Copyright © 2016 Albuquerque Journal
A darkling beetle here, a wolf spider there. Is that a camel cricket? No, a Jerusalem cricket.
Sifting through the backlog of samples collected in an ongoing climate change study is a painstaking task for University of New Mexico biology students hunched over trays filled with invertebrates. Working in a basement lab of UNM’s Museum of Southwest Biology, the students use tweezers, illuminated magnifying glasses and field guides to separate the tiny animals into the appropriate family, genus and species.
Initiated in 1992 and funded by the U.S. Geological Survey and the National Park Service, the UNM study is aimed at finding out how climate change affects ground-dwelling arthropods – beetles, spiders, crickets, grasshoppers, centipedes, and millipedes – at Bandelier National Monument in the Jemez Mountains.
“The more basic knowledge we have about insects in the Southwest, the more we understand how climate change affects insects and ultimately us,” said David Lightfoot, UNM research professor and senior collection manager in the Museum of Southwest Biology’s division of arthropods. “We are part of the natural world, and this study helps us understand how it works. Monitoring animals, including insects, in variations of climate and weather patterns gives us a better idea of how to predict what is going to happen and how to adjust to mitigate the effects, how to effectively manage forests and grasslands.”
Survey sites in the Bandelier study are divided into three different elevation levels, ranging from 6,000 feet to 9,500 feet. Piñon pine and one-seed juniper make up the predominant vegetation in the lowest level, with ponderosa pine in the middle level, and mixed conifer species (such as Douglas fir, Engelmann spruce and quaking aspen) at the highest level.
“It’s an outdoor laboratory. It’s the real world,” Lightfoot said. “It offers a diverse region – topography and elevation – and diverse species.”
A specialist in crickets and grasshoppers, Lightfoot has been part of the climate study since it started.
“All this research that was started in the early 1990s was focused on El Niño and La Niña (weather) patterns,” he said. “That was before climate change was a topic of discussion.”
But things are different now.
“Climate is always changing,” Lightfoot said. “But now it is changing faster and may be caused by humans. Temperatures are increasing faster than they have in the last 100,000 years. We are seeing more variation in the climate in the Southwest. We are not seeing a consistent trend in rainfall. Winters are warmer. The snowpacks are less.”
Because arthropods generally have short life cycles and are known to respond rapidly to changes in weather and habitat, a long-term study of these creatures is believed to be valuable in determining how evolving climate patterns affect biologic communities.
“When I first started doing grasshopper work, I knew what I was going to see based on El Niño (wet) and La Niña (dry) weather patterns. Now, nothing is typical. The weather is all over the place. Species that used to be dominant, I’m not seeing now. Species that were not so common, I’m seeing more of. ”
When the study was initiated, it was anticipated that one of two patterns would emerge. The first was that lowland species would be less affected by drought conditions because they live at the driest end of the study area and are more accustomed to life in an arid landscape. According to this theory, creatures living at higher elevations would be more adversely affected because they are less accustomed to drought conditions.
Another theory was that lowland species would suffer when their domain turned even drier, and species living higher up would be insulated from the worst of the drought .
“Science works by predicting things and then checking them out,” Lightfoot said.
Testing these theories meant gathering various species of arthropods over many years. There is no shortage of test subjects. A million species of insects exist in the world.
And previously undescribed species are still being encountered. One reason for that, said Sandra Brantley – a UNM research professor, Museum of Southwest Biology collection manager and spider specialist who joined the climate-study team in 1997 – is that fewer people are looking for insects “because they are not most people’s favorite animal.” Besides, they are small and not that easy to find.
The thousands of specimens collected since the climate study started 24 years ago have been caught in sets of pitfall traps located in all three elevation sites. A trap consists of a steel can about three inches in diameter, buried in the ground with the can opening even with surface. A plastic cup half filled with propylene glycol – a sticky, liquid, organic compound sometimes used as antifreeze – is placed in each can.
“Nocturnal arthropods crawl around on the ground and they fall into these traps,” Lightfoot said.
Comparing numbers collected in each of the elevation sites over the years helps Lightfoot and Brantley determine how each species at each elevation has been affected by climate and other significant events, such as the Las Conchas fire in the summer of 2012.
“In a good year, there are more species present and more individuals in that species,” Lightfoot said. “And in some years, some species are not present at all and there are fewer individuals in the species that are present. If it is too hot and too dry, for example, grasshopper eggs will not hatch.”
Lightfoot said so far the study is showing that low-elevation, ground-dwelling arthropods are more affected by drought than those at higher elevations, and low-level piñon and juniper are affected more by drought than the higher elevation ponderosa pine and mixed conifer.
But the study goes on. Lightfoot said the goal is to compile at least 30 years of data. He said the fact that goal is within reach is truly amazing and unique in this country.
“Most research grants are for three years,” he said. “You can’t do this kind of research in three years. In this country, you just don’t (usually) get this time to study.”