Two Myths of Nativism: Mutually Exclusive Relationships, and Eucalyptus Allelopathy

We re-publish with permission (and added emphasis) an article from  MillionTrees.me, a website that fights the unnecessary felling of trees in the Bay Area. The article, a report from someone who attended the February 2018 meeting of the California Native Plant Society (CNPS), is important for two reasons:
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The Myth that Nothing Grows Under Eucalyptus

Eucalyptus haters are fond of saying “Nothing grows under eucalyptus.” This refers to “allelopathy” of eucalyptus trees – a defense mechanism in some plants that uses chemical means to prevent other plants growing in the same area. This is empirically a myth, as laid out in this article: Eucalyptus Myths.

When confronted with the tangles of diverse vegetation thriving in the eucalyptus forests on Mt Davidson and Mt Sutro, they amend it to “No native plant grows under eucalyptus” – assuming that native plants as a class have particular characteristics that make them susceptible.  Recent scientific research shows that’s a myth too

 

ABSTRACT: EVALUATING THE MYTH OF ALLELOPATHY IN CALIFORNIA EUCALYPTUS GLOBULUS PLANTATIONS (NELSON, RITTER, YOST)

Here’s the abstract from a paper presented at recent conference of the California Native Plant Society (Feb 2018):

“14.05 Evaluating the myth of allelopathy in California Eucalyptus globulus (Myrtaceae) plantations
Kristen Nelson, Matt Ritter, Jenn Yost, California Poly, San Luis Obispo, CA

It is widely accepted that allelopathy is not only significant, but more or less singular, in the inhibition of understory vegetation in California Eucalyptus globulus (Myrtaceae) plantations. However, there is no published documentation of allelopathy by blue gums against California native species despite continuous references in the literature since the late 1960’s. Previous studies on allelopathy have been inconclusive and criticized for their lack of meaningful, ecologically relevant controls, test species, and test conditions.

We tested the effect of blue gum soil, volatile leaf extracts, and water-soluble leaf extracts on germination and early seedling growth of five California native species that are common components of native habitats typically found adjacent to blue gum plantations. We conducted greenhouse and laboratory experiments to compare the effect of blue gum extracts to ecologically-relevant controls including water, a non allelopathic native plant control (Quercus agrifolia [Fagaceae]), and a native allelopathic plant control (Salvia apiana [Lamiaceae]).

In these experiments, we found that germination and seedling growth of the species tested were not inhibited by chemical extracts of blue gum foliage, either at naturally-occurring or artificially concentrated levels. These results are significant because they are the first to test an allelopathic effect of blue gums against ecologically-relevant species. These results may have significant implications for management and restoration of land historically occupied by blue gum.”

In other words – they looked for allelopathy and they didn’t find it.

The picture below, incidentally, shows Pacific Reed Grass – a native plant – growing under eucalyptus. It’s often found growing under eucalyptus because the water precipitated from the fog provides its preferred growing conditions.

 

 

Mt Davidson: Tree Destruction Imminent?

There’s a lot of activity at the Juanita entrance of Mt Davidson, and neighbors fear the San Francisco Recreation and Parks Department (SFRPD) is rushing through its tree-felling program. At a time when we need trees more than ever to fight climate change, and mudslides in Southern California illustrate the devastating effects of destroyed trees and vegetation, this would be egregious.

Here’s a note from a forest-lover:

What I’ve seen so far as of last week is preparation and road, trail widening with landing areas for equipment, but no big cuttings or equipment in the interior yet. Just the one big landmark, living tree marked with dots, and all the prior destruction.”

Huge eucalyptus tree on Mt Davidson, San Francisco, marked with 3 green dots

Do these dots mark this iconic tree for killing?

TRAILS BEING WIDENED FOR HEAVY EQUIPMENT?


What equipment will go up here? Maybe a “Brontosaurus”?

TREES DESTROYED EARLIER

Tree have been destroyed on Mount Davidson some years ago, and this prior destruction gives some idea of what the desired end-condition is for the next round. The so-called “boneyard” has stumps of dead trees.

 

This tall mature tree was “girdled.” That’s a process of destroying cutting a deep ring around the tree, so that food and water cannot be transported and the tree starves to death.

A beautiful green and flourishing tree that provided food and habitat for birds, and brought joy to forest lovers, is a dead skeleton.

THE BEAUTIFUL FOREST WE ARE LOSING

The lovely forest we are losing is beautiful and historic, and provides habitat for a huge number of birds. But it’s not just beauty and habitat. These trees provide important eco-system services.  Some examples:

  • They stabilize the mountain, with their intergrafted roots forming a living geo-textile. The horrible mudslides in Southern California illustrate how important this is.
  • They fight pollution, especially pollution from particulate matter, by trapping the particles on their leaves until rain or fog drips them to the forest floor where they are not in the atmosphere – or our lungs.
  • They form a wind-break in what would be one of the windiest areas of the city, with the wind blowing in straight off the sea.
  • They regulate water flows, so that when it rains hard, the forest acts as a sponge, absorbing the water and letting it flow out gradually.
  • They catch moisture from the fog during summer, making the mountain damp and reducing fire hazard.

Please let City Hall and SFRPD know that you want this forest protected and saved, not gutted. The plan is to remove 1600 trees!

[Update 1/19/18:  We spoke with the contractor on site. Seven trees have been cut down, and that completes this contract. Hopefully we will have more public notice and explanation if other tree removals are planned.]

Season’s Greetings!

With this holiday season rolling around again, we’re pausing to realize that the San Francisco Forest Alliance is six years old! Our first post – about pesticide use on Twin Peaks – was on Dec 19, 2011.

It’s been six years of advocating for our trees, our trails, our wildlife habitats. Six years of fighting against toxic herbicides used in our parks.  This year we’re gearing up to bring our message of inclusive environmentalism to a broader audience.

To all our supporters and readers – SEASON’S GREETINGS!
We hope you’ll continue to stand with us and spread the word.

 

 

Pesticide Use in San Francisco Natural Areas Creeping Up Again – Oct 2017

We’ve received the pesticide usage reports for the first ten months of 2017, and we’re concerned. After reducing herbicide usage in the last four years, it’s creeping up again in the natural areas. The Natural Areas (now called the Natural Resources Department) has already used more herbicides (measured by active ingredient) than in all of 2016. It hasn’t reached 2015 levels, but park users hoped for further reduction, not an expansion in herbicide use.

San Francisco’s Department of the Environment runs the Integrated Pest Management (IPM) program for city-owned properties in San Francisco. It publishes an annual list of permissible pesticides, and classifies them into Tier III (Least Hazardous), Tier II (More Hazardous) and Tier I (Most Hazardous.)

The unnaturally-named Natural Resources division (NRD) of the San Francisco Recreation and Parks Department (SFRPD) used more Tier I  herbicides than the rest of SFRPD put together (excluding Harding Golf course, which is managed under a separate PGA contract – but including all the other city-owned golf courses). In fact, in the first ten months of 2017,  NRD used 69% of the Roundup and 100% of the Garlon used by SFRPD.

The parks mainly targeted thus far were:

  • Twin Peaks (sprayed 32 times);
  • Glen Canyon (sprayed 27 times);
  • McLaren Park (25 times);
  • Bayview Hill (14 times); and
  • Laguna Honda (PUC property – 13 times).

Other parks that got sprayed over five times in ten months were Mt Davidson (8 times); Marietta (a PUC property – 8 times); and Lake Merced, also 8 times.

NRD INCREASES USE OF CANCER-CAUSING ROUNDUP 

We especially noted that its usage of glyphosate (Roundup/ Aquamaster) has nearly doubled from 2016 (i.e., in ten months, NRD used nearly twice as much glyphosate as in the whole of 2016).

This is particularly worrisome since Roundup probably causes cancer. We wrote about that in these articles: World Health Organization: Roundup “Probably Carcinogenic” and in this report from an EPA scientist before she died reported on problems with pesticide assessments: “It is Essentially Certain that Glyphosate Causes Cancer”

This is the first time since the report came out we’ve seen an increase in its use.

GARLON IS WORSE

The other major Tier I pesticide being used is Garlon 4 Ultra (triclopyr). NRD is the only section of SFRPD that uses this chemical, which has been considered Most Hazardous and HIGH PRIORITY TO FIND ALTERNATIVE at least since 2009. It’s twenty times as harmful to women as to men. (Here’s our quick presentation on the subject: Garlon v. Oxalis in Ten Easy Slides.)

NRD uses this on oxalis, an early spring-flowering plant beloved of children, pollinators, and wildlife – and the general public, who enjoy its bright blooms as a sign of spring. It’s the only use of Garlon by NRD, and if they abandoned the vendetta against these Bermuda buttercups, they would not need to use this awful pesticide.

NEW WAR TARGETING CAPE MARIGOLD

Meanwhile, there’s a new city-wide war on a naturalized species: against arctotheca, or Cape Marigold. It’s another yellow-flowering plant that grows all over our city’s parks, and it’s on the list of 40 species (and counting) that the NRD wants to poison.  Here’s a picture from McLaren Park (together with Great Blue Heron that’s probably hunting gophers).

Cape Marigold occurs in both a fertile and an infertile form; both are considered only Moderately invasive by the California Invasive Plant Council – as is oxalis.

Unless NRD changes its approach and objectives to naturalized species of plants – and recognizes the need for inclusiveness in natural areas – there is little likelihood of eliminating pesticides from our parks. Aggressive management will inexorably result in increased herbicide use.

WHAT ABOUT THE REST OF SFRPD?

By contrast, the rest of SFRPD (excluding Harding Golf Course) seems to be on track to reduce usage again from 2016. For which kudos!

[Edited to Add: The graph below was corrected to indicate the last column shows usage only through Oct 2017, not the full year.]


The only department besides Natural Resources to regularly use pesticides is the Golden Gate Nursery. They wish to make sure the nursery stock they supply is pest-free before propagating it. This is less of a concern than NRD for several reasons: It’s not a public space, usage is confined in a small area and not on parks and hillsides where chemicals could spread to other areas.

We are concerned, though, that they are experimenting with several herbicides that were not earlier on SF Environment’s list: Axxe, Suppress, Clearcast and Finale. They are all considered Tier II, according to Dr Chris Geiger of SF Environment’s IPM.

Of these Axxe and Suppress seem to be less harmful. Suppress is considered acceptable for organic farming.

Clearcast is more concerning, as is Finale. You can see the Clearcast Label here: clearcast_Label.pdf 2016

Here’s the Finale Label: finale_msds

Both these pesticides have cautions regarding potential harm from immediate exposure. We will further research them, but more than the specifics, we’re concerned at the direction. Rather than working to eliminate herbicides from our parks, SFRPD seems to be looking for substitutes for Roundup. Thus far, these two chemicals have been used only in Nursery areas – the GGP Nursery, and the nursery at the Botanic Gardens.

SFRPD now has five Integrated Pest Management Specialists (compared to one before). This is good news to the extent that they will be working on mosquito abatement and alternatives to rat poisons. It’s bad news if it encourages SFRPD to open new battle fronts (like the war on Cape Marigold), or increase use of herbicides in the water, rather than changing its approach to eliminate pesticides in our parks. Here’s the note about their activities from an October meeting of SF Environment’s Policy Committee:  102317_attachment_c_-_agency_ipm_updates_for_2017

SF Forest Alliance reiterates our commitment to working toward No Toxic Pesticides in our parks. We recognize that it will be an uphill battle, as all current interests are in continuing pesticide use. Nevertheless, we believe that it is possible and is a worthwhile and environmentally-friendly goal for San Francisco.

 

 

Register for Town Hall Meeting about Montara’s Chainsawed Trees

We posted a few days ago about the planned meeting regarding the chainsawed trees of Rancho Corral de Tierra at Montara. Here are the details of the public notice, and a link to RSVP.

 

“Rancho Corral de Tierra Public Meeting | November 12, 2017

“Please join National Park Service staff and Congresswoman Jackie Speier for a public meeting to discuss Rancho Corral de Tierra. Park staff will discuss grassland restoration efforts, current management, and future park planning efforts. Grassland restoration efforts include removing invasive vegetation, such as grasses and trees, and revegetating with native plant communities.

Meeting Details
Sunday, November 12, 2017
2:00 pm – 3:30 pm
Farallone View Elementary School,
1100 Le Conte Ave., Montara, CA
RSVP requested: Please register HERE.

 

Lessons From the Terrible North Bay Wildfires of 2017

This careful analysis of the terrible wildfires in the San Francisco Bay Area is republished with permission from MillionTrees, a website that fights to prevent unnecessary tree removal in the Bay Area.

 

Lessons learned from fires in the North Bay

Recent wildfires in the North Bay were devastating.  At least 42 people were killed by the fires and over 8,000 structures were destroyed, including homes and businesses.  We don’t want to portray that fire as anything other than a tragedy.  However, for those with a sincere interest in fire safety, there are many lessons to be learned from that fire.  If people will open their eyes and their minds to the reality of those fires, there are opportunities to reduce fire hazards revealed by those fires.

What burned?

Watching videos of the fires is the best way to answer the question, “What burned?”  Here are two videos of the fires that we found on the internet by doing a search for “videos of wildfires in Napa and Sonoma counties.”

If you weren’t watching the news during the fires, you might start by looking at these videos.  There are many more videos on the internet of those fires.

Here’s what we can see in these videos:

  • The fire front moved rapidly through native conifers and oaks as well as through grassland and chaparral. After watching hours of these videos, we did not see any eucalyptus trees on fire.
  • Many homes burned without igniting the trees and vegetation around them. If the photo was taken while the home was still burning, the vegetation is rarely engaged in the fires.  If the photo was taken after the home burned, much of the vegetation is burned as well.  In other words, the burning homes ignited the vegetation, not vice versa.
  • In videos of actively burning homes, the air is filled with burning embers. The source of those embers cannot be determined from the videos.

Nothing in these videos suggests that native vegetation is less flammable than non-native vegetation.  Nothing in these videos suggests that the vegetation is more flammable than the structures that burned. 

CalFire has identified the specific locations where four of the fires originated.  Two are in groves of oak trees and two are in grassland and chaparral.  Photos of those specific locations are available HERE.

What role did the weather play in the fire?

All sources of information about the fire reported that strong winds were the biggest factor in the rapid advance of the fire.  The wind was associated with very high temperatures and it came from the east.  This type of wind is called a Diablo Wind in Northern California.  In Southern California it is called Santa Ana Winds.  In the Mediterranean, it is called Mistral Winds.

In coastal Mediterranean climates such as California and the Mediterranean regions of France and Spain, the wind ordinarily comes off of the ocean.  Because the ocean is cooler than the land, the wind is usually a source of moisture and cooler temperatures.  During periods of high summer temperatures, the wind sometimes shifts direction and starts to blow off the hot interior, drying the vegetation and increasing temperatures.

Such winds were also the main cause of the wildfire in the Oakland/Berkeley hills in 1991Jan Null was the lead forecaster for the National Weather Service in the Bay Area in 1991.  He recently said of the 1991 fire:  “At the time a fire starts, the really relevant conditions are the wind speeds, the temperature and the humidity. Again, the humidity goes to the dryness of the fuel. The temperatures also go to the dryness of the fuels and the wind speeds go to what the spread of the fire is. If we’d had that same Oakland Hills fire without any wind, we wouldn’t be talking about it now.”

Most wildfires in California are caused by strong, dry, hot winds.  Everything burns in a wind-driven fire.  Both native and non-native vegetation burns in a wind-driven fire.  Homes in the path of a wind-driven fire are more likely to burn than the vegetation that surrounds the homes because the vegetation contains more moisture.

Why are wildfires becoming more frequent and more intense?

Wildfires are becoming more frequent and more intense all over the world because of climate change.  Temperatures are higher, drought is more frequent, strong winds are more frequent.

Wildfires in the west have become more severe because of increased temperatures and lower humidity at night.  When it doesn’t cool off at night, the trees don’t have an opportunity to regain the moisture they have lost during the high daytime temperatures.  In the past, firefighters could count on wildfires to die down at night.  Now they can’t count on colder nights to make the fires less severe. (2)  Since the fires in the North Bay started in the middle of the night and did the most damage that first night, this observation about warmer nights is particularly relevant to those fires.

Deforestation is the second greatest source of the greenhouse gases causing climate change Every healthy tree we destroy releases its stored carbon as it decomposes.  Every tree that dies of drought releases its carbon as it decomposes.  Every tree that burns in a wildfire releases its carbon as it burns.

What role did power lines play in the fire?

The investigation of the recent wildfires in the North Bay is not complete, but early indications suggest that power lines probably ignited some of the fires.  Some power poles fell over in the strong winds, causing the power lines to break and spark ignitions.  Some trees were blown into the power lines, causing them to break or spark.

California State law requires that trees be pruned at least 4 feet from the power lines.  Although PG&E says they are inspecting thousands of miles of power lines to identify potential interference with trees, these inspections are apparently not adequate.  After the fires started, PG&E claimed they had removed 236,000 “dead and dying” trees and “destroyed or pruned” 1.2 million healthy trees in 2016.  These destroyed trees contribute to climate change.

California State law also requires that power poles are capable of withstanding winds of a certain velocity.  However, power poles fell over during the recent fires when wind speeds were below that standard set by State law.

Apparently PG&E’s efforts to inspect and maintain power lines were inadequate and State laws intended to ensure the safety of power lines are not being enforced.

Did Sudden Oak Death contribute to the fire?

Sudden Oak Death (SOD) killed 5 million oak trees in California from 1994 to 2016, when that number was reported by a study.  The study also said that the SOD epidemic could not be stopped and would eventually kill all oaks in California.  More recent estimates are that 5 to 10 million oaks have been killed by SOD. (2)

SOD is caused by a pathogen that is spread by rain and wind.  We had a great deal of rain in 2016 and 2017, which has greatly increased the spread of SOD.  In the past, SOD has been mostly confined to wildlands.  Now it is found in many urban areas, including San Francisco and the East Bay.  In the most recent SOD survey done in spring 2017, new infections were found on the UC Berkeley campus, the UC arboretum, and the San Francisco Presidio. (2)

The scientist at UC Berkeley who conducts the annual survey of SOD infections reports that “A dramatic increase this year in the number of oaks, manzanita and native plants infected by the tree-killing disease known as sudden oak death likely helped spread the massive fires that raged through the North Bay…” (3)

Dead trees are more flammable than living trees because living trees contain more moisture.  In addition to more than 5 million dead oak trees in California, 102 million native conifer trees in the Sierra Nevada foothills were killed by drought, warming temperatures and native beetle infestations during the drought years. All of these trees are native to California.  This is another indication that native trees are not less flammable than living non-native trees.

The ranges of native plants and animals are changing because of climate change.  They must move to find the climate conditions to which they are adapted.  Native plant “restorations” that attempt to reintroduce plants where they existed 250 years ago, prior to the arrival of Europeans, do not take into consideration that the plants may no longer be adapted to those locations.  That’s why many “restorations” are not successful.

If you haven’t seen the Sutro Forest, you should do so soon. The plans are to destroy about 50% of the trees and most of the understory.

Native plant advocates have their heads in the sand about Sudden Oak Death.  The recently published Environmental Impact Report for San Francisco’s Sutro Forest announced UCSF’s intention to destroy about 50% of the non-native trees on Mount Sutro and replace some of them with native trees, including oaks and bays.  Bays are the vector of the pathogen causing SOD.  The EIR said NOTHING about Sudden Oak Death, nor did it acknowledge the existence of the disease in Golden Gate Park and the arboretum, less than a mile away from Mount Sutro.  What’s the point of destroying healthy trees and replacing them with trees that are likely to die in the near future?

Where to go from here?

We are not powerless against bad decisions of public utilities and the forces of nature.  There are things we can do to address these causes of wildfires in California:

  • We must address the causes of climate change. We must stop destroying healthy trees and we must plant more trees.  We must choose species of trees that have a future in the changed climate.  The trees must be adapted to current and anticipated climate conditions.  We must quit destroying trees simply because they are not native.  Non-native trees are not more flammable than native trees and many are better adapted to current climate conditions.
  • We must regulate our public utilities and demand that regulations be enforced. The Public Utilities Commission initiated an effort to improve the safety of power lines in 2007, after destructive wildfires. The utility companies have been actively dragging their feet to prevent new regulations because they would increase costs, despite the fact that they would improve safety.
  • Improved regulation of utilities should minimize the need to destroy healthy trees, by undergrounding power lines in the most high-risk areas, improving insulation of the wires, replacing wooden power poles with metal and/or concrete poles, installing sensors that identify breaks in the power lines, etc.

Demonizing non-native trees is preventing us from addressing the causes of climate change and the closely related issue of increasing frequency and intensity of wildfires.  Let’s open our eyes and our minds to the reality of wildfires in California and develop the policies that will reduce fire hazards.


(1) The Detwiler Fire is active at night, and a scientist says that’s relatively new,” Fresno Bee, July 22, 2017

(2) “Disease killing oaks spreads,” East Bay Times, October 24, 2017

(3) “Disease in trees pointed at in fires,” San Francisco Chronicle, October 20, 2017