New research shows that the idea of environmental equilibrium ÷ historically a pervasive theme in ecology ÷ could be misleading, UA ecologist Don Falk said in a talk yesterday.

ăThe current state of thinking in ecology is that everything is in flux,ä he said.

Previously, scientists have tended to look at the average measurements of things like temperature or rainfall over large areas of time and space and then factored in disturbances ÷ large-scale variations from the average, which are events such as floods, droughts or eruptions.

ăThe problem with that way of thinking,ä said Falk, a doctoral candidate in ecology and evolutionary biology, ăis that equilibrium doesnât exist.ä

ăThe idea of disturbance calls for an equilibrium to be disturbed. And the reality is you would be hard pressed to find an ecosystem that has that attribute. Most organisms are out of equilibrium with their environment to some extent,ä he said.

Falkâs study, which tracks the fire history of the Jemez mountains outside of Los Alamos, N.M., allows him to question the definition of disturbance and to try to create a more reasonable scale-dependent framework for fire patterns.

ăThe scale of observation matters,ä he said. ăEven if the whole forest is experiencing fire once every five or six years, individual groups of trees can go 10 to 30 years in the very same forest without a fire. In fact, itâs very patchy. The mistake would be to think these disturbances are uniform across the landscape.ä

Tree rings are a reliable long-term teller of fire patterns because their rings leave a record of every season, enabling scientists to gather data on climate and fire occurrence as far back as the 1400s with a better-than-annual resolution.

ăThe variation is continuously distributedä in these tree patterns, Falk said. ăThe idea of an equilibrium condition is fading fast in ecology. It is being replaced with a view that recognizes that variation is more or less everywhere and more or less all the time.ä

One of the major applications of this understanding of continuing variability is to evolutionary biology.

ăThe evolution of organisms isnât driven by the mean of the variables, itâs driven by what they have to survive in year after year. Unfortunately, we donât know much about the conditions under which most organisms evolved, but this analysis shows us another dimension which we would have to understand,ä he said.