Webinar explains ecological drought

“Like a tree falling in the forest, does drought occur if there is no human to record or experience it?”

Shelley Crausbay, senior scientist with Conservation Science Partners, posed this question to attendees at the first segment of a four-part series on ecological drought.

“I think this question is a really important one for us to all think about,” she said. “It’s really important these days. We are starting to see very strong ecological impacts from drought.”

The National Integrated Drought Information System and the U.S. Geological Survey National Climate Adaptation and Science Center, are hosting a four-part webinar series during February and March to help increase awareness of ecological drought, tactics to strengthen ecosystem resilience and mitigate drought impact, and discuss research and management needs for future drought planning and preparedness.

In the first segment, ecological drought is introduced as a scientific concept distinct from other definitions of drought and explored research on the topic including ecological tipping points and transformational drought impacts.

Crausbay, based in Fort Collins, Colorado, is a plant community ecologist, ecological modeler and paleo ecologist whose research focuses on triggers of ecological state changes, climate drivers of vegetation patterns and dynamics and the role of disturbance within a changing climate context.

“These days, we are starting to see very strong ecological impacts from drought,” she said.

Crausbay defines ecological drought as an episodic deficit in water availability that drives—because of ecosystems—beyond a threshold of vulnerability. It impacts ecosystem services and it triggers feedbacks in both natural and human systems. It could be things like meteorological conditions or the sensitivity of the ecological characteristics in the environment.

“Maybe it’s fish, maybe it’s trees, and then the adaptive capacity of those systems,” she said. “So the evolutionary and sort of genetic basis for how these biotic systems can be plastic or adapt in response to drought.”

Looking at remotely sensed data in a new drought index called vegi dry that looks at the time vegetation is under severe drought conditions. A great deal of the United States has been under severe or extreme drought conditions for some time, she said, and it’s difficult to determine what kind of classification drought should be in some instances—whether the drought fits into hydrological drought, agricultural drought or socioeconomic drought.

“That’s what really brought our group to the table to really think about ecological drought,” she said. “And this goes far beyond thinking about just vegetation, or vegetation impacts. Drought is impacting lots of pieces of ecosystems.”

Things like wildlife, small animals, and those large animals in places like Africa are all affected by ongoing drought.

“It is affecting our forests and causing wildfires, it is threatening to convert forests to non-forested systems or convert grasslands and really just change the way our landscapes are operating,” she said. “It’s affecting our rivers, integrating our freshwater flows and we’re experiencing fish kills and streams. So this really is a very pervasive impact to ecosystems.”

Crausbay questioned why this is being seen so often now, rather than earlier on when drought definitions were first being defined. This is partially because drought is intensifying as time goes on.

“We know that our droughts are becoming stronger and longer and more intense,” she said.

In her studies, she looked at drought changes in the future, predicting changes by the year 2100. Of those she sees drought frequency and severity getting much stronger moving into the future.

“We’re going to keep seeing impacts like this to ecosystems and part of the reason is that as climate is changing, and as our environment is changing, these hydrological drivers of drought are also shifting,” Crausbay said.

For example, water storage, ice and snow are changing. Snow pack is reduced and winter precipitation is lower.

“Our precip patterns are shifting. Really importantly we have very strong evapotranspiration patterns with global warming,” she said. “Our atmosphere is much thirstier and it’s pulling water out of everything—soil, vegetation, and also teleconnection patterns are changing.”

Most often El Nino is thought as the driver of drought and climate change.

“But at the same time, our hydrological drivers of drought are changing because of people,” Crausbay said. “We’re extracting water. We’re impounding water. We’re moving water around in ways that ecosystems may not have water available to them when they need it in the moment.”

All of these things are setting “us up for what we see as new types of drought conditions.” There’s new terms for drought popping up—snow drought, hotter drought, mega drought, flash drought, etc.

“We haven’t really seen a mega drought in our historical period, but data from a paleo record—this is from the central Plains—that can point out that we do have extended periods of drought in the past with climate change, we are set to see more of that.”

Crausbay said more research has been showing how humans play “such an important part of our water cycle.”

“They can induce a water deficit, even when there’s no meteorological drought indicated, or what’s more likely humans can modify water availability for ecosystems during drought,” she said. “So all of these things are coming together to sort of create the perfect storm for all kinds of ecosystems and we’re seeing those impacts.”

People need to care about these impacts because of biodiversity and conservation in the environment, and the roles humans play in it.

“Ecosystem services are impacted by drought, once we change our vegetation types, we lose our ability to sequester carbon,” she said. “We also can change climate regionally, with teleconnections, based on how the land surface has changed.”

Because of the degradation of the land and soils from drought, Crausbay believes food security can be threatened since the lands are compromised.

“We think ecological drought is important and some of the main takeaways are, it’s increasingly likely with climate change,” she said. “It’s a major concern for biodiversity conservation. Drought is thought of as one of those triggers that could initiate whole biome shifts that we expect with climate change, but it’s also a very important component of vulnerability of people to drought.”

This also serves as a reminder for those who are in charge of devising new drought preparedness solutions as drought intensifies.

“We really need to consider how those preparedness solutions might in turn affect ecosystems, which would in turn affect people through their ecosystem services,” she said.

For more information about drought visit www.drought.gov.

Kylene Scott can be reached at 620-227-1804 or [email protected].