July 2023 – Conservation Sense and Nonsense

Dana Milbank: “How I learned to love toxic chemicals”

Dana Milbank is a political commentator for the Washington Post. Like many city dwellers, Milbank moved his family from Washington DC to the Virginia countryside during the Covid pandemic.

His new home inspired him to become a native plant advocate with the usual corresponding hatred of non-native plants. He announced his new hobby of killing non-native plants in April 2023, as described in thi s response to his article by several defenders of the natural world as it exists, rather than as some might wish it to be.

In a more recent articl e, Milbank expressed his frustration at the failure of his early efforts to destroy non-native plants on his property without using herbicides: “When last I wrote about my battle of the brush, I was losing, badly, to the invasive vines and noxious weeds that had turned forest and field at my Virginia home into an impassable jungle. I’d cut them back, but they would return in even greater numbers.”

And he explained how he “learned to stop worrying and love chemicals.” He is now both a native plant advocate and a promoter of herbicides (specifically glyphosate) which is typical of most native plant advocates.

He justifies poisoning both his property and the Shenandoah National Park near his home by turning to advisors who tell him what he wants to hear, people who make their living using herbicides to eradicate non-native plants.

Of course, renowned native plant guru, Doug Tallamy, is one of his advisors. Although Tallamy advised residential gardeners against using herbicides in his book, Nature’s Best Hope, published in 2020, he has now changed his mind about herbicides. In Milbank’s article, Tallamy says that herbicides are an “essential tool:” “‘I think of it as chemotherapy,’ said Doug Tallamy, a University of Delaware entomologist and guru of the native-plant movement. ‘We have ecological tumors out there. If we don’t control them, we have ecological collapse. We have the collapse of the food web.’”

Poisoning the soil

Milbank admits that glyphosate (Roundup) is toxic and he wears protective gear when applying it, including a respirator (which is not required for glyphosate applications by California’s pesticides regulations). He describes his application technique: “My preferred technique is ‘hack and squirt.’ With my hatchet, I cut gouges around the circumference of the invading tree, then spray the poison inside. For smaller invaders, I can chop the whole thing down and apply the chemical as a ‘cut stump’ treatment.

I read most of the over one thousand comments on Milbank’s article to determine the public’s reaction. Although many commenters express reservations about the use of herbicides, the majority of commenters are supportive of the use of herbicides. The manufacturers of pesticides are definitely winning the public relations battle regarding chemical safety. When supporters reply to doubters of herbicide use, they defend Milbank’s application technique as “surgical.”

Cut stump and hack and squirt application methods are less likely to disperse chemicals in the air, but they increase soil contamination. These application methods work by applying herbicide shortly after the woody plant is cut, while the cambium layer (between the bark and the heart wood) is still functional. The cambium layer delivers the herbicide to the roots of the plant to kill the roots. The application may appear to be “surgical” from the standpoint of above-ground contamination, but the damage is being done in the soil, the plants growing in the soil, and the animals that eat those plants.

Source: https://www.acompletetreecare.com/blog/what-are-the-layers-of-a-tree-trunk/

There are many consequences of poisoning the soil:

Because the roots of plants are intertwined as well as connected to one another by fungal networks in the soil, non-target plants are harmed and often killed. It is not possible to poison one plant without poisoning others. HERE is an example of a forest of native trees that was damaged by spraying herbicide under the trees.
Herbicides kill beneficial microbes and fungi in the soil that contribute to plant health. (1) For example, fungal networks that are killed by herbicides transport moisture and nutrients from the soil to the plants. Whatever vegetation remains or is planted in the future is handicapped by the loss of this living support system.
Glyphosate binds minerals in the soil, preventing essential nutritional minerals such as iron and manganese in the soil from being taken up by plants. (2) Glyphosate is so widely used that it is found in the blood and urine of most of the population, including children. Could glyphosate be a factor in widespread iron-deficiency anemia in adolescent girls and young women? (3)
Glyphosate is a well-known anti-microbial agent. These effects raise concerns regarding glyphosate’s influence on human health and behavior through secondary means, such as our gastrointestinal microbiome, given what is now known regarding the gut microbiome and its influence on human health and disease. (4,5)

Source: https://symsoil.com/soil-food-web-soil-cities/

Who are the climate change deniers?

Milbank repeats his accusation that those who believe the threat of non-native plants is exaggerated, are climate change deniers. He turns to the Executive Director of the federal Invasive Species Council for confirmation, who calls the threats of non-native plants “settled science.” Science is, by definition, never settled. Science is a process, not a conclusion. Every scientific hypothesis is constantly tested and usually refined or overturned as new knowledge and methods are available. Many scientists are testing the hypotheses of invasion biology and questioning their validity in a changing climate.

The only issue about invasion biology that is “settled” is that it has created a multi-billion dollar “restoration” industry that relies on and benefits the manufacturers of pesticides, as well as creating vested interests that perpetuate the industry.

Milbank also quotes one of his advisors who claims that native plants are better adapted to the changed climate than non-native plants: “The natives have the best ability to adapt — they’ve been adapting for tens of thousands of years in these areas — so they’ve got the ability to change as the climates and the landscapes have been changing.” This statement seems comical, given that the topic is the extreme difficulty of eradicating non-native plants and the fact that they are out-competing native plants. There is zero evidence that native plants are better adapted to the changed climate than the non-native plants that have replaced them. 500 million years of geologic history on Earth has informed us that when the climate changes—as it has many times–the vegetation changes.

All plants, whether native or non-native, convert carbon dioxide to oxygen and store carbon. Destroying them contributes to greenhouse gases causing climate change by releasing their stored carbon into the atmosphere and reducing the capacity of the landscape to absorb more carbon in the future. To deny that fact, is to be a climate change denier.

Reality trumps unrealistic hopes

Milbank describes the landscape he hopes to achieve with the help of herbicides. It is the landscape that existed in the distant past, in a different climate, before the environment was altered by the activities of humans. I am reminded of one of the presentations at the most recen t conference of the California Native Plant Society, an event where the audience hopes and the speakers douse the audience’s hope with the reality of their unsuccessful efforts. The presenter described a 20-year effort at the Santa Rosa Plateau Ecological Reserve to convert non-native annual grassland to native grassland, using annual (sometimes bi-annual) prescribed burns. Many different methods were used, varying timing, intensity, etc. The abstract for this presentation reports failure of the 20-year effort: “Non-native grass cover significantly decreased after prescribed fire but recovered to pre-fire cover or higher one year after fire. Native grass cover decreased after prescribed fire then recovered to pre-burn levels within five years, but never increased over time. The response of native grass to fire (wild and prescribed) was different across time and within management units, but overall native grass declined.” The audience was audibly unhappy with this presentation. One person asked if the speaker was aware of other places where non-native grass was successfully converted to native grass. The speaker chuckled and emphatically said, “NO. I am not aware of any place where native grasses were successfully reintroduced.”

(1) “Glyphosate kills microorganisms beneficial to plants, animals, and humans,” Beyond Pesticides, October 2021.
(2) “Glyphosate, a chelating agent—relevant for ecological risk assessment?” Environmental Science and Pollution Research International, 2018
(3) “Prevalence of Iron Deficiency and Iron-Deficiency Anemia in US Females Aged 12-21 Years, 2003-2020,” Journal of American Medical Association, 2023
(4) “Is the Use of Glyphosate in Modern Agriculture Resulting in Increased Neuropsychiatric Conditions Through Modulation of the Gut-brain-microbiome Axis?” Frontiers in Nutrition, 2022
(5) “Toxic Effects of Glyphosate on the Nervous System: A Systematic Review” International Journal Molecular Science, 2022

Calaveras Big Trees State Park: To burn or not to burn?

Coast redwoods (Sequoia sempervirens) and sierra redwoods, often called giant sequoias (Sequoiadendron giganteum), are members of the Sequoioideae family, a sub-family of the Cypress family. Both are native to California. Dawn redwood (Metasequoia) is the third genus in the small Sequoioideae family. Although there is fossil evidence that dawn redwoods lived in California some 40 million years ago they are now native only to a small region in China.

Coast and sierra redwoods have a common ancestor that is now extinct. They evolved into different genera in response to the creation of microclimates by geologic changes that isolated their gene pools and gradually drifted apart in directions adapted to their respective regions. (1)

Coast redwoods live in wetter climates than sierra redwoods and they are heavily dependent on coastal fog that maintains a moist environment when interior regions of California are hot and dry. As our climate continues to change, the future of coast redwoods will depend on whether or not our coastal fog persists. In turn, the fog depends on the coolness of the ocean relative to the warmth of the land. The greater that difference in temperature, the more fog is created as water in warm air condenses when it meets cold ocean air.

Sierra redwoods tolerate a much drier climate than coast redwoods, but they have been tested by our prolonged drought. They are also threatened by wildfires that have ravaged California during our long drought. Only about 70 small, isolated groves of sierra redwoods still exist on the western slope of the Sierra Nevada. In 2020 and 2021, wildfires killed 13 percent to 19 percent of the world’s giant sequoias, according to the U.S. Forest Service. (2) The Mariposa Grove of giant sequoias in Yosemite National Park burned in 2022, but none of the sequoias were killed.

Public land managers are under intense pressure to do whatever is necessary to save our sierra redwoods. Extreme measures have been taken, such as wrapping their huge trunks in fire resistant foil, spraying trunks with water and canopies with gel when fires approach. (3)

The prevailing opinion about conserving sierra redwoods is that prescribed burns will reduce fuel loads and therefore fire hazards as well as kill shrubby understory that can carry fire from the ground into tree canopies. The understory is also considered competition for moisture in the soil. Kevin McCarthy, the speaker of the US House of Representatives, has introduced a bill titled Save our Sequoias Act (SOSA) that would enable logging to reduce fuel loads in giant sequoia groves without requiring environmental impact reviews. Many experts disagree about that strategy. We visited the sierra redwood grove in Calaveras Big Trees State Park at the end of May to see for ourselves and consider the pros and cons of the strategy that is being used there to save the big trees.

Calaveras Big Trees State Park

Calaveras Big Trees State Park is located near the town of Arnold at an elevation of about 4,700 feet. It is near the northern end of the narrow range of giant sequoias. The southern end of the range is near the city of Visalia in Sequoia National Park at about 6,000 feet elevation. Most of the big trees that were destroyed by recent wildfires are at the southern edge of the native range. Recent wildfires have not reached Calaveras Big Trees, but several giant sequoias in the park were badly damaged by prescribed burns and may not survive. These damaged trees are a testament to the risks of prescribed burns.

Below is a picture of one of the areas that was intentionally burned in 2022 to reduce fuel loads:

Calaveras Big Trees State Park, May 25, 2023

Below is a picture of a giant sequoia that was scorched by that fire. The right-hand side of the tree looks seriously damaged, suggesting that the tree may not survive:

Larger prescribed burns were also conducted on the northern edge of the park, where there are few sequoias. Below is a picture of one of several large areas of the park that were intentionally burned:

There are only two sequoias in this part of the park, named the Orphans because of their isolation from other sequoias in the park. The Orphans were severely burned by this fire. (see below) It isn’t clear if the Orphans will survive.

The Orphans, Calaveras Big Trees State Park. Photo by Alan Beymer with permission.

Land management or mismanagement?

The potential loss of a few giant sequoias at Calaveras Big Trees may seem trivial, but their loss must be put in the context of the small and shrinking population of giant sequoias as well as their very long lifespan of roughly 3,000 years. The survival of the species is threatened by these unintentional deaths that could have been avoided.

Many major wildfires have been started when burn crews lost control of prescribed burns. In April 2022, the US Forest Service conducted two prescribed burns in the Santa Fe National Forest in New Mexico that merged and became a major wildfire that burned for months, ultimately destroying over 341,000 acres of forest. Although it was one of the most destructive of wildfires started by a prescribed burn, it is only one of many.

Logging to thin the forest is another strategy used by public land managers to reduce fuel loads, but we did not see any evidence of logging at Calaveras Big Trees. The giant sequoias in Calaveras County reside in a mixed conifer forest of ponderosa pine, incense cedar, white fir, and sugar pine. These tree species are valuable timber and therefore vulnerable to pressure from the logging industry. It seems likely that the Save our Sequoias Act sponsored by Republicans is a gift to the logging industry, rather than to the sequoias.

In 2017, the National Academy of Sciences published an evaluation of fuels management project s in the US. The authors of this publication reported that managing forest fuels has been ineffective: “Mechanical fuels treatments on the US federal lands over the last 15 years totaled almost 7 million hectares, but the annual area burned has continued to set records. Regionally, the area treated has little relationship to trends in the area burned, which is influenced primarily by patterns of drought and warming.” Where fuels treatment was done, wildfires subsequently occurred:“10% of the total number of US Forest Service forest fuels treatments completed in the 2004-2013 period in the western United States subsequently burned in the 2005-2014 period.” This suggests that “most treatments have little influence on wildfire.” In any case, only 40% of wildfires occurred in forests since 1984, with most fires burning grasslands and shrublands.

The authors of the study published by the National Academy of Sciences, recommend a new approach to forest management. Whereas past policies were designed to maintain forest conditions to historical conditions, this is no longer considered a realistic goal. The recommended goal is now “supporting species compositions and fuel structure that are better adapted to a warming, drying climate with more wildfire.”

The other, equally important new goal is to reduce the vulnerability of communities to wildfire by “changing building codes to make structures more fire-resistant…and providing incentives, education, and resources to reduce vulnerability to future wildfire.” The only tree removals that make sense to the authors are those immediately around residential communities, “strategically located to protect homes and the surrounding vegetation.” That is the principle of creating “defensible space” immediately around structures: “fuels management for home and community protection will be most effective closest to homes…where ignition probabilities are likely to be high.” The strategies used in Calaveras Big Trees to protect giant sequoias may not be the best strategies for surrounding residential communities.

Land managers who conduct prescribed burns in sequoia groves also believe they are assisting forest regeneration because the heat of fires is said to release the seed-carrying female cones from the tree canopy and open the cones to release their seeds. The track record on forest regeneration after wildfires depends partly on the severity of fire, but the results of studies are mixed. (4)

The purpose of prescribed burns is to reduce fuel loads with low-severity fire in order to prevent more destructive high-severity fires. However, in the case of giant sequoias, high-severity fires may be necessary for long-term survival of the species: “High-severity fires create robust seedling establishment and survival. For example, in a report on sequoia ecology, NPS researcher Nate Stephenson concluded: ‘Before the arrival of European settlers, successful recruitment of mature sequoias depended on fires intense enough to kill the forest canopy in small areas. Thus, sequoia is a pioneer species, and this conclusion has specific management implications.’” (5)

We saw an example of forest regeneration after a severe wildfire in the sequoia grove in Calaveras Big Trees. Below is a photo of the Mother of the Forest that was burned by a wildfire in 1908. That tree was particularly vulnerable to wildfire because the thick, spongy bark layer that protects sequoias from fire (as well as insects and disease) had been removed by entrepreneurs (more accurately called vandals) who reassembled the bark as a tree replica for display and profit.

The Mother of the Forest is surrounded by a young forest of trees, including many giant sequoias. (See below. Trees with reddish bark are young giant sequoias.) “The [1908] fire created ideal growing conditions for giant sequoia seedlings and today there is a healthy stand of young sequoias there. Many of these trees are the result of natural regeneration that happens after a fire, while others were planted during the 1930s by members of the Civilian Conservation Corps.” (6)

Mountain dogwood (Cornus nuttalli) and hazelnut (Corylus cornuta) are the predominant understory shrubs in the forest of Calaveras Big Trees. After an unusually long, cold winter most weren’t blooming yet at the end of May. A few dogwoods were blooming where sunshine penetrated the tree canopy. (see below)

Unfortunately, these lovely small trees are seen as competitors of the giant sequoias for available water and nutrients in the soil. Therefore, destroying the understory in Calaveras Big Trees is one of the management goals. According to the Calaveras Big Trees Association, most of the dogwoods were chopped down by park staff about 9 years ago. Dogwoods are vigorous resprouters, so they quickly grew back more densely than their taller predecessors. Pesticides (including herbicides) aren’t used in Calaveras Big Trees, so resprouting was inevitable. I wonder if those who destroyed the dogwoods understood that would be the outcome of their effort.

Management strategies of the timber industry are based on an assumption of competition. When clear-cut harvests are done by the timber industry they are typically sprayed with herbicides from helicopters to destroy the understory that they assume competes with the tree seedlings they plant for the next timber crop. Public land managers often use the same strategy.

The research of Suzanne Simard has informed us that there is more cooperation in the forest than there is competition. A lifetime of observing healthy forests taught her that the soil is occupied by vast networks of fungi that connect the plants and trees. These mycorrhizal fungi transfer moisture and nutrients from the soil to the trees and plants, to their benefit. She speculated that the destruction of all vegetation in clear cuts was eliminating that support structure and she designed experiments to test her hypothesis.

The specifics of fungal associations between tree species varies, which requires that we describe a specific relationship. Simard’s original studies focused on the fungal associations between Douglas fir and birch trees in the understory. Birch trees were destroyed in the clear cuts that were then planted with Douglas fir seedlings that were not doing well. Simard’s experiments eventually revealed that birch trees and firs mutually benefit one another through their fungal networks. Carbon stored and the sugar produced by photosynthesis by firs are shared with deciduous birch during winter months while they are leafless. In summer months when birch are foliated, they store more carbon that is shared with firs. Birch is resistant to a root pathogen to which firs are susceptible. In a sharing fungal relationship between birch and firs, birch confers some of that resistance to the root pathogen onto their fir neighbors. Is there a similar relationship between dogwoods and sequoias and other conifers in the forest at Big Trees?

The understory also shades the forest floor, which retains moisture in the soil that would otherwise evaporate in the absence of shade. The canopy of giant sequoias is near the top of mature trees and doesn’t cast much shade. In other words, the shaded forest floor provides more moisture for all members of the plant community in sequoia groves. Furthermore, a shaded forest floor is less likely to ignite a fire because of the moisture it retains.

Month: July 2023