Manzanita (Arctostaphylos spp.) as ROW and pole-clearance fuel

Manzanita is a genus of over 100 taxa, split between plants that resprout from a basal burl and plants killed outright that return from soil-stored seed. Cutting ends only the second kind. Common manzanita reaches 26 feet, so it sits inside the PRC 4293 clearance band as well as the PRC 4292 pole firebreak.

In early May, on two sites in the Siskiyou Mountains of southwestern Oregon, a study cut greenleaf manzanita. One treatment took the plants to ground level. The other removed half of each plant. Before the work, the ground under the total-removal treatment carried 40,895 stems per hectare. A year later it carried 308,504.

The half-cut plants sprouted by July 1. The plants taken to the ground showed no immediate growth at all, and then came back at the highest stem count in the study.

Greenleaf manzanita does that in the Sierra Nevada and in southwestern Oregon, where it has a lignotuber. Greenleaf manzanita elsewhere has no lignotuber. One species, one name on the ticket, two opposite answers to the question of whether cutting it ends anything.

That is a single taxon out of a genus the U.S. Fish and Wildlife Service describes as "taxonomically complex, including over 100 taxa of evergreen shrubs and trees, only 8 of which are found outside the California Floristic Province." Two California statutes reach those taxa in a utility corridor. Neither one asks which taxon it is.

Which rule reaches a shrub that grows to 26 feet

Start with the clearance rule, because this is the genus where it applies. Public Resources Code section 4293 reads:

Except as otherwise provided in Sections 4294 to 4296, inclusive, any person that owns, controls, operates, or maintains any electrical transmission or distribution line upon any mountainous land, or in forest-covered land, brush-covered land, or grass-covered land shall, during such times and in such areas as are determined to be necessary by the director or the agency which has primary responsibility for the fire protection of such areas, maintain a clearance of the respective distances which are specified in this section in all directions between all vegetation and all conductors which are carrying electric current

That reaches every plant near the wire, shrub or tree, on the land types it names. The distances follow in the same section: four feet at 2,400 or more volts but less than 72,000, six feet at 72,000 or more but less than 110,000, and 10 feet at 110,000 or more. What those distances are measured from and when is its own subject, as is the separate clearance GO 95 Rule 35 sets. Section 4296 lifts both 4292 and 4293 off any line at 750 volts or less.

Height is what puts this genus inside that band. The Forest Service Fire Effects Information System records common manzanita as "an erect, evergreen shrub that may also grow as a single-stemmed tree," that "typically grows from 6 to 12 feet (2-3.6 m) tall but can reach 26 feet (8 m) tall." Sticky whiteleaf manzanita runs 3 to 13 feet.

Chamise tops out at 12 and rarely triggers a measurement from the wire. A mature common manzanita under a low distribution span, or any manzanita standing on the uphill side of a cut slope, is a 4293 measurement. 14 CCR 1256 then adds sway to it, and names location, height and species as the inputs.

The same section carries a second obligation that is harder to apply here:

Dead trees, old decadent or rotten trees, trees weakened by decay or disease and trees or portions thereof that are leaning toward the line which may contact the line from the side or may fall on the line shall be felled, cut, or trimmed so as to remove such hazard.

That sentence asks an inspector to sort a plant into a condition class. Manzanita carries dead wood as its ordinary mature condition. In mixed chaparral of southern California, FEIS reports, more than 25 percent of standing Eastwood's manzanita consisted of dead branches, and its stems "often bear ribbons of dead wood." Mature sticky whiteleaf branches "often show ribbonlike, vertical strips of dead tissue, and dead branches usually remain attached."

Whether a multi-stemmed shrub that is a quarter dead in its ordinary condition is an "old decadent" tree is not answered anywhere in the text. PRC 4293 says who answers it: "The director or the agency which has primary responsibility for the fire protection of such areas may permit exceptions from the requirements of this section which are based upon the specific circumstances involved." Which agency that is on a given span decides the call, and the call is theirs rather than the inspector's.

The genus is two plants under one name

The 2015 recovery plan for pallid manzanita states the split in one sentence:

Two basic life history patterns are found among species within the genus Arctostaphylos with respect to wildfire; Arctostaphylos plants either survive wildfire and resprout from a basal burl (sprouter) or Arctostaphylos plants are killed by fire and regenerate from seeds stored in the soil (obligate seeder).

That division decides what a cut accomplishes, and it sits below the genus name that goes on the work order.

Taxon	Height at maturity	Basal burl
Common manzanita (A. manzanita)	6 to 12 ft typical, to 26 ft	Five of six subspecies lack one; Roof's manzanita has a prominent burl
Eastwood's manzanita (A. glandulosa)	3 to 10 ft	All infrataxa except subsp. atumescens form a large basal burl
Greenleaf manzanita (A. patula)	3 to 7 ft	Present in Sierra Nevada and southwestern Oregon populations, absent elsewhere
Sticky whiteleaf manzanita (A. viscida)	3 to 13 ft	None; does not sprout from the root crown
Pallid manzanita (A. pallida)	to 13 ft	None; obligate seeding

Two rows in that table do not resolve at the species level. Common manzanita splits five subspecies to one. Greenleaf manzanita splits by geography inside a single species. Bigberry manzanita is the example FEIS reaches for when it defines an obligate seeder, and it shares southern California chaparral with Eastwood's manzanita, which is not one.

The organ that settles it is usually not visible. Jepson found in 1916 that the basal burls of coastal Eastwood's manzanita in the Bay Area were completely buried. In the San Gabriel Mountains, plants repeatedly top-killed by fire carried burls 3 to 6 feet across, underground. A crew looking at two shrubs of the same height and the same red bark is looking at the aboveground half of the answer.

Cutting a burl-former multiplies the stems

FEIS is specific that the trigger is not limited to fire. Eastwood's manzanita "sprouts from its basal burl after top-kill by fire ... or mechanical injury, including mastication," and "sprouts are more common than seedlings after top-killing disturbances."

The Siskiyou clipping study put numbers on what a cut produces.

Treatment	Sample timing	Stems/ha	Basal area (m²/ha)
Total removal	Pretreatment	40,895	4.01
Total removal	Immediately after treatment	0	0
Total removal	1 year after treatment	308,504	1.4
Partial removal	Pretreatment	73,389	7.54
Partial removal	Immediately after treatment	56,092	4.65
Partial removal	1 year after treatment	208,098	4.72

Read the two rows that matter to a work plan. The ground cut took the stem count to zero and returned it at about seven and a half times the pretreatment figure in twelve months, while holding basal area down to roughly a third of where it started. The partial cut, which is the treatment closest to a clearance prune, left 76 percent of the pretreatment stems standing and then nearly tripled the count, and basal area came back to where the saw had left it inside the same year.

So the ground cut buys twelve months of very low volume and pays for it in stem count. The half cut buys neither. Both plots were denser a year after the work than before it.

That is a problem for the field that the record does not currently catch. Regrowth height is the number a unit usually carries, and 308,504 thin stems and 40,895 thick ones can stand the same height. What the growth rate implies for the cycle has to be read against stem count on this genus, because the next crew is cutting a different plant from the one this crew cut.

Cutting an obligate seeder is a germination treatment

The non-sprouting half of the genus is not the easy half. FEIS records the warning in the fuelbreak literature directly:

They caution that treatments that scarify soil are likely to result in substantial posttreatment establishment of sticky whiteleaf manzanita. It may "germinate profusely" from soil-stored seed after bulldozing for fuelbreaks.

Ground disturbance is the germination cue, and clearing work disturbs ground.

The Fish and Wildlife Service records the same mechanism from the conservation side, where it is the desired outcome. "Mechanical disturbance may be an alternative to fire under certain conditions," the pallid manzanita recovery plan says. "The regeneration of seedlings at stands where vegetation management activities disturbed the soil and increased light levels, in the absence of fire, indicates fire is not required for seed germination to occur." Two of its case records show the scale.

At the Pinehurst Road stand on East Bay Municipal Utility District land, a large Monterey pine was removed in 2009. The stand had fallen from 25 mature plants to 11 before that. The disturbance from horse logging stimulated the seed bank, and over 52 seedlings germinated. At Huckleberry Preserve, about 500 square feet was cleared in the summers of 2004 and 2005. The piles were burned in late February and early March of 2007. By 2008 there were 176 seedlings in the burned area.

The scale after a hot fire is larger again. In a ponderosa pine and Douglas-fir stand on the Rogue River-Siskiyou National Forest, common manzanita went from 0.12 shrub per square meter to 108 seedlings per square meter, an increase FEIS puts at 918 times.

The seed bank is old and it is patient. Jepson reported common manzanita seedlings appearing in large numbers 10 to 40 years after cleared farmland in the Napa Range was abandoned. Going the other way, obligate seeding Arctostaphylos may need 5 to 25 years before it produces substantial seed crops. Both numbers are longer than any maintenance cycle, which means the seed under an obligate-seeder clearing is not on the program's schedule at all.

Mastication leaves a fuelbed that dries from the top down

Mastication is the default treatment on a chaparral corridor floor, and common manzanita is one of the species the fuels research has actually measured. What that research found does not point one way.

On flame height, the fractured material is the better of the two. A laboratory study burned two fuelbeds assembled from Six Rivers National Forest samples, one of intact common manzanita sticks 1.2 to 7.9 inches long and one of fractured particles.

It found "mean flame heights were 36% higher in intact fuelbeds (33 inches (83 cm)) compared with fuelbeds composed of fractured particles (24 inches (61 cm), P<0.001)." The qualification arrives in the next line. "Both fuelbed types sustained flaming combustion with fireline intensities ranging from 60 to 140 kJs-1m-1, suggesting that masticated fuels can support flaming combustion despite their high bulk density."

On moisture, the fractured material is the worse of the two, and for a reason that reaches a fire danger rating. Intact and fractured particles dried at the same rate at the surface of the bed. Below the surface, both dried about three times more slowly. FEIS reports the conclusion plainly: masticated fuelbeds "have higher bulk densities and higher loadings of 1- and 10-hour fuels than intact fuelbeds," they "lose moisture slowly," and "longer-than-expected fuelbed drying times may lead to difficulties predicting fire behavior and rating fire danger."

Depth is the variable a crew controls, and there is a number on it. A second study ran prescribed fires on plots with mulch depths of 0, 1, 3 and 5 inches, at two soil moisture contents. The sites were two 18-year-old northern California ponderosa pine plantations with understories dominated by masticated manzanita. Soil heating caused biological damage in dry soil at mulch depths greater than 3 inches.

In dry soil, temperatures passed the 140 degree Fahrenheit lethal threshold for plants at nearly all mulch depths tested. At the two deepest depths they stayed above it for at least 7 hours throughout the 3.9-inch soil profile. Duration above the threshold rose linearly with mulch depth and ran 3 to 7 times longer in dry soil than in moist.

Inside a pole firebreak, the chips are also a compliance item. 14 CCR 1254(a) reaches "flammable materials, including but not limited to, ground litter, duff and dead or desiccated vegetation that will allow fire to spread," and what leaving the site clean requires closes the unit.

Mastication also buys less time than it looks like it buys. Ten years after treatment in chamise-manzanita chaparral north of Ukiah, shrub cover on treated plots was back to roughly the untreated control, and the masticated plots carried more nonnative annual grass than the burned ones.

A six-foot shrub throws a twenty-five-foot flame

Sixteen prescribed burn plots in montane chaparral in Yosemite National Park, codominated by greenleaf manzanita, huckleberry oak and whitethorn ceanothus, were measured for fire behavior. FEIS notes the stand height: "At the time of burning few shrubs exceeded 6 feet (2 m) in height."

Measure	Mean	Minimum	Maximum
Rate of spread (ft/min)	11.7	0.0	35.3
Flame length (ft)	12.5	1.0	25.0

A 6-foot manzanita under a 12 kV conductor hung 20 feet above the ground is 14 feet clear. PRC 4293 asks for four. That span is compliant on the day it is inspected, and the observed flame over that fuel reached 25 feet.

The clearance distance is a contact measurement, not a fire measurement. The rule written for fire is PRC 4292's ten feet at the pole, and 4292 only reaches a pole that carries a switch, a fuse, a transformer, an arrester, a junction, a dead end or a corner.

A span crossing a manzanita stand between two plain tangent poles owes 4293's four feet and nothing more by statute. Whatever else gets done on that span comes from the utility's own vegetation management program, and the number the program chooses is the one it has to defend afterward.

A listed manzanita is a pre-dispatch question

Arctostaphylos pallida was listed as endangered by the State of California in November 1979 and as threatened throughout its entire range under the federal Endangered Species Act on April 22, 1998. The 2015 recovery plan puts the whole species at 1,353 mature plants, in two naturally occurring populations and one out-planted population, all in the Oakland and Berkeley Hills. It is an upright, non-burl-forming, obligate-seeding shrub that grows to 13 feet.

The recovery plan lists eight attributed causes of mortality or decline. The first two are these:

1) removal for wildfire fuel reduction purposes (Manzanita Drive); 2) herbicide use below Pacific Gas and Electric (PG&E) powerlines (Manzanita Drive)

Elsewhere in the same document: "Kanz (2004) indicated that A. pallida plants below the Pacific Gas and Electric Company power lines, between Manzanita Drive and Skyline Boulevard, exhibited evidence of herbicide use." Pallid manzanita is not the only listed member of the genus either. The recovery plan describes Morro manzanita as "a federally endangered obligate-seeding species from Morro Bay, California."

California's Native Plant Protection Act carries an exemption that names this work. Fish and Game Code section 1913(b):

the removal of endangered or rare native plants from a canal, lateral ditch, building site, or road, or other right-of-way by the owner of the land or the owner's agent, or the performance by a public agency or a publicly or privately owned public utility of its obligation to provide service to the public, shall not be restricted by this chapter because of the presence of rare or endangered plants, except as provided in subdivision (c) of this section.

That lifts the NPPA's own take prohibition at section 1908 off right-of-way removal and off a utility's service obligation. Subdivision (c) is the condition attached to it:

where the owner of land has been notified by the department pursuant to Section 1904 that a rare or endangered native plant is growing on that land, the owner shall notify the department at least 10 days in advance of changing the land use to allow for salvage of that plant.

That notice runs from the landowner, and it is triggered by a prior notification from the Department of Fish and Wildlife rather than by a crew arriving. On an easement, the landowner and the utility are different parties, which is a question about the easement before it is a question about the plant.

Three limits on how far the exemption carries.

• It runs to "this chapter," meaning the Native Plant Protection Act. The California Endangered Species Act has its own prohibition at Fish and Game Code section 2080, which excepts what is "otherwise provided in ... the Native Plant Protection Act." Whether that cross-reference carries 1913(b)'s utility exemption into CESA is not stated in either text. The Department of Fish and Wildlife issues the permits under section 2081, so the Department answers it first.

• The federal prohibition for a listed plant on land that is not federal runs through state law. 50 CFR 17.61(c)(1) makes it unlawful to "remove, cut, dig up, or damage or destroy the species on any other area in knowing violation of any law or regulation of any State or in the course of any violation of a State criminal trespass law." Section 17.71(a) applies that provision to threatened plants listed on or before August 20, 2026, absent species-specific provisions. The state-law question above is therefore also the federal question.

• No exemption changes what a crew can identify. The recovery plan's own taxonomy section describes "vegetative diversification in Arctostaphylos, with little divergence in floral characters," and varying interpretations of the genus across a century of treatments. Nobody keys Arctostaphylos from a bucket.

All three point the same direction. A listed-species screen on this genus belongs in the pre-inspection package, with a date and a name on it, rather than in a decision made at the plant.

What a manzanita record has to carry

The genus name is the one field that tells the next crew nothing.

Field	What goes in it
Taxon, to subspecies where the species splits	A. manzanita subsp. rooffii sprouts; the other five subspecies do not
Burl observed	Yes or no, seen at the base, not inferred from the genus name
Listed-species screen	Cleared or not cleared, with the date and who cleared it
Height and ground position	Against the PRC 4293 band for that line's voltage, with the slope under the span
Treatment	Cut to ground, partial removal, masticated, grubbed or treated
Mulch depth left on site	Inches, because 3 is where the soil heating research turns
Stem count or cover at the last look	With its date, because a ground cut returns stems faster than it returns height
Soil disturbed	Yes or no, because on an obligate seeder that is a germination treatment

Four of those eight are not fields a standard unit record carries. None can be reconstructed afterward from a photograph of a clearing, which is why they belong in the inventory rather than in a note on the ticket. The rest is the ordinary closeout.

The Siskiyou plots went from 40,895 stems to zero to 308,504 in twelve months. None of those three numbers is a compliance failure, and all three describe the same hectare of ground that somebody cleared. What separates them is which plant it was and how long ago the saw ran.

Further reading

• PRC 4293: the radial clearance measured from the conductor: The distances by voltage, the 120-degree condition, and what counts as vegetation.

• PRC 4292: the ten-foot firebreak around a pole, and what counts: The cylinder, the three treatment layers by elevation, and which poles are subject poles.

• Chamise (Adenostoma fasciculatum): chaparral fuel in rights-of-way: The chaparral shrub the clearance rule mostly does not reach, and the lignotuber that outlasts the cut.

Frequently asked questions

Does cutting manzanita kill it?

It depends which manzanita. The U.S. Fish and Wildlife Service recovery plan for pallid manzanita describes two life history patterns in the genus: plants that survive fire and resprout from a basal burl, and plants that are killed and regenerate from soil-stored seed. Eastwood's manzanita sprouts from its basal burl after mechanical injury including mastication. Sticky whiteleaf manzanita does not sprout from the root crown at all. Common manzanita splits inside the species, with five of six subspecies lacking a burl and Roof's manzanita carrying a prominent one.

Can manzanita reach a distribution conductor?

Some taxa can. The Forest Service Fire Effects Information System puts common manzanita at 6 to 12 feet typically and up to 26 feet, growing as a single-stemmed tree on some sites, and sticky whiteleaf manzanita at 3 to 13 feet. PRC 4293 requires four feet of clearance in all directions between all vegetation and all conductors on a line operating at 2,400 or more volts but less than 72,000 volts. A mature common manzanita on the uphill side of a cut slope is a clearance measurement, not only a brush-clearing item.

Is manzanita a hazard tree under PRC 4293?

The statute requires that dead trees, old decadent or rotten trees, trees weakened by decay or disease, and leaning trees be felled, cut or trimmed. Manzanita carries dead wood as its ordinary mature condition. In mixed chaparral of southern California, more than 25 percent of standing Eastwood's manzanita consisted of dead branches, and mature sticky whiteleaf manzanita branches show ribbonlike strips of dead tissue with the dead branches still attached. The text does not say whether that makes a multi-stemmed shrub an old decadent tree. PRC 4293 gives the power to permit exceptions to the director or the agency with primary fire protection responsibility for the area.

What happens if a listed manzanita is inside the work area?

Fish and Game Code section 1913(b) exempts right-of-way removal and a public utility's performance of its obligation to provide service from the Native Plant Protection Act's take prohibition. That exemption runs to the NPPA chapter only. On the federal side, 50 CFR 17.61(c)(1) makes it unlawful to cut or destroy a listed plant on non-federal land in knowing violation of any state law or regulation, which routes back through state law. The question is settled before the crew is dispatched, by CDFW under Fish and Game Code section 2081 and by the Service on the federal side.

How often does a manzanita clearing have to be re-cut?

Neither PRC 4292 nor PRC 4293 sets an interval. The biology that should set it differs by taxon. A clipping study in the Siskiyou Mountains of southwestern Oregon cut greenleaf manzanita to ground level on plots carrying 40,895 stems per hectare, and the same ground carried 308,504 stems per hectare a year later. An obligate seeder cut in the same corridor produces nothing until something scarifies the seed, and then produces a cohort.