Biodiversity of the eucalyptus forest
Although they can provide no scientific evidence, native plant advocates claim that the eucalyptus forest is a “biological desert” in which nothing grows and nothing lives. We can see with our own eyes in the Sutro forest that a diverse understory thrives in the eucalyptus forest, but it is more difficult to quantify the biodiversity of wildlife in the forest. For that we turn to scientists.
We published some time ago a summary of a research study by Dov Sax (Brown University) in which he compared the species richness (number of species) living in the eucalyptus forest with species richness in native oak woodland in Berkeley, California. He found equal numbers of amphibians, insects, plants in the understory, and birds in the eucalyptus forest compared to oak woodland in the fall and significantly more species of insects in the eucalyptus forest in the spring.
Eucalyptus around the world
Professor Sax also reported similar studies all over the world that reached the same conclusions, i.e., the introduced eucalyptus forest is just as biodiverse as the native forest all over the world. According to the Encyclopedia of Biological Invasions there are about 40 million acres of eucalypts planted in tropical, sub-tropical, and temperate countries. We have had the opportunity to observe them in several counties.
Much of Argentina is a treeless grassland prairie, called pampas. They imported eucalyptus to provide their economy with pulp. We observed many acres of densely growing eucalyptus forest throughout Argentina during our visit there. They also seemed to be used on the perimeter of agricultural lands, presumably as windbreaks.
We also saw many eucalypts growing in Sicily. We were told by our guides that they were planted by Mussolini in the 1930s as the means of draining swampland to reduce the population of malaria-carrying mosquitoes.
We found more eucalypts in Morocco where they also were being widely used as landscape trees. There seemed to be more diversity of eucalyptus species and they were obviously considered valuable for horticultural purposes. We also saw eucalpts sheltering agricultural crops from the wind.
Eucalypts are obviously considered valuable trees in many countries all over the world. We marvel at the hatred they have generated in California.
More evidence of the biodiversity of the eucalyptus forest
Professor Robert Stebbins (Professor of Zoology and Emeritus Curator in Herpetology, Museum of Vertebrate Zoology, University of California, Berkeley) was hired to study the eucalyptus forest in Berkeley, California for the Nature Conservancy’s California Field Office. This is an excerpt from his report which was published in 1983. (It is available at wiki.bugwood.org)
“Contrary to popular belief, many animals, both vertebrates and invertebrates, have adapted to life in the Eucalyptus groves. Moisture from the air condenses on the leaves and the drippage keeps the groves moist and cool even during the dry season. This is a suitable ground habitat for a wide variety of animal life. Amphibians such as arboreal salamander, California slender salamander, ENSATINA, California newt, rough skinned newt, and Pacific tree frog live in the forest, primarily under fallen logs and duff. Amphibians feed on such invertebrates as millipedes, centipedes, sow bugs, COLLENBOLA, spiders and earthworms.
“Several snakes such as the ring-necked snake, rubber boa and sharp tailed snake have adapted to Eucalyptus groves. The ring-necked snake feeds on the California slender salamander, the rubber boa feeds on meadow mice, and the sharp tailed snake feeds strictly on slugs. Other common reptiles include the northern and southern alligator lizards, which live under fallen logs, and the western fence lizard and western skink, which live in the less densely forested groves.
“Over 100 species of birds use the trees either briefly or as a permanent habitat. The heavy-use birds feed on seeds by pecking the mature pods on trees or fallen pods; so they must wait for the pods to disintegrate or be crushed by cars. Among the birds that feed on seeds in the trees are: the chestnutback chickadee and the Oregon junco. Examples of birds that feed on ground seeds are the song sparrow, the fox sparrow, the brown towhee, and the mourning dove. Birds that take advantage of the nectar from blossoms either by drinking the nectar or by feeding on the insects that are attracted to the nectar include Allen’s hummingbird, Bullock’s oriole, redwinged blackbird, and blackheaded grosbeak. Birds that use the trees as nest sites include the brown creeper, which makes its nest under peeling shags of bark and feeds on trunk insects and spiders, the robin, the chickadee, the downy woodpecker, and the red shafted flicker. The downy woodpecker and the red shafted flicker peck into the trunk of dead or dying trees to form their nests. When these nests are abandoned, chickadees, Bewick wrens, house wrens and starlings move in. Downy woodpeckers use dead stubs to hammer out a rhythmic pattern to declare their territories.
“The red-tailed hawk prefers tall trees for a nesting site. It therefore favors eucalypts over trees such as oak or bay. Great horned owls use nests that have been abandoned by red-tail hawks or they nest on platforms formed between branches from fallen bark. The brown towhee and the golden crowned sparrow are birds that use piles of debris on the ground for shelter during rains.
“Several mammals have adapted to Eucalyptus. Deer find concealment in dense groves where there are suckers, coyote brush, and poison oak; moles live in the surface layer of the soil; meadow mice, gophers, and fox squirrels are found in the forest.
“A Eucalyptus grove is not a sterile environment. The population density of the animals mentioned can be partially attributed to the presence of eucalypts. With a program of cutting trees and burning debris, some animal residents will disappear because they have restricted home ranges or are sedentary. If an animal’s living area (leaf litter, logs, bark) and food supply are destroyed, the animal will either die or attempt to move to another area which is already fully occupied. ‘The wildlife section draws heavily upon conversations with Professor Robert Stebbins. No errors which may exist should be attributed to the professor.’”
Refusing to see the evidence
We stumbled upon this new information in the on-line comments on SFGATE (the San Francisco Chronicle’s website) on an article about the “tree wars of San Francisco.” (Available here) A defender of the forest was responding to the usual claims about the eucalyptus forest being a sterile environment. The defender of the forest was quickly attacked by a native plant advocate who called the commenter a “creepy imbecile.” The native plant advocate also attempted to discredit the source of information on the grounds that Professor Stebbins is apparently now dead. Obviously he was alive when he wrote his report, but the native plant advocate apparently believes that anything he wrote before he died is not credible. Or at least I think that was his/her “reasoning.” Oddly, another native plant advocate then chimed in, complaining that native plant advocates are being “demonized.” Wait! Who called whom a “creepy imbecile?”
Update: When we published this article we assumed that the native plant advocate who claimed that Professor Stebbins was dead at the time was correct about that. Since then we have learned that that was inaccurate information. Professor Stebbins died on September 23, 2013, according this obituary in the New York Times. So, the name-calling native plant advocate was fabricating “information” as well as engaging in ad hominem attacks. We are embarrassed that we assumed the native plant advocate was at least factually correct.
Unfortunately the name-calling comment has been removed from SFGATE which I suppose is consistent with their policy. However, it is a loss because it illustrated the low standards for civility and quality of information being used by native plant advocates to defend their destructive projects. (We are quoting from that comment only the portion for which evidence remains in replies to it.)
We saw these same low standards used by native plant advocates at the February 25, 2013 public hearing at UCSF about their plans to destroy the Sutro forest. There were only about 15 speakers in defense of the project, but their comments were devoid of information. One fellow walked to the microphone and said simply, “I hate eucalyptus” and walked away. Another claimed that the Angel Island fire of 2008 was evidence of the flammability of eucalyptus although 80 acres of eucalypts were destroyed over 12 years before that fire. Only 6 acres of eucalypts remain. The grass fire stopped at the edge of that small remaining stand of eucalypts.
One wonders where people find the energy to hate anything, let alone a tree. We struggle to understand the motivation of these crusaders against the forest. We believe that the most highly motivated amongst them are earning their living on these projects and are simply defending their economic interests. Nothing else makes sense to us.