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.

[ Like what you’ve read? Want more? Sign up for The Conversation’s daily newsletter. ]The Conversation

Emily Fusco, Postdoctoral Researcher, University of Massachusetts Amherst

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

Climate Change and Bushfires/Wildfires


The Amazon is on fire – here are 5 things you need to know



Huge fires are raging across multiple regions of the Amazon Basin.
Guaira Maia/ISA

Danilo Ignacio de Urzedo, University of Sydney

Record fires are raging in Brazil’s Amazon rainforest, with more than 2,500 fires currently burning. They are collectively emitting huge amounts of carbon, with smoke plumes visible thousands of kilometres away.

Fires in Brazil increased by 85% in 2019, with more than half in the Amazon region, according to Brazil’s space agency.

This sudden increase is likely down to land degradation: land clearing and farming reduces the availability of water, warms the soil and intensifies drought, combining to make fires more frequent and more fierce.




Read more:
Amazon rainforests that were once fire-proof have become flammable


1. Why the Amazon is burning

The growing number of fires are the result of illegal forest clearning to create land for farming. Fires are set deliberately and spread easily in the dry season.

The desire for new land for cattle farming has been the main driver of deforestation in the Brazilian Amazon since the 1970s.

Ironically, farmers may not need to clear new land to graze cattle. Research has found a significant number of currently degraded and unproductive pastures that could offer new opportunities for livestock.

New technical developments also offer the possibility of transforming extensive cattle ranches into more compact and productive farms – offering the same results while consuming less natural resources.

2. Why the world should care

The devastating loss of biodiversity does not just affect Brazil. The loss of Amazonian vegetation directly reduces rain across South America and other regions of the world.

The planet is losing an important carbon sink, and the fires are directly injecting carbon into the atmosphere. If we can’t stop deforestation in the Amazon, and the associated fires, it raises real questions about our ability to reach the Paris Agreement to slow climate change.

The Brazilian government has set an ambitious target to stop illegal deforestation and restore 4.8 million hectares of degraded Amazonian land by 2030. If these goals are not carefully addressed now, it may not be possible to meaningfully mitigate climate change.

3. What role politics has played

Since 2014, the rate at which Brazil has lost Amazonian forest has expanded by 60%. This is the result of economic crises and the dismantling of Brazilian environmental regulation and ministerial authority since the election of President Jair Bolsonaro in 2018.

Bolsonaro’s political program includes controversial programs that critics claim will threaten both human rights and the environment. One of his first acts as president was to pass ministerial reforms that greatly weakened the Ministry of the Environment




Read more:
Amazon deforestation, already rising, may spike under Bolsonaro


Regulations and programs for conservation and traditional communities’ rights have been threatened by economic lobbying.

Over the last months, Brazil’s government has announced the reduction and extinction of environmental agencies and commissions, including the body responsible for combating deforestation and fires.

4. How the world should react

Although Brazil’s national and state governments are obviously on the front line of Amazon protection, international actors have a key role to play.

International debates and funding, alongside local interventions and responses, have reshaped the way land is used in the tropics. This means any government attempts to further dismantle climate and conservation policies in the Amazon may have significant diplomatic and economic consequences.

For example, trade between the European Union and South American trading blocs that include Brazil is increasingly infused with an environmental agenda. Any commercial barriers to Brazil’s commodities will certainly attract attention: agribusiness is responsible for more than 20% of the country’s GDP.

Brazil’s continued inability to stop deforestation has also reduced international funding for conservation. Norway and Germany, by far the largest donors to the Amazon Fund, have suspended their financial support.

These international commitments and organisations are likely to exert considerable influence over Brazil to maintain existing commitments and agreements, including restoration targets.




Read more:
The world protests as Amazon forests are opened to mining


5. There is a solution

Brazil has already developed a pioneering political framework to stop illegal deforestation in the Amazon. Deforestation peaked in 2004, but dramatically reduced following environmental governance, and supply change interventions aiming to end illegal deforestation.

Environmental laws were passed to develop a national program to protect the Amazon, with clearing rates in the Amazon falling by more than two-thirds between 2004 and 2011.

Moreover, private global agreements like the Amazon Beef and Soy Moratorium, where companies agree not to buy soy or cattle linked to illegal deforestation, have also significantly dropped clearing rates.

We have financial, diplomatic and political tools we know will work to stop the whole-sale clearing of the Amazon, and in turn halt these devastating fires. Now it is time to use them.




Read more:
Huge wildfires in the Arctic and far North send a planetary warning


The Conversation


Danilo Ignacio de Urzedo, PhD candidate, University of Sydney

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

Climate change is poised to deliver more Black Saturdays in decades to come


Scott Hamilton, University of Melbourne

Ten years ago, on February 7, 2009, the Black Saturday bushfires killed 173 people. More than 2,000 houses were destroyed in Victoria, including at Kilmore, Kinglake, Vectis (Horsham), Narbethong, Marysville, Strathewan, Beechworth, Labertouche (Bunyip), Coleraine, Weerite, Redesdale, Harkaway, Upper Ferntree Gully, Maiden Gully, Bendigo, Eaglehawk, Lynbrook, St Andrews, Flowerdale, Narre Warren, Callignee, and my home town of Churchill, where my mother and father still lived. Their home wasn’t burned, but many of their neighbours were badly affected by the worst bushfire day in Australia’s history.

A week before, my uncle and aunt had to seek refuge at Mum and Dad’s place when a fire ember landed in their front yard during the Boolarra bushfires. Mum has since passed and Dad still lives in Churchill.

The climate is changing due to human induced greenhouse gas emissions, and this means more bushfire danger days in what is already one of the most fire-prone countries in the world. Unfortunately, we have not done enough to curb climate change and the situation is getting worse.

Climate change means more days of extreme heat, longer heatwaves and more frequent droughts. Droughts now occur further south than in the past and have been increasing in Australia’s southeast, including Tasmania. The records continue to tumble, and the evidence of dangerous climate change continues to mount.




Read more:
Fires are increasing in warming world, but a new model could help us predict them


Back in 2008, John Brumby was Premier of Victoria and Kevin Rudd was Prime Minister. I was working on climate change for the Victorian government, developing projections for increased risk of bushfires. A 2005 study had already predicted an increase in fire weather risk throughout most of southeastern Australia over the coming decades, with “very high” and “extreme” fire danger ratings likely to increase in frequency by 4-25% by 2020 and 15-70% by 2050.

There has been more research in this area, although certainly not enough, given the huge stakes. A 2007 report for the Climate Institute of Australia predicted increases in annual average fire danger of up to 30% by 2050, and a potential trebling in the number of days per year where the uppermost values of the index are exceeded. The largest changes are predicted for the arid and semi-arid interior of New South Wales and northern Victoria.

Projected increases in the number of days with very high or extreme fire weather for selected years. This study was based on scenarios producing 0.4℃, 1.0℃ and 2.9℃ temperature rises, which will respectively be reached by the years indicated, without emissions reduction.
Lucas et al. 2007, Author provided

The 2008 Garnaut Climate Change Review also warned that fire seasons will begin earlier, end slightly later, and generally be more intense. “This effect increases over time but should be directly observable by 2020,” it said.

In 2015, a further study by CSIRO and the Bureau of Meteorology concluded that:

Projections of warming and drying in southern and eastern Australia will lead to increases in [forest fire danger index] and a greater number of days with severe fire danger. In a business as usual scenario (worst case, driest scenario), severe fire days increase by up to 160-190% by 2090.

By combining all of this research, I created the graph below.

Projected annual number of days of very high or extreme bushfire danger.
CSIRO/BoM/Bushfire CRC

This shows that while there is some uncertainty as to the extent of increase in the number of bushfire danger days in southeastern Australia, the situation is undoubtedly getting worse, and it’s time for action.

In 2017, the independent Climate Council published a report on Victoria’s growing bushfire threat, which made several stark findings and recommendations:

  1. Climate change is increasing the risk of bushfires in Victoria and lengthening fire seasons.

  2. Victoria is the state most affected by bushfires, and is on the front line of increasing bushfire risk.

  3. The economic cost of bushfires in Victoria is an estimated A$180 million a year, and this is predicted to more than double by 2050.

  4. Bushfires will continue to adversely affect human and environmental health.

  5. In the future, Victoria is very likely to experience an increased number of days with extreme fire danger. Communities and emergency services across Victoria must be prepared.

  6. Reducing greenhouse emissions is vital for protecting Australians.

Risk to water supplies

Our grandfathers and grandmothers had the wisdom to build amazing water infrastructure, protected by the “closed catchments” that give Melbourne and Victoria some of the best water in the world. Bushfires are a major risk to these water supplies – particularly in the catchments of major dams such as the Thomson.

A bushfire followed by a downpour that washes ash into the dam could potentially force the closure of the trillion-litre capacity Thomson reservoir, making it unusable for months. Firefighters have been battling exactly this kind of blaze at Mount Baw Baw in recent days and at the time of writing the situation has improved.

Major bushfires often occur in time of severe drought. Black Saturday itself happened towards the end of the 15-year Millennium Drought, when Victoria’s water supplies were already strained. I remember vividly the then chief executive of the Melbourne Water Corporation urging the government to deal with any fire in the Thomson Dam catchment immediately, given the threat to Melbourne’s water.

Fortunately, amid the devastation of Black Saturday we avoided major disruption to our water supplies. But this risk poses a huge challenge to both firefighters and policy-makers. The rule is that protection of human life is ranked above assets and infrastructure, and rightly so. But when there is a clear and present danger of towns and cities going without water, it’s also true that safeguarding water means saving human lives in the ensuing days.




Read more:
The bitter lesson of the Californian fires


Any way you look at it, these are hard questions. On our current trajectory, we are heading for terrible trade-offs.

In 2050 my daughter Astrid and my son Atticus – Mum and Dad’s grandchildren – will be 45 and 43, respectively. I hope it is not too late for our leaders in Canberra, Davos and throughout the world to wake up and take urgent action to limit global warming 1.5℃. That would mean that the most fearful predictions of our bushfire future never come to pass.The Conversation

Scott Hamilton, Strategic Advisory Panel Member, Australian-German Energy Transition Hub, University of Melbourne

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

Forest soil needs decades or centuries to recover from fires and logging



File 20190121 100288 15v1q9i.jpg?ixlib=rb 1.1

David Blair, Author provided

Elle Bowd, Australian National University and David Lindenmayer, Australian National University

The 2009 Black Saturday fires burned 437,000 hectares of Victoria, including tens of thousands of hectares of Mountain Ash forest.

As we approach the tenth anniversary of these fires, we are reminded of their legacy by the thousands of tall Mountain ash “skeletons” still standing across the landscape. Most of them are scattered amid a mosaic of regenerating forest, including areas regrowing after logging.




Read more:
Comic explainer: forest giants house thousands of animals (so why do we keep cutting them down?)


But while we can track the obvious visible destruction of fire and logging, we know very little about what’s happening beneath the ground.

In a new study published in Nature Geoscience, we investigated how forest soils were impacted by fire and logging. To our surprise, we found it can take up to 80 years for soils to recover.

Logging among the charred remains of Mountain ash after the 2009 fires.
David Blair, Author provided

Decades of damage

Soils have crucial roles in forests. They are the basis for almost all terrestrial life and influence plant growth and survival, communities of beneficial fungi and bacteria, and cycles of key nutrients (including storing massive amounts of carbon).

To test the influence of severe and intensive disturbances like fire and logging, we compared key soil measures (such as the nutrients that plants need for growth) in forests with different histories. This included old forests that have been undisturbed since the 1850s, forests burned by major fires in 1939, 1983 and 2009, forests that were clearfell-logged in the 1980s or 2009-10, or salvage-logged in 2009-10 after being burned in the Black Saturday fires.

We found major impacts on forest soils, with pronounced reductions of key soil nutrients like available phosphorus and nitrate.

A shock finding was how long these impacts lasted: at least 80 years after fire, and at least 30 years after clearfell logging (which removes all vegetation in an area using heavy machinery).

However, the effects of disturbance on soils may persist for much longer than 80 years. During a fire, soil temperatures can exceed 500℃, which can result in soil nutrient loss and long-lasting structural changes to the soil.

We found the frequency of fires was also a key factor. For instance, forests that have burned twice since 1850 had significantly lower measures of organic carbon, available phosphorus, sulfur and nitrate, relative to forests that had been burned once.

Sites subject to clearfell logging also had significantly lower levels of organic carbon, nitrate and available phosphorus, relative to unlogged areas. Clearfell logging involves removing all commercially valuable trees from a site – most of which are used to make paper. The debris remaining after logging (tree heads, lateral branches, understorey trees) is then burned and the cut site is aerially sewn with Mountain Ash seed to start the process of regeneration.

Fire is important to natural growth cycles in our forests, but it changes the soil composition.
David Lindenmayer, Author provided

Logging compounds the damage

The impacts of logging on forest soils differs from that of fire because of the high-intensity combination of clearing the forest with machinery and post-logging “slash” burning of debris left on the ground. This can expose the forest floor, compact the soil, deplete soil nutrients, and release large amounts of carbon dioxide into the atmosphere.

Predicted future increases in the number, frequency, intensity and extent of fires in Mountain Ash forests, coupled with ongoing logging, will likely result in further declines in soil nutrients in the long term. These kinds of effects on soils matter in Mountain Ash forests because 98.8% of the forest have already been burned or logged and are 80 years old or younger.

To maintain the vital roles that soils play in ecosystems, such as carbon storage and supporting plant growth, land managers must consider the repercussions of current and future disturbances on forest soils when planning how to use or protect land. Indeed, a critical part of long-term sustainable forest management must be to create more undisturbed areas, to conserve soil conditions.




Read more:
New modelling on bushfires shows how they really burn through an area


Specifically, clearfell logging should be limited wherever possible, especially in areas that have been subject to previous fire and logging.

Ecologically vital, large old trees in Mountain Ash forests may take over a century to recover from fire or logging. Our new findings indicate that forest soils may take a similar amount of time to recover.The Conversation

Elle Bowd, PhD scholar, Australian National University and David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

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