In the beginning this blog was centered on San Francisco parks and open space issues with special emphasis on natural areas and natural history. Over time it began to range into other areas and topics. As you can see, it is eclectic, as I interlace it with topics of interest to me.

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Sunday, November 29, 2015

 Published in Westside Observer November 2015

The response of Nancy Wuerfel et al to my article in the September Westside Observer on the dangers of the blue gum plantations in the city is rife with errors that are too numerous to correct here.  I will select a few of the more egregious ones; a full rebuttal would necessitate an article longer than the editor would accept.  The subject is of great import to the city, as there are issues of public safety as well as recreation.  A few of the errors, in no particular order:

1.  Some people want to cut down our healthy forests simply because the trees are not "native".

Cutting down trees simply because they are not native has never been a part of City policy or operations, nor is it a valid reason for removing them.  My article, and the City's draft management plan, calls for managing the Mount Davidson plantation, which includes selective tree removal where they constitute a problem.  Their being nonnative is not especially relevant.

2.  The City's Natural Areas Program has plans to convert existing habitat (including eucalyptus forests) in one-quarter of the city's parkland to native plant gardens, and that it would cut 18,000 healthy, mature trees to accomplish this.

No such conversion is proposed by the City.  The Natural Areas Program works to preserve the biological systems surviving on the pieces of original landscape (those which have never been plowed, bladed, or built on).  Most of the world's cities have similar programs to accomplish just this, as people recognize their heritage is something worth saving. 

3.  Sometimes epicormic sprouts are a response to stress, but other times they're just part of the normal growth cycle.

These sprouts are always in response to stress or injury, and the reason they are not part of the normal growth cycle and why they are a danger was clearly explained in my September article.  Production of these shoots is a desperation move to save the tree's life and even if successful it leaves the tree misshapen, aesthetically displeasing, and unsafe, and likely an intermediate stage on the way to ultimate death.

The prodigious sprouting of these stricken trees has been mistakenly interpreted as evidence of vigorous recovery.  The dying tops is the result of the breaking of the hundreds of capillary water columns resulting from the trees' inability to supply sufficient water to keep the water columns intact.  Sprouting in this case is a desperation move by the tree to keep the lower part of the column intact.  If sufficient water becomes available it may have a precarious hold on life for awhile, but even the best scenario would leave us with a bunch of short, leafy weakly-attached sprouts clothing what was formerly a smooth, clean bole--one of the traits that endears the tree to us.  Those sprouts are subject to coming loose in winds, and this will always be there because they lack the deep anchoring of naturally-formed limbs.  Photo on Mount Sutro by Craig Dawson.

4.  Mount Davidson is half covered in a eucalyptus forest.

The thousands of trees on Mount Davidson do not constitute a forest; it is a plantation, and the difference is important.

Inappropriate language creates confusion and obscures proper management.  A forest is a self-managing biological community which appears similar over time; a plantation is essentially a garden.  This is not playing with words--it cuts to the core of the matter. 

To manage, we need to understand the difference between a forest and a plantation.  To illustrate, let's take a glance at a forest:  When you drive across the Sierra Nevada the scene you see is similar to what the American Indians saw 500 years ago:  forests of pines and firs punctuated by grassy wildflower meadows, lakes, and bogs.  You see a community of plants and animals, as well as organisms from other kingdoms that are used to living with each other, as they have for thousands of years, tightly-knit into a fabric.  That scene is stable and doesn't change much over time.

A plantation, on the other hand, is artificially imposed on a land that didn't normally support those plants and it is in a constant state of disruption as the plants are forced to compete with others they are not accustomed to, and lacking the animals and other components that serve to keep the system in balance.  The result is chaotic, with usually two or three species eventually predominating.  Ivy and blackberry have claimed the understory to the exclusion of other species--and they account for the drear monotony of large stretches.  They even prevent regeneration of the blue gums, something that never happens in forests.  The plantation, therefore, contains the seeds of its own destruction because smothering blankets of ivy and blackberry prevent germination of blue gum seeds.  Ivy crawls 150-200 feet into the crowns and deprives the trees of light needed to photosynthesize.  The results are visible today with trees dying and toppling from light deprivation and the heavy burden of tons of ivy.  This tangled mess does not require expertise to diagnose; it is obvious even to a layperson.  In fact the plantation's problems are horticultural, and academic expertise is of little use.

5.  I am personally identified as "a native plant advocate [who] has called for cutting down blue gum eucalyptus in city parks for over a decade".

Not so.  I love blue gums and ask for removal only when there is compelling reason.  I do advocate for preservation of our indigenous plants and encourage their use in gardens as a means of attracting and supporting wildlife, many of which are dependent on native plants, which they co-evolved with.  Because nature has served notice that this tree is not suited to our changing climate, this represents an opportunity to diversify the overstory to make it more friendly to wildlife--part of the mission of the City's Natural Areas Program.  At present it is a biological wasteland, with only generalist species present.

About 50 years ago I became smitten with the genus Eucalyptus, and in 1977 toured Australia for six weeks specifically to learn more about this huge genus--at the time considered to contain over 600 species.  Part of that time was in the field in the company of the world's top eucalyptologists.  In 1979 I wrote my first article in praise of the Tasmanian blue gum, and have written several since, including in the February 2014 Miraloma Life.  I love this tree and have been in conversation with the Recreation and Park Department to plant them in our irrigated parks, where they can thrive.  Did you know that it has abandoned planting blue gums and hasn't planted them for several decades?  The grand old specimens in the eastern end of Golden Gate Park and its Panhandle--a de facto arboretum that should be declared a heritage site--are over 130 years old and won't live forever.  That means there will be a period of several decades when park visitors will be unable to be inspired by these majestic, clean-limbed behemoths.

In 1990, long before the City created a Natural Areas Program, I talked to the Miraloma Park Improvement Club about the state of the Mt Davidson plantation; there are some who remember that event.  My aim was to save the "forest", as most called it.  I loved its atmosphere--especially in fog or rain--evocative of the mood created in redwood forests, and as a gardener I knew that ivy and blackberry could destroy it.  In addition--and of great concern to me--was that the understory, consisting mostly of native plants that were able to survive the shade and extra moisture from fog drip, would be decimated, and with it the wildlife community.  It was primarily the understory that concerned me at the time.  Alas, nothing was done and the health and attractiveness of the grove continued to deteriorate, and we see the result in the present unruly tangle and dead and dying trees.

I see this unfortunate situation as bordering on the tragic.  A potentially prize area that can enrich the city is left to stagnate, is yearly becoming less attractive to humans, is of little use to wildlife, and is a safety hazard to not just visitors but to the entire city.  Urgent action is called for.

These trees can never assume a "tree" shape again even if they should live, as they may for two-three years should they get the promised heavy rain this winter.  Scenes like this are common in the blue gum plantations throughout the city, including Mount Davidson.  Photo on Mount Sutro by Craig Dawson.

Ms Wuerfel et al have tried to comfort the public on a subject that is dangerous and needs full exposure and debate.That debate of necessity would be contentious because it is about a subject that is very expensive and that stirs strong emotions.  Facts must trump emotions if the public is to be served.

In December I plan to write about the City's proposed draft management plan.

Jake Sigg