Invasive grasses are fueling wildfires across the US



Burning invasive, nonnative grasses on federal land at Lower Table Rock, Oregon.
BLM, CC BY

Emily Fusco, University of Massachusetts Amherst

The Santa Ana winds that help drive fall and winter wildfires in California have died down, providing welcome relief for residents. But other ecological factors contribute to fires in ways that scientists are still discovering.

I study how human actions affect fire regimes – the patterns through which fires occur in a particular place over a specific time period. People alter these patterns by adding ignition sources, such as campfires or sparking power lines; suppressing fires when they develop; and introducing nonnative invasive plants.

My research suggests that nonnative invasive grasses may be fueling wildfires across the United States. Some fires are occurring in areas that rarely burn, like the Sonoran Desert and the semiarid shrublands of the Great Basin, which covers most of Nevada and parts of five surrounding states. In the coming months, some of the grasses that help feed these blazes will germinate, producing tinder for future fires.

The Great Basin.
KMusser/Wikipedia, CC BY-SA

In a recent study, I worked with colleagues at the University of Massachusetts and the University of Colorado to investigate how 12 nonnative invasive grass species may be affecting regional fire regimes across the U.S. We found that eight species could be increasing fire in ecosystems across the country.

Altering historical fire patterns

A fire regime is a way to describe fire over space and time or to characterize fire patterns. Understanding fire regimes can help make clear that fire is a natural and integral component of many ecosystems. Knowing historical fire patterns also enables scientists to begin to understand when new or different patterns emerge.

The link between invasive grass and fire is well established. Invasive grasses are novel fuels that can act as kindling in an ecosystem where readily flammable material might not otherwise be present. They can catch a spark that might otherwise have been inconsequential.

For example, in August 2019 the Mercer Fire burned 25 acres in Arizona, scorching native desert plants, including iconic saguaro cacti. A much larger event, the 435,000-acre Martin Fire, destroyed native sagebrush ecosystems in Nevada in July 2018. Invasive grasses helped fuel both fires.

Cheatgrass, which fueled the Martin Fire, is a well-studied invasive grass known to promote fire. But many other invasive grass species have similar potential, and their roles in promoting fire have not been assessed at large scales.

How land managers are fighting invasive grasses across the Great Basin region of the West.

Introducing the suspects

Researchers describe fire regimes in many ways. Our study focused on fire occurrence (whether or not fire occurred), frequency (how many times fires occurred) and size (the largest fire associated with a place) in 29 ecological regions across the U.S. For each location we tested whether invasive grasses were associated with differences in fire occurrence, frequency or size.

A nonnative invasive species typically comes from another continent, has become established, is spreading and has negative impacts. We used an online Invasive Plant Atlas of the United States as a starting point to determine which invasive grass species to investigate.

Next, we searched the scientific literature and the U.S. Forest Service’s Fire Effects Information System to see whether there was reason to believe that any of the invasive grass species promoted fire. This process helped narrow our scope from 176 species to 12 that were suitable for our analysis.

Who are these “dirty dozen,” and how did they get here? Buffelgrass is native to Africa and was intentionally introduced to Arizona in the 1930s, probably for erosion control and forage. Japanese stiltgrass and cogongrass are native to much of Asia and were introduced to the southeastern U.S. in the early 1900s, in some instances as packing material. Medusahead, which comes from Eurasia, was introduced to the western U.S. in the late 1800s, probably by accident as a contaminant in seed shipments.

The remaining eight species – giant reed, common reed, silk reed, red brome, cheatgrass, Chinese silvergrass, Arabian schismus and common Mediterranean grass – have similar stories. People introduced them, sometimes accidentally and at other times intentionally, without an understanding of how they could impact their new settings.

Cogongrass, which is invasive in the U.S. Southeast, may burn hot enough to kill native fire-adapted tree species.
Alabama Cooperative Extension System, CC BY-ND

Big data for big questions

Understanding how multiple species influence fire over many years at a national scale requires using big data. One person could not collect information on this scale working alone.

We relied on composite data sets that provided thousands of records of invasive grass occurrence and abundance across the country. Combining these records with agency and satellite fire records helped us determine whether fire occurrence, frequency or size were different in places with and without grass invasions.

We also used statistical models to assess whether human activities and ecological features could be driving observed differences between invaded and uninvaded areas. For example, it was possible that grass invasions were happening near roads, which are also linked with fire ignitions. By including roads with grass invasion in our statistical models, we can be more confident in the role invasive grasses could play in altering fire regimes.

Our results show that eight of the species we studied are associated with increases in fire occurrence. Six of these species are also linked to increases in fire frequency. Invasions seem to be affecting a variety of ecosystems, ranging from buffelgrass in the Sonoran Desert to Japanese stiltgrass in eastern U.S. forests to cogongrass in southeastern pine systems.

Our statistical models suggest that grass invasion, along with human activities, are likely affecting fire patterns in these ecosystems.

Surprisingly, none of the invasive grass species analyzed appeared to influence fire size. We interpret this result to mean that the areas we studied are seeing more of the same types of fires that already occur there, at least in terms of size.

Dispersing seeds over a burned area of the 2015 Soda Fire in southwest Idaho to help stabilize soils and combat invasive weeds such as cheatgrass.
BLM via AP

Factoring invasive grasses into fire planning

People start an estimated 84% of wildfires in the U.S., with the rest ignited by lightning strikes. Studies show that climate change is increasing wildfire activity.

With an understanding of interactions between invasive grasses and fire, agencies that handle either fire or invasive species may find opportunities to work together to control invasions that can lead to more frequent burns. Our research can also strengthen predictions of future fire risk by incorporating the presence of invasive grasses into fire risk models.

Although it sometimes may feel as though the world is on fire, this information can provide potential for remediation, and may help communities prepare more effectively for future wildfires.

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Emily Fusco, Postdoctoral Researcher, University of Massachusetts Amherst

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What the US defence industry can tell us about how to fight climate change



The GPS system of global positioning satellites is just one of the innovations that have sprung from the US military and transformed our lives.
Shutterstock

David C Mowery, University of California, Berkeley

Achieving the large-scale cuts in greenhouse gas emissions that will be needed will require the development and adoption of new technologies at a rate not seen since the information technology revolution.

Which presents a fairly obvious idea. Why not do what we did in the information technology revolution?

There’s no mystery about what that was.

The IT revolution was sparked by the work of the US defence department and associated agencies in three related fields: semiconductors, computer hardware, and computer software.

More recently it has spawned the system of GPS global positioning satellites that can give us a readout on our locations wherever we are.




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The lessons from how the US military industrial complex transformed information technology throughout the world can tell us a lot – but not everything – about what might succeed in stalling climate change.

It did it by spending a huge amount on research and development in its own right (as much as 80% of all government R&D spending during the late 1950s) and acting as a “lead customer,” for early and often very costly versions of technologies developed by private firms, enabling them to improve their innovations over time.

Seeds sown during the cold war

The improvements reduced costs and enhanced reliability, facilitating their penetration into civilian markets.

The US made the money available because of the cold war. Universities were also harnessed for the task, training the scientists and engineers who later assumed key leadership roles in emerging R&D enterprises.

As well, similarities in the technologies and operating environments of early military and civilian versions of new information technology products meant civilian markets for many of them expanded rapidly.

The defence programs also had a “pro-competition” bias.




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New firms played important roles as suppliers of innovations such as integrated circuits, and – in a series of largely coincidental developments – the rigorous enforcement of US antitrust laws meant potentially dominant firms as IBM or AT&T found it hard to impede others.

As a result, intra-industry diffusion of technical knowledge occurred rapidly, complementing high levels of labour mobility within the emerging sector.

The very success of these military research and development programs in spawning vibrant industries means defence markets now account for a much smaller share of the demand for IT products than they did at the time.

Today’s challenges are different…

Climate change is different from post-war research and development in that it is as much an issue of technological substitution as development.

The urgency of the challenge will require the blending of support for the development of new technological solutions with support for the accelerated adoption of existing solutions, such as replacing coal-fired electricity generation with renewable generation.

“Stranded assets” such as abandoned coal-fired power stations and related political and economic challenges will loom large.




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The geographic and technological breadth of the responses needed to limit climate change also dwarf that faced by the US defence establishment during the Cold War.

Also different is the fact that the prospective users of new technologies are by and large not the funders or developers of it. When US defence-related agencies acted as “venture capitalists,” beginning in the 1950s, they were focused primarily on supporting their own needs.

…but there are lessons we can learn

There are some things the diffusion of defence-related information technology can tell us.

One is the importance of rapid adoption.

Much of the large-scale investment in technology improvement and deployment will be the responsibility of private firms. They will require policies that create supportive, credible signals that their innovations will have a market – policies such as carbon taxes.

Another is that what’s needed is a program of research and development that spans an array of institutions throughout the developing and industrial economies.

Yet another is the importance of policies that encourage competition and co-operation among innovators rather than patent wars.

The success of the US military industrial complex in creating one revolution provides pointers to (but not a complete guide to) the next.


Emeritus Professor David C. Mowery will be presening the Tom Spurling Oration at Swinburne University on Wednesday 27 November at 5.45pm.The Conversation

David C Mowery, Professor Emeritus of New Enterprise Development, University of California, Berkeley

This article is republished from The Conversation under a Creative Commons license. Read the original article.