Light Pollution, the Environment, and Us

Moths flock to man-made light sources, like this outdoor light, instead of orienting to the moon. This is just one example of how artificial light can interrupt the natural behaviors of wildlife. (Photo by Mohibul Hoque)

By Kelli Housley, Valles Caldera National Preserve

With contributions from Monique Schoustra and Starr Woods

Humans and animals have always relied on the stars for seasonal awareness, navigation, and understanding. But increases in artificial lighting and light pollution cost us our connection to the past and produce devastating effects on our own health and our environment.

Animals have evolved to use natural cycles of day and night for migration, mating, pollination, and more. But countless species have been adversely affected because of the increase in lighting and light pollution over the years. Artificial light and skyglow have caused disruptions to many species’ natural cycle of life, contributing to reductions in population and even extinction.

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Restoring Our Night Skies

Comet NEOWISE photographed in July 2020 at Valles Caldera National Preserve. Valles Caldera recently achieved International Dark Sky Park status. (Photo by Glen Wurden)

By Galen Gisler

Ancient cultures populated the night sky with fanciful imaginary creatures, and told their stories so frequently and so vividly that the stars were named for specific parts of those creatures’ bodies.

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Forest Restoration in the Jemez Mountains

A firefighter manages a burning pile of dead and downed wood during a pile burn operation in Upper Pueblo Canyon in January 2015. (Photo by Craig Martin)

By Siobhan Niklasson, based on a conversation with Bob Parmenter of the Valles Caldera

The forests of the American West look much different today from how they looked 150 years ago. Around that time, a handful of large and destructive fires in the United States convinced land managers and the public that fires should be stopped as soon as possible in order to protect natural resources.

However, the decision to suppress wildfires had unintended consequences. Historically, frequent fires in ponderosa pine forest removed excess growth and kept the landscape open. Historical ponderosa pine forests were described as open and park-like and it was said that you could ride a horse through the forest for miles without hitting your head on a branch. This 2011 article from The Durango Herald gives some insight into the history of the forests of the Jemez Mountains and how fire suppression changed them

Without fire to clear the landscape, many more trees were able to take root, increasing the tree density from around 40 – 60 trees per acre to 1,000 – 2,000 trees per acre in some cases. It’s painful just to think about trying to ride a horse through such a dense forest! 

An overgrown stand of trees at Banco Bonito in the Valles Caldera before and after thinning. The before photo, on the left, was taken in 2011. The after photo, on the right, was taken in 2014. (Photos by Bob Parmenter/NPS)

So many trees in the forest meant that each tree had to compete for water and nutrients with all its neighbors, surface water running in streams was reduced, sunlight was largely blocked from the ground level, leading to a dearth of grasses and other understory plants, and animals that depended on these small plants for grazing were squeezed out. Crucially, for fires, the increase in fuel in the forest turned what would once have been healthy ground fires into raging infernos that could wipe out an entire forest, and get so hot that the soil was sterilized.

Today, we have a better understanding of the importance of fire in our forest ecosystems. But the 150 years of fire suppression policy left a legacy of overgrown forests that must be returned to a healthy state, both to restore healthy ecosystems, and to reduce the risk of severe megafires.

In the Jemez Mountains, agencies have joined forces in a collaborative forest landscape restoration program to undertake this work. The first step is to thin the forest using mechanical means or cutting by hand to reduce the density from 1,000+ trees per acre to about 100 trees per acre. This means potentially cutting out 90% of the trees in the area! Once the trees are cut, they can either be removed and used for wood products, or they can piled and burned. This work is expected to be completed in the southwestern Jemez Mountains within another two to three years.

Once the forests are thinned, natural mortality will further reduce the number of surviving trees. The idea is that after another 100 – 200 years, we will end up with a mature forest with about 40 – 60 trees per acre.

With the first thinning completed, natural and prescribed fire can be used to manage the forest. It’s much cheaper and safer to manage fire in a thinned forest than it is to bring in helicopters and air crews to battle high-intensity fires that threaten lives and neighborhoods. For example, the 2011 Las Conchas fire burned over 150,000 acres, and cost almost $50 million to control.

The 2019 Redondo Fire burned at a low intensity through forest that had been thinned, with no injuries or property damage. (Photo by Brian Faith/NPS)

In 2019, a lightning strike in the Valles Caldera started a low-intensity ground fire that burned through thinned forests. Firefighters saw an opportunity to use this fire to maintain some forested areas that needed to be burned. With the cooperation of local residents, they managed to safely allow the fire to burn right up to the boundary between the preserve and the Sulfur Flats neighborhood.

For the trees, thinning makes it easier for each individual tree to secure the resources (water and nutrients) it needs to survive. This should help the trees be more resilient to rising temperatures due to climate change.

A tree can live for several hundred years. Even if we are able to reverse the trend in our greenhouse gas emissions by 2050, we can expect temperatures to keep rising for another 50 years after that, and it could be an additional 50 years before temperatures cool off again.

So while that timescale of around 150 years is a long time in human terms, it means that the trees that are living now could potentially see the other side of the climate change curve, if we can help them survive fires and beetle infestations now.

Next time you’re out, see if you can find signs of forest thinning and prescribed burns. This is important work that’s keeping our forest ecosystems healthy for everything, including us, that depends on them.

Learn more about the history of forest fire suppression here.

The Rugged Ponderosa Pine

The history grove at Valles Caldera National Preserve serves as a reminder of how our forests looked before fire suppression. (Photo by Terry Foxx)

By Terry Foxx

One of my favorite tree species is the lofty ponderosa pine (Pinus ponderosa) with its straight trunk, vanilla and butterscotch scented bark, and branches with needle-like leaves that hover above my head. The trees appear to me to be like a person, standing tall and stately, with a straight trunk and branches reaching out like arms beckoning a hug.

Standing beneath a tree, I tip my head back to see what is living or foraging in the treetop. To my delight, I may observe an Abert’s squirrel chattering, a woodpecker searching for insects, or nuthatches hopping down the tree headfirst.

One of my favorite places in the Jemez Mountains is the history grove in the Valles Caldera National Preserve. The widely spaced ponderosas with the grassy understory are a reminder of how our forests looked before fire suppression. They were a mosaic of open stands, interspersed with meadows.

In the history grove, the ponderosa pines stand as witnesses to the past. The oval wounds in the bark are bark-peel trees from when Native Americans exfoliated sections of bark in the spring to obtain the sweet inner cambium for food. The trees marked with crosses remind us of sheepherders and their lonely existence. And the triangular wounds at the base of the tree, called “cat faces,” tell the story of fire and survival. Many of the large trees in the history grove are 200 to 300 years old. Within their growth rings are stories of fire, injuries, and people.

A Pygmy Nuthatch perched on the side of a ponderosa. (Photo by Sally King/NPS)

Loggers and ranchers called older and larger trees “yellow pine” because of the yellowish-orange puzzle-like bark and the young, darker trees “blackjacks.” It takes a tree about 40 years for the bark to change from black to yellow. The bark patterns also become furrowed and more puzzle-like as the tree ages. The thick bark protects the tree from low-intensity or surface forest fires. However, years of fire suppression have created conditions for hot-burning crown fires that kill the trees. 

Each natural growing tree is a miracle of nature. It takes many years before a ponderosa pine begins to produce cones that hold the seeds. Every three to five years the tree produces numerous cones. But from the countless seeds produced, only a few seeds sprout and grow. That tiny germinated tree must survive fires, insects, and competition for resources. I am amazed at the ruggedness of the species when I see a tree growing in harsh environments like rocky cliffs, dry canyons, and steep slopes. A mature tree represents resilience and survival!

In the past 20 years, the Cerro Grande and Las Conchas fires have burned over 200,000 acres of forest. The first two weeks of May is the twentieth anniversary of the Cerro Grande Fire of 2000, an event that changed the physical and emotional landscape of the community.

My upcoming book, Resilience and Renewal, a Landscape and Community Twenty Years After, will soon be published by the Los Alamos Historical Society in honor of the twentieth anniversary of the Cerro Grande Fire and its impacts on our community. When the museum opens, they will have a display entitled “Resilience and Recovery.” In the meantime, you can explore this exhibit online.

Valles Caldera Rim Trail

Valle San Antonio from the north rim. Redondo Peak on skyline at right. Valle Grande in far distance, left. Click photo for larger view.

By Dorothy Hoard, January 2014

The Valles Caldera is a volcano in the Jemez Mountains of north-central New Mexico. The caldera is about 15 miles long by 12 miles wide, with a rim about 75 miles around.

The Valles Caldera is the type locality for Resurgent Dome Calderas. It is where geologists studied and described the features that make up the structure.

The rim of the Valles Caldera is the ridgeline right above Los Alamos. Many people used to hike there before it became public land in 2000 and was closed to public access.

Each year, thousands of motorists pause along State Road 4 to view the Valle Grande, presuming that it is the entire caldera. It is not. The best way to comprehend the scope and structure is from the rim. Unfortunately, the resurgent dome, in this case Redondo Peak – second highest point in the Jemez Mountains, obstructs a sweeping view of the entire caldera. This fact necessitates a series of viewpoints around the rim and a trail connecting them.

About 60 percent of the rim is on the Santa Fe National Forest and open to the public. The remainder is on the Valles Caldera National Preserve and is closed to public access. Of interest to Los Alamos hikers is the closed section between Cerro Grande and Cañada Bonita behind the VCNP fence, which has many excellent viewpoints. The east rim and parts of the north and south rims were severely burned in the 2011 Las Conchas Fire. Dead sticks of trees are depressing, but the fire opened up the views. In the long term, when the snags fall and aspen groves cover the slopes, a rim trial will be a true asset.

Advocates hope to establish a trail around the caldera rim.

A hardy band of hikers completed a reconnaissance of the 75-mile rim in January 2014 and produced reports, trip reports, and proposals. To view the results of the rim recon, visit