Space to Move

Plot of Mass Extinction Data
A plot of data on mass extinctions. Credit: University of Chicago

Connie Millar studies responses of forests to climate change, both dramatic and subtle. Summer research finds her near the crest of the Sierra Nevada and Great Basin ranges measuring the advance and retreat of mountain meadows and snowfields or coring gnarled, weather-beaten pines for tree rings to decipher high-elevation climate change.

A research geneticist with the Pacific Southwest Research Station since 1987, Millar joined with other station scientists to form the interdisciplinary Sierra Nevada Research Center (SNRC) in 2002. Within the SNRC,Millar’s research group focuses on climate as an ecosystem architect: how it affects forest structure and species composition.

With her collaborators, Millar also looks at how climate catalyzes and combines with other natural agents of change such as fire, disease, insect infestations, and flooding, as well as with human-related impacts such as grazing, fire suppression,and timber harvest.

living biosphere
"Planetary biospheres are complex entities whose histories are fraught with contingency, accident, and luck." -David Grinspoon
Image Credit: NASA

Millar received her Ph.D. in Genetics and M.S. in Wildland Resources Science fromthe University of California, Berkeley. She also holds a B.S. in Forest Science from the University of Washington. Millar is a PEW scholar in Conservation and the Environment. Prior to her interest in climate change research, Millar focused on forest genetics, especially the way genes ebb and flow across landscapes over time.She is a recognized expert in the evolutionary dynamics of pines. Millar talked with writer Anne M. Rosenthal as published orignally by the US Forest Service, where Millar described species diversity and terrestrial conservation.

Q. Forest managers no longer see fire as a scourge to be prevented. Instead, theyview fire as an inevitable, natural process integral to forest management. Do you anticipate a paradigm shift of similar magnitude for climate change?

Yes in fact, the shift both in viewpoint and management approaches could be evengreater. Traditionally, forest managers have attributed changing conditions in forests toreadily apparent natural processes like fire, insects, disease, and floods. But often,climate change is the underlying reason for landscape alterations.

Earth’s biodiversity.
Credit: Alexis Rockman

Sometimes what is blamed on overgrazing, fire suppression, invasive species, or other human-related factors is also a result of climate change.Today, managers are beginning to consider climate both natural and modified by humans as the major cause of forest changes. This realization, or paradigm shift, will markedly change how forests are monitored and managed.

Q. With the importance of climate change coming to light, what should managers be thinking about?

Managers could consider whether treating secondary factors will be successful. If the goal is short-term mitigation, for example to preserve trees for timber harvest, then fighting fire, insects, or disease is reasonable. Populations and places least sensitive toclimate change may often be successfully managed for resilience in the short run.

Sometimes the stated objective is to stop change that is, to preserve in perpetuity aspecies, population, or landscape the way it currently exists or to restore it to a former condition. However, attempting to preserve the past is futile if the landscape is highlysensitive to climate change. In these cases, change may be inevitable, and resisting it could lead to abrupt and undesired consequences in the future.

Alien species, terrestrial biodiversity.
Credit: NGS

Forests established during pre-settlement times (the 1800s) are poor models for restoration today; they are even worse models for forests adapted to future warming conditions. Pre-settlement forests developed in response to the harshest period of the Little Ice Age, which ended during the late 19th century, and are generally not best adapted to the changing climates of the present and future.

Forest transformations as a result of climate change may occur within a human life-time. To gain insight into what lies ahead, managers could look at how comparable landscapes responded historically and combine this knowledge with information onpredicted climate change.

Q. How does this new outlook affect conservation of rare and endangered species?

Over time plants and animals may cycle, as a result of climate change, between being rareand widespread. If populations are shrinking because climatic conditions are changing, aspecies may no longer survive well within its former range. Alternately, if climate is favorablein other parts of a species’ range, populations are likely to thrive and expand there. It sounds like species need space to move.

The fossil record shows that species have often responded to climate change byadjusting their ranges. They died out in some locations and pioneered others. By maximizing the size and diversity of management units and keeping land uses flexible,managers might make it possible for species to adjust to climate change by moving.

Managers could also consider species introductions in areas where climate change is encouraging habitat growth congenial to the species in question. These sites may not have been occupied by the species in the recent past, because the site’s ecosystem was different. This should be done only after careful assessment of the species’ history and potential effects of introducing a species to a new environment.

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