Ecology – Page 24 – Conservation Sense and Nonsense

Deforestation update is good news

We don’t have many opportunities to tell our readers positive stories, so we are grateful for a recent article in The Economist magazine about deforestation. (1) In many places around the world the rate of deforestation has slowed and some places are being reforested. Greenhouse gas emissions from deforestation were contributing 25% of all emissions just 15 years ago. Now deforestation accounts for only 12% of total emissions. The Intergovernmental Panel on Climate Change which represents international scientific consensus said in its most recent report, “deforestation has slowed over the last decade.”

Amazon rainforest. Creative Commons - Share Alike — Amazon rainforest. Creative Commons – Share Alike

The reasons for this improvement are important because they give us clues about how we can make further progress. The Economist sees a pattern in the success stories: “Typically, countries start in poverty with their land covered in trees. As they clear it for farms or fuel, they get richer—until alarm bells ring and they attempt to recover their losses. This happens at different stages in different places, but the trajectory is similar in most: a reverse J. steeply down, then bottoming out, then up—but only part of the way.” Here are a few examples that illustrate this principle:

Fifteen years ago, Brazil was losing 20,000 sq kilometers (7,700 sq miles) of forest per year. Since then a national policy has created national parks and protected patches of forest which has reduced deforestation to a rate of less than 6,000 sq kilometers per year.*
Mexico has cut its deforestation rate even more than Brazil.
India and Costa Rica are replanting their forests. India had 640,000 sq km of forest left in 1980. It now has 680,000 sq km of forest. Only 20% of Costa Rica was forested in the 1980s. Now 50% of Costa Rica is forested.

These countries have in common some of the factors that predict success in reducing deforestation. They are all more prosperous than they were in the past. Their fertility rates are declining. They are all democracies, in which public policy is largely a reflection of what the voters demand of their elected officials. These are also countries in which the government is sufficiently functional to enforce their forest policies. Developments in satellite imagery have helped these governments to monitor and enforce their policies.

(*Since this report was published by The Economist, the Yale Environmental Review 360e has published data on deforestation in Brazil for 2013. After reducing the rate of deforestation since 2004, the rate of deforestation increased from 2012 to 2013 due to new roads and dams, and illegal logging.)

None of these factors would predict the relatively low deforestation rate in the Congo because its population is growing rapidly, it is still very poor, and its government is dysfunctional. The Economist attributes the relatively low deforestation rate of the Congo to the movement of its rural population to distant urban areas. The distance of forests in the east of the country from the cities in the west makes them less vulnerable to deforestation.

Deforestation continues to be a serious problem in Indonesia, despite the fact that the fertility rate has declined and farm output increased. The rate of deforestation in Indonesia has exceeded that of Brazil since 2011. The government of Indonesia is hostile to anti-deforestation policy, seeing it as foreign intervention. Indonesia has only recently achieved democratic elections, which may enable reconsideration of forest policies.

China is also an interesting case because it has invested huge effort in reforestation without making any perceptible progress toward democratization. However, the population is stable and increasingly urbanized and the country is significantly more prosperous than it was in the 1980s. The effects of China’s deforestation were so dire as to motivate its autocratic rulers to take immediate action. (2)

Only 2% of China’s original forest is still intact, according to Greenpeace. Rampant logging and overgrazing have degraded its soil to the point that 25% of its territory is now covered in sand. The desert is so close to Beijing that its roads are often clogged with sand, its railways inundated, and its pastures desiccated.

In 1978, China began one of the biggest reforestation projects in the world. Since then 66 billion trees have been planted to create a shelterbelt along the edges of its northern desert that is projected to be 2,800 miles long by 2050. Unfortunately, the Chinese selected few species of trees, which would grow quickly. Some species were short-lived and some weren’t suited to soil conditions, so only 15% of trees planted since 1949 are still alive. This is probably another example of a country that could make greater progress against deforestation with a more open democracy, which improves decision-making.

Deforestation in the United States

Deforestation in the United States is largely a thing of the past. About half of the United States was forested in 1600 compared to about one-third today. Most of this deforestation occurred by 1910, when demand for lumber decreased significantly due to changes in building materials. In the northeast of the country, much of the land has been naturally reforested as land that had been cleared for agriculture was abandoned. It was always marginal land for agriculture, so as the population became more mobile, it moved west to find better land for farming. This graph reflects these changes in land use and informs us that the south and the west are still supplying lumber for the world. The US is supplying about one-fourth of the world’s timber. Wildfires and insect infestations caused by climate change are also factors in declining forest cover in the west (although probably not reflected in this graph which ends in 1997). (3)

Meanwhile, our local experience with deforestation is an outlier in these national trends. Much of California was naturally treeless grassland and chaparral and it is being returned to that landscape by the native plant movement. Most of our urban forest in the San Francisco Bay Area is not native to California. It is being destroyed by most managers of public land because it is not native. The public often objects to these destructive projects, but we are being ignored.

As we have seen in the examples above, deforestation and reforestation are largely political decisions. American democracy is increasingly more responsive to economic interests than to the public. Declining voter participation rates are undoubtedly a factor in this disturbing trend. If you are not registered to vote, please give some thought to how our democracy has been damaged by lack of participation. Midterm elections will take place this November. Much is at stake.

(1) “A clearing in the trees,” The Economist, August 23-29, 2014

(2) “Great Green Wall,” The Economist, August 23-29, 2014

(3) http://en.wikipedia.org/wiki/Deforestation_in_the_United_States

Rosalie Edge, conservation hero

We are grateful to Dyana Furmansky for turning a suitcase full of letters into a fascinating biography of an important conservationist, Rosalie Edge. (1) Rosalie Edge was one of the first ardent defenders of wildlife—particularly birds—in America. She came to this mission late in life, from unlikely previous experience. Her life is therefore an interesting story, but it also interests us because her experiences as a conservationist shed light on our struggle to preserve our urban forest. Specifically her struggle with the Audubon Society foretold our attempts to convince the local chapter of the Audubon Society (Golden Gate Audubon Society) that some of their policies are harmful to birds.

From privilege to the trenches of conservation warfare

Rosalie was born Mabel Rosalie Barrow in New York City in 1877 into a family of great wealth and privilege. She married Charles Noel Edge in 1909 and followed him around the Orient for several years while he earned his living as a civil engineer and then as an investor.

They returned home, where Rosalie joined the woman’s suffrage movement in 1915. She wrote passionate pamphlets for the suffragists, which later became her hallmark as a conservationist. When women won the vote in the United States in 1920 with the passage of the 19^th Amendment to the Constitution, Rosalie didn’t have much time to find another mission. Her husband fell in love with another woman, effectively ending their marriage, which continued in name only to their death.

At the age of 44, in 1921, Rosalie was grief-stricken about the failure of her marriage. She found solace in walks in Central Park in New York City and soon discovered that watching the birds gave her comfort. The birders of Central Park were a community in the 1920s as they still are today. They took Rosalie under their wing. Soon she was embroiled in the organizational politics of the National Association of Audubon Societies (NAAS), the precursor to the National Audubon Society. She learned that NAAS was engaged in activities that some members considered harmful to birds:

The President of the NAAS was taking donations from manufacturers of guns in exchange for adopting policies that were supportive of hunting birds.
NAAS also refused to oppose policies and practices that are harmful to birds, such as:
- Killing birds to use their feathers in women’s hats, and
- The policy of the federal government that paid large bounties for dead birds of prey, such as bald eagles.
NAAS was trapping and selling fur-bearing animals on its bird reserve in Louisiana to pay the salaries of their staff.

With only the force of her strong personality, Rosalie tried to shame the NAAS into abandoning these practices by attending their annual meetings. When that approach failed, she sued NAAS for its mailing list and won. With the mailing list of the 11,000 members of NAAS, Rosalie was able to communicate directly with the membership. This approach put substantially more pressure on NAAS leadership as well as reduced its membership. She had very little help with this effort. She named her operation the Emergency Conservation Committee (ECC), but she was a proverbial one-woman-band.

Many of the NAAS policies to which Rosalie objected where eventually changed. However, she was alienated from most members of NAAS and its successor NAS, until shortly before her death in 1962 at the age of 85. She attended their banquet in 1962, along with 1,200 conservationists, where she was given a standing ovation. Rosalie said, “’I have made peace with the National Audubon Society.’” (1)

The accomplishments of the Emergency Conservation Committee

The accomplishments of the ECC are particularly impressive if you keep in mind that most were achieved in the 1930s and 40s. In the 1930s, there was very little money for anything other than creating jobs and putting food on the table. In the 1940s the cost of World War II was our highest national priority. Conservation was perceived as a luxury by both the public and the government. Yet, Rosalie and those who helped her, accomplished many great things.

Migrating hawks shot in one day prior to establishing sanctuary. Courtesy Hawk Mountain Sanctuary Archives

Hawk Mountain in Pennsylvania was a place where wind currents funneled tens of thousands of hawks during their fall migration. It was therefore a popular place for hunters to stand on the mountain and shoot the birds out of the air. Tens of thousands of hawks were slaughtered every year, which was just too much to bear for Rosalie. Nearly penniless during the deepest years of the depression, Rosalie borrowed $500 from a friend with an interest in the hawks to lease Hawk Mountain. Fortunately the land wasn’t useful for most purposes and economic conditions depressed land values, so she was eventually able to buy it. It was the first privately acquired property for the sole purpose of conservation. It was considered the model for The Nature Conservancy by one of TNC’s co-founders, Richard Pough. Today, Hawk Mountain is visited by tens of thousands of visitors every fall to witness the migration. There are far more visitors to see the birds than there had been to shoot them in the past. The data gathered at the Hawk Mountain Sanctuary about immature hawk and eagle migration were very helpful to Rachel Carson in making her case against DDT.
When Franklin Roosevelt became President, things got a little easier for Rosalie because his Secretary of the Interior, Harold Ickes, shared her interest in conservation. Together they collaborated to create Olympic National Park in Washington State, to incorporate a sugar-pine forest into Yosemite National Park, and to create King’s Canyon National Park in the Sierra Nevada in California. None of these achievements was easy. The story of how opposition was overcome would sound familiar today. Timber and other economic interests had to be satisfied or neutralized by overwhelming public support. Rosalie’s passionate pamphlets were instrumental in creating public support.

Familiar themes

Rosalie’s experiences with the National Association of Audubon Societies sound familiar to us. Despite the organization’s stated mission of protecting birds, economic interests sometimes influence its policies and practices. The paid staff of an organization is under constant pressure to fund its salaries. The temptation for quid pro quo arrangements is great, particularly during hard economic times. Although Rosalie was successful in ending such arrangements, the temptation is always there. Therefore, constant vigilance is required to prevent it from happening again.

Towards the end of her life, Rosalie’s unpublished memoir explains why her Emergency Conservation Committee was successful:

“In her memoir, she had commended volunteerism as the most meaningful way to bring about change. ‘I beg each one to keep conservation as his hobby, to keep his independence, his freedom to speak his mind,’ she had written years before. She had seen too many professionals become jaded or fall captive to special interests. She, on the other hand, had spoken freely. There would always be a need for those who could do that, she warned.” (1)

We believe that the local chapter of the Audubon Society (Golden Gate Audubon Society) is supporting projects that are harmful to birds. We have detailed those projects in a recent post and won’t repeat them here. The story of Rosalie Edge’s confrontation with the National Association of Audubon Societies warns us that changing those policies will not be easy. However, we are inspired by Rosalie’s success and we follow her lead: We are a loose confederation of volunteers who work collaboratively, but independently. We are compensated solely by the occasional success of our venture to save our urban forest and the animals that live in it. We cannot be compromised by any economic interests.

(1) Dyana Z. Furmansky, Rosalie Edge Hawk of Mercy, University of Georgia Press, 2009

Polarized views of nature mirror our politics

We recently posted an article about our on-going debate with the Audubon Society regarding its misguided support for the projects that are destroying the urban forest in the San Francisco Bay Area. That article provided a few examples of our widely divergent views of nature:

We don’t see how birds will benefit from the destruction of tens of thousands of trees and countless plants that provide food and cover for birds and animals.
We don’t enjoy walking in nature with a judgmental eye, which points fingers at plants and animals that others claim “don’t belong there.” We are unwilling to divide nature into “good” and “bad” categories.
We don’t think humans have the right to pass a death sentence on wild animals because they prefer another animal, which they claim will benefit from the death of a potential competitor.
We don’t consider a “managed” forest a “more natural forest.” We don’t think humans are capable of improving what nature can accomplish without our interference. We don’t think a public park that is routinely sprayed with herbicides can be accurately described as a “natural area.”

English sparrow. US Fish & Wildlife photo

However, these widely divergent viewpoints about nature are not inconsistent with the extremes of our polarized politics in America. Just as we don’t expect to change the minds of those at the opposite end of the political spectrum, we don’t expect to change the minds of those who view nature through the darkly colored lens of nativism. Just as elections for public office are decided by the independents in the middle of the political spectrum, the debate about the future of our public lands will be decided by those who have not yet formed an opinion about what is best for nature. Today’s post is addressed to them. We will tell the “independents” about two recent op-eds published by The New York Times which represent the two extreme viewpoints about nature. Both op-eds use sparrows as representatives of the natural world, which we hope will make the differences in these viewpoints starker and therefore clearer.

First a word about how important the “independents” are to the debate about the ecological “restorations” which are dictated by invasion biology. Political independents are usually not more than a third of the electorate. But, a survey conducted by University of Florida suggests the majority of the public are still open to learning more about “invasive species.” They report that 62% of Floridians they surveyed said they are not knowledgeable or only slightly knowledgeable about invasive species. Ironically, the same survey claimed that “a majority voiced support for raising sales tax to combat invasive species.” One wonders why voters who acknowledge that they know nothing or next to nothing about invasive species would be willing to tax themselves to combat something they don’t understand. In any case, if Floridians are typical, the majority of the public needs to know more about invasion biology. We hope they have access to balanced information that is not written by those who make their living killing animals and poisoning our public lands. Million Trees was created over four years ago for that purpose.

“The Truth About Sparrows”

Some time ago, we told the story of how sparrows were brought to America in the 1850s by people who believed they would eat the insects that were killing trees. We concluded that article by saying that 150 years later house sparrows are no longer despised as alien intruders. We were wrong.

In May 2014, the New York Times published an op-ed entitled “The Truth About Sparrows.” The op-ed was written by Peyton Marshall, whose mother was an exterminator of house sparrows. This was no idle pastime for Ms. Marshall’s mother. It was her mission.

Mom’s crusade against house sparrows began when Ms. Marshall was a child. Mom loved bluebirds at a time when their population was dwindling in the east where they lived. Mom decided that house sparrows were to blame and so she took it upon herself to kill every house sparrow that had the misfortune of entering her yard or within reach of it.

Mom began by trapping the house sparrows. “Good” birds caught in the traps were freed, but the house sparrows were put into plastic garbage bags and asphyxiated. Mom started the family car in the garage and wrapped the open end of the garbage bag around the tailpipe. When the birds did not die, she consulted her husband who informed her that the car was a diesel and would not produce enough carbon monoxide to kill the birds.

So, mom took her operation on the road. She helped elderly ladies with their groceries in the parking lot in exchange for a shot at their tailpipe. When dropping off her children for play dates and birthday parties, she asked their parents if she could make brief use of their cars to kill birds. Polite parents watched in horror as they became accessories to this execution.

Ms. Marshall concludes her story by noting that the population of bluebirds has rebounded since she was a child. But mom continues to trap house sparrows in her yard and now uses a less public means of killing them: “Now, she uses a carving knife and cutting board, at her leisure, in the privacy of her own kitchen.”

Although Ms. Marshall doesn’t say so, we doubt that the recovery of the bluebird population has much to do with the extermination of house sparrows in her mother’s backyard. The recovery of the bluebird population is attributed to building nest boxes that substitute for the dead trees which are their preferred nest sites. There are few dead trees in urban and suburban areas because people consider them hazardous and unsightly. Once again, animals pay the price for the choices of humans.

“What the Sparrows Told Me”

The New York Times published “What the Sparrows Told Me” in August 2014. It is a fitting antidote to the grisly tale of the sparrow exterminator.

Trish O’Kane, the author, was a human rights investigative journalist in Central America for 10 years before moving to New Orleans to teach journalism. Less than a month after arriving in New Orleans, she and her family were displaced by hurricane Katrina in 2005. Four months after the hurricane, she rented a room in a dry part of town so that she could return to her teaching job. It was a hard time for everyone in New Orleans, but her gloom was deepened by learning of her father’s terminal cancer which would kill him in a matter of months.

Ms. O’Kane had never had an interest in birds before, but she knew she needed “to focus on something beautiful, something positive, something alive,” and so she did:

“I bought two bird feeders. Each morning I sat on that back stoop and watched those sparrows. Instead of wondering what was going to happen to the city, to the Gulf Coast, to the planet, I started wondering why one sparrow was hogging all the seed. I started thinking about their resilience, their pluck, their focus on immediate needs. If they couldn’t find food, they went somewhere else. If they lost a nest, they built another. They had no time or energy for grief. They clung to the fence in raggedy lines heckling one another like drunken revelers on Bourbon Street. Their sparring made me laugh.“

Audubon Park, New Orleans. Public domain

Ms. O’Kane started holding her classes in Audubon Park, named for John James Audubon. Her students began to find the same solace in watching the birds going about their business, finding a way to survive, carrying on. And that gave her and her students the strength and the will to do the same at a time when life was hard in New Orleans.

Ms. O’Kane is now a doctoral student in environmental studies at University of Wisconsin, Madison. She has found a way to connect her interest in human rights with her new found interest in birds. She teaches an undergraduate course in environmental justice in which she pairs undergraduate students with middle school students in a mentoring program called Nature Explorers. Many of the middle school children are immigrants from Central America. She finds that they enjoy learning about the birds that migrate between Central America and Wisconsin, just as their families did. The birds, like the people of America, are citizens of the world.

Ms. O’Kane tells us that many of her undergraduate students are frightened of the future of our planet. She likes to start each new class with the story of the sparrows in New Orleans: “I tell them that the birds are a gift to help them get through each day, a way to enjoy the world while we change it so that young people, everywhere, have a chance.”

Whose eyes do you choose to look through?

It’s no secret that our viewpoint regarding nature is more closely aligned with Ms. O’Kane’s. If you haven’t yet taken a stand on the issue of what plants and animals are welcome in your ideal nature, think for a moment. Which of these starkly different viewpoints do you prefer?

Understanding the eucalyptus forest – Professor Joe R. McBride

This article has been republished from the website of Save Mount Sutro Forest, with permission.

Dr. Joe McBride of UC Berkeley spoke at the Commonwealth Club in April 2014 as part of the series “The Science of Conservation and Biodiversity in the 21st Century.” His main message:

Eucalyptus groves in California provide habitat for as many native species as do most ‘native’ habitats.
They grow well at high densities and an average spacing of 8 feet between trees is quite typical.
They have relatively high fuel loads, but the cool and damp dense eucalyptus forests reduce the risk of fire.
Eucalyptus is subject to few diseases or pests, and parasitic wasps provide pest control.
It provides a host of ecosystem services including carbon sequestration, pollution reduction, slope stabilization, windbreaks, wildlife habitat, and recreational value.

Dr. Joe R. McBride was Professor of Landscape Architecture and Environmental Planning, Department of Environmental Science, Policy, and Management, UC Berkeley. (He has since retired.)

Read on for notes from Dr. McBride’s talk. (There are also links to his Powerpoint presentation.)

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THE HISTORY, ECOLOGY AND FUTURE OF EUCALYPTUS PLANTATIONS IN THE BAY AREA

Notes From a Talk By Dr. Joe R. McBride

Dr McBride’s wide-ranging talk covered a lot of ground. He talked about the ecology of the eucalyptus forest in the Bay Area: its structure, the variety of plants and animals that live within it, its health and the ecological functions it performs; the dynamics within these forest stands; and their invasive potential.

WHY EUCALYPTUS CAME TO CALIFORNIA

Eucalyptus was first planted in California during the Gold Rush, possibly for oil to use in gold-mining and in medicine.

In the 1870s, eucalyptus planting was encouraged for many objectives: to beautify cities, to improve farmland, as windbreaks, and to dry out swamps to combat malaria.

It was grown in woodlots for firewood, but as people switched to natural gas and other fossil fuels this became rare. Later, it was planted for timber – which didn’t work out because the trees were harvested too young; and still later for bio-fuel, which did not become commercially attractive.

By the 1950s, it had become an integral part of the California landscape. Six species were planted, primarily blue gum in Northern California, and red gum and river gum in Southern California. (Worldwide, there are perhaps 640 species.)

Eucalyptus beautifies our cities, and helps stabilize soil on steep hills. The surface area of the leaves, broader than those of conifers, help trap particulate pollution. Unlike deciduous trees, the evergreen foliage of eucalyptus removes pollutants all year long.

HOW DENSE MAKES SENSE?

The density of eucalyptus plantations in Bay Area ranges from 150-160 trees per acre to about 1700 trees per acre. mt davidson understory (The highest density resulted from a freeze in 1970s: trees were cut down because of the perceived fire hazard, but the trees presumed dead later resprouted.) On Angel Island, the normal density was 8ft spacing (about 680 trees per acre) but it ranged to 30 feet between trees.

In the East Bay, 8 ft. x 8 ft. is quite typical eucalyptus plantation density. Left to grow naturally, stands become denser through in-growth, mainly by sprouting and also by sibling establishment.

Is management by thinning necessary for the health of the forest, someone asked, and what density is ideal?

Dr McBride had seen no examples of stands that could be improved by thinning. Eucalyptus grows well with a high density at an average of 8 ft x 8ft spacing between trees. In Australia and New Zealand no one thins; they just harvest the trees and let them regrow from sprouts.

In the US, eucalyptus was not marketable, so there’s no history of managing eucalyptus plantations. Also, until recently there were no diseases or insects. The long-horned borer and the psyllid have now appeared in some places, and thinning is not seen as a solution to these insect problems; they are better controlled by certain predatory wasps.

Logging eucalyptus would mean a lot of ground disturbance and erosion. If the logs are removed, the skid trails can destabilize the soil.

MUCH GROWS UNDER EUCALYPTUS – NATIVE AND NOT

Contrary to popular belief, eucalyptus forests have as many species (or more!) growing in their understory as do oak woodlands. A 1990 survey in Tilden Park found 38 species in the understory of eucalyptus forests (24 native plants; 14 introduced plants), while the oak woodland had 18 species in understory (14 native plants; 5 introduced plants). Only the riparian woodlands in Murray Park are somewhat richer in species than riparian eucalyptus forest (58 species vs 34). In East Bay eucalyptus forests, California Bay, Coast live oak, poison oak, bedstraw, California blackberry, and chickweed were ubiquitous. The amount of light reaching the ground influences which species can be found in the understory.

What about allelopathy? Under experimental conditions, eucalyptus litter inhibited germination and growth of cucumber seeds, so eucalyptus litter may be somewhat allelopathic to some plants. But a study from UC Santa Barbara indicates that if eucalyptus litter is removed, within 2 years there’s no inhibitory effect on other plants germinating. And clearly, it isn’t allelopathic to all the species mentioned earlier.

Someone asked whether it would be advisable to “manage eucalyptus stands that have an invasive understory.”

Dr McBride responded: “I have no prejudice against invasive plants. I am an invasive Californian myself.” (There was amused applause.) He continued that each eucalyptus grove is different, so it’s important to look at it on a stand-by-stand basis and measure the fire hazard of eucalyptus plantations against the value of each stand for wildlife habitation, recreation, and wind break functions.

In response to a question about whether ivy kills eucalyptus trees, Dr McBride said he has not seen evidence the ivy shades the foliage of eucalyptus trees. He’s seen no evidence of ivy killing eucalyptus, although on Mt. Davidson, he did see ivy growing over trees that had been killed by girdling with an axe or chainsaw.

INSIDE A EUCALYPTUS FOREST

Shading and leaf litter changes the microclimate of a eucalyptus grove. As you move in from the edge to the interior of the forest, conditions change. The species change from the edge to the interior of the forest as the amount of light decreases, so there are different species at the edge of the forest and inside it. A 1980s study in the Presidio compared conditions outside a eucalyptus forest and inside it. It showed:

Temperature moderation: Daytime temperature fell an average of 10%, and night-time temperature rose an average of 5%
Windbreak: Wind velocity dropped 40%
Relative humidity was 5% higher (from the edge to the interior).
Shade: Light intensity was 90% lower.
Moisture: Precipitation (rain) decreased 12%; but fog-drip (i.e., moisture precipitated from the fog) increased 300%

EUCALYPTUS STORES CARBON

Eucalyptus increases the carbon content in the soil compared to grasslands (Zinke et al, 1988). Its fast growth and large size means it sequesters a lot of carbon in its trunk and root systems.

EUCALYPUS SUPPORTS WILDLIFE

Again, contrary to belief, eucalyptus provides a good environment for a wide variety of wildlife. A number of studies demonstrate this.

A 1970 study showed many birds make “moderate use” of eucs as habitat and a few birds make “great use” of eucs. (Almost all these species are native.) Birds that make most use: mourning doves; Great Horned Owls, whose range has been extended by CA eucalyptus; Stellar’s jays; yellow-bellied sapsuckers; Allen’s hummingbirds; olive-sided flycatchers; brown creepers; dark-eyed juncos; Audubon warblers.
Some reptiles make great use of eucalyptus groves: Southern Alligator lizard and the slender salamander. Among mammals, deer mice make “heavy” use of eucalyptus.
photo credit: Janet Kessler

Robert Stebbins’ monumental 1978 study on the attractiveness of eucalyptus for habitat in the East Bay found that all species making use of eucalyptus for habitat found eucalyptus about the same as grasslands in attractiveness, but oak/bay woodlands were even more attractive.
Monarch butterflies most commonly use eucalyptus trees in state parks. But some of the insects in eucalyptus hurt the trees. One is the eucalyptus long horned borer – but can be controlled by a parasitic wasp. The red gum lerp psyllid is more of a problem in Southern California, which has more red gum. However, it’s part of the food chain: woodpeckers and other bird species feed on their larvae.
A study showed that eucalyptus in a riverside environment doesn’t impact species diversity of stream insects or pollution tolerance compared with native riparian environments.

NATURAL SUCCESSION IN EUCALYPTUS?

Over the next 200-300 years, the eucalyptus forests in the East Bay could gradually – and naturally – shift to oak-bay woodlands. In the East Bay (though not at Mt. Davidson or Mt. Sutro), the eucalyptus plantations have California Coast live oaks and California bay trees in the understory, and they are doing well. The live oaks are “tolerant” of shade and the bays are “very tolerant” of shade. If they aren’t disturbed, the oaks and bays regenerate well in the understory, and being even longer-lived than the eucalyptus trees, they will eventually naturally succeed the eucalyptus. The bay tree is higher in regeneration than the Coast live oak in Tilden Park (McBride, 1990).

WHAT ABOUT FIRE HAZARD?

Eucs support considerable fuel load on the ground because of rapid decay of foliage and shredding of its bark. They have a higher fuel load than California bays or Coast live oaks. They release an aromatic compound that can ignite with sparks, and they burn hot.

However, while the tree density of eucalyptus plantations can mean a greater accumulation of fuel in the understory, the higher density means a cooler, wetter understory that might not dry out as fast. Three risk factors in fire risks of any tree: amount of fuel it produces; tissue moisture content; fuel ladder based on presence of other plants in its understory.

IS EUCALYPTUS INVASIVE?

Under certain circumstances, eucalyptus can spread – for instance, on Angel Island, some stands spread through road cuts and prescribed burns (which destroyed competing vegetation). However, in most cases they don’t: aerial photographs show that boundaries are stable. The eucalyptus forests on Mount Davidson and in Tilden Park show stable boundaries.

In the Bay Area, Dr McBride found eucalyptus forest area declined between 1939 and 1997. The natural spread hasn’t increased the area of eucalyptus groves.

DO TREES DEPLETE AQUIFERS?

Someone mentioned attending a talk where the speakers said that tree removal would help to replenish aquifers. Was that true? Dr McBride thought it very unlikely; most aquifers are much deeper than tree roots.

WHAT ABOUT PESTICIDES?

Someone speaking for people with disabilities owing to chemicals said herbicide use in these areas violated their right to access, and wondered how “environmental” organizations – like the Sierra Club – could support this. Dr McBride sympathized, said he was also concerned about toxic herbicide use. He mentioned that the East Bay tree-felling project is on hold owing to a number of unanswered questions that would need further research.

Here are links to his Powerpoint presentation in ppt and pptx formats.
PPT: McBride Presentation – Eucalyptus
PPTX: McBride Presentation – Eucalyptus

Here is a link to the audio notes taken by a member of the audience

Global increases in biodiversity resulting from new species

Great horned owl in eucalyptus. Courtesy urbanwildness.org

One of the most popular justifications for eradicating non-native plants is the claim that they will out-compete native plants, ultimately causing their extinction. Innumerable studies have found no evidence to support that claim, but the belief persists amongst those who demand the eradication of non-native plants.

Islands have been considered particularly vulnerable to extinctions because they contain many endemic species (found only on that island) that have evolved in physical isolation from their ancestors from other places and become unique species. And there were many animal extinctions–particularly of flightless birds–with the arrival of humans who were both their predators and brought predators with them.

However, despite the conventional wisdom that the introduction of new species of plants to islands would result in extinction of their predecessors, there is no evidence that this is indeed the case with introduced plants. In 2008, Dov Sax and Steven Gaines published a study of species diversity on islands. This is what they found:

Honeybee on wild mustard. Courtesy urbanwildness.org

“Predation by exotic species has caused the extinction of many native animal species on islands, whereas competition from exotic plants has caused few native plant extinctions…By analyzing historical records, we show that the number of naturalized plant species has increased linearly over time on many individual islands. Further, the mean ratio of naturalized to native plant species across islands has changed steadily for nearly two centuries. These patterns suggest that many more species will become naturalized on islands in the future.” (1)

In other words, the introduction of new plants to islands has not resulted in extinctions of the plants that preceded them. Therefore, the result of plant introductions has been greater plant diversity on islands.

But what about the continents?

Painted lady butterfly on Weigela. Courtesy urbanwildness.org

Recently a new study was published that asked the same question on a global scale: Has the introduction of new plants and animals resulted in the extinction of their predecessors? The answer is a resounding NO! (2)

The study was conducted on a huge scale by an international team of scientists:

“6.1 million species occurrence records from 100 individual time scales”
“35,613 species were represented…including mammals, birds, fish, invertebrates, and plants”
“The geographical distribution of study location is global, and includes marine, freshwater, and terrestrial biomes, extending from the polar regions to the tropics in both hemispheres.”
“The collective time interval represented by these data is from 1874 to the present, although most data series are concentrated in the past 40 years.”

Like most scientists who expect to find evidence of decline, this team of researchers was surprised to find little evidence of loss. Here are some of their key findings:

“Surprisingly, we did not detect a consistent negative trend in species richness or in any of the other metrics of α diversity.”
“There is no evidence of consistent loss of biodiversity among terrestrial plants.”
“Time series for terrestrial plants exhibit, on average, a positive slope for species richness.”
“Collectively, these analyses reveal local variation in temporal α diversity but no evidence for a consistent or even an average negative trend.” (Alpha diversity is species richness at the local level.)
“An analysis of slopes by climate regions reveals that temperate time series have a significantly positive trend…”

In other words, new plants result in more plants, particularly where we live, in the temperate zone. There is no empirical evidence that new plants have resulted in the loss of the plants that were there before they arrived.

So what’s the beef?

Song sparrow in wild radish. Courtesy urbanwildness.org

You might think that this huge new study would put the controversy to rest. You would be wrong. For every answer we find, there is a new question from nativists. The response of native plant advocates to the good news that the plants they prefer will not disappear if new plants are allowed to live in their company is that the plant world is being “homogenized.” They say that if new plants are permitted to remain, all landscapes will become the same, resulting in the loss of unique landscapes that existed in the past.

They are, of course, mistaken. Their dire prediction will not come to pass because the biotic and abiotic conditions of every landscape are unique. The climates are different. The soils are different. The atmosphere is different. The plants and animals that are there when they arrive are different. If the new plant survives in its new home, it will be capable of adapting to these local conditions and over time it will change, ultimately becoming a unique species. When the first family of monkeys made the voyage from Africa to South America, they were the same species as those they left behind. Now they are unique species as a result of genetic drift and genetic divergence.

The process of adaptation and evolution is often more rapid than we expect. Sometimes such changes have occurred within the lifetimes of scientists who were able to witness these changes. More often, the changes occur more slowly and are only visible in museum collections or fossil records.

Consider the consequences

Garter snake in eucalyptus leaf litter. Courtesy urbanwildness.org — Garter snake in euclypatus leaf litter

It is physically impossible to prevent the arrival of new species. Even when they are not intentionally introduced they find a way to piggy back on the daily activities of humans. They arrive on our airplanes and cargo ships. We aren’t going to stop importing or exporting our products all over the world. Nor are we going to quit traveling. We must accept the consequences of the way we live and quit blaming plants and animals for their passive participation in our movements.

Aside from the question of whether or not it is physically possible to stop the arrival of new plants and animals, let’s acknowledge that at least in the case of plants no great harm has come from their introduction. Since we now enjoy more plants than were here when they arrived, just what is it that we’re griping about? We seem to be griping about change. Change will occur whether we like it or not. We can’t prevent change, so we must quit fighting against something that we are powerless to prevent. That is the definition of wisdom.

Finally, we must consider the consequences of trying to eradicate non-native plants that are firmly entrenched in our landscapes. Huge amounts of herbicide are being used in the futile attempt to eradicate them. Fires that pollute the air and endanger our homes are set for the same purpose. Trees that are performing valuable ecological functions are being destroyed. The animals that use these plants and trees for food and cover are being deprived of their homes and their food. We are doing more harm than good.

Dov Sax and Steven Gaines, “Species invasions and extinctions: The future of native biodiversity on islands,” Proceedings of the National Academy of Sciences, August 12, 2008
Maria Dornelas, et. al., “Assemblage times series reveal biodiversity change but not systematic loss,” Science, April 18, 2014

Open letter: Does Audubon Society advocate for birds or birders?

Our family was a member of the Audubon Society for decades because we love birds and birding all over the world is our primary hobby. So, it was painful to give up that membership a few years ago when we were unable to convince the Bay Area chapter of Audubon (Golden Gate Audubon Society (GGAS)) that its support for the projects that are destroying hundreds of thousands of trees, are harmful to birds. We didn’t give up easily. We tried for many years to convince GGAS that their policy is harmful to birds. Since leaving Audubon, the GGAS has become progressively more aggressive in its support for these projects. Here are a few recent examples of policy decisions they have made:

GGAS signed a letter of support for the planned project that proposes to aerial bomb 1.3 metric tons of rodenticide on the Farallon Islands to kill mice. You can read about that horrible project HERE.
GGAS is also supporting the US Fish & Wildlife project that is shooting barred owls based on the belief that another native bird will benefit. Read about that project HERE.
Recently they sent a letter to University of California, San Francisco, asking them to proceed with their original plans to destroy approximately 30,000 trees on Mount Sutro. These plans are presently on hold in response to the objections of the public.

Today, we are going to take a closer look at Audubon’s support for the destruction of most trees on Mount Sutro. Jack Dumbacher, member of the GGAS Board of Directors and Chairman of the GGAS “Conservation” Committee, has written an article for the GGAS blog about that project, which gives us this opportunity.

Who are “WE?”

Mr. Dumbacher’s article begins with a litany of “what WE want:”

“We understand that just seeing birds is not enough – we want diversity. It is not enough to have a life list of one species that you’ve seen really well.
“We want a long life list with many species. We want to count as many species as we can on each field trip.
“We want to see birds doing a variety of interesting things.
“We want reasons to visit a variety of habitats and regions. And we love seeing that occasional rare, out-of-place species.”

Many birders and Audubon members have tried unsuccessfully to engage Mr. Dumbacher in a dialogue, so we are resorting to this “open letter” venue to ask these questions:

Who are “WE” in this list of what Mr. Dumbacher claims “WE want?” Does he speak for you? Does he speak for the birds? If not, is he speaking for himself? Is he speaking for all Audubon members? If you are an Audubon member, is he speaking for you?
If this isn’t a list that speaks for you, what do YOU want? Do you want to be able to walk in a forest in which many birds live now? Or do you prefer grassland and dune scrub, which is what the forest in San Francisco is being converted to by native plant advocates?
If Mr. Dumbacher’s wish list doesn’t speak for the birds, what do you think the birds want? Where do you think the owls and raptors will nest if all the tall trees are destroyed? Where do you think the bats will live if the tall trees are destroyed? What do you think the hummingbirds will eat in the winter if all the eucalypts that flower in the winter are destroyed?

Red-tailed hawk nesting in eucalyptus. Courtesy urbanwildness.org

We are too ignorant to understand what THEY want

Mr. Dumbacher wonders how those who share his opinions regarding nature can convince us to want what they want: “…how do we make the case for diversity?” Then he proceeds to try to make the case, by looking back on his childhood experiences in nature and passing judgment on them:

“My father spent much of his spare time in open green spaces. Sometimes I would go with him, and we heard birds and saw squirrels and geese, and we believed that we loved and understood nature. After spending many more years of my life studying biology, I realized that we were just golfers on a relatively impoverished golf course landscape.”

It struck us as unspeakably sad that he would look back on his childhood experience in nature with such condescension. It seems that each of us should have the right to enter nature with whatever level of knowledge we can bring to that experience. Mr. Dumbacher has a Ph.D. degree. Does he think a Ph.D. degree is required to appreciate nature? Such a prerequisite would leave most of us out. Don’t we have a right to enjoy nature too?

Burdened with too much knowledge

We will use our personal experience to present a contrarian viewpoint. A few years ago we had the opportunity to drive the length of the Blue Ridge Highway from the Shenandoah Valley in northern Virginia to the heart of Tennessee. Of course, we had many walks in the woods. It was early spring. The dogwoods were blooming. The birds were actively starting their nesting season. As much as we enjoy a walk in the woods here in California, there was even greater pleasure in those walks in the eastern woods because we have almost no knowledge of what is native or non-native there. It was a great relief to be able to walk without passing judgment, as we have been taught to do in California. There was no need to point fingers and declare that something “doesn’t belong there.” We could accept the beauty of everything we saw on equal terms. Ignorance was bliss.

Monarch caterpillar on milkweed. Tilden Botanical Garden

We will contrast that experience with a more recent experience in the East Bay Regional Park District Botanical Garden in Tilden Park. We were taking a course in which several participants in the class were members of the California Native Plant Society. You might think that a botanical garden in which solely natives are planted, would be a pleasant place for them to walk. It wasn’t. They were outraged by the few non-native “weeds” we saw. They crawled over the plantings to pull the uninvited plants from their roots. One was a lovely scarlet pimpernel, blooming in its bright coral amongst native plants in their dormant, brown phase. Their destructive attitude detracted from our enjoyment of the garden.

The “tiny minority” myth

As the “restoration” projects in the Bay Area have become progressively more destructive, the public has become progressively more opposed to them. Mr. Dumbacher calls us a “vocal minority” in his article. He is mistaken. We consistently outnumber native plant advocates (sometimes ten to one) whenever we have an opportunity to express our opinion in a public venue: in public hearings, on petitions, during written public comment periods. We are not a minority.

Mr. Dumbacher is also mistaken in his description of the project which he is defending in his article. He says, “…a Sutro Management Plan was formed that balanced incremental thinning with incremental planting of native species, in order to increase diversity and reduce the fire threat.” We will give Mr. Dumbacher the benefit of the doubt by assuming that he has not read the Environmental Impact Report of February 2013, in which the project was described in detail. Within ~~a year~~ five years, that project would have destroyed 90% of the trees (about 30,000 trees) and understory on 75% of the acres of Mount Sutro. It proposed no planting of native plants, with the exception of a few small areas if money became available to pay for them. The word “thinning” is used by native plant advocates to describe their plans to destroy the forest because it sounds less destructive. However, it is not a word that accurately describes the destruction of 90% of the forest.

What happens to the birds that are there now?

Blackberries in the Sutro forest. Courtesy Save Sutro Forest

Unfortunately, we can’t share with our readers the lovely pictures in Mr. Dumbacher’s article because we don’t have permission, although you can visit the article to see for yourself. You will see beautiful birds sitting on plants that exist now on Mount Sutro and Mount Davidson. They are native plants that thrive in the understory of the forest and are unlikely to survive the devastation of the destruction of the trees and understory. There are also non-native plants in the understory. Many of them, such as blackberry, are valuable sources of food for birds. There is no evidence, and no reason to believe, that destroying the Sutro forest will increase the number of bird species in San Francisco.

Native red elderberry on Mount Sutro. Courtesy Save Sutro Forest

One wonders if Mr. Dumbacher isn’t aware of this obvious contradiction: he illustrates his article with birds that live in the forest now while trying to make the case that the forest must be destroyed so he can see more birds. Perhaps the answer is that he doesn’t really want more birds, he is only interested in certain birds: “But If you want migrants to visit your city, if you want rare birds to breed in your local parks, and if you want a county list that exceeds 200 species, then please get involved in local habitat management and restoration, and be ready to speak up for nature in your city.”

The "managed" portion of the Sutro forest: orange flags and weeds — The “managed” portion of the Sutro forest: orange flags and weeds

Here is another contradiction in Mr. Dumbacher’s appeal for your support for destroying most of the Sutro forest: “we should try to manage a more natural forest.” In what sense is a “managed” forest also a “more natural” forest? The Sutro forest is natural now, wild and unmanaged, a delightful mess. We see no benefit in “managing” it. Our experience with the managed summit of Mount Sutro is herbicide use (in the past), irrigation, wood chips, and dry weeds populated with colored flags where someone has apparently planted something that didn’t emerge from the wood chips.

Does Mr. Dumbacher speak for you? Do you share his view of “nature?”

Postscript: Mr. Dumbacher’s viewpoint is particularly troubling because he is Chair of the Department of Ornithology and Mammalogy at California Academy of Sciences, the Bay Area’s leading institution of science education. It seems that there is little science in Mr. Dumbacher’s viewpoint as expressed in his article.

Invasive Species?

We spent nearly two months analyzing the California Invasive Plant Council’s draft reassessment of blue gum eucalyptus and informing our readers of the fallacious reasoning used to continue its classification of blue gum as “invasive.” We are badly in need of comic relief and we assume our readers could use some as well. We are republishing with permission an article by Robert Platt Bell from his blog, “Living Stingy.” Mr. Platt is a patent attorney on Jekyll Island, Georgia. His blog gives advice about “how to live a better life with less money.”

His sarcastic criticism of invasion biology reveals that he is a man of considerable good sense. Although we tend to use scientific arguments on Million Trees to critique invasion biology, Mr. Platt’s article demonstrates that a little common sense is really all that’s needed. Mr. Platt ends his article with the disclaimer that he doesn’t have a cat and we will do the same. We don’t have a cat, never have, never will.

Some folks claim that the ordinary house cat is an "invasive species" — Some folks claim that the ordinary house cat is an “invasive species”

Your tax dollars at work. Here on the island, they have attached little cameras to cats to monitor their behavior. The University of Georgia is funding the study, which in turn is funded by your taxes.

They also have sent out a “feral cat awareness survey” to everyone on the island, and again, this is funded by UGA. The “survey” is more of a “push-poll” in that it asks questions that are more answers than questions. “Did you know that cats are responsible for killing billions of songbirds every year?” – that sort of thing, courtesy of the bureau of specious statistics.

Actually, the results of “kitty-cam” so far are that cats (1) lick themselves a lot, (2) sleep, and (3) eat cat food. Only one cat has been caught killing for food, and no word on whether it was a rodent or a bird.

But the oddest thing about this “poll” was that they were trying to characterize house cats as “invasive species” by the way the questions were asked.

“Invasive Species” is the hot, new, trendy term for biologists and wildlife managers to use – and one they use to justify poisoning the air, water, and soil, all in the name of “preserving nature”.

We are told (get this) that some species are “native” and others are “invasive” and that the latter need to be slaughtered, as they will push out the “native” species over time.

This may or may not be true. The point is, the species doesn’t consider itself “invasive” anymore than the species it is displacing (which at one time was no doubt “invasive” as well).

Some try to put a spin on this based on a human vector. If the species is relocated due to some act of mankind, then it is “invasive”, whereas if it just migrated here, I guess it is natural. This also is a load of hooey, as the vectors that move species from one area to another have little to do with whether the species would eventually get there under its own power, or whether it would adapt to the new environment.

And speaking of “invasive species,” this sort of discussion usually neglects to address the most invasive species on the planet – a species that has occupied every ecological nook and cranny on the planet and adapted itself to harsh environments and even space.

Yea, I’m talking about you and me – human beings. We have over-run the planet, but no one talks about euthanizing or neutering people on a massive scale.

On the other hand, we can poison some trees or a carp or whatever, and that’s going to fix everything up just Jim-Dandy!

I think biologists who believe that have their head up their ass, or are just looking for grant money.

In the Northeast, we are told the Zebra Mussel is “invasive” – but it has turned murky brown lakes crystal clear. The powerplant that has to clean its inlet screens, we are told, is justification for dumping poison in the water, or for fining some unwitting fisherman hundreds of dollars for dragging a piece of seaweed on his boat trailer. The upshot is, the zebra mussels are winning, much as the lamprey eels are (and the snakehead fish).

In the Everglades, we watched as “wildlife managers” drilled holes in trees and filled them with poison. Their crime? Being non-native. Whether this will permanently kill off these trees is debatable, and the long-term effect of poisoning nature is something not studied. And the cost of this “cure” is pretty staggering.

Nature expands into environments where it can adapt, and you can’t stop that. It is like Boyle’s law about gas – it expands to fill a vessel. Trying to hold back the tide of species is pointless and fruitless (pardon the pun) as nature will sneak around at every turn, as soon as you let your guard down.

Yes, it is bad there are Boas in the Everglades. It is also irrelevant whether they got there as escaped pets or were dropped from an airplane or swam over from South America. They are there, and trying to extinguish them is going to be a long, difficult, and expensive job that will never get done.

Here on the island, a couple runs a program that captures and neuters cats and then releases them. It has been effective as the cat population has plummeted from the 1990’s until today. (They did a similar thing in Key West, and now there is no cat problem, just a chicken problem).

But on the other hand, we are being overrun by deer – and not in the sense that “the deer ate my flowers” nonsense. We simply have more deer than the island can support, and they are becoming smaller and more sickly as a result (and more brave, as they are not afraid of humans at all). New breeding stock was brought in to try to reverse the trend, but it has not really helped. Talk of managing the deer population or relocating deer is shouted down as “inhumane”.

But apparently, it is open season on cats.

(Disclaimer: I do not presently own any cats. I like them, but don’t like cleaning out litter boxes. Hence I have no cats).

Birds and butterflies in the eucalyptus forest

The deadline for sending comments to the California Invasive Plant Council (Cal-IPC) about their draft reassessment of blue gum eucalyptus is Thursday, July 31, 2014 (send to info@cal-ipc.org). We are hoping to inspire you to write your own comment by sharing our personal favorites of some of the goofy statements Cal-IPC uses to justify its classification of blue gum as “moderately invasive.”

Eucalyptus trees do NOT kill birds!

Our regular readers have heard the absurd claim that eucalyptus trees kill birds by “gumming” up their noses or beaks with the nectar of the eucalyptus flowers. We have published detailed critiques of this claim, so we won’t repeat them because you can visit those posts by clicking HERE and HERE.

Of course, all of this detailed information was provided to Cal-IPC when the original request to reconsider their classification of blue gum was submitted in December 2013. In their draft reassessment, Cal-IPC now sinks to a new low by claiming Ted Williams as the source of the claim that eucalypts kill birds. Mr. Williams writes an opinion column published by Audubon magazine, which is appropriately entitled “Incite.” In 2002, Audubon magazine published Mr. Williams’s opinion of eucalyptus, which he called “America’s Largest Weed.”

Ted Williams is not a scientist or a journalist. He is a commentator. His column in Audubon magazine is not entitled “Insight,” because it is intentionally inflammatory. It engages in rhetoric and hyperbole in support of Mr. Williams’s opinion. In an article in High Country News, Mr. Williams describes “Incite” as a “muckraking column” and he calls himself an “environmental extremist.” Citing Mr. Williams as a source of information undermines the credibility of Cal-IPC’s draft reassessment. Quoting Mr. Williams on the subject of eucalyptus is a bit like quoting Rush Limbaugh on the subject of immigration.

But let’s be more specific with examples of the absurd statements Mr. Williams makes and the evidence that these statements are not factually correct.

The truth about Anna’s hummingbirds

Hummingbird in eucalyptus flower. Courtesy Melanie Hofmann

Cal-IPC’s draft reassessments says, “Williams reported that PRBO found that 50% of the Anna’s hummingbird nests [in eucalyptus] are shaken out by the wind, while only 10% of nests are destroyed by wind in native vegetation.”

Cal-IPC’s quotes from Williams are not found in any publication of the Point Reyes Bird Observatory (PRBO), which Williams claims as the source of the information. Statements about the nests of Anna’s hummingbird are explicitly contradicted by Cornell Ornithology Laboratory, America’s preeminent research institution of bird biology and behavior:

“In the first half of the 20^th century, the Anna’s Hummingbird bred only in northern Baja California and southern California. The planting of exotic flowering trees provided nectar and nesting sites, and allowed the hummingbird to greatly expand its breeding range.”
“Anna’s Hummingbird populations increased by almost 2% per year between 1966 and 2010, according to the North American Breeding Bird Survey…The Anna’s Hummingbird is the most common hummingbird on the West Coast, and it has thrived alongside human habitation. Its range has increased dramatically since the 1930s, when it was found only in California and Baja California. Thanks to widespread backyard feeders and introduced trees such as eucalyptus, it now occurs in healthy numbers all the way to Vancouver, Canada.”
“Females choose the nest site, usually a horizontal branch of trees or shrubs 5-20 feet off the ground (occasionally higher) near a source of nectar. They often build nests in oak, sycamore, or eucalyptus trees…”
“They [Anna’s Hummingbirds] are notably common around eucalyptus trees, even though eucalyptus was only introduced to the West Coast in the mid-nineteenth century.”

In other words, the nation’s most prestigious ornithological research institution tells us that Anna’s Hummingbirds have benefited greatly from eucalyptus trees, which provide both winter sources of nectar not otherwise available in California as well as safe, secure nesting habitat. Since Anna’s Hummingbirds nest preferentially in eucalyptus, their populations would not be increasing if 50% of their nests were destroyed, as Mr. Williams claims.

Furthermore, the implication that eucalypts provide a less stable nest site than native trees is also explicitly contradicted by a study that Cal-IPC cites elsewhere in its draft reassessment. Stephen Rottenborn studied the nesting choices and reproductive success of red-shouldered hawks in Santa Clara County. He found that the hawks prefer eucalypts to native trees and that their nests were more successful when they made that choice. He attributes that greater success rate to the fact that eucalypts are “large, sturdy trees” that provide “greater stability and protective cover.”

“Fourteen of 27 nests in 1994 and 38 of 58 nests in 1995 were in exotic trees, predominantly eucalyptus. Nesting and fledging success were higher in exotic trees than in native trees in both years, owing in part to greater stability and protective cover. Most nest trees in upland areas were exotics, and even in riparian habitats, where tall native cottonwoods and sycamores were available, Red-shouldered Hawks selected eucalyptus more often than expected based on their availability. Of the habitat and nest-tree variables measured at each nest, only nest-tree height and diameter were significantly associated with reproductive success, suggesting that large, sturdy trees provided the best nest sites. Red-shouldered Hawk populations in the study area have likely benefited from the planting of exotic eucalyptus and fan palms.” (1)

Magic! Turning 2 dead birds into 300

Cal-IPC’s draft reassessment says, “Stallcup reported finding two dead warblers and ‘about 300 moribund warblers with eucalyptus glue all over their faces’ over the years, including ‘a large number of gummed-up Townsend’s warblers, yellow-rumped warblers, ruby-crowned kinglets, Anna’s and Allen’s hummingbirds, and a few Bullock’s orioles. Anyone who birds around eucalyptus trees sees it all the time’ (Williams 2002).”

This particular quote from Ted Williams is easily discredited because Rich Stallcup published his theory about birds being harmed by eucalyptus trees (available HERE). In this publication, Mr. Stallcup reports seeing just two dead birds (one hummingbird and one ruby-crowned kinglet) in the eucalyptus forest during his long, illustrious career as an amateur birder. He says nothing about seeing “300 moribund warblers” in his publication. A small measure of common sense enables the reader to evaluate Mr. Williams’s claim: If Mr. Stallcup had seen 300 dying birds, why would he say he had only seen 2 dead birds in his published article in which he is trying to make the case for removal of eucalyptus?

Overwintering monarch butterflies use predominantly eucalyptus

Monarch butterflies roosting in eucalypus tree.

Cal-IPC’s draft reassessment says, “Natural experimental evidence from mixed stands (native trees mixed with eucalyptus) show that Monarchs do not consistently cluster preferentially on eucalyptus, and at times, appear to prefer native trees in some seasons and locations. (Griffiths & Villablanca 2013)”

This is a misleading statement because it implies that monarchs have the option of overwintering in native trees. In fact, the reference cited by Cal-IPC is speaking specifically of three species of native trees with small native ranges: Monterey pine, Monterey cypress, and redwoods. The study is reporting observations of monarchs within the native ranges of these three tree species. These tall trees provide a similar microclimate to overwintering monarchs. However, the native ranges of these tree species are small.

Monterey pines are native in “three disjunct populations in San Mateo and Santa Cruz counties, Monterey County, and San Luis Obispo County. The native population of Monterey cypress is significantly smaller: “The native range of the species was confined to two small relict populations, at Cypress Point in Pebble Beach and at Point Lobos near Carmel, California.” Where Monterey pine and cypress have been planted outside their native range, they are being eradicated by the same public land managers who are eradicating eucalyptus.

For example, when UC Berkeley destroyed approximately 18,000 non-native trees over 10 years ago, many were Monterey pines. Their plans to eradicate 80,000 more trees include all Monterey pines in the project area. In San Francisco, the plans (SNRAMP) of the Natural Areas Program propose to destroy many Monterey cypresses on Mount Davidson. The GGNRA has destroyed about 500 Monterey pines on Hawk Hill in Marin County and many Monterey cypresses throughout their properties.

Furthermore, both Monterey pine and Monterey cypress have much shorter lives than eucalyptus. Monterey pine lives at most 150 years and Monterey cypress about 250 years, compared to E. globulus, which lives in its native range from 200-500 years. Therefore, even where they are not being eradicated, they will die long before E. globulus and are unlikely to be replanted outside their small native range by public land managers who are committed to a “natives-only” policy.

We are unaware of any attempts to eradicate redwoods outside their native range, in the few locations where they still exist. They seem to have escaped the wrath of nativism. However, the range of redwoods is very narrow: “The redwoods occupy a narrow strip of land approximately 450 miles (724 km) in length and 5 to 35 miles (8-56 km) in width. The northern boundary of its range is marked by two groves…within 15 miles (25 km) of the California-Oregon border. The southern boundary of redwood’s range is marked by a grove…Monterey County, California.”

Although native plant advocates may be willing to plant redwoods outside their native range, they do not have that option because of the horticultural requirements of redwoods. Redwoods require more water than Monterey pine and cypress and they do not tolerate wind, which prevents them from being successful in many coastal locations, where monarchs overwinter. Redwoods cannot be successfully grown south of Monterey County where the climate is warmer and drier than its native range.

In other words, monarchs do not have the option of roosting in native trees in most of the places in California where they overwinter. This is a more accurate description of the behavior of overwintering monarchs and the alternatives that are available to them in about 300 locations along the entire coast of California, where they have overwintered in the past:

“Three types of trees were used most frequently by roosting monarchs: eucalyptus (75% of the habitats primarily Eucalyptus globulus), pine (20% of the habitats; primarily Pinus radiata), and cypress (16% of the Cupressus macrocarpa). Twelve other tree species were identified…with a combined prevalence of only 10%…The negative sign for this indicator means that habitats had smaller populations when the roosting tree type was a species other than eucalyptus, pine, or cypress…our long-term analysis showed that abundance has historically been greater at habitats dominated by eucalyptus, pines, or cypress than at those with ‘other’ species. Stands of these three signature taxa may be more likely to produce a community structure and associated microclimate that increases the residence time of monarchs. Furthermore, these taxa may produce a more attractive landscape architecture in terms of sensory cues to migratory monarchs arriving in a certain region.” (2)

For the record, we will add that we would be happy to have more Monterey pines and cypress and if public land managers would quit destroying them, we would consider them attractive alternatives to eucalyptus. However, for the moment, we must assume that the crusade against all non-native trees will continue unabated.

What is your personal favorite?

We have shared our personal favorites with you, but everyone comes to this issue from a different place. We have been flabbergasted by the unfounded claims that the eucalyptus forest is devoid of life. We wonder if the people who say that, really believe it. Or is it just one of the many strategies used to justify their demands that our non-native landscape be destroyed?

Please choose your own personal favorite and write your own comment by Thursday, July 31, 2014. Are you primarily concerned about the herbicides that are needed to prevent the trees from resprouting when they are destroyed? Are you concerned about the loss of your protection from wind or noise? Or do you value eucalyptus as a sight screen or for shade in an otherwise treeless environment? Are you concerned about the carbon loss that will contribute to climate change? Please help us to save our urban forest from being needlessly destroyed by telling Cal-IPC why they should take blue gum eucalyptus off their “hit list.”

Thank you for your help to save our urban forest.

Update: On March 13, 2015, the California Invasive Plant Council published its final reassessment of Blue Gum Eucalyptus (available HERE). Cal-IPC has downgraded its rating of invasiveness and ecological impact from “moderate” to “limited.” Although the detailed assessment is less than perfect, the over all rating itself is an improvement. Thanks to those who sent comments to Cal-IPC.

(1) Stephen Rottenborn, “Nest-Site selection and reproductive success of urban red-shouldered hawks in Central California,” J. Raptor Research, 34(1):18-25

(2) Dennis Frey and Andrew Schaffner, “Spatial and Temporal Pattern of Monarch Overwintering Abundance in Western North America,” in The Monarch Butterfly Biology and Conservation, Cornell University Press, 2004.

Tracking down the truth about blue gum eucalyptus

Last week, we told our readers about the California Invasive Plant Council’s (Cal-IPC) draft reassessment of blue gum eucalyptus, Eucalyptus globulus. (available HERE) Cal-IPC is accepting comments on its draft until July 31, 2014 (send to info@cal-ipc.org). Although Cal-IPC now acknowledges that blue gum has “low invasive potential” and its population is stable in California, it proposes to maintain its over-all classification of “moderately invasive.” You might wonder how Cal-IPC manages to accomplish this sleight of hand, so we will tell you how its scoring system enables it to maintain its overall rating of blue gum.

Cal-IPC has three main evaluation categories: “Impact,” “Invasiveness,” and “Distribution,” which are combined to produce an over-all rating. Cal-IPC’s draft lowers the rating of “invasiveness” to “limited,” but it has changed its rating of “impact” from “moderate” to “severe.” These changes cancel one another, enabling them to reach the same over-all rating of “moderately invasive.” In this post, we will focus your attention on Cal-IPC’s opinion of the “impact” of blue gum so that you can see how they arrived at their conclusion.

Drought is on our minds

Epicormic sprouts on trees in Glen Canyon Park, June 2014

As we told our readers recently, the drought in California is making water use an important issue that is getting a lot of attention, as it should. Native plant advocates have not hesitated to jump on that band wagon. For example, they now claim that eucalypts in San Francisco are dying of drought. With the help of a highly qualified arborist, we evaluated that claim in a recent post and reported that the trees are reacting to the loss of their understory and their neighboring trees, as well as the herbicides used to kill the understory and prevent their former neighboring trees from resprouting from their stumps.

Given this recent experience, we weren’t surprised to find that Cal-IPC has introduced accusations of extreme water use into their assessment of blue gum for the first time, and this new issue helps them to claim that blue gums have a “severe” impact on the environment. Now let’s drill down into this claim, examine the source of the claim and tell you why we believe this is another bogus issue used to vilify eucalyptus.

Tracking down the truth about water use by blue gums was a bit like a game of gossip. Starting with the final version of the rumor in Cal-IPC’s draft reassessment, we tracked that version back to its original source. We found exaggeration at each iteration of the rumor, from its source to its landing in the Cal-IPC draft. The final version bore little resemblance to the original version. The original version is over 100 years old and therefore describes circumstances that have since changed substantially.

Exaggerated and outdated description of root structures

Cal-IPC’s draft assessment of “impact on hydrology” is: “Eucalyptus globulus is adept at tapping into deep groundwater, even under drought conditions (DiTomaso & Healy 2007), altering water availability to depths of 45 feet and distances of 100 feet from the trunk.”

The first distortion of evidence occurs with Cal-IPC’s exaggeration of its cited source. Here’s what DiTomaso & Healy actually said about the roots of blue gum: “In deep soils with high water tables or other deep soil water source, lateral roots grow toward the moisture source and can deeply penetrate soil to 14 m deep.” In other words, DiTomaso and Healy say that such deep roots occur only in certain conditions of “deep soil,” “high water table,” or a “moisture source.”

The source of DiTomaso & Healy’s description of the roots of blue gum is a similar statement in Bean & Russo, who wrote an evaluation of blue gum for the Nature Conservancy in 1989: “Large roots have been discovered at a depth of 45 feet below the surface, and surface roots frequently spread over 100 feet away from the trunk. (Sellers 1910)”

Bean & Russo provide a reference for their statement, which takes us to the original version of this rumor. A book about eucalyptus in California by C.H. Sellers was published in 1910. Here is what Sellers actually says about the roots of E. globulus, grown in the State of California:

“The root system consists mostly of numerous strong laterals; the tap root rarely penetrates to a depth of more than 10 feet. Abundant supply of moisture is demanded and as the roots grow quickly toward water Eucalyptus globulus should never be planted near wells, cisterns, water pipes, irrigating ditches or similar water impounding structures. In loose, sandy or gravelly soils the large lateral roots penetrate to great depth, and extend almost incredible distances. In digging wells large roots have been discovered at a depth of 45 feet below the surface and the surface roots of large trees frequently spread over 100 feet from the trunk of the tree.” (1)

In other words, the extreme root lengths reported by DiTomaso & Healy are an anomaly, only found in specific conditions and unusual cases. The roots of E. globulus are “rarely” deeper than 10 feet, according to this original source of information regarding the roots of E. globulus.

Contemporary sources which are not trying to make a case against E. globulus describe its roots in a less extreme manner: “Bluegum eucalyptus generally does not form a taproot. It produces roots throughout the soil profile, rooting several feet deep in some soils.” (Esser 1993) Also: “Bluegum eucalyptus generally does not form a taproot. It produces roots throughout the soil profile, rooting several feet deep on soils that permit it, or shallowly otherwise.” (Skolmen & Ledig 1990) Esser and Skolmen wrote their evaluations of blue gum for the US Forest Service.

Bringing Sellers up to date

We will assume that Sellers’s observations are accurate, but we will now consider the possibility that an observation that is over 100 years old may not be relevant to present conditions. For a more contemporary perspective on blue gum, we turn to R.G. Florence, an Australian academic scientist who studies eucalyptus and was also a visiting professor at UC Berkeley. R.G. Florence helps us to understand why the observations of Sellers may be very different from more recent observations: “As a tree develops through the sapling and pole stages it will tend to form a main root which penetrates vertically downward, but this main root is rarely significant in a large tree.“ (2) Florence reports that E. globulus uses more water during early stages of growth, when it is growing quickly, than it does as a mature tree. Sellers was reporting in 1910 at a time when most eucalypts in California were young. Their roots may have been longer during these early stages of growth. Since E. globulus has not been planted in California for decades and is no longer available for planting, its root structure at early stages of development is irrelevant to evaluating its behavior in California presently.

Is blue gum drought tolerant?

Cal-IPC denies that blue gum is drought tolerant: “E. globulus is able to withstand prolonged dry summers by tapping into deep water reservoirs; they do not economize in the use of water but have far-reaching root systems and can extract water from the soil at even higher soil moisture tensions than most mesophytic plants (Pryor 1976, Florence 1996).”

Once again, Cal-IPC misquotes its cited sources. R.G. Florence does not make the statement that Cal-IPC attributes to him. Rather, this is how Florence describes the water needs of eucalypts: “…the eucalypt might be generally characterized as being a drought-tolerant mesophyte, that is, it tends to maintain transpiration and cell metabolism under conditions of developing drought.” (2)

Florence says drought tolerance and water use varies by species of eucalyptus. He places E. globulus in this category of drought tolerance: “coastal zone species with high rates of growth and water use, but with somewhat wider environmental [drought] tolerance.” He makes these observations about water use by E. globulus:

Water use is greatest when the trees are young and generally tapers off as the tree grows, between 10-15 years of age. As we have said, only mature E. globulus exists in California presently or will in the future.
E. globulus has been observed to regulate water use by opening and closing its stomata in response to temperature and moisture: “Water use may be regulated in this way.” (2)

Pryor’s description of drought tolerance of eucalypts was published 20 years earlier than Florence at a time when variations in drought tolerance of different species of eucalyptus had not yet been studied. He therefore, does not report on the ability of E. globulus to withstand drought, as Florence does in 1996. He acknowledges some variability with respect to drought tolerance in genus Eucalyptus, which is consistent with Florence’s later report specifically about E. globulus, although Pryor says nothing specifically about E. globulus.

Self-watering blue gums

Sutro forest on a typical summer day. Courtesy Save Sutro Forest.

E. globulus was planted most widely along the coast of California. Most of the coast of California is foggy during summer months, when there is little if any rainfall. Tall eucalypts are known to condense the moisture in the fog which has been measured to double annual rainfall. (3) In these regions, eucalyptus is essentially self-watering. Ironically, Cal-IPC acknowledges this self-watering feature of eucalypts: “The volume of water channeled down the stem is about eight times more than that of falling rain, so soil at the base of trunks receives relatively large quantities of water…” (May & Ash, see “allelopathy” section of Cal-IPC draft).

A recent study conducted in 24 parks in San Francisco measured moisture in the soil in the late summer months (August to September), when the soil would be driest in the absence of fog condensation. That study reported that the greatest amount of moisture (15%) was found in the parks with eucalyptus forests. Soil in parks vegetated with grassland or scrub contained significantly less moisture. In other words, even late in the dry season mature eucalypts were not draining all available moisture from the soil. Their water needs were met by the condensation of moisture from the fog during the dry summer season. (4)

Please come to the defense of our urban forest!

We hope that we have made the case that the draft reassessment is not a fair evaluation of the predominant tree in our urban forest, blue gum eucalyptus. We ask that you write to Cal-IPC by July 31^st about their biased reassessment. Tell them why you think our urban forest is important to the environment and the people and animals living in it. Ask them to remove blue gum eucalyptus from their “hit list” which is being used by managers of our public lands to justify the destruction of our urban forest.

Thank you for your help to save our urban forest from being needlessly destroyed.

(1) C.H. Sellers, Eucalyptus: Its history, growth and utilization, published by A.J. Johnston, Sacramento, CA, 1910

(2) R.G. Florence, Ecology and Silviculture of Eucalypt Forests, CSIRO, 1996

(3) Page 37, Weather of the San Francisco Bay Area, Harold Gilliam, 2002

(4) Kevin M. Clarke, et.al., “The influence of urban park characteristics on ant communities,” Urban Ecosyst., 11:317-334, 2008

California Invasive Plant Council sticks to its guns aimed at eucalyptus

Monarch butterflies roosting in eucalyptus tree.

In December 2013, one of our collaborators in the effort to save our urban forest from pointless destruction submitted a request to the California Invasive Plant Council to reconsider its evaluation of blue gum eucalyptus (Eucalyptus globulus) as “moderately invasive.”

The California Invasive Plant Council (Cal-IPC) has responded to that request with a draft reassessment which is available here: http://www.cal-ipc.org/ip/inventory/eucalyptus.php. Cal-IPC’s draft maintains the same over-all rating of blue gum as “moderately invasive.” Cal-IPC is inviting “substantive comments and questions” by July 31st to info@cal-ipc.org.

Today we are publishing with permission the cover letter of a public comment that will be submitted by one of our collaborators. We hope it will inspire you to write your own public comment by the deadline of July 31,2014.

From the perspective of humans, there are pros and cons to most species of plant and animal. E. globulus is no exception to this general rule. Cal-IPC reaches a negative conclusion regarding blue gum by exaggerating negative issues and de-emphasizing or omitting positive issues. Cal-IPC now acknowledges that blue gum has “low invasive potential” only in specific conditions and that its population in California is stable, but it has introduced new issues and intensified others so that it can maintain its overall rating of “moderately invasive.” I remind Cal-IPC that its name is Invasive Plant Council, not fire council or hydrology council.

Cal-IPC also fails to take into consideration the negative side-effects of attempting to eradicate eucalyptus. There are environmental benefits associated with leaving blue gums alone. These damaging consequences of eucalyptus removal should appear on the “asset” side of the ledger:

When eucalypts are destroyed, repeated applications of herbicide to stumps are required to kill the roots of the trees to prevent them from resprouting multiple trunks. If the resprouts are not aggressively managed, the result will be more eucalypts than presently exist, which has been the result of some past projects.
The herbicides used to kill the roots (usually Garlon) are known to damage mycorrhizal fungi and microbes in the soil. Therefore, the growth of whatever plant succeeds the eucalypts is hindered by the damage that is done to the soil.
Because many of the herbicides used to kill non-native vegetation are mobile in the soil or are taken up by the roots of the plants that remain, plants and trees, which are not intended targets, are often damaged or killed.
Existing eucalypts are often sheltering plants and trees that are considered valuable by Cal-IPC. When the eucalypts are destroyed, the plants that remain are subjected to increased light and wind, which sometimes damages or kills the remaining plants.
Eucalypts are storing many millions of tons of carbon, which are released into the atmosphere when the trees are destroyed, contributing to the greenhouse gases causing climate change. Scientists tell us that the native ranges of plants and animals have changed in response to climate change and must continue to change. Therefore, Cal-IPC’s interest in preserving native plants in their historic ranges is not served by contributing to climate change.

It is also not in Cal-IPC’s strategic best interests to continue to advocate for the eradication of eucalyptus in California:

As the eradication projects get progressively more destructive, the public’s negative reaction to the destruction becomes progressively more aggressive. There are now thousands of us all over the State and all over the country, working to stop this destruction and we are often effective in preventing these projects from being approved or funded. An op-ed in the New York Times in September 2013, expressed support for our opinion that the word “invasive” has become a destructive tool and is inappropriately applied to eucalyptus in California.
The scientific community has also become progressively more critical of the attempts to eradicate eucalyptus. Last fall, Nature magazine quoted several well-known academic scientists in an article that criticized plans to destroy 30,000 eucalypts on Mount Sutro in San Francisco. In May 2014, the CEO and Chief Scientist of the Nature Conservancy expressed their opinion on TNC’s website that destroying eucalypts in California is unnecessary.
Since blue gum eucalyptus is no longer available in nurseries in California and has not been planted for many decades, it has no long-term future in California. To the extent that eucalyptus is a problem, it is a problem that will resolve itself in time.

Cal-IPC’s continued support for these projects is no longer in the mainstream of scientific or public opinion. Removing eucalyptus from Cal-IPC’s “hit list” would significantly improve Cal-IPCs chances of success with the plants that remain on its inventory of invasive plants. The public is unlikely to expend the same amount of energy opposing the eradication of broom, for example.

Cal-IPC has an opportunity to defuse a controversy that is handicapping the success of its venture. Cal-IPC would be wise to abandon its crusade aganst blue gum eucalyptus.