Long-Term Studies of Ground-Dwelling Arthropod Biodiversity at Bandelier National Monument: Relationships between arthropod community dynamics, elevation, and precipitation in the Jemez Mountains

Lightfoot, David; Fagerlund, Richard

This annual report provides results of an on-going long-term monitoring study of ground-dwelling arthropods at Bandelier National Monument. A long-term study was begun at Bandelier National Monument in 1992 to monitor ground-dwelling arthropod communities in different environments across an elevation and temperature/moisture gradient to gain information on the effects of climate variation on arthropod communities in mountain environments in the Southwest. The purpose of this study was to examine the effects of annual variation in precipitation on ground-dwelling arthropod communities across an elevation gradient. In the semi-arid Southwest United States, annual precipitation is positively correlated with increasing elevation due to orographic precipitation. Mountains provide a gradient in local climatic conditions from dry, warm low elevation environments, to moist, cool high elevation environments. Such environmental gradients are reflected in plant formations, ranging from low-land deserts, to cool moist montane forests. Annual variation in regional precipitation from global climate patterns such as El Niño/La Niña events may have different effects on biotic communities at opposite ends of such elevation/moisture gradients. This study was designed to determine patterns of ground-dwelling arthropod communities across an elevation gradient in the Jemez Mountains of New Mexico, and to determine how communities across the gradient respond to variation in regional climate resulting in abnormally wet years and dry years. The El Niño (wet)/La Nina (dry) cycles provide a regional pattern of above average annual precipitation and below average annual precipitation respectively, in the Southwest United States. We expected to find one of two possible patterns. In one possible scenario, arthropod species living in normally dry and warm low elevation environments may be adapted to dry conditions, and show little response to drought conditions. In contrast, species living in moister, and cooler high elevation environments may be relatively more negatively affected by reduced rainfall in drought years. In a second alternative scenario, species living in dry low elevation environments may be more severely impacted by even drier conditions during drought years. In contrast, the relatively moist, cool conditions of high elevation environments may buffer the effects of drought conditions on biotic communities. The purpose of our research project was to determine if data on a group of organisms living across such an elevation gradient supported one of the above predictions, or perhaps some other pattern.

Long-Term Studies of Ground-Dwelling Arthropod Biodiversity at Bandelier National Monument: Relationships between arthropod community dynamics, elevation, and precipitation in the Jemez Mountains

Collections