Sweet Springs Eucalyptus Removal Raises Questions

by Holly Sletteland

No doubt many of you have seen various letters to the editor and articles in local papers regarding the plans that Morro Coast Audubon has put together for the new addition to Sweet Springs, on the corner of 4th Street and Ramona. Although it appears that most people are supportive of the proposed access improvements and restoration of the areas dominated by veldt grass, some have taken serious exception to the proposal to remove up to 120 eucalyptus trees on the property over 10 years.  I'd like to take this opportunity to correct some of the misconceptions about what we are proposing to do, as well as to address some of the concerns that have been expressed.

First, I think it is important to stress that this proposal only applies to the new addition.  We currently have no plans to remove any eucalyptus on the central preserve that most people are currently familiar with.  We do have a certified arborist inspect the trees annually to determine if any of them are hazardous, and remove limbs and trees per his recommendations.  Last year, he advised that one cypress at the entrance should come down and that we trim a number of the other cypress trees.   We also eventually would like to provide more sun on the ponds for the turtles to bask in, so we may request permits to thin some of those trees at some point in the future.  But beyond that, the 400+ trees on the central preserve currently open to the public will remain in place for the foreseeable future - including eucalyptus, cypress, oaks, willows, and wax myrtles.  We will also continue to plant native trees in order to insure that the preserve has woodlands for future generations.

I also think it is important to point out that we are only proposing the gradual removal of up to 12 eucalyptus trees per year.  The 40+ mature cypress trees found on the property will remain, even though they are not native to the area.  They are far less disruptive to the native plant communities than are eucalyptus. There are also a number of mature oak trees on the property, as well as quite a few mature willows and wax myrtles in the wetland areas.   We will be planting hundreds of new trees, primarily coast live oaks, that will eventually grow up to screen the street and nearby homes and succeed the cypress as they grow old and die naturally. 

Many people have expressed concern for wildlife, and I am grateful for that.  Wildlife is a key concern for us as well.   Many have indicated that they fear the removal of the eucalyptus will remove nesting and roosting sites for a variety of birds including raptors, herons and egrets.  Others have expressed concern over the loss of monarch habitat. Still others have worried about the impact on bees.

We don't dispute the fact that eucalyptus provides important habitat for these species.  It is for that reason that will be asking professional biologists to conduct wildlife surveys prior to the removal of trees and we will avoid any that we find are actively being used.  We will also be planting new trees that will eventually provide the native habitat that these species evolved with. The mature cypress and trees on the central preserve can provide interim habitat.

We will also be planting new trees that can eventually provide the native habitat that these species evolved with and, during the interim, the mature cypress and eucalyptus on the central preserve can provide habitat.  The native vegetation will also benefit the species that people have voiced the most concern about. 

For example, both Great Horned Owls and Red-shouldered Hawks prey on small mammals, birds, and reptiles.  Even herons and egrets are known to take a lizard now and then.  There are currently very few of these animals on the new addition, but we anticipate that will change as the habitat improves and there is more food and cover to support them. 

We are working with the Monarch Project to determine how we might improve habitat for the butterflies, including planting alternative trees to roost in—such as sycamores—and providing better sources of nectar.  We will also be planting a variety of early flowering shrubs and wildflowers—such as ceanothus and the endangered Morro Manzanita—to compensate for the loss of eucalyptus flowers as a food source for honeybees.  Increasing the abundance and diversity of native plants should also greatly benefit our native pollinators and other insects, which, in turn, increases food sources for animals higher on the food chain.

Another legitimate concern raised by a number of people is the potential of exacerbating climate change by removing the eucalyptus.  It would seem that more trees absorbing carbon dioxide would be a good thing, not a bad thing.  Unfortunately, there has not been a lot of research in this particular area to provide a definitive answer.  We are still searching for additional information. 

We did approach the Union of Concerned Scientists, an organization that is actively engaged in finding and promoting solutions to climate change and invasive species.  Their analyst, Calin May-Tobin, pointed out that native ecosystems also have the capability to sequester carbon (particularly wetlands), so we will not be destroying a carbon sink and replacing it with nothing.  May-Tobin suspected that carbon sequestration would be comparable for both plant communities, but did not have any specific information to support that.  However, she also indicated that "native ecosystems have tremendous value in their own right, beyond carbon capacity…The more area covered by native vegetation the better the chances that native species will be able to adapt to a future, changed, climate."

People have also expressed concern about our proposed methodology.  Some are worried about the damage that will be done to the landscape in taking out the trees and applying herbicide to the stumps to prevent resprouts. I'm not sure how to respond to this other than to say we will be using the least intrusive methods possible. 

Tree removal will occur in the fall after nesting season, but prior to the rainy season so the ground is solid. In order to protect the understory, we will not be bringing in any heavy equipment to fell the trees.  We will be using California Conservation Corps crews traveling on foot using approved access/egress routes to minimize trampling of vegetation.  They will be using handheld chain saws to remove trees.  We will make every effort to direct the falls to open areas that will cause the least impact, using block and tackle equipment if needed.  If a tree fall cannot be directed away from a significant natural resource, such as a mature oak tree, we will consider hiring an arborist to climb the tree or girdling the tree and leaving it in place. Stumps will be cut at ground level in conformance with the slope of the terrain.  This will help to stabilize the soil until the native plants become established.

All stumps will be treated within one to five minutes of the cut by painting a 50% solution of the herbicide glyphosate around the cambium layer of the trunk to prevent resprouts. This method has proven to be extremely effective over many trials and has few, if any, impacts on the environment.  Glyphosate works by inhibiting the formation of an enzyme that is found only in plants – not animals – and is essential to their growth.  The herbicide application is restricted to the trunk, so opportunities for drift to neighboring plants or soils are very limited.  Even if it did, glyphosate has a very low acute toxicity and has an average half-life in the soil of 60 days (EPA Fact Sheet 2011).  It biodegrades into natural compounds such as nitrogen, phosphate and carbon dioxide.   It also has a very low toxicity to mammals and birds, and appears to be non-toxic to fish.  There have been problems with surfactants used in combination with glyphosate, particularly on amphibians.  We will be applying Rodeo™ or Aquamaster™, which are approved for use near water, for this reason.

Another rather unexpected criticism we've received is that we are somehow "xenophobic" or "prejudiced" against anything that is non-native.  This reflects a lack of understanding of the difference between "non-native" and "invasive" plants. 

The vast majority of non-native plants are not invasive.  We happily grow roses and lilac and wisteria in our gardens just like the next person.  We also munch on apples and pears and tomatoes and peas and string beans and a myriad of other fruits and vegetables without batting an eye.  These plants were imported into our environment for their aesthetic and nutritional value and have provided enormous benefits.  They have also tended to be well behaved and have stayed where we put them. 

Invasive plants, by contrast, are those plants that are introduced to our environment, either intentionally or by accident, that are then able to spread unchecked in the new setting in the absence of their natural competitors and predators.  Invasive plants can outcompete and harm native habitats, destroying native plant communities that provide essential food, shelter and nesting sites for a wide array of animals. 

Only about 3% of the non-native plants growing in the wild in California are considered invasive, but they are much more abundant in the landscape. The blue gum eucalyptus found at Sweet Springs was given the highest rating of "A-1" by the California Exotic Pest Plant Council (CAL-EPPC) and is assigned a moderate rating by the California Invasive Plant Council (CAL-IPC). These are species that have "substantial and apparent – but not severe - ecological impacts on physical processes, plant and animal communities, and vegetation structure."

Lastly, some people have expressed concern about the visual impacts of losing the eucalyptus trees.   It is true that the very tall tree canopy will eventually be gone forever under our plan.  Although mature native trees can grow to be quite tall under certain conditions, none of the trees native to our coast approach the height of a eucalyptus.  We fully expect oak groves with a dense understory of shrubs and herbs will eventually block the wind and provide screening to give a sense of being "surrounded by nature."  However, there is no question that it will take time for that to happen.  But I might also suggest that aesthetics are highly subjective and the old adage, "beauty is in the eye of the beholder," still rings true. 

Once you become aware of the harm caused by eucalyptus to our native landscape, it is hard to look at them the same way. They cease to be a thing of beauty and start to become an eyesore, especially when they form dense stands and become monotonous in their lack of diversity.  I personally look forward to the day when the new preserve supports the diverse mosaic of colors and textures found in healthy coastal dune scrub, surrounded by a rich evergreen forest of coast live oak.

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Coast Live Oaks photo by Danielle Caziarc
Red-tailed Hawk by Morgan Ball

Western Pond Turtle Image on Banner by Dave Johnson