Street Tree Numbers are Down - and there's a Reason


The Department of Public Works (DPW) Bureau of Urban Forestry recently announced that the number of street trees removed by the City in 2017 exceeded the number of trees planted - meaning the total number of street trees in San Francisco went down last year. That’s not a big surprise - with the passage of Prop E in 2016 (now called “Street Tree SF”), the City took back responsibility for all street trees in the city, and with a backlog of aging, sick or dead trees, most experts expected there to be an upward blip in removals.

However, there’s another structural reason that tree numbers may continue to decline, which I noticed when DPW tagged a number of trees in my neighborhood of Cole Valley for removal (one of the notices is in the photo to the left). If you look carefully at the notice in the photo, you’ll see that a total of 21 trees were tagged for removal, but (look at the bottom of the flier) only 12 permitted to be replaced. Why? In some cases, the existing trees were too close to underground utilities; in other cases too close to streetlamp poles. In yet other cases the trees were too close to other existing trees. DPW maintains a set of standards for planting street trees, and in some cases these rules have tightened over the years, so a tree basin that was plantable years ago may no longer work today.

What this means is that there is a structural factor that will result in fewer street trees, year after year. DPW’s rules for the placement of street trees are there for a good reason, and I’m not suggesting that they be changed.* However, we need to realize that as we lose street trees in the ordinary course of urban life - from age, or disease, or getting hit by a delivery truck, many of them won’t be replaceable.

What’s the solution? We need to accelerate plantings in places where no trees existed before. And now that the City is in charge of our street trees, that means getting more funding. We all need to push our supervisors for more funding for street tree planting - because if we don’t, you’ll start to see fewer and fewer trees in the neighborhoods.


* OK, I do have one quibble. The City disallows trees within a few feet of a streetlamp pole - because you don’t want a tree blocking light to the street. But there are plenty of small trees that would work in those spots, and never grow large enough to be a problem. Especially now that DPW controls things (including the species of trees that get planted), I think that’s a rule that could be relaxed.

TransBay Roof Park is SPECTACULAR!

Chilean wine palm ( Jubaea chilensis )

Chilean wine palm (Jubaea chilensis)

I got a tour of the park that is the roof of the new Transbay Transit Center last week - Adam Greenspan, the landscape architect who led the design of the park, was kind enough to give me a guided peek at what is about to open to the public this weekend.   It's hard to decide which superlative to use to describe the new park (many would apply), so I'm just going to say that it's *spectacular*.   I had known for some time that the designers of this park were curating interesting species from around the world, but you have to see this place to appreciate what a special amenity is about to be bestowed on San Francisco.  

I will leave it to others to comment on the landscape design of the park - I'll just describe the imagination and deep botanical knowledge that went into the collecting of the trees and plants you'll find here.   Greenspan has largely used trees and plants from Mediterranean regions of the world, taking advantage of plants that will do well in San Francisco's climate.   There are trees from California, of course - California buckeyes, Monterey cypress, and other trees commonly seen in San Francisco, but also a dozen or more California sycamores (Platanus racemosa), a coastal California tree which is almost never seen in San Francisco streets.

As you walk around the perimeter of the park, you come to a Chilean garden (with several monkey puzzles), a South African garden, an Australian garden (with some amazing Brachychitons - both B. acerifolia but also B. rupestris (Queensland bottle tree - with a striking bulbous trunk), and two separate desert gardens on the west end of the park, with three striking dragon trees (Dracaena draco).

My personal favorite in the garden is a still small Wollemi pine (Wollemia nobilis) - the tree that had been thought to have been extinct for hundreds of millions of years until a couple dozen of the species were discovered in a ravine near Sydney, Australia.  (Hello, Rec Park - we need a lot more of these in San Francisco parks!)  The wollemi pine is located in the roof's "ancient garden", with ginkgos, cycads and other plants that have graced the earth for millions of years.  

monkey puzzle tree ( Araucaria araucana )

monkey puzzle tree (Araucaria araucana)

But I think the most spectacular trees in the park are the palms - Greenspan loves palms, and it shows, especially with the majestic Chilean wine palm that is set in a central lawn of the park, not far from pindo palms, some nikau palms (native to New Zealand), various Trachycarpus species (not just our common windmill palm, T. fortunei), a few Brahea species, and on and on and on....  There are probably a dozen palm species here that are rarely or never seen in San Francisco.   

So run, don't walk, to see this park when it opens!   I just hope that we can keep the Transbay Roof Park in the shape it's in now - it's going to take a lot of work to keep this garden looking as good in 10 years as it does now.  I volunteer to be a maintenance docent!   

“Snow in Summer”!

Wow - was biking in Noe Valley today and saw this  amazing tree at 118-120 Jersey Street. We call it flaxleaf paperbark, but not hard to see why it’s called “snow in summer” in its native Australia!  Melaleuca linarifolia is the scientific name; it’s one of the most common species in the Melaleuca genus as San Francisco street trees. 


118-120 Jersey Street

Visit to Madeira

Just got back from a week visiting the island of Madeira - a Portuguese island off the coast of Morocco, just north of the Canary Islands.  About 33 degrees latitude, so about the same as San Diego, and it also has a similar climate - coastal, not too hot, but warm enough to appear semitropical.  It used to be a big producer of sugar cane, and you still see sugar cane growing and being harvested in spots around the island, but the bigger crop now is bananas, which have become a big export crop.  And of course vineyards, for the world-famous madeira wine.

African tulip tree in Funchal's old town

African tulip tree in Funchal's old town

Since the climate is similar to coastal California, I was curious to see what trees were used in Funchal (the capital and largest city - really the only city of any size on the island).   We were lucky to be able to stay at a hotel (Quinta da Casa Branca, if you ever go) that was formerly an estate owned by a guy who was obsessed about tropical trees - the entire 4 acre property was covered with spectacular and unusual tropical and semitropical trees, all of them with identifying plaques with scientific name, common name (in Portuguese and English) and location of origin.   OK, so that might have had something to do with our choice of hotel. 

Once we got out into the city, the most spectacular trees were the African tulip trees (Spathodea campanulata) - all of them in bloom (we were there in early April).  The tree is native to tropical Africa, and not all that well suited to our cooler Bay Area climate - not sure I have ever seen one in the Bay Area.   The trees are amazing in bloom - football-size clusters of intense red-orange trumpet-shaped flowers.   

Laurus novocanariensis -  closeup of leaves and flowers

Laurus novocanariensis - closeup of leaves and flowers

We spent one day hiking in out in the country, in the laurel forests of the island (also called laurissilva), a type of forest found in the Atlantic islands of Madeira, the Canaries and the Azores - areas with high humidity and relatively stable, mild temperatures.   This type forest is a remnant of what once covered big parts of Europe before the ice age.  The forest had a species from the Laurus genus (the genus that gives us Laurus nobilis, the sweet bay tree that is used in Mediterranean cooking).  The Madeiran species is Laurus novocanariensis, which is endemic to Madeira and the Canary Islands (meaning it exists only there), and was just recently declared a separate species - it was previously thought to be a variety of Laurus azorica.  Apparently it hasn't been around long enough to develop a common name, so I'll dub it Madeira laurel.  (The hikes in Madeira  are amazing - they typically follow irrigation channels called "levadas" that follow the ridge lines of the mountains and bring water from the wetter northern side of the island to the drier south.)   

Dragon tree - Funchal botanical garden

Dragon tree - Funchal botanical garden

We saw lots of examples of Dracaena draco, the Canary Islands dragon tree.   The tree is native to Madeira (and to the Canary Islands, Cape Verde and western Morocco), but we never saw any in the wild.  They were common in Funchal - perhaps evidence of some local pride in a native tree :-)   Unlike most trees, dragon trees are monocots, related to palms and grasses.  The largest example we saw was in Madeira's botanical garden (a real gem, by the way - not to be missed if you're visiting the island). 




Queensland kauri in Funchal

Queensland kauri in Funchal

One of the big tree-surprises in Funchal was that the city's principal street was Agathis robusta - the Queensland kauri - a tree in the Araucaria family from northern Australia, closely related to Agathis australis, the more famous kauri from New Zealand.   The trees were very erect/fastigiate - perhaps a variety that's been bred for that quality?   I've never seen this species used as a street tree anywhere in the world, but they were very happy in Funchal.  Maybe something to experiment with in similar California conditions?  



And, of course, there were pride of Madeira (Echium candicans).  They weren't quite in season (surprisingly, since they're in full bloom in San Francisco).