Tree Care During a Drought: A Conversation w/ Western Arborists (Part 1)
California’s four-year drought has been well-profiled in the media, but we haven’t come across any stories profiling how arborists on the west coast are adapting to the challenging conditions.
We were curious to hear how they’re continuing to re-tree their communities in the face of these obstacles.
So we picked up the phone and called three friends — Matthew Fried, Managing Arborist at the Department of Parks and Recreation for the City of San Mateo; Gordon Mann, Consulting Arborist and Urban Forester for Mann Made Resources; and James Scheid, Urban Forest Advisor-Bay Area for the California Department of Forestry and Fire Protection — to pick their brains.
We’ve compiled the conversations into one thread for your reading pleasure.
Casey Trees (CT): How has the drought affected your city’s day-to-day tree care?
Matthew Fried (MF): We have a lot of questions from residents about whether or not it’s appropriate to plant trees during the drought, given that there is a drought and that there are water restrictions imposed by our water authority.
There have been droughts here for several years now. The trees have kinda hung in there, the mature trees anyway, but we are starting to look more critically at ways to help them do better.
We just bought a 1,000-gallon water trailer. It can take water from any source – lake, pond, lagoon – and capture non-potable water to use on our trees. The device can fill gator bags; it can spray; we can attach a probe to it to water our larger trees. But in short, we are trying to up our watering and trying to source from recycled water sources. This is both for the new trees that we’ve planted, and for our specimen trees that are in parks.
There are a lot of requirements here about lawn and ball field watering which I don’t deal with directly. But others in my department do: they are limited to one to two days where they can irrigate fields and landscape shrubs, and so we do have a lot of irrigation for our trees that is tied into the irrigation for the shrubs and fields. So we use this trailer as a way to make up for those places that are not getting as much water.
Gordon Mann (GM): I think the biggest issue is where we’ve had to cutback watering lawns. If we didn’t then the trees won’t get the water they need and will experience some dieback. [Gordon is referring here to both city and residential tree care]
James Scheid (JS): We as a program provide technical expertise and financial assistance through grant funds to organizations that plant and maintain trees. We encourage folks that we work with to use best practices related to day-to-day care. Despite the drought, there’s still a level of tree care that needs to exist. We’ve done educational outreach in terms of just telling people to water their trees, and really promoting the idea that trees are still going to be an important facet of the landscape even after the drought passes.
We’ve also worked with our major tree advocacy nonprofit group here in the state, the California Urban Forest Council, to develop different messages and campaigns around this to get the word out so that people know still need to water their trees [during the drought].
But ultimately we all have to be more vigilant.
Is there a moratorium on new plantings?
MF: There is no moratorium. We feel that planting shade trees is a very good use of water and you get a better return on investment compared to anything else in your landscape.
We are still planting pretty much the same stuff, but I am cutting back on things that require moist soil. We have a lot of redwoods in [San Mateo] and they’re not doing especially well, particularly where there’s no irrigation source. You need to irrigate redwood trees in this climate and this part of the peninsula where we are. So I’m not encouraging the planting of redwood trees anymore. It’s just not a good tree for this city at this time.
GM: The good news of the drought is that we are trying to eliminate the planting of redwoods in the Central Valley area. In the Bay Area it’s not as big a deal because they have a milder climate but it still affects someof the trees.
The biggest benefit of this drought for me is that it’s discouraging people from planting lawns. In California we really don’t have a drought issue so much as we have a water supply issue and no one’s dealt with it until now in terms of people putting lawns in.
Have you changed your invasive species management plan because of the drought?
GM: The challenge we have, like most cities have, is a diversity problem. So the opportunity to plant new trees that are drought-tolerant helps solve this diversity issue. We are looking for these new trees. Taking into consideration some of the climate change predictions that say the area will warm up by 2 to 5 degrees over the next 40 to 50 years, we are now looking at some species changes that might survive in a hotter climate.
What are the arguments in your region for planting trees in dry areas, meadows and other landscapes that normally don’t have trees?
MF: We are very serious about saving water, but I don’t think deleting all the trees from our landscape here is necessarily the best way to do it.
GM: An arborist organization considers trees infrastructure; trees are infrastructure that have specific benefits for the community and for property. So why would we plant trees in these places?
Specifically, it’s for shade and reduction of the heat island effect. When you have drought and a drier ground, water dries up less in the shade than in the full sun, so having shade and some mulch versus bare soil and dry grass is a better long-term plan to reduce the island effect.
I think that if you can’t maintain the trees then you shouldn’t plant them, and if you don’t have a real reason for planting them then I wouldn’t. I hope that people are looking at places where trees need to be planted, whether for shading parking lots or big and large concrete areas, or maybe shading buildings to reduce AC bills and showing people the positive effects trees have in that way.
The benefit of planting trees during a drought compared to lawns is that there are so many creative ways to water trees, like taking a bucket and reusing household waste. You take that spare water that’s going down the drain, so people who are showering with a bucket or have one in the sink while they’re brushing their teeth are saving gallons of water a day that can be used on their trees.
JS: The definition of a meadow out here doesn’t pertain to the folks that we traditionally work with. Instead it’s usually sidewalk settings or backyard space. The closest thing we might have is the open space hills that haven’t been developed. In a lot of those cases you’re hoping for successional planting with the native species that are present.
But it’s pretty infrequent; most things out here are already developed or if not, the land is completely blighted over and paved. That’s one thing we’re trying to buck; to take these man-made places and make them more natural.
With the drought, the big thing you have to look at is where the water is going when it does hit eventually, running off and going into the sewer system. So we need to be capturing it and utilizing it for the greater good. How you do that comes down to advocacy – a a regional ordinance system or even a localized one that addresses that development. When most cities have a new mall or new construction come in, they’re not adequately prepared, at least in my estimation, to really address those needs.
Are you planting native or more drought tolerant tree species?
GM: In California, there is a Water Use Classification of Landscape Species List (WUCOLS) that details the water use tolerance and drought resistance of different plants.
Some cities are encouraging people to use this list to plant trees on their property. There’s definitely a range of species that are more resistant to drought, including liver birch, maples and amber, but those are also trees in areas where there’s more water use, so those trees would require more water to stay healthy.
Redwoods are another one. In the Sacramento region they have a large amount of redwoods have been over-planted and because of the drought these trees are dying. And as sad as it is, it’s probably a good thing because they’re the wrong tree for the space.
JS: It depends on the landscape. People call up and say ‘I want to plant a street tree’ (versus a backyard tree) so a lot of times we want people to select the right tree for the right space. Some trees may work in certain parts of the county; there are various micro-climates that affect this. Long-wood sycamores, fruitless olive trees, different oak varietals and things like that. They’ve prolonged their existence because they can withstand the drought.
That being said: the last thing we want to do is have a community inundated with a certain species of tree. Doing so opens up the area to massive die-off due to diseases like the Emerald Ash Borer, Dutch Elm Disease and more.
Check back in on Tuesday (7/14), when our west coast arborist friends tackle premature die-off and more.