disturbances can have important impacts on biodiversity through habitat fragmentation and the creation of edge effects. However, much of our understanding of the effects of linear disturbances has come from studies that have been limited in their geographic extent, taxonomic breadth, or both. Additionally, poor records of linear disturbances like dirt roads can lead to under-estimation of the degree to which linear disturbances are present within a study area. To overcome these challenges, we examine how linear disturbances affect biodiversity at 47 terrestrial sites within the National Ecological Observatory Network (NEON) across five different taxonomic groups: terrestrial ground beetles, small mammals, breeding land birds, mosquitoes, and ticks. Light detection and ranging (LiDAR) data from the NEON Airborne Observation Platform were used to generate high spatial resolution (1-m) elevation maps of all NEON terrestrial sites. These maps were combined with road, railroad, and stream spatial layers from the United States Census and National Hydrography datasets, respectively, then shapefiles of additional, undetected linear features visible in the LiDAR map were made in QGIS. Final cumulative road and railroad layers for each NEON site were validated with high resolution Google Earth imagery during leaf-off period in areas with deciduous canopy and additional archives of site-specific maps. Using this linear disturbance data product, we created generalized mixed models for each of our focal taxa to examine how biodiversity metrics such as species richness, evenness, and beta diversity were affected by distance to the nearest road and habitat fragmentation due to roads and railroads. We also included climatic variables and National Landcover types in these models to account for other factors that can regulate the biodiversity of our focal taxa. Preliminary analyses suggest that small mammal richness is not directly impacted by the distance to roads. However, the overall effect of linear disturbances appears to vary among taxonomic groups and with the number of roads crossing through a site. Ultimately, this research suggests that the effects of linear disturbance are scale and taxon dependent.