How (and Why) to Do Habitat Restoration

Michael J. Vandeman, Ph.D.

May 25, 2023


     I would like to record, in case I get run over by a truck (or, more likely, a mountain biker), what I've learned from several years of intensive work to remove invasive non-native plants from my local parks.


     Rationale: Native plants and animals have evolved together for millions of years, and therefore are probably better off together than with invasive non-native plants that they don't know how to deal with.


     Clothing: Wear all white, so that any ticks will be maximally visible, and to stay as cool as possible in direct sun. Painter's cotton pants work very well, and don't pick up seeds. Tough cotton socks are vulnerable to foxtails (grass seeds), but less so than other fabrics. Gaiters over the socks (possibly augmented by rubber bands to keep out ticks) are very helpful. Tall boots, into which you can tuck your pant legs, are even better. A long-sleeved polyester shirt and nitrile gloves with elastic overlapping the shirt sleeves are excellent, and keep out ticks. Socks with the toes cut off can be worn under the gloves to cover any gaps and protect you from poison oak. Leather gloves over the nitrile gloves will protect you from thorns of thistles and Himalaya blackberry (grab them close to the ground). A broad-brimmed hat and sun glasses are important, and have protected me many times from poison oak, falling branches, thistles, etc. Your shoes should of course be closed-toed, with good traction. If you wear glasses, a strap to hold the glasses on (connecting the earpieces) is very helpful (try finding glasses in the bushes, when you can't see well!). After you are done, shower immediately. I hear that Technu is good for removing the oil that poison oak leaves on the skin. Certain soaps (not Ivory) are also good for doing that, but I don't know what they are called. Boraxo would probably help; it's good for removing bicycle grease.


     Plan: Carry plenty of water! When there are many hikers in the area, work near the trail and make eye contact with them, so they will thank you for your work, and maybe even volunteer to help some time! You can use, Craig's List, etc. to solicit help. You may need technical help learning how to use the software. Feel free to email me about that. When I'm at home, I envision the project is do-able in X days. It inevitably takes longer. When I arrive at the site, the project looks infinite. Both estimates are wrong! It is certainly do-able, but you need to be patient. I find this kind of "mindless" work very conducive to thought. Carry a pen and paper to write down all your brilliant ideas, before you forget them. You don’t want to miss that chance for your Nobel Peace (or other) Prize! J Carry a cell phone (to report illegal mountain biking) or small digital camera to photograph plants you need help identifying, and/or cut a small sample. The Jepson Herbarium at U.C. Berkeley – or a nursery - will help identify it. Don't think you can complete your project in a single visit! These plants are all at least as smart as we are, and have many tricks up their collective sleeves! You will need to follow up at least once a year. But how many activities are there that provide instant results, as habitat restoration does? When you pull a plant out of the ground, it is not coming back! How satisfying is that?


     Tools: Tools can sometimes be borrowed from tool libraries affiliated with the public library. Use whatever you feel comfortable with: clippers, loppers (long-handled clippers), weed wrench, etc. I use loppers, because they will cut anything up to about 1 inch in diameter (if the main stem is too thick, just cut all the smaller stems), and they allow me to work fast, and feel like I am making progress. Lately I have found a pruning saw to be even better. I can grab a bunch of small French broom sprouts with one hand, and cut them all with the saw in one second! If I have more than one tool to keep track of, inevitably I lose one somewhere and have to spend frustrating time searching for it. Even a weed wrench (designed to pull a large plant out of the ground) won't always succeed, e.g. on a steep slope or where you can't get the leverage you need. The loppers and pruning saw (if you keep them sharp) never fail. Pulling a large plant out of the ground disturbs the soil, helping its seeds germinate and causing erosion. I leave all cuttings on the ground, so that the nutrients will go back into the soil, erosion will be minimized, and so that I can work at maximum speed: habitat restoration is a race between you and the plants: you have to eradicate them faster than they can grow. Volunteers' time is rare, precious, and shouldn't be wasted! (However, loppers are better for dealing with certain difficult plants, such as Himalayan blackberries (tough and full of thorns) or thoroughwort (dense clumps of woody stems).)


     Theory: Plants get their energy only through their leaves (or occasionally, green stems). The energy stored in the roots is finite. If you keep removing the leaves, eventually the plant will die. That is a simple application of the Law of Conservation of Energy. Advocates of pulling usually say that if you only cut the plant (e.g. French broom), it will re-sprout, as though its energy is infinite. But re-sprouts are small and easy to cut, if you don't wait too long. Eventually, the plant will give up. According to Einstein, nothing in this world is infinite – except human stupidity. J Leave all cuttings in place, to return their nutrients to the soil. Of course, all plants should be cut before they go to seed. But there may be seeds in the ground, so plan on returning the following year, or, if possible, sooner. Often, removing the non-natives is enough to allow the natives (which may have seeds in the ground) to return. If not, you may need to plant some, but now we are beyond my expertise. Get to know what poison oak looks like: leaves in threes, smooth on top, smooth edges, "oak-shaped" leaves, smooth stems. Also learn what the bare stems look like in winter! They also contain the oil that causes itching.


Ticks: Ticks are very slow-moving, so you generally have time to remove them before they bite you, if you shower as soon as you get home. You can take them to the County Health Department to have them checked for Lyme disease. I'm the discoverer of Lyme disease in the Bay Area, because I did that a couple of decades ago. They hadn't known that Lyme disease had come to the Bay Area. The experts tell me that even if you get bitten, you may not be infected, because (1) very few ticks have Lyme disease, and (2) it takes them at least a couple of days to actually infect you. We also have antibiotics to kill the Lyme disease bacteria, if you are aware of having been bitten. Sometimes it will show up as a "bull's eye" pattern on your skin. Lyme disease gets serious, though, if it is unnoticed and not treated at the time of infection. The best tool for removing an embedded tick is a thin metal tool with a "keyhole" that fits around the tick and can gradually pull it backwards and out of your skin. See


     French broom: You can try to pull it out by hand, especially if it is less than ½ inch thick. This is easier after a rain or on steep or loose soil. If it won't budge, cut it. If more than one stem share the same root, pull them all together, so that they all contribute toward pulling that root out. It's easier if you use both hands. I've noticed a strange phenomenon that, for lack of a name, I'm calling the "Vandeman Effect": it's easier to pull up a broom plant if I use both hands, even if my left hand does no work (i.e., if there is no tension on my left arm)(I'm right-handed)! Have you ever noticed that? Be careful not to confuse broom with coyote brush, which is native. French broom stems are straight. The leaves are narrow and lens-shaped, with smooth edges. The flowers are yellow. Coyote brush stems are irregular, and the leaves are wide, with irregular edges. The flowers are white.


     Italian thistle: If it is vertical, cut it low. If it is on a slope, the stem may be curved near the bottom, making it hard to see where to cut it. In that case, knock it down first. Then you can see exactly where the lowest part of the stem is, and cut it on the first attempt. Trick: the bottom of the stem has no thorns! So you can grab it there and pull it out of the ground. Either method is fine, since it is a biennial and will die, hopefully before producing any seeds. Even if a plant has gone to seed (the flower will be white instead of purple), I like to cut it so I can see the other plants; and maybe the seeds won't travel as far. You will soon learn to avoid the thorns; they are very sharp! If one sticks you, expose the skin, and you will see the thorn and can remove it easily. I prefer to start at the lower end of the slope, so the plants will naturally fall out of my way after being cut. If not, the loppers are good for sweeping them out of the way.


     How to remove thorns or splinters: If you sense that you have a thorn, immediately stop and look carefully at your skin. You should see the thorn and be able to remove it. If you delay, it could become embedded and impossible to see. Once you are home, if you still feel that you have a thorn, go where you have bright sunlight or a bright lamp, and use a sharp needle to prick your skin and tear it sideways. That should be painless. You can also use your fingernail to tear the skin away, sideways. This process should painlessly remove the thorn or splinter. Apply antiseptic (I use Bacitracin) and a bandaid.


     Fennel: The stems can be cut easily with a pruning saw or clippers. Repeat periodically, until the plant runs out of energy.


     Milk thistle: They have stout, but hollow stems, and can easily be cut with loppers, without getting your hands near the thorns.


     Poison hemlock: It is poisonous to eat, but not to touch. They are very easy to cut. They have smooth stems with purple splotches. Don't confuse them with cow parsnip, which is native and has larger, less carrot-like leaves and no purple splotches.


     Himalayan blackberry: They have leaves generally in groups of five, although often three. Their thorns are strong and lean backwards (toward the base of the plant). The stems tend to rise up from the ground. Try to trace the stems to their origin, so you can remove them with a single cut. (Native blackberries have thinner stems and leaves in threes. Their thorns are weak and perpendicular to the stem. The stems tend to remain low to the ground.)


     Pampas grass: cut off the green stalks and leaves with a pruning saw or clippers whenever they appear. Eventually the plant will exhaust the energy stored in the roots, and die.


     Oxalis pes-caprae (Sourgrass): Oxalis is actually the easiest invasive plant to remove. Without any tools at all - with gloves if you prefer - you can pull it up easily. I think it's a waste of energy to worry about the underground parts. Sure, you have to return periodically, but eventually the energy it has stored in the roots will be exhausted and it will die. That follows directly from the Law of Conservation of Energy: plants only get their energy from their leaves (and other green parts), so if you keep removing the leaves, eventually the finite store of energy in the roots will be used up and it will die.

     The real problem is how we think: its extent seems infinite. But according to Einstein, the only thing in this universe that is infinite is human stupidity. Oxalis removal is perfect for a bunch of grade school students, and soon after a rain is the perfect time to do it. The use of chemicals is unnecessary, wasteful, and harmful.


     Volunteers: Volunteers are precious, and volunteers' time is precious. Therefore, it is important to try to use the most energy-efficient methods (the methods that accomplish the task with the least expenditure of energy, in the long run). I am not aware of any scientific study of this issue, but in my experience and judgment, the use of the pruning saw (leaving all cuttings in place; repeated as needed to cut the resprouts) is the most energy-efficient method of plant eradication. For smaller plants, a pair of clippers is even better. (My clippers had a spring that would open the clippers after each cut, but the springs inevitably fall out or get damaged. I eventually gave up trying to maintain the spring, and re-open the clippers manually.) For the smallest plants, or soon after a rain, you can often pull the plants out of the ground – the best possible outcome. Plant removal can be exhausting. Conserve your energy! Kneeling takes less energy than standing, and sitting on the ground takes the least amount of energy.


     Education: Mathematics: A field of invasive plants can appear infinite! Of course it's not. Discuss the nature of infinity. Estimate the actual number of plants after counting them in a randomly-selected square. Discuss the nature of randomness, and how a random selection should compare with the actual quantity being estimated. Weed your square and use the time it takes to estimate the time it will take to weed the whole area. Describe how to use exponents to succinctly express large numbers. Physics: Where do plants get their energy? How would you measure the energy required to grow a given plant? Would burning the plant indicate how much energy was required for it to grow? What gives seeds the energy to start growing? Where do plants get the energy to begin growing in the spring?  If a plant is cut, where does it get the energy to re-sprout? Will a cut plant always re-sprout? Why do we feel warm when in the sun and cool in the shade? What effect does wind have on plants and people? Can plants and people make use of energy from the wind? Why do some animals, such as reptiles, not come out until the sun is out? Why do they like to sit on rocks? Biology: Why are non-native plants and animals often very successful in new habitats? Do native animals prefer native plants? Why or why not? What "enemies" do non-native plants have in new habitats? What happens to native plants and their seeds when a habitat is overrun by non-native plants? What do you suppose will happen when the non-native plants are removed? When plants grow, do they extract nutrients from the soil? What will happen if they are removed? Will the soil lose nutrients? What is preferable, removing cuttings or leaving them to decay and return to the soil? How long do you think it will take for cuttings to completely return to the soil? How long will seeds remain viable? Why might invasive plants reappear after being eradicated? If you were a plant, what would your strategy be? Try to grow as quickly as possible? Or invest in a lot of energy storage in your roots? Build strong stems, or stems that can be created quickly? Can you identify plants with various differing strategies? Compare the strategies of thistles, poison hemlock, pampas grass, and French broom. What makes some stems stiff and others weak? Which are more likely to be eaten by animals? How can plants protect themselves from herbivores? Name some plants and their methods of self-protection. Which plants are edible by humans? Which are poisonous? Which animals are harmful to humans? How does that benefit the plant? Are there any plants that are invulnerable to humans? How do plants and animals benefit humans? How can we ensure that we continue receiving those benefits?





California Invasive Plant Council:

California Native Plant Society

Friends of Five Creeks:

Skyline Gardens Alliance:

Take to the Hills:

Tending the Ancient Shoreline Hill:

The Watershed Project:

Weed Photo Gallery

Invasive Non-Native Plants of the East Bay Regional Parks

The California "noxious weed" list: or Per California Penal Code Section 384a, no one needs permission to remove any of these noxious weeds from a public park, since they are considered pests and a public nuisance. They are just like trash. No one needs permission to remove trash from a public park.

Legislative history: It was initially made illegal to remove any plant from a park. Then the legislature realize that that was a mistake, and created Section 384a to exempt invasive non-native plants, as well as plants removed for fire suppression, passing it with unanimous votes of the Assembly and Senate.


To recommend a plant to be added to the California
"noxious weed" list: or

Send your recommendation to


Invasive non-native plants are considered a "public nuisance"! That allows them to be removed from a public park by anyone, with or without permission, under California Penal Code Section 384a - just as we don't need permission to pick up trash, which is obviously a public nuisance:

Ordinance 38 SECTION 804. PLANTS. No person shall damage, injure, collect or remove any plant or tree or portion thereof, whether living or dead, including but not limited to flowers, mushrooms, bushes, vines, grass, turf, cones and dead wood located on District parklands. In addition, any person who willfully or negligently cuts, destroys or mutilates vegetation shall be arrested or issued a citation pursuant to Penal Code Section 384a.



  ( Part 1 enacted 1872. )


  ( Title 10 enacted 1872. )

(a)         (1) A person shall not willfully or negligently cut, destroy, mutilate, or remove plant material that is growing upon state or county highway rights-of-way.

(2) A person shall not willfully or negligently cut, destroy, mutilate, or remove plant material that is growing upon public land or upon land that is not his or hers without a written permit from the owner of the land, signed by the owner of the land or the owners authorized agent, as provided in subdivision (c).

(3) A person shall not knowingly sell, offer or expose for sale, or transport for sale plant material that is cut or removed in violation of this subdivision.

(b) For purposes of this section, plant material means a tree, shrub, fern, herb, bulb, cactus, flower, huckleberry, or redwood green, or a portion of any of those, or the leaf mold on those plants. Plant material does not include a tree, shrub, fern, herb, bulb, cactus, flower, or greens declared by law to be a public nuisance.

(c) (1) The written permit required by paragraph (2) of subdivision (a) shall be signed by the landowner, or the landowners authorized agent, and acknowledged before a notary public, or other person authorized by law to take acknowledgments. The permit shall contain the number and species of trees and amount of plant material, and shall contain the legal description of the real property as usually found in deeds and conveyances of the land on which cutting or removal shall take place. One copy of the permit shall be filed in the office of the sheriff of the county in which the land described in the permit is located. The permit shall be filed prior to the commencement of cutting or removal of plant material authorized by the permit.

(2) The permit required by this section need not be notarized or filed with the sheriff when five or less pounds of shrubs or boughs are to be cut or removed.

(d) A county or state fire warden; personnel of the Department of Forestry and Fire Protection, as designated by the Director of Forestry and Fire Protection; personnel of the United States Forest Service, as designated by the Regional Forester, Region 5, of the United States Forest Service; or a peace officer of the State of California, may enforce the provisions of this section and may confiscate any and all plant material unlawfully cut or removed or knowingly sold, offered, or exposed or transported for sale as provided in this section.

(e) This section does not apply to any of the following:

(1) An employee of the state or of a political subdivision of the state who is engaged in work upon a state, county, or public road or highway while performing work under the supervision of the state or a political subdivision of the state.

(2) A person engaged in the necessary cutting or trimming of plant material for the purpose of protecting or maintaining an electric powerline, telephone line, or other property of a public utility.

(3) A person engaged in logging operations or fire suppression.

(f) A violation of this section shall be a misdemeanor, punishable by a fine of not more than one thousand dollars ($1,000), by imprisonment in a county jail for not more than six months, or by both that fine and imprisonment.

(a) All plants defined as a noxious weed under Title 3, California Code of Regulations, Section 4500, are a pest plant.

Food and Agricultural Code - FAC


  ( Division 4 enacted by Stats. 1967, Ch. 15. )
PART 1. GENERALLY [5001 - 6299]

  ( Part 1 enacted by Stats. 1967, Ch. 15. )
CHAPTER 6. Abatement, Generally [5401 - 5494]

  ( Chapter 6 enacted by Stats. 1967, Ch. 15. )
ARTICLE 1. Authority [5401 - 5405]

  ( Article 1 enacted by Stats. 1967, Ch. 15. )


Any premises, plants, conveyances or things which are infected or infested with any pest, or premises where any pest is found, are a public nuisance, and shall be prosecuted as such in all actions and proceedings. All remedies which are given by law for the prevention and abatement of a nuisance apply to such a public nuisance.

Food and Agricultural Code - FAC


  ( Division 4 enacted by Stats. 1967, Ch. 15. )
PART 1. GENERALLY [5001 - 6299]

  ( Part 1 enacted by Stats. 1967, Ch. 15. )
CHAPTER 1. Definitions and General Provisions [5001 - 5035]

  ( Chapter 1 enacted by Stats. 1967, Ch. 15. ARTICLE 1. Definitions [5001 - 5012]

 ( Article 1 enacted by Stats. 1967, Ch. 15. )


Pest means any of the following things that is, or is liable to be, dangerous or detrimental to the agricultural industry of the state:

(a) Any infectious, transmissible, or contagious disease of any plant, or any disorder of any plant which manifests symptoms or behavior which the director, after investigation and hearing, finds and determines is characteristic of an infectious, transmissible, or contagious disease.

(b) Any form of animal life.

(c) Any form of vegetable life.

Health and Safety Code - HSC

PEST ABATEMENT [2000 - 2910]

  ( Heading of Division 3 amended by Stats. 1957, Ch. 205. )
CHAPTER 8. Pest Abatement Districts [2800 - 2910]

  ( Chapter 8 enacted by Stats. 1939, Ch. 60. )
ARTICLE 1. Definitions and General Provisions [2800 - 2805]

  ( Article 1 enacted by Stats. 1939, Ch. 60. )

As used in this chapter, public nuisance includes, but is not limited to, both of the following:

(a)  Any breeding place or place of growth of a pest for which a district may be initiated under Section 2822, which exists by reason of any use made of the land on which it is found, or which exists by reason of any artificial change in the natural condition of the land on which it is found. The presence of any immature stages of any pest, or the rooted stages of any plant pest, shall constitute prima facie evidence the place is a breeding place for the pest.

(b)  Water which is a breeding place for any pest for which a district may be initiated under Section 2822.