Assessing Ecological Climate Impacts in New Mexico

Populations of drought-sensitive species are decreasing in response to climate change, even in conservation areas and especially at high-elevations, according to a report prepared by two New Mexico ecologists to help wildlife managers prioritize conservation plans.

Species and ecosystems in the Jemez Mountains near Los Alamos, New Mexico, have experienced greater climate-induced stress relative to other priority conservation areas in the state, according to the Nature Conservancy report.
Credit: ©Mary J. Lewis, istockphoto.com

While most studies focus on future climate change, “our study looks at what’s actually been happening,” said Carolyn Enquist, climate ecologist for The Nature Conservancy in New Mexico.

Enquist and ecologist David Gori are producing a three-part report addressing the effects of climate change on biodiversity in New Mexico. The first part, Implications of Recent Climate Change on Conservation Priorities in New Mexico, analyzes past data to assess local areas vulnerable to climate change.

Natural resource managers have heard the global warnings of climate change, but the threats do not always apply locally. Managers hunger for local scientific information they can use now. Still, homegrown research is a rare item on the menu.

“Geography matters,” said Gori, Director of Science for The Nature Conservancy in New Mexico. More rain and warmer temperatures may manifest themselves on a global level, but managers need to know what is happening locally. Location plays a vital role, and managers should not assume all areas will experience the same magnitude and direction of temperature and precipitation change.

Decision makers sometimes lack the applicable science information needed to make appropriate conservation policies. Local ecological research available for management bridges the divide between scientists and managers.

Enquist and Gori assessed the ecological responses to climate change in New Mexico by reviewing past research in changes in population, species distribution and mortality (death rates), invasive (non-native) species influxes, and wildfire relationships to temperature increases.

Population changes appeared as the most common ecological response—specifically population declines, Enquist said. The report found 11 cases linking population change to climate change, including the declining populations of two southwestern bird species: the willow flycatcher and the yellow-billed cuckoo.

The report analyzes climate data from the second half of the century, using 1961–1991 as a baseline. This period “captures the time just prior to, as well as at the beginning of, a notable temperature trend that is attributed to human-caused global warming,” according to the report.

Climate projections have shown a mean global rise in temperature and precipitation. However, Enquist and Gori analyzed local data in New Mexico and illustrated fluctuating mean temperature and precipitation throughout the state.

The report shows temperatures rising in some areas more than others. The Jemez Mountains ranked highest among the key conservation areas in terms of “climate exposure,” an index based on temperature and precipitation patterns.

Figure 1. The Nature Conservancy assessed key conservation area exposure to recent climate variability and change by analyzing temperature and precipitation data from 1991-2005 relative to the previous 30 years (1961-1990).
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Credit: Conservation Science Program, The Nature Conservancy, New Mexico

The warmer, drier conditions in this region, combined with a large number of drought-sensitive species, suggests this mountain range may be vulnerable to ongoing climate change. This is particularly true in light of the dramatic events that have occurred in the area: the Cerro Grande wildfire in 2000 and the widespread pinyon and ponderosa pine forest dieback between 2000 and 2004, Gori said.

“Precipitation changes have been more variable than temperature with 54 percent of the state tending toward wetter conditions, 41 percent drier conditions, and 5 percent showing no discernable change in precipitation,” when comparing recent data to the 1961–1991 climate period, according to the report.

Managers operate with limited financial and human resources, and this study can help establish priorities. Perhaps wildlife managers focus on a less vulnerable conservation area with a good chance of preservation, or perhaps they focus on areas of increasing vulnerability, Enquist said.

Identifying areas that are more, rather than less, affected by climate change may help mangers establish critical habitat based on ecological data. However, because species are predicted to disperse and assemble in novel places, this task will be challenging. Studying these areas even after reserves are set up is also important because the climate will continue to change, affecting the quality of the protected land.

“Monitoring is going to be incredibly important,” Gori emphasized.

The second of the three-part report focuses on recent climate impacts to New Mexico’s watersheds, including trends in snowpack over the past two decades. Part three will build on the first two by adding future climate change projections for managers.

UPDATE: Since this article was written, The Nature Conservancy's New Mexico Conservation Science Program has completed the second of three reports and expects the third report to be available in Summer 2009. Please visit their website to access the reports (see link below).