Long-term studies of ground-dwelling arthropod biodiversity at Bandelier National Monument: 2014 Annual Report

Brantley, Sandra; Lightfoot, David

This annual report summarizes recent results of an on-going long-term monitoring study of ground-dwelling arthropods at Bandelier National Monument. This study is sponsored and implemented by the U.S. National Park Service; Valles Caldera National Preserve and Bandelier National Monument, the U.S. Geological Survey, Jemez Mountains Field Station, and the Division of Arthropods, Museum of Southwestern Biology, University of New Mexico. The purpose of this research is to evaluate the responses of ground-dwelling arthropods to variation in climate across an elevation gradient in the Jemez Mountains of north-central New Mexico, USA. Climate change has become a serious environmental perturbation that has enormous consequences for natural resource management, especially in the American Southwest. As the climate of the Southwest becomes warmer and more variable with increased frequency of extreme weather events, natural resource managers need a better understanding of how ecosystem function and component biota are responding to climate change. Ground-dwelling arthropods are abundant, high in species richness, and ecologically sensitive to climate conditions. Studies of montane ground-dwelling arthropods in the U.S. have been few, especially at the species community level. This study was designed to describe patterns of these ground-dwelling arthropod communities across an elevational gradient, and to associate those changes with large-scale weather patterns, such as El Niño Southern Oscillation (ENSO) events and ongoing atmospheric warming and changes in precipitation patterns that are changing the overall climate of the American Southwest. Long-term (i.e., decade plus) research enables us to evaluate changes in arthropod community compositions in order to relate such changes to especially dry (La Niña) or wet (El Niño) years, and to detect possible time lags in responses among different taxonomic and ecological groups of arthropods. Mountains of the Southwest provide elevational gradients that extend from lower elevations, which are typically dry and warm, to high elevations, which are typically cooler and receive more precipitation. These abiotic differences produce obvious changes in vegetation patterns and associated animals. The ENSO cycle and other patterns of climate change can be considered natural "treatments" applied across the gradient. If arthropods respond to ENSO events or other changes in precipitation, we expect to see one of two likely patterns. Our first research hypothesis is that lowland species would be less affected by drought conditions because they are adapted to dry and warm conditions. Species at high elevations, which generally do not experience warm or dry conditions, might be more strongly and negatively affected. Our second research hypothesis is that lowland species may experience more negative conditions when their habitats become even drier, while montane species are more buffered against the severity of the drought. Furthermore, both potential processes may occur simultaneously, with some arthropods responding one way, while other arthropods respond the other way. The purpose of this research project was to determine if data on a group of organisms living across such an elevational gradient supported one of the above predictions, or perhaps some other pattern. This project has been funded by Dr. Craig Allen, formerly of the U.S. National Park Service, now of the U.S Geological Survey, from 1992 until 2013. Dr. Robert Parmenter of the National Park Service provided funding in 2015 to process a backlog of samples; 2014, 2015, and 2016. This entire study was terminated in April, 2017. This report provides information on the 2014 arthropod samples.