Eucalyptus removal: A dilemma of habitat and history

by on June 12, 2013

 
These eucalyptus north of Claremont Avenue are mostly thin and densely packed because they grew back as stump sprouts after a major freeze in 1972. These trees would be removed by UC Berkeley under a proposed plan being considered by FEMA. Photo by Dan Rademacher.
 

 

Our article about the tree removal debate in the East Bay inspired a lot of discussion, including questions about the value of eucalyptus as raptor habitat and the risk to local amphibians of extensive herbicide use in wild lands. The proposal is up for public comment through Monday and there’s a meeting sponsored by critics of the plan this evening. (Here’s more info on those.)

There’s no way to cover either the impacts on raptors or amphibians exhaustively, except perhaps in the context of a scientific monograph of some kind (which we don’t write here at Bay Nature!). But we did go in search of some answers from folks who know more than we do. First, I went back and reread our own article, Ubiquitous Eucalyptus, from 2006. That reminded me of Dan Suddjian’s 2004 survey of bird use of eucalyptus around Monterey. Suddjian notes that eucs aren’t much use for cavity nesters, but he did find 59 species of birds nesting in eucalyptus, and 90 species that use the trees regularly for perching, roosting, and feeding. That’s a lot of birds. On the other hand, he found that bird species that favor oak woodlands and riparian areas lose out in the presence of densely planted eucalyptus. It’s hard to know how that plays one way or the other: some creatures will lose out, and some will benefit.

The raptor expert

Cooper's Hawk, Juvenile

Juvenile Cooper’s hawk. Creative Commons photo by Kevin Cole.

I contacted Allen Fish, director of the Golden Gate Raptor Observatory, for more information. He’s not taking a position one way or the other on the tree removal proposals, but he does provide some useful context regarding raptors: “Eucalyptus provide nesting sites for red-tailed hawks and great horned owls in particular (since the latter often nests in the platforms built by the hawks),” he said, “and red-shouldered hawks show up in eucs often, although their nests seem to get blown out of eucalyptus trees pretty easily.” So eucalyptus are good for those big, charismatic birds that are important predators.

But the story doesn’t end there: “Eucalyptus forests give redtails, redshoulders, and great horns an edge in these semi-rural zones (and ranchlands and parklands) that harbor lots of euc forests. But an edge over what? Over smaller, more ecologically specialized raptors, such as Cooper’s hawks, sharp-shinned hawks, American kestrel, western screech-owl, spotted and saw-whet owl—at least in the bay-oak-madrone and Douglas-fir forests.  In grassland-savannah, redtails could edge out northern harriers, white-tailed kites, and even barn, short-eared, and long-eared owls.” Again, winners and losers either way.

“Part of the storyline here,” Fish continued, “is that the three euc-favored species (redtail, redshoulder, and great horns) are big, ecologically wide-ranging, human-tolerant raptors that are capable of preying on the smaller, crow- and robin-sized hawks and owls. And they do. Bottom-line: eucalyptus removal from the East Bay Hills – if those lands are restored with native broad-leaved forest and savannah—will likely increase diversity of raptors, maybe numbers as well.” But Fish would probably agree that the big “if” here is whether those lands will in fact be “restored with native broad-leaved forest and savannah.”

The amphibian experts

Slender salamander, (c) Robert Clay

Tiny slender salamanders, on the other hand, are so ubiquitous that they might be the region’s most numerous land vertebrates. Photo (c) Robert Clay.

That caveat of how the work will be done is weighing heavily on the mind of David Wake, an expert on amphibians (and a main source for our January 2013 cover story on salamanders). “This issue has been a matter of considerable discussion in my neighborhood, Park Hills in Berkeley,” Wake wrote to me. “This is kind of like a small town, with about 500 people, and we border on Tilden Park. We are a prime target for any wildfire.  Of course, we are adults and purchased our homes in the full knowledge of risks.”

“Personally I am ambivalent about the entire project,” he continued. “I would like to see some thinning of dense stands, but eucalyptus will root sprout for up to six years and the manpower necessary to do this mechanically without pesticides could be dauntingly expensive. I fear that we might end up making a mess of things.  Also of concern is my fear that the people who will do this work are likely to be undereducated, young, and lightly supervised, so that care might not be uppermost in their minds.”

So then Wake is left with a quandary: “I know that one goal is to encourage the growth of understory native species such as bay laurel, live oak, and willow. However, my own observations would suggest that what is most likely to thrive will be an amalgam of introduced grasses, weedy forbs, introduced blackberry bramble and native poison oak.  We could replace the current eucalyptus with a mess.” As to the herbicides, Wake has reviewed a number of papers over the years by Rick Relyea, at University of Pittsburgh, who has found some worrisome impacts from prolonged exposure to Roundup (here’s more about his work).

“Without doubt the substances are toxic to many organisms,” said Wake, “especially amphibians, and they are at least low-level carcinogens. Roundup and Garlon 4, two mentioned in the EIR, have been proven to have negative effects.”

I called Relyea to ask him how he’d weigh the merits of a project like this one. The short answer: Not easily. From his vantage in Pennsylvania, he’s not familiar with the particulars of this project, but he’s well aware of the debates and compromises that occur in large-scale restoration and invasive species management. The main issue with Roundup and related chemicals is not actually the herbicide itself (glyphosate, in the case of Roundup), it’s the “inerts,” which include surfactants. These work like extra-strength dish-soap to break down the waxy layers on leaves and allow the herbicide to penetrate into the plant.”It’s really hard to make something that’s good at killing weeds but that doesn’t kill frogs,” he said.

The East Bay hills EIS contains mitigation measures to avoid spraying herbicides near wetlands and stream courses, but there may still be impacts on amphibians. That said, Relyea was pleased to hear that even foliar applications of herbicides (those sprayed on leaves) will be done plant by plant and not through broadcast spraying. “If we’re talking about hand-applying to specific plants, it’s an order of magnitude lower application rate than fogging corn or soybeans,” he said. “You’re not having it drift over the landscape and into aquatic areas.”

“This is a really difficult risk assessment to make in my view. I would say that applying it to individual plants is a much better way, a much saner way to go about using the product. You’ve reduced the risk a great deal, in my opinion. Even those of who work at this all the time, it’s very difficult to say what the risk is, especially in light of the goal of the project, because having those nonnative trees there has an impact on habitat as well.”

“Every individual person has a different line or balance point where the benefits to society outweigh the cost to wildlife. We’ll never agree where that line should be.”

The ecologist and neighbor

South African eucalyptus plantation, Creative commons photo by MeRyan

South African eucalyptus plantation, Creative commons photo by MeRyan

Understanding the interactions of people and habitat is the main work of Alan Shabel, an ecologist and a neighbor of David Wake’s.

Here’s what Shabel told his neighbors in one email: “I have now worked through the ~3250 pages in the Environmental Impact Statement (EIS), and I find it to be a very well researched set of documents. I studied forest succession as an undergraduate in the early 1990s, and I have been studying animal and plant ecology since that time. We should not miss this opportunity to better manage the local landscape and to become better ecosystem stewards.”

Shabel and I sat down to talk this week, and he told me about his own experience in eucalyptus forests here and in field work sites in Africa and South America. I was keen to hear his take on the situation because his main research concerns how humans and another hominid species coexisted in the African Rift Valley — with each other and a whole ecosystem — for a million years and more. Here’s a person with a long view of our role in the landscape, someone likely to have insight into the threads of this debate that center on whether and how native plants should or shouldn’t have priority in our management of local parklands (most forcefully argued at milliontrees.me).

“As simple poles: ‘only native’ and the opposite extreme, ‘no priority for natives,’ those are foolish ends of the spectrum,” he said. “What we have are changing systems with new elements that by most people’s accounts can’t be fully eradicated, nor would that be desirable.”

It turns out Shabel also has a more varied than average experience with eucalypts, having encountered plantations of them during fieldwork in Africa and South America.”I see eucalyptus through how they grow in Malawi, South Africa, Chile,” he told me. “When you move around the world and you see some of these particular species that are succeeding so well at the expense of locals, you can’t help but have concern for the diminishing locals everywhere. This isn’t xenophobia, this is a concern for the natives everywhere. Eucalyptus, whether it’s in Patagonia or Africa, completely dominates.”

But deciding how to deal with that dominance isn’t necessarily simple. “You’re talking about a dynamic ecosystem and working toward some goal, whatever it may be,” said Shabel. “Usually those goals relate to an assumption about a previous ecosystem condition. What was the ecosystem pre-eucalyptus? People speak with authority of what the system was at various times. Based on historical records and early photographs, there were very few trees. Why was that?”

Ecologists and botanists have pollen records and other evidence they can draw on for that, but nothing that will get down to specific canyons. “We don’t know what it was like 400 years ago, let alone 2,000 or 14,000. What was it before people got here? This was ground sloth county, this was camel country, not to mention the predators. There was a huge fauna that’s no longer here. Geologically that’s yesterday.”

And the hills as we know them will change again, either through the proposed aggressive management or through natural processes like fire. Shabel worries about potential drying out of treeless habitats and wonders if planting redwoods be a good idea in some areas where they don’t currently grow, but, for him, the managed succession embodied in the EIS seems like the best we can do with the evidence we have. “I prefer someone doing something, if aggressively, to doing nothing.”

Public Forum and Commenting

You can attend a public forum about the project this evening. The forum, sponsored by The Hills Conservation Network, is tonight, June 12 at 7:30 pm at The Hillside Club, 2286 Cedar Street (at Arch). You can comment on the FEMA proposal until Monday, June 17. Here are instructions on how to comment.

You can also read an extensive Q & A with Tom Klatt, UC’s project manager for the tree removal work, over at Berkeleyside.

Nature news junkie? Get our weekly news digest!

 

5 comments:

Madeline Hovland on June 15th, 2013 at 4:20 pm

When the eucalyptus are cut down on UC property, they will be chipped on site, and the chips will be left on the ground up to a height (supposedly) of 2 feet. We have seen (and photographed) large mounds of euc chips and trash from removing trees that UC has left on the ground in Claremont Canyon in the past, so we doubt very much that the height will be limited to 2 feet. As MillionTrees first pointed out, having discovered the critical correspondence in documents to FEMA obtained through the Freedom of Information Act, URS, which was at that time consulting with FEMA on this project, stated that there was little or no possibility that the native landscape or habitat for animals would be restored, that the euc chip mulch would not favor regeneration of native vegetation over weeds, even after the mulch had decomposed, and that the chipped eucalyptus mulch would be a greater fire hazard than the living euc trees. In the absence of a revegetation plan for these sites where the eucs would be removed, the URS letter went on to say, several types of plant species, including shrub/brush/chaparral species, could move in, and these species would create their own fire risks, in many cases, a much greater risk than eucs create. Is it any wonder that FEMA (or UCB) replaced URS with another consultant?

Bev Von Dohre on June 16th, 2013 at 12:09 am

I have heard/read so much misinformation by “experts,” including the UC scientist who advised Audubon to cut down all the plants in the Berkeley Cesar Chavez burrowing owl habitat (they didn’t know or care which were native or non-native), ignoring the fact that the owls come back to stand behind a particular shrub, and that their shrubs help shield them from the off-leash dogs allowed to go after the owls. So after the habitat was cut to the ground, the owls came and stood forlornly behind the stumps of their shrubs. One possibly was killed by a dog. Since then, the last two owls disappeared when a bench was placed on top of one burrow the owl used, and the other burrow was paved over. Audobon’s efforts to unnecessarily limit the ground squirrels has also limited options for the burrowing owls who use the squirrels’ burrows. Before Audubon and the “experts” got involved, there were at least six owls we saw each winter. (I tried being a docent for the owls, but it was so frustrating trying to work with Audubon and so heart-breaking for the owls, that I quit.)

Anyway, I have read similar “expert” comments that contradict my own experience, like this article saying that having larger raptors comes at the price of smaller raptors, which is used to once again malign eucalyptus. One of my favorite East Bay nature trails has horned owls and red-shouldered hawks who nest in eucalyptus, but also has smaller raptors, like kestrels, white-tailed kites, cooper’s hawks, saw-whet owls, etc. all in within a half mile of each other. It is a wonderful varied and diverse habitat with native forest and a Monterey pine section, acacias, non-native plums, and eucalyptus.

Keith McAllister on June 16th, 2013 at 5:12 pm

Dan, I know you are strongly in favor of the native plant restorations you are writing about. So I must say that your attempts at being even handed, and listening to experts, are admirable. I’m not sure I could match your standard. As you have contacted various experts, have you found anyone who can give an authoritative evaluation of the amount of CO2 that will be released by the projects, and the future sequestration that will be forfeited by removing the large trees? The DEIS ignores most of the CO2 to be released, and doesn’t quantify the future sequestration that would occur if the trees were left in place. I ask because I consider the DEIS to be an advocacy document, not scientific evaluation.

Dan Rademacher on June 16th, 2013 at 8:59 pm

Hi Keith, I haven’t dug into the carbon question. We have a story coming up in our next issue about redwoods that says that large redwoods actually continue to sequester more carbon per year than young redwoods, even though it seems like young trees grow faster. Whether that carries over into eucalyptus, I don’t know.

I was struck in reading a manuscript by Jerry Kent on the history of California’s eucs that we really don’t know, yet, how long they’ll live or how big they’ll get. I’d think the keys in determining how much additional carbon large eucs would sequester would be (a) how long will they live and (b) how big they’ll get. If the trees would live as long and grow as large as they do in Australia, then that’s a lot more carbon they could sequester. If not, then it’s less by some unknown amount. I also don’t know how much carbon an oak/bay woodland absorbs.

Then there’s the issue of the carbon currently locked up in the trees. In a fire situation, most of that carbon would obviously be released. I assume in a mulch/left to rot situation (like UC proposes) it is also released, though I’m honestly not sure if that’s the case — perhaps some is also absorbed into the soil, like in grasslands covered in compost (according to a Marin Carbon Project story we did a while back).

I’ll let you know if I find anyone who can speak to this with more authority.

Bob Strayer on July 29th, 2013 at 6:40 pm

I don’t believe the EPA’s concerns about the impact of the Project and how it will effect the Project area, is not about CO2 sequestration. I believe their focus was on how the remaining native woodland would survive in a changing climate. Which would include the possibility of longer and more sustained droughts.

Additionally, the carbon in the trees is geologically speaking, in the short-term carbon cycle. The carbon we need to focus on is the carbon depleted of C14. Besides, the net effect of the Projects carbon emissions are infinitesimal in the larger carbon/climate change scheme. The Eucalyptus tree is a good carbon sink, but since it suppresses most other vegetation, the microbes and fungal growth within the soil itself, it’s net carbon influence is negated by it’s deleterious effects on the soil and native flora.
As for the EPA’s concern over the Projects impact regarding climate change; removing the E. Globulus from the East Bay Hills would have a positive impact on drought mitigation because they do not economize on water by closing their stomata like native trees do, so they tend to exacerbate drought conditions by sucking the moisture from the soil and dissipating it into the air.

http://ccfirestorm.blogspot.com/2013/07/eucalyptus-globulus-exacerbates-drought.html

Leave a Comment

Name

Email

Website

Comment