BREEDING SEASON AVIAN COMMUNITY COMPOSITION AND PREY AVAILABILITY IN EUCALYPTUS AND SLASH PINE PLANTATIONS OF SOUTHWESTERN LOUISIANA

摘要

The increased demand for wood products related to industries such as bioenergy and paper has resulted in a need for a consistent supply of raw materials. Eucalyptus (Eucalyptus spp.) plantations have the potential to boost wood production for pulpwood and biomass feedstocks. Species characteristics such as rapid, indeterminate growth, coppice regrowth, resistance to disease and insects, and tolerance of a range of environmental conditions make these species successful short-rotation woody crops (SRWCs). Camden white gum (Eucalyptus benthamii), a more cold tolerant species, has made management of eucalyptus plantations viable in southern portions of the United States such as the Western Gulf Coastal Plain. However, few data exist to determine biodiversity impacts of plantation conversion from pines (Pinus spp.) to eucalyptus. Rather, most literature compares biodiversity between native forests to non-native plantations in various parts of the world. To make a preliminary assessment of biological impacts from conversion of native plantations to eucalyptus plantations, I determined arthropod abundance, family richness, and diversity as an indicator of prey availability for breeding birds in eucalyptus plantations. I compared these results to slash pine (Pinus elliottii) plantations of similar age and also of similar height in southwestern Louisiana during bird breeding seasons of 2014 and 2015. I also compared avian diversity, occupancy, density, and community composition among stand types. Finally, I identified landscape and stand-level factors that affect occupancy by various avian species of conservation concern.Eucalyptus plantations had similar arthropod richness and diversity to pine stands of both ages. Arboreal arthropod abundance was less in eucalyptus plantations and this may be attributed to their being an exotic species. However, arboreal arthropods were a minor component of overall arthropod communities across all stand types. Understory vegetation diversity and structure in eucalyptus stands were similar to younger pine plantations and may be the major factor influencing arthropod availability in all stand types. Contrary to arthropod occurrence, bird species occurrence and communities were more similar between eucalyptus plantations and mid-rotation pine plantations of similar height. However, these stands were still able to retain species and communities associated with early successional pine habitat, thus suggesting avian communities in young eucalyptus plantations were intermediate between the communities in 1-2-year-old and 6-7 year old pines. Future implications of conversion to these plantation types may include reduced arthropod abundance with stand age and reduced grassland-associated and cavity-nesting birds.