Plant Communities & Habitats

CLASS READINGS Key to Common Trees of Bouverie Preserve

Bouverie Vegetation Map This class will be held Deciduous & Evergreen Oaks of Bouverie Preserve almost entirely on the trail so dress Sun Leaves & Shade Leaves accordingly and bring Characteristics of the Oaks of Bouverie Preserve plenty of water Chaparral & Fire (California’s Changing Landscapes, Michael Barbour et.al., 1993) Bouverie Preserve Chaparral (DeNevers) ACR Fire Ecology Program Mixed Evergreen Forest (California’s Changing Landscapes, Michael Barbour et.al., 1993) Ecological Tolerances of Riparian Plants (River Partners) Call of the Galls (Bay Nature Magazine, Ron Russo, 2009) Oak Galls of Bouverie Preserve Leaves of Three (Bay Nature Magazine, Eaton & Sullivan, 2013) Mistletoe – Magical, Mysterious, & Misunderstood (Wirka) How Old is This Twig (Wirka) CALNAT: California Naturalist Handbook Chapter 4 (98-109, 114-115) Chapter 5 (117-138)

Key Concepts By the end of this class, we hope you will be able to: Use a simple key to identify trees at Bouverie Preserve, Look around you and determine whether you are in oak woodland, mixed evergreen forest, riparian woodland, or chaparral -- and get a “feel” for each, Define: Plant Community, Habitat, Ecotone; understand how to discuss/investigate each with students, Stand under a large oak and guide students in exploring/discovering the many species that live on/around it, Find a gall on an oak leaf or twig and get excited about the lifecycle of the critters who live inside, Explain how chaparral plants are fire-adapted and look for evidence of these adaptations, Locate at least one granary tree and notice acorn woodpeckers that are guarding it, List some of the animals that rely on Bouverie’s oak woodland habitat, and Make an acorn whistle & count the years a twig has been growing

SEQUOIA CLUB

Resources When one tugs at a

In the Bouverie Library single thing in nature, he A Manual of California Vegetation, second edition, finds it attached to the John Sawyer and Todd Keeler‐ Wolf (2009). The rest of the world. classification system for California vegetation, with descriptions of vegetation types at the level of local ~ John Muir “series.” A Natural History of California, Allan A. Schoenherr (1992). A good description of the California landscape, including plant communities, geology, and natural history. Trail Tip – Acorn Whistle! Investigating the oak community: A curriculum guide for grades 4‐8, Kay Antunez de Mayolo. California Making an acorn cap whistle is a time‐honored Oak Foundation. docent skill and can provide hours of fun, literally, to you and your group. But it takes Oaks of California, Bruce Pavlik, Pamela Muick, practice! Sharon Johnson, and Marjorie Popper (1991). Plant Galls of California and other Western States, Ron Here’s how: put your thumb knuckles together Russo (2007). The most comprehensive field guide and form a “Y” shape with your thumbs. Grasp to galls in California. the acorn cap between your thumb and index finger so that a small triangle (slightly less than Secrets of the Oak Woodlands, Kate Marianchild 1/3 of the cap area) is showing (see diagram, (2014). A delightfully readable book that tells the right). Put your lips up to your thumb knuckles, stories of some of the oak woodland’s most constrict your lips and blow hard. If at first you charismatic critters. Very relevant to Bouverie don’t succeed, try varying your grip: Preserve! *Rotate your wrists forward and backward to Terrestrial Vegetation of California, third edition, change the angle of the acorn slightly. You are Michael Barbour and Jack Major (2007). The original seeking a balance between part of the air “bible” of vegetation ecology in California. stream curling around in the acorn cap while The Life of an Oak, Glenn Keator (1998). A detailed the rest of the air rushes over the top edge. and readable, classic by one of the foremost experts *Vary the size of the triangle of acorn visible between your thumbs. Online

Even though it’s geared to Southern California, “Climate, fire, and habitat in Southern California” is a very informative website sponsored by U.C. Cooperative Extension: http://ucanr.edu/sites/SAFELandscapes/Fire_in_Sout hern_California_Ecosystems/

The California Native Plant Society maintains a vegetation science program and publishes the For more info: Manual of California Vegetation. The society’s http://www.sciencetoymaker.org/acorn website includes more information about growing native plants and an online version of the manual: http://www.cnps.org/ SEQUOIA CLUB

Information on wild California plants for conservation, education, and appreciation. Search feature allows search by plant name, location (county, elevation, plant community), life form, native/non‐native, and rarity: http://www.calflora.org/ The California Native Grasslands Association is dedicated to preserving grassland ecosystems. Check them out at http://www.cnga.org The California Oak Foundation’s site includes many valuable resources about oaks. You can even download a free on‐line version of Acorns and eat ‘em by Suellen Ocean, a 50‐page cookbook for different kinds of acorns. http://www.californiaoaks.org/ Check out our online field guide Oaks of the Bouverie Preserve on iNaturalist.org (click on “guides” and type “Bouverie” in the search field) or go to: http://www.inaturalist.org/guides/1718 Excellent website sponsored by the U.C. Hastings Reserve. Includes pictorial keys of tree oaks, scrub oaks, and galls as well as fun information on oak flowers, acorns, oak masting, sudden oak death and more. http://hastingsreserve.org/Oakstory/oakintro.html

TRAIL TIPS Third and 4th graders love to count and spell. Here are a few trail ideas that use math and language arts. When passing through an ecotone at Bouverie (the transition between two plant communities), stop and ask the students to look around and list 5 things that are different in the habitat they are leaving compared to the habitat they are entering. Say “we are in a very special place. It’s called an ECOTONE. Can anyone spell ECOTONE? “ See if they can guess what it means. Tell the students that the different plant communities are like rooms in a house--each one looks and feels different. Get them to relate to the different plant communities by asking questions about their own houses (which room is hottest, which room is coolest, where are there more places to hide?) Then relate it to the habitat—“Why might an animal like this room better than that room?” Use the “How Old Is This Twig” handout at the back of this section to show them how to count the bud scale scars on a twig. This will tell them how old a twig is as well as how fast the tree is growing. Compare the different types of trees (slow-growing oaks in stable habitats versus fast-growing riparian species like alders in habitats prone to disturbances like floods).

Deciduous oaks of Bouverie Preserve Evergreen oaks of Bouverie Preserve Valley Oak Coast Live Oak Quercus agrifolia Leaves deeply lobed (7-11 Leaves small (1-2.5”), tough, lobes); no spines. Shiny convex; “like a boat.” Spiny- dark green above; softly toothed. Tufts of hairs often hairy underneath. Acorns corners of veins on underside. up to 2” (largest acorn at Acorns long and slender, Bouverie); caps very pointed at tip; caps with over- bumpy. Riparian areas, lapping scales. Oak wood- oak woodlands. lands, mixed evergreen

Interior Live Black Oak Leaves small (<2”), mostly flat. Lobed or not, toothed or not. Twig galls common. Leaves deeply lobed with Acorn caps with overlap- spines at tips; variable in ping scales. Acorn tapered size but can be quite large not pointed. Dry areas; (> 6”), especially in shade. Gilman’s Knoll; knobcone Acorns fat, slightly hairy; pine forest, caps large with overlapping near waterfall. scales. Riparian areas, oak woodlands. Canyon Live Oregon Oak Leaves small, toothed or Leaves with fewer lobes not. Dark green on top; pale than Valley Oak (no more underneath with yellow than 7); sometimes toothed. fuzz. Acorn caps large, bowl Shiny dark green above; -shaped, gold-hairy inside. short-hairy underneath. Riparian areas, upper Can- Acorn caps small; bumpy. yon Trail. Hybridizes readily with Blue Oak. Oak woodlands. Shrubs: two species at Bouverie, both in chaparral and other dry areas Bouverie Preserve is part Blue Oak Scrub Oak of Audubon Canyon Ranch (ACR). This trail card was Leaves small (1-2”); bluish Leaves small (<1”), spiny- compiled by Jeanne Wirka -green. Un-lobed or shal- toothed; shiny on top, curled for ACR Education. Pho- lowly lobed. Often many like holly, not hairy. tos by J. Wirka, M. Wit- galls. Acorns caps small, kowski, and P. Schmitt. bumpy. Hybridizes readily October with Oregon Oak. Leather Oak 2012. Oak woodlands; Bouverie Leaves small, spiny-toothed; Preserve parking area. tightly convex, densely hairy.

Sun Leaves and Shade Leaves

The amount of light available effects the development of a leaf’s size and thickness. Under different light exposures, leaves from plants of the same species, and even those growing on the same plant, often develop distinctly different features. These differences can be seen in trees, shrubs, and herbaceous plants.

While many plants can grow under both sunny and shady conditions (and therefore show characteristics of both sun and shade leaves), some species are genetically adapted to develop exclusively under one time of exposure. These species will only develop one type of leaf.

Where at Bouverie would you expect to see sun leaves? Shade leaves? A mixture of both?

SUN LEAVES may have: SHADE LEAVES may have:

Smaller size Larger size

Greater thickness Less thickness

Shorter internodes (the distance between where Longer internodes leaves attach on the stem)

More extensive system of veins Less extensive venation

Greater rates of photosynthesis (PS) under high Lower rates of PS under high sunlight sunlight1

Palisade cells (those most involved in PS) are Palisade cells are less compact2 longer or in multiple rows

Examples at Bouverie include: Examples at Bouverie include:

Leather oak Big-leaf maple Chamise Black Oak Scrub oak White Alder Manzanita Elderberry Coast live oak Thimbleberry

1 Under low light conditions, sun and shade leaves will photosynthesize at equivalent rates. But, when the heat gets turned up, shade leaves shut down PS while sun leaves take advantage of it.

2 Pigments in leaves growing in shade are arranged to maximize their exposure to the lower light levels. Characteristics of Oaks of The Bouverie Preserve of Audubon Canyon Ranch Prepared for ACR Education by Rebecca Anderson Jones 1998; modified by Jeanne Wirka July 2011.

SPECIES PREFERRED SOIL/ELEVATION WATER LEAF* WHERE AT BOUVERIE Mostly along Stuart Creek near main Valley Bottomlands with deep alluvial soils or Riparian zones or places with D entrance. Some scattered in Oak Quercus lobata low elevation stream sides shallow water table. Woodlands and Lower Field. Dry! Very tolerant of seasonal Blue Foothills bordering hot interior valleys; Dominant tree in the Oak Woodlands drought and hot winds; go DD Q. douglasii soils usually poorly developed. south and east of Gilman Hall. dormant in very hot, dry years. Upland slopes, exposed ridges, open Relatively moist areas, riparian Mixed in with blue and coast live oak Oregon Q. garryana valley bottoms; wide soil range from zones, less drought-tolerant than D in the Oak woodlands, and on the rocky to heavy clay. blue oaks. Loop Trail. In drier habitats than tree oaks; Scrub Chaparral; ranging from coastal bluffs to Very common on Chaparral and Rim tolerate poor water holding E Q. berberidifolia foothill ridges; rocky, poor soils. Trails. capacity of chaparral soils. In drier habitats than tree oaks; Leather Chaparral; most common in soils derived Very common on Chaparral and Rim tolerate poor water holding E Quercus durata from serpentine rock. Trails, especially near Cougar Pond. capacity of chaparral soils Common among boulders & rubble of mountain canyons with little soil Tolerate extreme summer Upper part of Canyon Trail, above Canyon Q. chrysolepis development; foothills, mountain drought and year-round nutrient E Creek Access 4. Some on the Rim canyons, upland slopes and exposed shortages. Trail. ridges. Uncommon in serpentine. Mostly in mountainous areas away from Scattered throughout moister areas of Relatively moist, riparian zones, Black the coast; usually on coarse well-drained the Preserve. Some near base of places where long-term drought D Quercus kelloggii soils of slopes and ridges; also valleys of Woodland Trail, near the Redwood less common. the North Coast Range. Circle, and along the Creek. Well drained soils of coastal plains and Mixed in with blue oaks in Oak Coast live Tolerant of salt spray, found bluffs, also inland valleys, steep hillsides, E Woodland, and a major component of Q. agrifolia closer to coast than most oaks. rocky canyons and creeks. the Mixed Evergreen Forest. Upland slopes, low foothills, floodplains, Interior live Historically associated with Uncommon at Bouverie. Some on valley bottoms away from coast; no soil E Q. wislizenii inland riparian zones. Gilman’s Knoll Trail. preference, but rarely in serpentine. *D=Deciduous E = Evergreen DD = Drought Deciduous

Three Sub-Genera of Oaks (Genus Quercus)

Lineage White Oaks Intermediate oaks Red / Black Oaks Subgenus Lepidobalanus (scale acorn) Protobalanus (first acorn) Erythrobalanus (red acorn) Species at Bouverie Valley, Blue, Oregon, Scrub, Leather Canyon Live Black, Coast Live, Interior Live Bark Light grey or brown; scaly or Dark grey, blackish or brown; Light grey-brown; scaly or rough -mature trees rough smooth Wood Yellowish or light brown Light brown Reddish-brown Leaves -lobes Round lobes or unlobed Unlobed (but toothed) Pointed lobes or unlobed Leaves Smooth or blunt green teeth or spines Smooth with green teeth or spines Tawny bristles and spines -margins Acorns or -inner shell Smooth Smooth hairy Densely hairy Acorns often -cup scales Thick and knobby Thick, knobby Thin and flat Acorns 1 year 2 years 2 years -maturity (except Coast Live Oak in 1 year) Much hybridization with other white Hybrids not fertile; Oracle oak Hybridization oaks; especially among blue and Much hybridization an example on Rim Trail (black Oregon oaks. Offspring fertile. and coast live oak hybrid)

Valley oak Blue oak Oregon oak Scrub oak Canyon live Black oak Coast live Interior oak live oak 90 CALIFORNIA'S CHANQING LANDSCAPES

Sideby Sidewith (f een from the air or from the ground, the texture of the landscapeof the Woodland: r*)Califomia foothills is varied. Each tum seemsto bring something different: Chaparraland Fire first woodland comes into view, then the next hillside is covered with dense shrubs; cresting a hill we are in open savanna and grassland,then we plunge down into a densely wooded canyon. And then the sequenceof sceneryrepeats all over again. Each piece of the mosaic has its own color and texture: woodland is irregularly bumpy, dotted with gray-green foothill pine and blue'green oak; grasslandis open and golden-brown; shrubland is uniformly muddy green, the vegetation so tightly intertwined and closely fitted to the topography that it is difficult to distinguish individual plants from a distance. Spanish explorers adopted the word chapanal from the Spanish chapano, a low growing type of vegetation. Chapanal covers about ten million acres of Califomia. Many important r.vatershedswhich collect water for agricultural and urban needsare vegetatedby

Successioninburned chcp ar r al. Immedi at ely after the fire (top), only skeletonized shrub canopies and ash remain abwe-ground. With the otuet of winter rcins, shrubs stump-sprout, shrub see& genninate, and fir e -f ollouting annual herbs genninate (next cro.ss-section ). OcJer seueralyears, shrub canopies grcnularger and the herb layer becunes dmninated by grcrsses. Finally (bottrmt), after about sixyears, shrub canopies haue regruun to their pre-fire steture and the herbs hsue disaPPeared,. VALLEY HEAT 9l chaparral. Chapanal occupies the same 300 to 3,000 foot elevation belt as grassland,savanna, and woodland. In terms of annual rainfall and the progresslon of seasonaltemperatures, there is no difference between a chaparral site and an oak woodland or grassland;the macroenvironment or regional climate is the same.These communities coil about and mix with each other in intricate pattems becauseof local diffcrencesin soildepth and chemistry, frequencyof fire, and slope steepnessand aspect. Typically, chapanal vegetation is a single layer of impenetrable shrubsfour to eight feet tal1,with evergreen,sclerophyllous leaves and rigid, intricately branched, interlacing canopies.The ground is bare of plants, stony, and covered with dry litter. An occasional Califomia bay tree (tJmbellukvia califomica),clump of cypress,or foothill pine overtopsthe shrub layer,and only a few perennial herbs- such as soap plant (Chlorogalum pomeidianum), melic grass, and globe lily (Calochortusalbus)-fleck the ground, but most of the biomassis in a single shrub layer.Chapanal shrubsare twiggy, rather than leafit.The leaveswhich arepresent are small and verticaily oriented, so the shrubscast mcager shade and lose little water. Chaparral is a drought-tolerant landscapecovcr. The most common shrubsin Central Valley chaparral are chamise (Adenostoma fasciuiatum),scruboak(Queraudumc.,sa),Christmasberry,Californiacoffeeberry, and more than twenty specieseach of manzanita and ceanothus. Several other shrubsare common in southem Califomia chaparral: yucca (Yucca whippler),red shanks (Adenostoma sporsifolitm), laurel sumac (Rhus lauruw syn. Malosma Isunnn), and lemonadeberry (Rhus integnf olia). Chapanal occurs in tr fire-prone region of Califomia. Fires are hot, all- consuming crown fires becausethere may be fifty tons of dry shrubsper acre, and the shrubsaccumulate flammable oils. The intensity of fire is expressedas BTUs releasedpe r secondper fcrotof fire front. While grasslandfires are relatively cool, releasing 150 BTUs per second per foot of fire front, and produce soil surface tcmperaturesof 300'F, chaparral fires release12,000 BTUs per secondper foot in winds of only six miles per hour (much more in higher winds), and producesoil surfacetemperatures of 1,000'F-hot enough to melt aluminum. Chapanal fires are so intense that they create local wind stormssuch asoccurred in the Oakland hllls fire of October 1991 . (lt is thought that the intensity of this devastatingfire was augmented by heat frorn buming homes and eucalyptustrees. ) Fire bombs of hot air and buming wood can be hurled tens of yards in front of the fire, easily crossing fire breaks. Chapanal fires are hard to control bccause of these high temperatures,the leaping fire front, and the rugged terrain on which chapanal typically grows. Suburban growth in Califomia has expanded into chaparral, exposinghomeowners to potential catastrophc.Since fire is an integral part of this landscape,development of chaparral is economicallv unwise. After fire, chaparral architecture changes in predictablc ways. Above the groun.1,fires leave skeletonsof shrubsand treesand a thick layer of trsh.The area 92 CALIFORNIA'S CHANqING LANDSCAPES

kroks devastated,but the promise of revegetation already lies in the soil. Seedsancl roots deeperthan a few inchesbelow the surfaceremarin alive becausethe insulating quality of the earth keepsthem safefrom the intenseheat. Althor-rgl-rtemperatures high enough to melt ahlminum persist f..'r as lt-ng as twcnty minutes on any surftrcesquare fcrot of grouncl cluring the fire, temperatllresthree inches below the surt:rcc reach only 150' for half that time. Roots and seecis deeperthan three inches and animals in burro'uvsare merely warmed for a few minutes. Since rnanl chrrp- anal shrub specieshave enlargedroot crr)wnscovered with dormant bucls,and generallythese are deep enor.rghin the soil to surr,'ive,the shrr-rbshave an excellent chance of sur','iving thc fire by crown-sproutine. With the onset of winter rains, seedsgenninate, buds sprout, and roots resumegrowth. A carpet of herbs,shrub scccllings,ancl shruh suckcr shootscovcrs much of the ground by the following spring. Most of the herbs which grou' and flower this first yeirr irre not seenagain until the next fire. Thcy cither have seed coats which do not permit germination unlesscracked by high temperatures, VALLEY HEAT 93

or they have embryos which require some chemical released from burned chaparral wood. Until these conditions are met, seeds lie dormant in the soil, Stump-sprouting in chamise chaparral a few sometimes for decades. months after thefire and For several years after the fire the shrub suckers and seedlings grow larger while rain. The wavy-leaved the mix of herb species shifts in composition. Annual grasses become more herb is soap plant, a numerous, while fire-following forbs eventually decline to a dormant seed pool. perennial whose bulb is Within six years of the fire the shrub canopy has closed and almost all herbs have protected from fire by a A disappeared. Changes in soil chemistry and the numbers of small mammals cause couple of inches of soil. the disappearance of herbs, not shade cast by growing shrubs. When leaves of close-up (below) of chamise ( and perhaps other shrubs) drop and decay, they release chemicals which manzanita sprouting from a large rootcrown or burl. inhibit the germination and root growth of most herbs, and of shrub seedlings as well. Fire removes living leaves and consumes leaf litter on the ground, eliminat­ ing the source of inhibition. The inhibitor effect does not returnuntil the canopy closes over once again. Changes also are created by small rodents which nest beneath shrub cover. They forage for grains and young shoots most intensively near their nest sites. When chaparral hums the cover is lost and these animals move or die, releasing the site to herb growth. As the canopy closes back, animals re-enter the site and chew hack the herb cover to its previous low level. For the next thirty to forty years shrub growth continues, hut at a slower pace. Woody plants which have short life spans die during this period. These short-lived shrubs are species which re-invade a burnedsite by seed only because they lack the capacity to stump sprout. Over time the community becomes simpler, and gradually comes to include only shrubs which sprout following fire. The dormant seeds of missing shrubs and herbs are in the soil, and will be triggered into germinating by the next fire and following winter rains. In many places chaparral fires follow each other on a twenty to twenty-five year cycle, and it is rare to find an unburnedchaparral stand older than fifty years. When such old stands do bum, as they did on Mt. Diab lo ( Contra Costa County) in the 1970s, the firestorm is especially intense because of the high biomass of accumulated living fuel. Bouverie Preserve �haparral Talk Greg de Nevers

1. The Dwarf Forest, the Elfin Forest, the Fire Forest

A Chaparral is a Spanish word, derived from the Spanish "chaparro". Chaparro refers to a thicket of evergreen oaks, which occurs in the "maquis" (= chaparral) of the MediterraneanRegion. Med. Climate in 5 areas, 30 degreesN & S of equator, on westernedge of continents. Santa Ana winds(= foen winds). Chaparralis the most extensive vegetation type in CA, covers 3.5.million hectares, or I/20th of the state. Baja CA to S. OR, 300 to 3,000 ft.

B. Environmental constraints -Regional climate(macroenvironment) same in chaparral and woodlands; slope; aspect(north vs.�south); soil usually well, · drained; rainfall seasonal, drought annual.

C. Plant Adaptations -Leaves reduce water loss by befog small, evergreen,thick, hard, stiff, with a waxy coating; leaves often positioned vertically. Bare soil beneath chaparral. Why? I. Allelopathy: chamise leaves contain root inhibiting chemicals, upon decomposition of leaves chemicals released to soil;fire destroys these chemicals, allows germination; chemicals short lived, cut chamise shrub, seeds germinate; manzanita similar, but chemicals long lived, cut shrub,no germination response. 2. Shading. 3. Small mammal grazing.

D. Typical Shrub Species. Chamise: the most abundant shrubin CA; the 2nd most importantfood for deer ( after acorns); new leaves on burl sprouts look very differentfrom adult leaves. Manzanita: "little apple", tarttasting fruits,good juice; bloom early (Dec.-Jan.);bark wine red (vs. madrone more orange-brown), peels offannually, shedding lichens. Wild lilac: nitrogen fixer,flowers good for soap. Scrub oak and leather oak: important animal food. Toyon: red berries feedwinter resident birds, abundant nectar. Stickymonkey flower: yellow­ orange, tubular, horizontal flowers with mobile, white stigma. Chaparral pea: a spiny nitrogen fixer. Knobcone pines: grayish pine trees with 3 needles, and cones closely adhering to the trunk; seeds are released only after fireor branch death.

E. Chaparral Animals

Numerous rodents(mice and wood rats); rodent numbers are reduced or eliminated by fire. Wren titis "the voice of the chaparral;"year round resident, females& males both sing year round to defend territories. Brown towhee and scrubjay are year round residents. Jackrabbits use chaparralfor cover. 2. Fire, and Chaparralresponses to fire.

.d Shrubsintricately branched; accumulate flammable oils (chamise,toyon, wild lilac).

B. Nutrient Cycling - Nutrientsstored in planttissue, released by fire. Ceanothusis a nitrogenfixer (via fungalsymbiosis).

C. Seedresponses: chaparral shrubs produce seeds at anearly age; seeds are long lived, canlay dormant; seedbanks; on treeseed storage (closed cone pines, fire pines). Postfire flora includesephemerals seen only afterfire (or landslide), manyof theseCA endemics.Some plants produce two t)?es of seed,one that germinatesimmediately, another that lies dormant(chamise, clover, wooly sunflower,deer.weed)

D. Adult Responses- crownsprouting, lignotubers 250+ years old. Epicormic shoots(sprouts on the branches).Flowering (bear grass; bracken fern).

E. SuccessionFire cycle z}-3}years; first threeyers after fire = forbesand resprouts;years 4rS = grassesand resprouts;years 7-9 shrubcanopy reestablishesitself, herbsdisappear. Many short-livedshrubs in young(5-15 yr old) chaparral,these die out as standages; short lived shrubsinclude sticky monkeyfloweE bush poppy, deerweed, bush lupine, Pentstemoq golden fleece. Chapanalsuccession is oddin that the clima:rspecies are present immediately afterdisturbance, no relaysuccession.

VOCABULARY

Allelopatlry= Chemicalwarfare between plants. Oneplant produces chemicals that make it difficult or impossiblefor anotherplant to germinateor grow.

Anmral= a plantthat completesits life cyclein onegrowing season (six to eightmonths). In CA annualsgerminate in November-December.In easternnorth America annuals sproutin April-May. Examplesinclude conr" wild oatsand Sonoma sunshine.

Aspect= the directiona hill faces(nort[ south,east or west).

Burl = lignotuber= Thefire-resistant, woody baseof manychaparral shrubs, which may be superficialor subterranean.This is the organthat resproutsafter fire.

Crown sprout= the new shootsput out by manyshrubs when their existing stemsare killed (typicallyby fire).

Endemic= saidof an organismknown from only onearea. A plantor animalcan be endemicto the solarsysterq the earth,North Americ4 the CaliforniaFloristic Province, California,Sonoma County, or two smallmarshes in SonomaCounty. Epicormic= uponthe branches(literally upon the stump,or log). Saidof sprouts(new shoots,branches) that arisefrom existingbranches or tnrnlcs.Redwoods, oaks and bays exhibit epicormicsprouting (= epicormicgrowth) after fire.

Fire anmtal= ephemeral= a plantwhose seeds lay dormantin the soil until awakenedby fire.

Fire pine = closedcone pine =a series.ofclosely related species of treesin the genera Pirus andCupresxrs characterized by on-treeseed storage, with releasefollowing tree death.Examples include knobcone ping bishopPing Montereypine, Monterey cypress Sargentcypress. This is a specialtyof the CaliforniaFloristic Province.

Forb = a dicot herb. Not a grass. Generallynon-woody annual or perennialplants with " more-or-lessshowy flowers.

Germinate= to sprout(said of a seed).When the seedcoat is brokenthe seedimbibes water, which causesthe embryoto initiate growth. Resistantseed coats inhibit water penetratiorl thus enforcedormancy.

Grass= a memberofthe grassfamily, Poaceae. Narrow-leavedherbs with non-showy flowers.

Herb= a non-woodyplant. Saidof grassesand/orbs.

Perennial= a non-woodyplant that lives for morethan one year (typically five to 20). Examplesare soap root, hound'stongue and coast sanicle.

Seedbank = saidcollectively of all the seedsstored in the soil. Seedsof somespecies canlay dormantin soil for 100years or more.

Stope= the angleof a hill; its steepness.

Stigma= the receptive(female) part of the flower; the placethe pollen lands and initiates growth. ACR Fire Ecology Program Restoring Ecosystem Health and Improving Wild re Safety

A renewed approach to fire that can improve human safety, wildlife habitat, vegetative health and balance, and overall ecosystem services.

Audubon Canyon Ranch, through its new Fire Ecology Program, is taking a leadership role in the North Bay to restore ecosystem health and improve wildfire safety. Working with various agencies and land managers, ACR's new program, led by ACR’s Fire Ecologist The ACR Fire Ecology Program will: Dr. Sasha Berleman, will address hazardous fuel loads and declining ■ ecosystem health through the coordination of cooperative, develop a prescribed fire and fuels treatment program for ACR’s preserves with a prioritized schedule and ecologically planned, scientifically monitored, and safely implemented long-term plan for bringing fire back into its controlled burns. preserves as a natural ecosystem process and For the first time in the Bay Area, ACR will develop and host a management tool; Prescribed Fire Training Exchange (TREX) for diverse regional ■ lead collaboration with private and public agencies agencies and land managers. TREX is a nationwide, interagency, and land managers across the North Bay to bring cooperative prescribed fire training and implementation program low-intensity, safe, controlled fire back into landscapes created in 2008 by the Fire Learning Network. throughout our region and across our borders;

ACR’s proactive role to restore North Bay landscapes ■ develop and host a North Bay Prescribed Fire Training Audubon Canyon Ranch protects over 5,000 acres in Marin, Exchange (TREX) module with the collaboration of Sonoma and Lake Counties. Our core nature preserves exist in a the Northern California Prescribed Fire Council – the TREX program will be a biannual one-week event matrix of urban, rural and open space areas. It is more important bringing together diverse agencies and land managers than ever that we take a proactive role in our relationship with fire to conduct controlled burns throughout the region with in these landscapes to restore ecosystem health and to improve all participants offering some form of training to others, wildfire safety for our own properties and those of our neighbors. all participants receiving training and controlled burn Roughly 95 percent of ACR’s Modini Ecological Preserve, for experience, and leading community outreach and media example, burned in the 2004 Geysers wildfire. High fuel loads in communications strengthening community cohesiveness, the lower Mayacamas range have built up since the last major support and education around regional fire issues; fire in 1964. In addition, we’ve documented reductions in native plant diversity and oak tree recruitment in our grasslands and ■ design and implement a scientific research and . oak woodlands due to the build up of thatch and increased presence monitoring program for fire effects with methods of fire-intolerant pests (such as oak acorn weevils and sudden oak being tailored to site specific needs, and publish death). With proper timing and preparation, these landscapes can results in peer-reviewed journals, ACR newsletters, be safely burned at low-intensity to remove excess fuel and and general conferences; return natural processes to the land. This reduces the potential for ■ lead interagency meetings, host community meetings catastrophic wildfires while also promoting native species such and give general presentations to engage and educate as a diverse array of wildflowers, many of which are fire dependent, the public, facilitate conversation, and garner support improving oak recruitment, reducing thatch and invasive species, for safe and ecologically valuable use of controlled slowing spread of sudden oak death, and improving habitat for wildlife. burning.

bouverie preserve 13935 Sonoma Highway 12, Glen Ellen CA 95442 707.938.4554 egret.org [email protected] Martin Griffin Preserve Bouverie Preserve Cypress Grove Research Center Modini Mayacamas Preserves AUDUBON CANYON RANCH – FIRE ECOLOGY PROGRAM Frequently Asked Questions The Role of Fire in the Ecosystem

Why is fire important to the ecosystem? What about the smoke? Fire is a core ecological process in most California Controlled burns are managed to minimize smoke ecosystems. For thousands of years, Native Ameri- impacts. Smoke and emissions from controlled burns cans utilized fire in California as a tool to manage are significantly less negatively impactful than those landscapes for food, textile production, and improved from wildfires. The Bay Area Air Quality Management wildlife habitat. In the North Bay specifically, nearly all District has strict controls on when prescribed burns of our terrestrial ecosystems depend on site-specific may occur in order to ensure that weather conditions fire regimes. Here, plant species are nearly all adapted are appropriate to dissipate the smoke. We will not to specific fire types and animal species depend on be able to proceed with the burn until we get a green eects of fire to thrive and coexist in balance. The light from the Air District the morning of the burn. healthy function of our ecosystems cannot be untied Additionally, if smoke somehow unexpectedly from this core ecosystem process. After over a becomes a public health problem, contingency century of fire suppression, however, California response plans are in place to reduce smoke prob- landscapes are in a dire fire deficit. Where fire has lems, which include extinguishing the fire if necessary. been long suppressed, we struggle with threatened human safety as tremendous wildfires become What about animals living in the burn zone? imminent in the face of accumulating fuel loads and Animals that live in California’s landscapes coevolved lengthened fire seasons. Fire agencies, land managers with regular fires in their native habitat. Many of these and researchers have learned over recent decades animals even depend on fire to maintain their habitat. that fire cannot be prevented, only postponed, often During a burn, research has shown that ground with drastic consequences. burrowing animals typically survive fires by staying in their burrows until the fire has passed. Additionally, How safe are controlled burns? controlled burns are specifically timed to avoid No fire is completely safe. However, because they are nesting bird season, in order to ensure no negative carefully monitored and managed, controlled burns eect. Additionally, in the year following a controlled rarely create unintended consequences. In 2012, for burn in grassland or oak savannah, an increase in the example, the National Interagency Fire Center reported presence of deer is commonly noted due to improved that 16,626 controlled burns treated 1,971,834 acres. forage quality. Of those 16,626 fires, only 14 exceeded the defined perimeter (0.08%). ACR, in collaboration with CalFire and local fire departments, will have adequate resources on site to quickly control any unexpected condition.

LEADING OUR PROGRAM:

Sasha Berleman, PhD, ACR Fire Ecologist ACR’s Dr. Sasha Berleman recently completed a PhD in Scott Stephens’ wildland fire science research lab at UC Berkeley. She conducted her PhD research on prescribed fire use in California landscapes for restoration of ecosystem health. She has been an active participant in Prescribed Fire Training Exchanges (TREX) since 2010, with most being located in Northern California (Mt. Shasta and Klamath regions). She is a qualified firefighter with “Fire Effects Monitoring” and “Squad Boss” taskbooks and approximately 600 hours of hands-on prescribed fire experience. In addition to her PhD work, she has been actively involved in fire ecology and fire-use in the North Bay region since 2011, planning prescribed fire and monitoring projects with managers. at Mitsui Ranch of Sonoma Mountain Ranch Preservation Foundation and at Sasha Berleman, PhD Pepperwood Preserve. Sasha is a board member of the Central Coast Prescribed Fire Council. ACR Fire Ecologist

[email protected]

58 CALIFORNIA'S CHANGING LANDSCAPES

Mixed Evergreen he mixed evergreen forest is a sandwich layer between slices of low and Forest T high elevation forests. It grows on steeper, warmer, and higher slopes, ascends the west flank of the Coast Ranges, spills over 5,000-foot elevation ridges, and runs down interior-facing slopes eastward to the edges of foothill oak woodland and chaparral. Less majestic than redwood forest, but twice as extensive in acreage, this mixed evergreen forest covers five percent of California's area. In the wettest part of California-the Klamath Mountains of the north­ west-mixed evergreen forest occurs between 1,000 and 4,000 feet elevation. Above 4,000 feet montane conifer forest replaces mixed evergreen forest. The evergreen forest is intolerant of serpentine soil, so serpentine slopes within that elevation belt are dominated by brush fields with scattered conifers. South of Monterey County the coastal strip docs not contain redwoods. Here mixed evergreen forest lies just above coast oak woodland and chaparral at elevations between 2,000 and 5,000 feet. In the Transverse and Peninsular ranges of southern California, mixed evergreen forest lies between 3,500 and 5,700 feet elevation. The mild climate of this mid-elevation zone in California is character­ ized by less annual rainfall than the redwood forest, and a greater range of daily and seasonal temperatures. Like any sandwich, the mixed evergreen forest contains flavors of the slices above and below it. It contains plants found at low and high elevations in addition to species unique to its own zone. Dominant trees include needle-leaf evergreens (conifers) and broadleaved evergreens. Needle-leaf tree species change with latitude. Typically they are Douglas-fir in the North Coast Range and Coulter pine (Pinus coulteri)from Monterey south. Broadleaved trees usually include coast live oak (Quercus agrifolia) or canyon oak (Q. chrysolepis), accompanied by other species with narrower ranges.

Northern Mixed Douglas-fir dominates the lower montane zone of California's North Coast Evergreen Forest: ranges. Along with redwood, it belongs to the Pacific Northwest biotic province, Douglas-Fir but its range is more extensive than the redwood, spilling east into the Cascade Hardwoods Range and the Rocky Mountains. Its best growth occurs near the coast, large individuals there reaching over fourteen feet in trunk diameter, over 250 feet in height, and more than 1,000 years in age. Typical mature trees are five to seven feet in diameter, 200 feet tall, and 600 years old. COASTAL FORESTS 59

In the cool and wet PacificNorthwest, Cascades, and Rockies,Douglas-fir fcrrmsa closedoverstory. In drier and warmerCalifomia, however,it formsa ragged,patchy, incomplete canopy that allowsfull sunto reachdown between the trees.Sunlight is intercepted by a continuouscover of broadleavedtrees, far below the conifer tops, standingonly forty to sixty feet tall: tanbark oak, madrone

;""i's:'l" . ---j ;:, ..:, .i,tr,)-*"9

(Arbutusmenzresii),bigleaf maple (Acermacrophyllum),Califomiabay (Umbelluktria colifomica),Califomia black oak (Quercrtskel\ogpi), coast live oak, interior live Arooy frr*, the wet coastal mountains, mixed oak (Quercusplsllzenli var. trrlslitenli),canyon oak (Quercuschrlsolzpis), hazelnut euergreenforest is a Luu, (Corylus cornLLt{tvar.californica), and mounrain dogwoo,,1(Cornus nuallii). dense assemblcgeof oaks, The richness of this vegetation type is mostly in its trees, becauseshmbs, madrone, andbay that mosses,and perennial herbs arerelatively few. A thick bed of slowly dccomptrsing oftenborders on oak leaf litter comprletelycovers the ground. Most of the tree cover is evergreen,but w oodland and gr as sland. maple, black oak, hazelnr-rt,and dogwood are winter-deciduc-rusand their leaves contrihr-rtegolden, yellorv, irnd purple hues to the fall landscape.Proximity to thc ocean and moderate elcvations confer gentle wintertime conditions favorable tcr evergreens.Evergreens are irble to grow actively twelve months of the y.,rr. L)eciduoustrecs are dorrnant firr several months, so they art: at a competitivr disadvantage.Leaflessness in winter r,vouldbe an advantage only in the face of COASTAL FORESTS 61 hard frost or heavy snow. Snowfalls do occasionally occur, and they damage the broad-leaved evergreens, whose leafylimbs intercept too much snow and break off under the weight. Douglas fir is the most commonly cut timber tree in North America. It once was a major element in the mixed evergreen forest of northernCalifornia. Because of logging, old growth Douglas fir forests are now rare. The Nature Conservancy's 5,000 acre North Coast Preserve in Mendocino County is the largest single old­ growth tract left in the state-probably containing half of the entire state's old­ growth acreage. Timber harvesting in mixed evergreen forest is currently both an economic and an ecological disaster, because it can't be accomplished on a sustained, repeatable cycle. Understory hardwoods-especially tanbark oak and madrone-are capable of stump sprouting following disturbance. They regenerate enthusiastically after logging. Many stems arise close together and competition among them results in a "dog hair" stand composed of as many as 1,000 spindly trees per acre. Douglas fir cannot stump sprout and must come back from logging by seed. Young seedlings and saplings are close enough to the ground to be grazed by animals. Since deer and domestic livestock prefer Douglas fir to hardwood foliage, grazing intensity can be so high that conifer seedlings will not survive unless protected by wire fencing. Fencing is an unrealistic expense to adopt on the large scale of a commercial logging operation. The thousand stems of hardwood stump sprouts per acre put a severe competitive stress on Douglas fir saplings. Tanbark oak and madrone are nearly worthless as timber species in today's market. Often, herbicides are applied to kill hardwood species, releasing Douglas fir from competition. They are killed by injecting herbicide into their trunks. Small scale tests have shown that the growth of Douglas fir stems triples if the hardwood density can be reduced by eighty percent . This procedure, however, is too expensive to be employed on a large scale. Old-growth forests are not ecologically the same as young second growth forests, even if they share all the same species. The architecture of the young forest is different from mature forest. The density of each canopy layer, the size of emergent trees, and the pattern of tree distribution are not what they were a century ago, and these differences are important to animals. Old-growth Douglas Northern mixed evergreen fir forests are the only habitat of some rare animals, such as spotted owls, marbled forest along the south fork murelets, and red tree voles, which nest in or on large Douglas firs or dead snags. of the Eel River Old-growth forests also contain large amounts of standing or fallendead wood that (Mendocino Co.), provides habitat for a diversity of insects and fungi. Certain species of salamanders dominated by Douglas fir and broadleaf evergreen l l are a so found only on the wet floorof old-growth Douglas fir forests. The juveni e trees. A few redwood trees forest that follows logging or fire does not contain these organisms. are also present in this wet Some foresters disparagingly call old-growth forests "over-mature." The portion of the North Coast implication is that they are senescent, slow-growing shadows of their once grand Range. 62 CALIFORNIA'S CHANGING LANDSCAPES selves. It is true that old growth trees grow slower than young trees, but the species richness and complexity of old growth forests are immeasurably greater. Old­ growth forests are banks of genetic resources, resources not found in second.­ growth, younger forests.

Ecological Tolerances of Riparian Plants

From River Partners (a riparian restoration organization) http://www.riverpartners.org/resources/riparian- ecology/veg-wildlife-habitat/ecological-tolerances/index.html

The location of riparian plants on the floodplain depends largely on individual plant adaptations to variations in depth to the water table and soil texture. Many of the plants’ ecological tolerances can be explained by examining their location on the floodplain relative to the river channel.

Close to the river channel, plant roots have easier access to water, but the plants have to contend with increased flooding and physical battering from hydraulic forces during high flows. The root systems of plants that are frequently flooded are adapted to survive the low oxygen conditions created when roots are completely saturated. Typically, low floodplain species have flexible stems that can withstand the physical stress, and when branches do break off they can sprout into new trees if they become lodged into the river bank.

White alder Valley oak

Soil particle sizes tend to be larger closer to the channel as well, because as the floods distribute sediments, larger particles (sand) fall out of suspension earlier, while finer sediments (silt) get carried farther out on the floodplain. This means that while plants closer to the channel may get flooded more often, the large soil particles allow water to drain through the soils quickly. Therefore, the plants in well drained soils must be able to either tolerate long periods of drought during dry seasons, or send their roots into the water table.

Farther away and higher than the main channel, there are many layers of soils that the river has deposited over time. These are fine textured, nutrient rich sediments that allow productive riparian forests to develop. The fine sediments can hold moisture longer, enabling many upper floodplain species to endure droughts. These fine soils on the upper floodplains are generally higher in organic matter and nutrient content, however they compact more easily, which causes them to be less aerated, and have lower amounts of oxygen. Plants located on the higher floodplains are typically not tolerant of long duration flood events. Due to the stratification of the many layers of sediment deposited over time, there may also be thin lenses of gravel, sand, silt or clay, and each of these can affect plant growth. These lenses in many cases explain why plants that should grow well based on the soil type at the surface are stunted or unhealthy. Plants at higher elevations to the water table must reach farther to access ground water or be able to tolerate drought.

White alder (Alnus Rhombifolia)

White alder roots must have close access to the water table; roots must be within 1m reach of water. They are not drought tolerant. Though they must have access to permanent water, they are not able to tolerate long floods. White alder requires sufficiently aerated roots and standing water cannot provide enough oxygen. Often, white alder is found growing in boulders and large grained sediments, possibly because this substrate keeps roots well aerated. White alder seeds can establish quickly on freshly deposited point bars if they are adequately moist.

White Alder grows into moderate to large trees, 9-30m tall and 28 cm in diameter. Typically they grow with a single trunk, but they can develop multiple trunks that arise from one clump. White alder commonly provides shaded riverine aquatic habitat because the trees typically grow along river banks. Insects drop from white alder into the river, along with leaves and twigs that support aquatic insects. White alder is therefore an important source of nutrients to aquatic systems. The smooth bark is frequently eaten by beavers. Alder seeds are eaten by birds and mammals, and mammals will eat the twigs and leaves.

White alder in wintertime

Oak Galls of the Bouverie Preserve of Audubon Canyon Ranch

Pumpkin galls on the tops of Red c one gall on both sides of blue, coast live oak leaves. Look Two-horned gall on the veins of Oregon, and valley oak leaves. Look near Observation Trail. coast live oak leaves. Look on tree at on valley oak on Yellow Brick Road intersection of Loop and YBR Trails. Trail.

Crystalline galls on underside of blue, Oregon, leather, and scrub Clustered gall on the underside of Disk gall on underside of blue, oaks. Look along the Rocky blue, Oregon, and valley oak leaves. Oregon, and valley oak leaves. Road Trail and on the YBR Look along the Rocky Road Trail. Look along the Rocky Road Trail. trail.

Striped volcano gall on underside Saucer galls on upper surface of blue, Oregon, and valley oak Spiny turban gall on the underside of blue oak and scrub oak. leaves. of blue, Oregon, and valley oak Look along the Rocky Road leaves . Yellow Brick Rd. Trail.

California oak gall (“oak apples”) Beaked twig gall on the stems of Clasping twig galls on leather and found on stems of blue, valley, and blue, leather, and scrub oaks. scrub oak. Look near Cougar Pond. Oregon oak. Throughout Preserve. Look near Cougar Pond.

Prepared by Jeanne Wirka for ACR Education. September 2010.

Mistletoe: Magical, Mysterious, what is “bad.” and Misunderstood Jeanne Wirka The word “mistletoe” (from old German words meaning ‘dung’ and ‘twig’) refers the “Everybody knows a turkey and some mistle- fact that birds defecate the seeds of many mis- toe, help to make the season bright…” tletoes onto tree branches. The most familiar species of mistletoe in the temperate parts of Well, I don’t know about the turkeys, but mis- the world are the in the “Christmas Mistletoe” tletoe sure brightens the landscape here at family (Viscaceae), named for the sticky Bouverie this time of year! It is mistletoe’s viscin in their berries that allows seeds to stick habit of holding out while all else fades that to the stem of a host plant while germinating, has contributed to its aura of mystery. or to a bird’s feathers for dispersal. After the Throughout history, humans have attributed seed germinates, the radical grows through the magical and healing powers to this humble bark of the host tree and into the water- plant. Mistletoe was the "Golden Bough" that conducting tissues, where root-like structures led Virgil’s hero Aeneas through a gloomy develop. Species in the “leafy mistletoe” ge- forest on his visit to the netherworld. Mistle- nus Phoradendron (the kind we have at Bou- toe has been thought to protect houses from verie) then develop a branched, golden- passing demons and witchcraft, prevent fires, colored woody stem and green leathery induce ominous dreams, heal wounds, cure leaves. These species get carbon through pho- epilepsy, and even promote conception. It is tosynthesis, relying on their host plant only probably this connection with fertility that for water and minerals. The more damaging first gave rise to the custom of kissing under dwarf mistletoes, which infect primarily coni- the mistletoe. The role of mistletoe in modern fers, have small scale-like leaves that do not culture persists: a compound called provide enough carbon so the host tree is “recombinant mistletoe lectin (rML), for ex- tapped for carbohydrates as well as water and ample, is currently being used to treat ovarian mineral nutrients. cancer! Leafy and dwarf mistletoes also differ in how Yet mistletoe has its dark side as well. It is their seeds are dispersed. Phoradendrons pro- hemi-parasitic, meaning it gets some of its duce small white berries in early winter that nutrition and water from its host plant. Some are highly sought after by Western Bluebirds, types of mistletoe—especially the small Cedar Waxwings, and other birds. Dwarf “Dwarf” forms in the genus Arceuthobium are mistletoes, on the other hand, can forcibly responsible for large economic losses. Ac- eject their seeds up to 50 feet into the air at a cording to one source, 11.3 million cubic me- speed of 55 mph! ters of commercially important conifer trees are lost annually in North America alone due The two mistletoe species at Bouverie are to dwarf mistletoe infestation. Unfortunately, among the kinder, gentler ones. Oak Mistle- mistletoes in general suffer from this bad rap. toe (Phoradendron villosum), our most com- In fact, the damage that mistletoes inflict on mon species, grows only on oak trees. It can their respective host plants varies depending be found in the blue and valley oaks along the on the species of mistletoe, the health of the Yellow Brick Road. Big Leaf Mistletoe (P. host plant, the severity of infection, local site macrophyllum), infects only non-oak tree spe conditions, and even human perception of (cont’d p.4) 3 MISTLETOE (CONT’D) cies like alders, ash, cottonwoods, sycamores, and willows. At Bouverie, I have only seen it on a few alder trees on Stuart Creek. Both species have small leathery oval leaves, but the leaves of Oak Mistletoe tend to be slightly smaller, darker, and hairier.

So are Bouverie trees safe from the ravages of the more damaging mistletoes? Maybe. Maybe not. While 13 different species of dwarf mistletoes occur in Sonoma County, none have been found yet at Bouverie. A more likely threat comes from European Mis- Big Leaf Mistletoe (Phoradendron macrophyl- tletoe (Viscum album) a noxious weed lum) on an alder at Stuart Creek near Creek Ac- (originally introduced by Luther Burbank and cess #4. (Photo: Jeanne Wirka) still found in the US only in Sonoma County) that infects many non-oak and non-conifer trees. To be safe, please don’t bring outside sprigs of mistletoe to the Bouverie to cele- brate the holidays. We have plenty of our own thank you!

The noxious weed European Mistletoe (Viscum al- bum) found only in Sonoma County within a 71 km radius of Sebastapol. (Photo: Douglas Barbe)

This dwarf mistletoe (Arceuthobium douglasii) is Oak Mistletoe (Phoradendron villosum), found only found only on Douglas Fir. Severely infected trees on oak trees, is the most common species of mistletoe often have dead crowns or characteristic "witches at Bouverie Preserve (here on Valley Oak on the Yel- brooms," especially on lower branches. (Photo;Dave low Brick Road). (Photo: Jeanne Wirka) Powell) 4 Trail Technique for Oak Woodlands: How old is this Twig? This activity helps kids learn about how plants grow through their own observation and discovery. It works especially well on buckeye trees in the fall, but other deciduous trees work as well (e.g. black oak or valley oak). Twig anatomy vocabulary Bud – a little bump on a stem or twig where new growth happens. Buds can turn into new leaves, new stems, or even flowers. There are two kinds of buds on a twig Terminal bud - at the tip (only one per twig). Only one terminal bud is formed each year. Terminal buds result in new growth that makes a twig longer Lateral bud - on the sides (several to many per twig). Lateral buds allow side branches to form. Bud scales – small structures that protect unopened buds, especially over the winter.

What are all those bumps and scars?

Bud scar – small scar left on a twig after a bud

opens and scales fall off. When a lateral bud

opens, the bud scale scars are only on one side

of a twig.

Leaf scar – scar left when a leaf falls off.

Lenticels – are small openings in the bark that

allow gas exchange with the atmosphere (i.e.

they allow the tree to “breath.”). These are

not bud scale scars. Terminal bud scale scar - When a terminal bud opens, it leaves scars all around the twig like threads on a pipe.

How do I tell how old a twig is?

By counting the terminal bud scale scars! Since each twig makes only one terminal bud per year, the number of terminal bud scale scars indicates The fine print: Revised by how old it is. Look for the rings that go all the way Jeanne Wirka for ACR Education. July 2013 around the twig like pipe threads! How old is the Images used for educational twig on the right? (FIVE YEARS) non-commercial purposes as allowed by the Fair Use doctrine.