University of the Pacific Scholarly Commons
University of the Pacific Theses and Dissertations Graduate School
1964
Ecology of the Sclerophyllous plants of Mount Tamalpais
George Edwin Corson Jr. University of the Pacific
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Recommended Citation Corson, George Edwin Jr.. (1964). Ecology of the Sclerophyllous plants of Mount Tamalpais. University of the Pacific, Thesis. https://scholarlycommons.pacific.edu/uop_etds/1558
This Thesis is brought to you for free and open access by the Graduate School at Scholarly Commons. It has been accepted for inclusion in University of the Pacific Theses and Dissertations by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. ECOLOGY OF THE SCLEROP HYLLOUS PLANTS OF MO UNT TAMA LPAIS
A Thesis Pr esented to t he Faculty of the Department of Biological Sciences University of t he Pacific
In Partial Fulfillment of the Requirements for the Degr ee Master of Arts
by Ge orge Edwin Corson Jr. August 1964 This thesis, written and submitted by
is approved for recommendation to the
Graduate Council.
Department Chairman or Dean:
Thesis Committee:
_..:..d-=~~:....._-~_..:._ __~.c__-----' Chairman TABLE OF CONTENTS
PAGE I NTRODUCTION ...... 1 GEOLOGY • • • • • . • • • • • • • ...... 6 TOPOGRAPHY AND BOUNDARI ES . • • . • • . . . . . 8 CLI.lJIA TE • • • • • • • • • • • • . . . . . 9
HISTORY • . . • • • • • 0 ...... 0 • • 17 ECOLOGY . . . • • • ...... 22 Introduc·t ion ...... 22 Methods and Procedure • ...... 24
~e~uoi a semEervirens Association • • . • • • • • 30
Lithocar2u~-Umbe llulari ~-Arbutus Association • • 36
Litho c ~rp~s aspect • • • ...... 40
Pseudotsuga aspect . • • • • • • • 0 • • 0 • • • • 42
Umbellulari a ~ Association ...... 45 Chaparr a l Association • • . • • • • • • . . . 49 Arctosta2pylos gushingiana aspect • 51 Adenostoma fascicul¥tum aspect • • • • . • . 54 Castanopsis chrysophylla aspect . . • • • . . .. 57 Arctost aphyl os canescens aspect • . • • . • • • 59 Arctostaphylos montana aspect • • • . • • • • • 59 Cupressus sargcntii Association • • • • • • • • . • • 59 SUMMARY •...... 69 LITERATURE CITED ...... 71 LIST OF TABLES
'!'ABLE PAGE I. Precipitation: Honthly and Seasonal, Averages in Inches • • • . • • • • • • . . . . 10 :.II. Average Number of Days with 0.01 Inch or l•lore of Precipitation ...... 11 III. Greatest Precipit ation in T\tenty-four. Hm.,rs
on Mt. Tama1pai s - T"t'lenty-t\'ro Year Record • • 11 IV. Average 1-iaximum , Average Minimum, and Average Temperatures . • . • • • 12 v. Average Hourly \find Velocity (niles) on Mt. Tama1pais - Twenty-two Year Record • . . . 13 VI. Maximum Wind Velocity, Direction, and Date on Mt. Tamal pais - Twenty-two Year Record . . 13 VII. Frost Data: Aver age Dat es and Length of Season • • • • • • • • • • • • • • • • • • 14 VIII. Size Class Distribution of Tree Species and Number and Presence of Subordinate Species in Two Stands of Sequoi a Sempervirens Association ......
I X. ~~ocarEYJL-Umbel1ulari a-Arbutus Association • •
X. Coverage Data for the Lithocarpus-Umbe1lulari~- Arbutus Association; Lithocarpus Aspect . . . 41 v
TABLE PAGE XI. Size Class Distribution of Tree Species in Llthocarpus-Umbellularia-!!butus Association; Pseudotsuza Aspect • ...... 43 XII. Coverage Data for the Umbellularia
Cal i forni~ Association • • . . . ~ . . . 47 XIII. Coverage and Frequency Data for the Arctostaphylos Cushingiana Aspect of the
Chaparral Association • • • • * • • • 52
XI V. Cover~ge and Frequency Data for the Adenostoma Fasciculatum Aspect of the Chaparral Association • . • • . • . • . . . . 55
XV . Coverage Data for the ~~stanopsis Chrysophylla Aspect of the Chaparral
Association • • • • . . . • • ...... XVI. Coverage and Frequency Data f or the Arctostaphxlos Canescens Aspect of the Chaparral Association • ...... 60 XVII. Coverage and Frequency Data for t he
Ar cto stap~yl~ Montana Aspect of the
Chaparral Association • • • . • • . . . . 62 XVIII. Coverage and Frequency Data for the CuEressus Sargentii Association • • • • • • . 64 vi TABLE PAGE XI X. Distribution and Rol e of Tree Speci e s of the Tamal pais Study Ar ea . • • • • . . 66 XX . Distribution of Non-Arborescent Species . 67 LIST OF' FIGURES
FIGURE PAGE 1. Stand Representative of the Sequoia sempervirens Association • • • • • • • • • • • • 33 2. General Vie\'.r of Seguoia sempervirens Association in a Moist Ravine • • • . • • • • • • • • • • • 33
3. Re l ationship of lLeguoi~ Association to
a Water Source • • • • • • • • • • 0 • . . . . . 35 4. Stand Representative of the Lithocarpus-
Umbe llular~-Arbutus Association • • • . . . . . 39 5. Stand Representative of the Lithocarpus Aspect of the Lithocarpus-Umbellularia Arbutus As sociation • • • • • • • • • • . . . . 41 6. Stand Representative of Pseudotsuga Aspect of the Lithocarpus-Umbellularia-Arbutus Asso ciation • • • • • • • • • • • ...... 44 7. Stand Representative of Umbe llularia Association • • . • • • • • • • . . . .
8. ]~p~Jlylari ~ As sociation as it Ascends and Merges with the Chaparral ......
9. General View of the Arctosta~hylos cushin~iana Aspect of the Chaparral Association on the South Slope of Mt. Tamal pais ••••••• . . . 53 10. General Aspe c-t• of the Adenostorna Aspect of the Chaparral Association • • . • • • • • • • • 56 viii
FIGURE PAGE 11. Representative Stand of Arctostaphylos canescens Aspect of the Chaparral Association ...... 61 12. Representative Stand of 9upressus sargentii
Association • • • • • • • 0 • • • • • • • • • • 65 LIST OF PLATES
PLATE PAGE
l. 11ap Shol'ring Location of the Study Area • • • . . 3
2-6. Overlay 14ap of the Various Associations • • • • • 27 7. Map Sho\!nng Location of Sampl e Stands • • • • . . 29 ECOLOGY OF THE SCLEROPHYLLOUS PLANTS OF MT. TAMALPAIS
I NTRODUCTION
Mt. Tamal pais, 2571 feet in elevation, is found eighteen miles north of San Fr ancisco in southern Mari n County (see Pl ate 1) . My interest i n the mountain began during my childhood. Mt. Tamal pai s was chosen as the area for this ecological study because of my personal interest as well as my belief t hat this is an excell ent area which demonstrates a gr eat diversity of pl ant communities in a small area. Despite its close proximity t o a worl d por t and me tropolis , its slopes still displ ay a wildness and natural beauty that have been but little impaired. The flora of the mountain has remained relatively unaltered as compared with other areas of t he Bay Region and demonstrates ready accessi bility to detailed e cological study. The study began duri ng the spring of 1963 when plant specimens were first collected. Af t er a period of recon naissance and mapping of the vegetation, quantitative samples were taken in t he study area in hopes that relationship s could be established between pl ant communities and environmental f a ctors. 2
Pl at e 1 Map showing l ocation of the study area. 3
' MT. TAv:MALPA[£}
PACIFlC OCEAN
SAN
MT, TAMALPAIS STUDY AREA long 122 o 34 ' 30" lot. 3r 55' 71" 4 The veget ation of Mt. Tamal pai s presents probl ems that 't•rould require many years of serious study. This inves tigation endeavors to define the several plant associ ations, to relate t he associati ons t o t he environment, and to present some of the many probl ems that can be answered only by continued ecologi cal study. Past \'Tork i n the area has been mainl y of a t axonomic nature. Dr . Herbert L. Mason , Director of the University of Californi a Herbarium , has stated (personal communication), "I may say I do not know of any ecological studies that have been made on Mt. Truna l pai s. There certainl y are many prob lems t o t a ckle i n the area . " Botanists have collected on Mt . Tamal pais and in Marin County since 1800. The area supplied the early botanists of the Cal ifornia Academy of Sciences with a profitable field for exploration and collec tion. Some of t hese earl y workers were Albert Ke llogg, H. Behr , II . Bol ander , Katharine and T. S. Brandegee , Alice Eastwood , and E. L. Gr eene. In 1885, E. L. Greene became instructor of Botany at t he Universit y of Califor ni a where he imparted his interest in Marin flora t o V. K. Chessnut , E. Drew , c. A. Michener, F. T. Bioletti, and U. L. Jepson.
John Thomas Howe ll's book , r~ar i n Flora, has been an invaluabl e aid in this project . Hi s \·mrk on the mount ai n was largel y of a descriptive nature and no quantitative data have been published. He stated {personal communi cation), 5 " I don't knm.t of any ecological study on Mt. Tamalpais since I did my field \'fork for Marin Flora before December, 1949 . It is a marvelous field for study and I hope you have abundant success in your work." GEOLOGY
During the Jurassic and early Cretaceous periods the Coast Ranges of California wer e covered by a shallow sea. From 20 , 000 to 30,000 feet of l ate Jurassic sediments were depo sited i n the geosyncline wher e the present Coast Range was born. As the ar ea was upl ifted and then subsided several times throughout the Eocene, Pliocene, and Pleistocene, the sea invaded the low areas of the range and flooded the inland va lleys of Cal ifornia . There were regions, including Mt. Tamalpais, that r emained above the sea. The i nundated areas were covered by new deposits of sediment while the high regions remai ned untouched, other than for erosion , and ar e now found with the ol d Franciscan deposits of the Jurassic and early Cretaceous periods. These deposits are made up of har d gray sandstone, dark sha le, and serpentine, all of wh ich are pr esent on Mt . Tamal pais (Taliaferro, 1951). The Franciscan formation is widespread in the Coast Ranges but almost everywhere except Mt . Tamalpais it is found together with younger sedimentary rocks. Mt. Tamal pais and t he surrounding area, ther efore, has been above sea l eve l as long as any area in coastal California and much longer than most ar eas (Howell, 1949). The rugged country of Mt . Tamal pais i s especia lly rocky and on the steep slopes t he soil l ayer is extreme l y 7 thin or entirely l acking. Outcr·ops of serpentine, sandstone, or shale are quite frequent in t he area. Where soil is more prevalent , a clay or sandy loam cover is f ound, depending upon the underl ying rocks (Ho\'lell, 1949). Serpentine out crops are common from Bootjack Camp extending north over Tamalpais Ridge folloNing the \'restern boundary of the study area. TOPOGRAPHY AND BOUNDARIES
The study area has the foll owing boundary: It begins at the l.fountain Home Inn (el evation 925 feet) and follo\rlS the Panoramic Hi ghway to Bootjack Camp (el evation 1500 feet ) and then a l ong Bootj a ck Trail to Ridgecrest Boul evard (el eva tion 2000 feet) and north on the Ro ck Spring-Lagunitas Road. This road borders the western side of the study area and descends in el evation from 2000 feet to 1300 feet . At the junction of Lagunitas Road and Berry Trai l , the northern boundary is reached by way of Bill Wi lliruns Gulch (el evation 450 feet ) . South and east"t·rard it follo-vrs Bil l vli lliams
Creek and then the I ndi an Valley Fire Road to Corte ~~dera Creek to t he Mt ·. Tamal pais Rail r oad grade. This eastern border is at about 500 feet el evation. The railroad grade climbs back to the Mountain Home Inn, thus enclosing the st udy area (see Pl at e 7, page 28 , f or base map ) . The main r i dge of Mt . Tamalpais incl udes \vest Peak, Mi ddl e Peak, and East Peak and rises in el evation from 2000 feet to 2571 feet at the summit. The r idge extends from southwest to northeast and its slopes fall to the north, south, and east. The top of West Peak is not included within the st udy area inasmuch as it is the location of a United St ates Radar Station. CLIMATE
The climate of the Tamalpais region is very much l:i.ke that of tho remainder of the Coast Range . It varies slightly from the Mediterranean climate of southern Europe and northern Africa as a result of the cold Pacific and the prevalent summer fogs . The summer heat is usuall y modified by the cool sea breezes that often carry a dense bl anket of fog. Winters aro tempered by the closeness of the ocean. The fog l ayer generally does not extend to the top of the mountain, due to temperature inversion. The fog l ayer , usually 600 to 1700 feet thick , generally lies 100 feet above sea l evel. The uppermost $00 feet of the mountain is not covered by the fog layer whil e the loHer canyons are cold and damp until the fog rises. Information concerning rainfall, temperature, wind , and frosts is summarized from data of t he United St ates Weather Bur eau at weather station at the summit of the moun t ain and at its base i n Kentfield, and presented in Tabl es I through VII. The rainfall data taken at the Lake Lagunitas site were obtained from the Marin Municipal Water District which still maintains a station there. The Mt . Tamalpais weather station was located on the rocky, brushy slopes of East Peak , elevation 2571 feet, while the Kentfield station was centered near t he eastern boundary 10
TABLE I PRECIPITATION : MONTHLY AND SEA SONAL, AVERAGES I N I NCHES
-fJ) H Mt . Tamal pais 23 East Peak 1899-1922 .02 .02 . 65 l. 52 3.32 4.42 40 Kentfield 1890-1930 • 03 .02 . 80 2. 49 5. 11 8.06 Lake 73 Lagunitas 1890-1962 >. r-i H Mt. Tamalpais East Peak 5. 81 4.98 3.93 1.39 1. 22 . 27 27 . 55 Kentfield 10.01 8.51 6.55 2. 60 l. 78 .38 46.34 Lake Lagunitas 51.73 §" ~ :;>;: ~ IDate ct <1) . :::1 t'-1 ct 0 t-3 H) () 1-'· Sl> "' January ~ <1) ct Sl> ...... J.-1• ~ 20 , 1908 ...... 0. 0 1 0 'd :::1 > ::0 Sl> ~ "' tzj 1-'· trl w February > (/) ::0 I t-3 > s 11-12, 1904 t.rJ 0 (1.) l_":l:j t-3 Length of "' March 'i:J l\) +- §i ::0 l\) ~ r ecord ~ 22-23 , 1899 t:J:j ffi ...... 1 0 tr:! H ::0 ,_. April H 1--' 1--' Januar y 0 "'t-3 '":r:j ~ 14-15, 1920 > +- 1 t-3 "' t:l H > ~0 1--' 1--' Febr uary 1-<1 ,_. May _:z \..tJ \..tJ {J) t.rJ ~ 27- 28 , 1906 :O:.: H ..,. 1 t-3 :2: 1--' March ....; 1-<1 l\) ..,...t-3 t-3 June > "' - t-3 ,_. I ~tzl· ~ til April 0 > s 23-24, 1912 0:0::: t'-1 .._J i="" • til t-3 t?:J 0 t'-1 t- Annual, 00. "' I Annual November II II V'l .._J 5- 6, 1912 ~ I 11 ll TABLE IV AVERAGE IvJ.AXTIJIUHI , AVERAGE fJII NI MUl'-'I , AND AVERAGE TEMPERATURES Cr-i H 0 >. Q) ~ ~ .0 S-4 Q) Q) '0 >. S... Q) ,..-{ .t::H (1j +> s .0 .0 ,..-{ CJ) Q) .0 8 (1j +>0 ~ :::1 ..s:: Q) Ivlaxim.um () •ri Q) >. +> 0 w b.O O H p.. () g Q) g s:: ,..-{ So +:J s:: .0 H f..! () > Mi nimum Locati on Kent fiel d 24 37.139. 6 40.3 42.6 L'r4.6 47.2 48 . 1 47 . 7 47.3 44.3 40.3 37.0 43.0 Mt. Tamal pais 25 39.3 40.4 41.5 l~-4. 0 47.0 54.2 61.2 60. 7 57. 8 52.9 45.8 40.8 48 . 8 Average Location Kentfield 24 45.6 49.7 52.1 55 . 5 58.2 63. 2 65 . 6 64.6 63.6 59.3 52 . 7 46. 4 56.4 Mt . Tamalpai s 25 43.7 45.2 47.1 50.7 54.2 62 .0 69 .0 68 .4 65 .0 58.8 50 . 6 45.2 55.0 !--' l\) ! II TABLE V AVERAGE HOURLY WI ND VELOCI TY (MI LES ) ON MT. TAl1LAPAI S TVJENTY- TilO YEAR RECORD Janu ary 17.8 t-1ay 17. 4 Se p tember 14.1 Februar y 16.9 .June 16. 5 October 14. 7 I'1arch 16.3 Jul y 14.0 November 16. 5 Annual 16. 0 April 17.0 August 13.0 Dec ember l~L2 TABLE VI MAXI MUM ~'li ND VELOCI TY, DI RECTI ON , AND DATE ON J,1T. TAHALPA I S T\VENTY - TI/0 YEAR RECORD J...i :>. a> ~ H :>. ~ ..0 ~ a> a> ~ ro +' E a> ..0 ..0 r-l Cil ::l ..c: r-1 (I} Q) ..0 s Ctl ;:I ~ () •r-! (!) » ::l +' 0 (!) w ::l ~ ..0 ~ ~ :>. ~ r-1 bD p. +' ::> () ~ Ctl a> ro p. ro ::l ::l ::l (!) () 0 a> s:: 'J r:r.. ~ <1! ~ 'J 'J <:: (f) 0 z ~ < Miles per hour 69 65 68 70 69 70 62 70 62 60 68 60 70 Direction se nw m rr nw nv.J n '.·r nv-r nw U '\1'1 m -"1 n S '\1'1 nw Date 3 26 13 l 15 13 12 20 23 29 27 10 Aut 20 Year 1901 1899 1920 1920 1903 1910 1920 1S99 1915 1919 1919 1907 1 99 wI-' 14 TABLE VII FROST DATA : AVERA GE DATES AND LENGTH OF SF.ASON Kentfield Mt . Tamalpais Length of record 25 years 23 years Average date of l ast killing frost i n spring March 12 February 6 Average date of first kil ling frost in aut umn Nov. 19 Dec . 25 Average lengt h of growing season (days ) 252 322 Lat est dat e of killing f r ost in spring April 23 May 9 Earliest dat e of killing f r ost in autumn Oct. 11 Nov. 26 15 of the study area at an el evation of 65 feet. The Lake Lagunita s station i s maintained at the spillway at an el eva tion of 873 f eet near t he northern boundary of the project site . Precipitation occurs mainl y during the winter months while t he summer s ar e practicall y void of rainfall. ~fu il e the average mean t emper ature varies but a f ew degrees bet ween weat her stations, t he rainfall differs as mu ch as t went y-four inches per year. This variation in rainfall, fog el evation, and exposure influences the t ypes of vegetation found i n t he area. Chaparral occupi es the upper southern and easter n s lopes whil e the lower canyons and northern s l opes are occu pied by forest and woodland which ext end i nto the chapar ral count ry only al ong the creeks and gullies where springs provide a mor e permanent suppl y of water. De spite the fog , t he mountain becomes exceedingl y dry i n summer . With t he encroachment of man , fires have come to pl ay an even greater role in t he distribution of pl ants. Before 1930 , comp l ete fire r ecords wer e not kept by the l ocal fire departments. Knowledge of exact location and extent of burns is only as comp l et e as t he memories of a f ew of the old f i re fight ers. The Marin County and Mill Va lley Fi re Depart ments were ver y hel pful in suppl ying the following information. 16 A large portion of the southern and east ern slopes of Mt. Tamal pais \'las burned over i n the summer of 1913. I n 1929 a disastrous bl aze which l asted many days destroyed much of Blithedal e Canyon and entered the study area near Double Bow Knot on the ol d railroad. During the war, in 1945 , a pl ane crashed on the nor thern s lope near Potrero l-4eadm'fs which started a fire t hat burned brush and timber for five days. The most recent of the l arge fires took pl ace i n 1957 when a half acre of chaparral was burned above Double Bow Knot. Countless spot fires have broken out from time to time throughout the area . HI STORY Long before white man came to Mari n County, the Ol ament ko tribes of the Coa st Milmk Indians roamed t he hill s and valleys of the Tamalpai s r egion. On l y t he peak of the mountain itself \'las uninhabited by the Indians , for t hey believed that evil and dark spirits dwe l t there (Ortman, 1964). As they l ived i n a mild and rel atively warm climate, t hey t·Tore little or no clothing. \'/omen ii'IOre gr a ss skirts on festive occasions. During cold weather t hey woul d bring out their crudel y made j ackrabbit f ur capes or plaster themselves t hickl y wit h mud t o keep out the bitter col d. The Ol amentko Indians at e every variety of living creature except t he skunk. Elk and deer were stalked and killed with crude weapons made of local mat erials. The men trapped small game such as r accoon , quail, and r abbit whil e the women collected acorns, buckeyes, roots , manzanita fruit, and shell fish of all varieties (Rice and Raymond , 1957}. Their homes were a make-shift frame\"lork of pol es and bushes. Some can still be found today with only the charred pol es remaining . Pr esent-day ethnol ogists have l earned much from the abundant shell mounds which served as village dumps. In 1579, \·Then he careened his galleon on the beach a few miles north of Mt. Tamal pais, Sir Francis Drru with curiosi ty and f ear ( ~iagner , 1941} . The mountain tribes were content with t heir 'IJray of life i n t he Tamal pai s country. They r esent ed the Spanish and the padres who tried to change their l ife. General Va llejo bl amed the Ol amentko tribes for the s lowness of development of t he Marin peninsula , because t hey kept t he northern f rontier impassable t o the Spanish. Ar ound 1815 Chief Marin and his braves fought the Spanish troops for nearl y nine y ears. He was finally captured , onl y t o escape and r eturn to his raiding party. He was captured again in 1824. Chi ef Marin spent hi s l ast years serving as a pilot for a small bay f er ry. He died in 1834. By 1840 the mission at San Rafael was cl osed and t he converted I ndians r eturned t o t he hills , only to die of starvation. By the mi ddl e of the nineteenth century , most of t he Indians l·rere gone from the r egion. Warfare and disease wiped out the t ribes. An epidemic of small pox took the lives of sixty thousand Ol ament ko Indians. 19 The Indians are the source of several names. The Spanish called them t he Tarnal or Bay Indians. Their l and was called Tarnal-pais or Tarnal land, and thus the meaning of Tamalpais. Marin County was named after Chief Marin and Point San Quentin after Marin's a i de. Captain John .J. Reed , the first American settler in t he Tamalpais regiont \'laS granted the Rancho Corte l·1adera in 1834 by t he Mexican government where he built the first saw mill i n Marin County. He supplied most of t he r ed\'lood lumber for the earl y homes of San Francisco, an area which had tremendous gro~~h after the gold rush of 1849. Much of t he 1'amal pai s region was cut over by Reed's lumber industry but the redwoods have r eproduced rapidly from crovm sprouts so that today onl y an occasional stump is evidence of t he century- old harvest {Howe ll, 1949). The gro~nng popul ation in San Fr ancisco demanded bri ckst so the cl ay soils of the hills were skimmed for t he purpose. Woodcutter s s l ashed t hrough t he Tamalpais 1~o odland in order to supply f uel for the city . A surprising market was created for game . An i mportant business was creat ed in the hunting of quail, ducks and geese , and blackt ail deer. The streams and l akes supplied fish to the market. While San Francisco l'Tas experiencing growing pai ns, the Tamal pais region remained relatively \'lild. The \1at ers of San Fr ancisco and San Pablo Bays isolated the northern 20 peninsula for many years. Ferry service from the city enabled tiny hamlets to spring up around the base of the mountain. Mill Valley, Corte r1adera, and Fairfax became favorite summer retreats from the busy city life. In 1896 Mt . Tamalpais entered an era of mechanization. Through the agency of the Mt. Tamalpais and Muir Woods Rail ~·ray, the " crookedest railway in the 1.·mrld" was born. When completed, the narrow gauge scenic train had its depot in dmmto'im Mill Valley. It passed through the heavily forested Corte Madera Canyon on its ~.,ay up the steep southern face to the summi t. The area is so steep that the railroad had 2$1 curves which made forty-tNo conplete circles in its eight and one half miles of track. During its thirty years of existence, it became a custom for millions of ordinary trav elers and tourists to ride the Tamalpais Railway steam train to the top, coast by gravity car dm·m into lovely l-iuir Woods, and take the steam train back to Jvlill Valley. The railroad dret.'l peopl e from all over the world to Marin County. Every travel guide mentioned its wonderful engineering and thrill ing trip up and do'im the mountain (Wurm and Graves, 1960). A mountain tavern situated near the summit offered food and drink to the sightseer. By 1930 the old railroad was gone although its roadbed still serves as an important fire trail. One can still find 21 the old \'later t ank and platform at the site of the Mesa St ation on Double Bo\'r Knot. The population of the Tamalpais area is experiencing a great i ncrease. Suburban homes are bei ng built ever closer to the mountai n itself. Fortunately for conservation of the region, a major part of the mountain is managed by the Marin Municipal Water Di strict while other portions are \'ri thin state and national parks or monuments wherein homes cannot nmrr be built. ECOLOGY Introduction According to the Merri am Life Zone system as presented by Jepson (1960) , two distinct life zones can be found on Mt. Tamal pais. Due to a wide variation i n climate i n such a small area , both the Upper Sonoran and Transition Zones are recoenized. On t he more mo ist slopes and in the canyons extending up the water courses , the Transition Zone is characterized by forest and woodl and. On the drier rocky exposed ridges, the Upper Sonoran Zone is characterized by chaparral and grassland formations. Th i s zone is actually drier and may be due to steep slopes, rocky soil, sunny exposures , less rainfall, or a combination of them a ll (Howell, 1949 ). Investigation of the few areas of grass l and to be found in the study area was not attempted. The life zone concept is helpful in anal yzing the vegetation in a general manner but other variations, such as soil and steepness of slope, are so prominent that one plant associati on may be completely different from another only a few feet away. On t he other hand , associations may tend to intermingle with one another over a l arge area and sometimes show characteristics of their own. An attempt was made to restrict much of the study to an investigation of homogeneous stands of vegetation. 23 The pol ycl imax concept seems to be the most practical as applied to Mt. Tamal pais. Daubenmire (1952 , pp. 302-304) presents an association concept that can be applied with few modifications to Mt . Tamal pais as foll ows: The association i s considered the basi c uni t of vegetation classification. The term association embraces all unions that are superimposed on the same area and each disti nctive combination of vascular plant unions growing i n uniform habitat conditions i s ordinarily con sidered a separate association. The term associ ation refers to climax or near climax vegetation. Daubenmire defines the climatic climax as that type of climax vegetation which is characteristic of undulating topography and loamy soils that are moderately drained. An edaphic climax is a stabl e type of vegetati on caused by cer tain soil conditions. A topographic climax is a t ype of stable veget ation resul ting from certa in exposure effects of the topography. A topoedaphic cl imax is a stable form of vegetation resul ting from the combined effects of both topography and soil. Vegetation which has attained an equilibrium ~rith fire is called a fire climax. Each climatic, edaphic , and topographic climax may have its o~m series of fire climaxes. The former gr oup may be considered primary climaxes, and the l atter a secondary climax. Each associa tion may have several aspects or facies as a result of the effects of di ffering soil conditions, topography, etc. Daubenmire uses a system of nomenclature involving binomials. To define an association, the name of the 24 dominant species of its dominant union is used, followed by the species name of the plant or plants of the next most dominant union. By this system, an aspect of the chaparral a ssociation of the study area \•rould be named Arctostaphylos cushingi ana- Adenostoma fasciculatum-Quercus wislizenii var. frutescens-Vaccinium ovatum-Rhamnus californica/ Pteridium aguilinum. The dominant union is typified by five species. The subordinate union is made up of onl y one speci es and in some areas the union is entirel y l acking. By this system, the association names would be very l engthy and at times would have no subordinate name. A modification of this system of naming seems to be more practical. The name of the associa tion will consist of not more than three names of species of the dominant union. A subordinate union will not be added to the name of the association. The above aspect is called the Arctostaphylos cushingiana aspect of the chaparral association. Methods and Procedur e The preliminary period of reconnaissance and mapping took pl ace during the spring ~ f 1963. A United States Geo logical Survey map number NE/4 Mt. Tamalpais 15' Quad rangle \•ras used as the basic reference. From strategic point s on ridges opposite the study area, the vegetation was 25 mapped. \'Ji t h t he use of a surveyor ' s transit, stactometer , and rangefinder the various pl ant communities were pi npointed on the survey map . The results of the survey are presented on Pl at es 2 through 6 in overlay form. Several homogeneous stands as nearly climax as possibl e wer e studied in each association described . See Pl ate 7 for the exact location of the stands sampled. A calibrated line mar ked off in meters was used in the chaparral. Coverage and frequency data wer e obtained from each plot of one met er r adi us along t he transect . ~~en no new speci es along t he transect were found, t he size of the sampl e ~Jas r egarded as adequate. Not less t han f ourteen plots were anal yzed for each transect. Coverage dat a were obtained f or each species by use of t he system of Trepp as presented in Phillips {1959 ). Scal e 1E range of cover Average fo cover X to 1.0 0 . 1 1 1 - 9.9 5. 0 2 10 - 24.9 17.5 3 25 - 49. 9 37.5 4 50 - 74. 9 62 . 5 5 75 - 100.0 87.5 Coverage i s defined as the area occupied by a species and is usually a measure of the ar ea cover ed by the cro ~~n , stem, 26 Pl at es 2-6 Overl ay map of the various associations -~------~ ~ ~ • ..~ 27 26 Pl ate 7 Map sho\'ri ng l ocati on of sample stands Key to Pl ate 7 Seguoia sempervirens Association Stand l 1 Stand 2 2 Lithocarpus-Umbellularia-Arbutus Association Stand 1 3 Stand 2 typical 4 Lithocarpus Aspect 5 6 Pseudotsuga Aspect Umbellularia cal ifornica Association 7 Chaparral Association Arctostaphylos cushingiana Aspect St and 1 8 Stand 2 9 Stand 3 10 St and 4 11 Adenostoma fasciculatum Aspect S·tand 1 12 Stand 2 13 Castanopsis chrysophylla Aspect 14 Arctostaphylos canes cens Aspect 15 Arctostaphylos montana Aspect Stand 1 16 Stand 2 17 Cupressus sargentii Association 18 29 30 or a patch {Phillips, 1959). Fro.n the coverage data , the f requency was obtained. Frequency expresses the percentage of sampl e plots in trhich a given species occurs. I t \'las obtained by dividing the number of plots in which a part icu l ar speci es lrlas present by the number of total plots anal yzed i n the particul ar stand. I n the forest and woodland communities , quadrats not l ess than 100 square meters \\Tere used. I;ach tree that had a diameter greater than 5 centimet ers was measured and counted. The underst ory speci es were treated as in the above scal e. The lists of pl ant s in the various tables for each association or aspect of an associ ation are pl aced i nto certain groups. The tree species arc kept separate from t he understory pl ants. 'I'he underst ory plants are separat ed into groups according to phenology, habitat, and life form. These groups, lrrhethor they be considered unions or no t, mal:e up the plant association or association aspect. Sequoia sempervircns Association This association l i es a l ong the narrm.; stream courses that extend up to an el evation of approximately 1700 feet. The associ ation i s more extensive i n t he more secluded can yons such as I-1uir Woods belo\'r the st udy area. In the particu l ar stands analyzed, Lit hocarpus densiflorus (H.& A.) Rchd. (Tanbark Oak ) and Umbe l l ul ari a ca lifornica (H. & A.) Nutt. 31 (Cal ifornia Bay ) are found intermingl ed with the Sequoia sempervir ens (Lamb .) Endl. (Coast Redwood ) . Tabl e VIII presents a summary of size classes for the various tree species occurring i n the tvm stands of ·this association studied (refer to Pl ate 7, numbers 1 and 2, for l ocat ion of samp l es t aken ). Sequoia sempervi rens is consi dered the dominant speci es in that if it were removed , the Lithocarpus-Umbellu l aria-Arbutus association wou l d take over as has happened in logged areas. Veget ati ve reproduction of the Redwood is very common. In the stands anal yzed, a ll age classes were represented. Arbutus menziesii Pursh. (Madrone) was repre sented by a singl e individual and did not demonstrate self regeneration. As a result of the closed canopy formed by Sequoia , few subordinate species were present. Thi s associ ation is consi dered to be climatic climax vegetation . Sever al climatic fact ors i nfl uence its distribu tion, a ll of them related to evapo-transpi ration rates during the summer months (Byers, 1953 ). According to Cooper (1917) , who made a study of redwoods , rainfall, and fog of t he Santa Cruz Mountains, Seguoia r equires a high r atio of wat er supply to water loss and is unusually sensitive to extreme rapid transpiration even when t he wat er suppl y i s amp l e. Heavy rai nfall during winter months is necessary but alone i s not sufficient. In areas wit h deficient rainf all, redwoods are confined to stream courses or springs. Abundant summer fog 32 TABLE VIII SIZE CLASS DI STRI BUTi otT OF TREE SPECI ES AND Nill4BF.R AND PRESENC~ OF SUBORDHrAT""; SPGCI":S I N TVO STANDS OF SEQUOI A ~Er.WERVJRENS ASSOCI ATION {I) 'd ~ CJ) ·.J.' (I) CJ) (J)CJ) WH N Q$(!) r-i.J.' li"\ 0 0 0 0 0 $::l ()(!) ,..; C"\ lC"\ "(X) N ·r-1 ,..; H · ~ +> Q).J.' I I s:: .J.'S:: ·(I) (I) (I) ,..; ,..; r-1 r-1 ,..; r-1 If} Spccicn • • . • . • Q) ~() l.(\ 0 0 0 0 S-.4 •rl s:: r-1 C"\ lC"\ "(X) p.. (.:I •rl Se?uoia ncmpcrvircns Lamb .) Endl. 11 7 12 g 1 3 2 Arbutus menziesii Pursh. 1 1 Umbe1lularia ca1ifornic.9 (H. & A.) Nutt. 25 1 1 Lithocarpus densiflorus {H. & A.) Rehd. 30 1 5 1 Subordinate species Number of i ndividual s Vacci nium ovatum Pur sh. 1 1 Polystichum mm1itum ( Kau1f. ) Pres1. 31 2 \!oodwardia fimbriat a Smith 12 2 33 Figure 1. Stand r epresentative of t he Sequoi a sempervirens association. Fi gure 2. General view of Sequoia sempervirens associ ation in a mo ist ravine. 34 is essential because it reduces evapo-transpiration, by reducing the number of hours of sunshine, and r educes the dayt~ne temperatures (Byers, 1953) . Aft er a wind storm in May, Cooper observed tha t exposed r edwoods turned bro~m as if s corched by fire whil e nearby Pseudotsuga mcn ziesii (Mirb. ) Fr anco (Dougl as Fir) r emained unharmed. Excessive wind is detrimental to the Sequoia because of its effe ct on rapid transpiration rate. The climatic factors of wind , r ainfa ll, and fog together strongl y influence the distribution of this asso cia tion on f4t. Tarnal pais. 'l'he rainfall at the summit is decidedly lo'\rTer than at lov1er el evation. The redwoods are confined to the moist canyons. They \·muld not be there at a ll, ho'\rlever , if the summer fog \"las not present (Cooper , 1917 ) . The fog l ayer generally does not ext end above 1700 f eet· (\'lagner, 1941). At this l evel t he members of this association become stunt ed as they merge \"lith the Umbe llu l aria , Lithocarpus-Umbellularia-Arbutus or the Chaparral I association, which is not as vulnerabl e to dryness. Obser vation reveals that the association extends t o a higher e l evation on the northern face of Mt. Tamal pais than i t does on the souther n face . Figure 3 pr esents a diagram illustr ating the r el ationship of Sequoia associ ati on to a water source. Note that as wat er becomes limited, differ ent associati ons are 36 found; Chaparral being found on the dry ridges and Lithocarpus Umbellularia-Arbutus associ ation between the Sequoia association and the Chaparral. The long hi story of fire cannot be i gnored, for it has affected this associ ation to some extent. However , Sequoia association is quick to recover from a fire. Badl y charred trunks u i th only a little of the cambium area l eft \'rill resprout ne'\lr growth '\IJ'ithin a fe-vr "reeks after a fire (Howell, 1949). With the rapid r ecovery of the dominant tree, sub ordinate species are abl e to return relatively soon after the fire. Although this a ssociation is considered pri maril y as a climatic climax, it can be thought of as a secondary fire climax as a result of its relationship with fire. Lithocarpus-Umbellularia-Arbutus Association This association i s found between the moist Sequoia association and t he exposed dry slopes where the chaparral associations are typical. It has its widest range on the northern and western sides of the Tamal pais ridge. This association i s somewhat variabl e in makeup. Four st ands were studied. Two of the stands represent t he more typical aspects of the association on the north side, wh ile the other two represent important areas that ~dll be considered separatel y. Refer to Pl at e 7, numbers 3, 4, 5, and 6, as to precise location of the samples. 37 As shown by Table IX, the association is dominated by three species, Lithocarpus densiflorus, Umbellularia calif ornica, and Arbutus menziesii. If any one of the species were removed, there seems t o be little affect upon the sub ordinate species, yet if all three were removed, the canopy woul d be gone and drastic changes would develop. Lit hocarpus seedlings are the most numerous of the three species. Although Umbell ularia seedlings do occur , it is rare to find Arbutus seedlings. Arbutus is somewhat intolerant to deep shade (Wells, 1962), thus its seedlings are found a long disturbed areas such as road beds and fire trails. Torreya cal ifornica Torr. , (California Nutmeg ) i s another species represented frequently in this association. This association can be considered primarily as a climatic climax and secondarily as a fire climax. According to Costing (1956) the broad sclerophyll forest of North America consistently appears on north slopes and the better sites, while chaparral appears on the south slopes and drier sites. As the overlay map indicates , the northern slope is typified by the Lithocarpus-Umbellularia- Arbutus association , except on the exposed ridges, while the drier southern face is typified by the chaparral associations, except in the more moist canyons where this association borders the Sequoia association. Climatic factors of moisture and temperature do influence the distribution of this association. TABLE IX LITHOCARPUS -UMBELLULARIA-ARBUTUS ASSOCIATION Species Arbutus menziesii Pursh. 2 40 Umbe11u1aria ca1ifornica (H. & A.) Nutt. 2 43 53 Lithocarpus densif1orus (H. & A.) Rehd. 2 60 31 Quercus chryso1epis Liebm. 1 25 15 Quercus agrifo1ia Nee 1 tra ce 5 Torreya ca1ifornica Torr. 2 25 30 Corl1us ca1ifornica ( • DC . ) Rose 1 25 Po1ystichum munitum ( Kau1f. ) Presl. 2 trace 39 ,------~------:----] Figure 4. Stand representative of the Lithocarpus Umbellul ari a- Arbutus Association. Note Lithocarpus seedlings in the foreground. 40 Fire is al so an important factor. The association has adapt ed itself to fire. After the 1945 fire on the north side of the mountain, Arbutus, Lithocarpus, Umbellularia, Torreya, and Quercus chrysolepis Liebm. were found to cr0\1n sprout in a fe\rl \'leeks (Howell, 1949}. Even t hough these species cro~m spr out , it may take up to fifty to one hundred years to recover and form a canopy similar to the original one (\iells, 1962) . Fire usual ly f avors t he spr ead of chaparral at t he expense of the IJithocarpus-Umbellularia Arbutus association ( Oosting, 1956). F'requent fires may eventually el imi nat e t he association , a ccording to Oosting (1956 ) . It t herefor e seaas rea sonabl e that the association should not b e considered pri marily as a fire climax. On the other hand, fire in small amounts may hel p to perpet uate the association as it is found. 'rhe third samp le area, t he Litho carpus aspect of the Lithocarpus-Umbellularia-Arbutus associ ation may help to clarify this point. Lithocarpus-Umbellularia-:Arbutus Association; Lithocarpus Aspect. Lithocarpus densiflorus t ends t o form • pure stands. One stand \rTas studied in an ar ea \'Ther e this seemed to be the case. As sho\vn in Table X, a closed canopy of mature Lithocarpus was present. For t y per cent of the samp l e area was covered by young Lithocarpus pl ants. Only s cattered mature Arbutus \vere f ound with no seedlings present. 4J TABLE X COVERAG:S DATA FOR THE LITHO C.\R:OUS - UIJffiELLULARIA ARBUTU S ASSOC I ATI ON ; LITHOCARPUS ASPECT Per cent Species coverage Lithocarpus densiflorus 100 (H. & A.) Rehd. Arbutus menziesit 10 Pursh. Pseudotsuga menziesii 5 (r.Urb.) Franco Figure 5. St and representative of the Lithocarpus Aspect of the Lithocarpus-Umbellularia-Arbutus Association 42 According to V7ells ( 1962} , the Arbutus is intolerant to the shade of Lithocarpus. No Umbe llularia was present. I t was apparent that fire had not reached this area for years as t he individuals are extraordinarily large. The typical stands of this association had been burned oince this area had been burned. Fire therefore gives the typical speci es of this association a chance for mutua l survival. Ultimatel y , how ever, ~rithout fire the association may become a Lithocarpus association. Fire is definitely an important i nfluence to this association , for i f too many fires r avaeed the area, it mi ght eventua lly be succeeded by chaparral or if no fires started , the association might l ose its presont i dentity to a Litho carpus association. This poses a .proble.n \·rhich could not be ans\'lored in the course of this study. Lithocarpus-Umbellularia- Arbutus Association; Ps cudotsuga Aspect. The fourth sample was taken from the western side of the area where t his association is t ypified by mat ure stands of Dougl as Fir, which forms another aspect of this association . The samp l e represents an almost pure stand (see Table XI ). Pseudot suga menziesii, on first observation , seemed to play a dominant rol e in the area due to its large size. Hmtever, if removed, little change would develop due to the presence of the canopy of the typical species of the a ssocia tion. Litho carpus seedlings 'trlere pr esent i n abundance. 1'he 43 TABLE XI SIZE CLASS DIS'l'RIBUTI ON OF TREE SPECIES I H LI'fHOCARPUS -Ui\lBELLULARIA -ARBUTUS ASSOCIATION ; PS EYDOTSUGA ASPECT Di amet er classes i n centimeters lt"\ 0 0 0 0 0 .--1 (V'\ lt"\ tx) N .--1 I .--1 .-1 .-1 .-1 .--1 .--1 • • • • . . lt"\ 0 0 0 0 Species .-1 (V'\ lt"\ '00 Pseudot suga menziesii 2 1 0 10 2 1 {1Jiirb . ) Franco Arbutus menziesii 1 0 2 3 0 1 Pursh. Umbe llul aria californica 0 1 0 0 0 0 (H.& A.) Nutt. Lithocarpus densiflorus (seedlings) 30 per cent (H. & A.) Rehd. coverage in quadrat 44 Figure 6. Stand representative of Pseudotsuga Aspect of t he Lithocarpus-Umbellul aria-Arbutus Association. Note young Lithocarpus low to the ground. 45 Dougl as Fir is represented mainly by very large old trees except for two seedlings. It is not uncommon to find dead seedlings of the same size. Because of this l ack of self replacement, Dougl as Fir cannot be considered climax vege tation in this associ ation. However, Pseudotsuga menziesii seedlings grow vigorously in burned or cleared areas. Log ging practices in Or egon and else"t>rhere are centered around this fact . Areas are cleared in the forest so that the Douglas Fir seeds can germinate and the young seedlings can grow vigorously and not be restricted by a closed canopy. In this way, the Dougl as Fir Forest can perpetuate itself. In the Pacific Northwest, where Pseudotsuga forms its own association, it has generally been considered as a fire climax. The true Pseudotsuga menzi esii association of the north is represented by species which do not occur on Mt. ,Tamal pais. The forest here is more closely r el at ed to the Lithocarpus-Umbellularia-Arbutus association, although it is sometimes found mixed vlith the Sequoia sempervirens association. Umbellularia californica Association This association extends from the Sequoia and/or Lithocarpus-Umbellularia-Arbutus associ ations of the more moist areas up the steep canyons where it finally merges 46 with the chaparral associations. Figure 8 demonstrates how the association follows the gully rather explicitly but spreads at1ay from it on the l eft side (northern exposure) • This association is not as pr ominent on the northern side of the mountain. Be cause of mor e moisture , the Lithocarpus Umbellularia-Arbutus association is abl e to survive in the same type loca l e on the north-facing s lopes. The marginal effect of the association i s demonstrated by the stunted grovrth of the dominant species, Umbe llularia (see Fi gure 7). The species i s much l arger in more favorable conditions. The particul ar stand studied wns a typical area on the southern s lope (see Plate 7, number 7, page 28). The dominant species provides cover for a variety of subordinate species as indicated in Table XI I. Some may consider this association mer ely as an aspect of the Sequoia or Lithocarpus-Umbellularia-Arbutus associa tion yet the various domi nant species of these t\'10 groups are not found in this dry, exposed habitat. Umbe llularia has a '\l'ride ecological amplitude t'lhich enabl es its survival in t his dry habitat. The subordinate species do occur in other association but \·TOuld not be present in the dry canyons if Umbe llularia did not form a protective canopy. Or , perhaps, these are the only species which can tolerate the shade caused by t he closed canopy of Umbe llularia. 47 TABLE XII COVERAGE DATA FOR THE U~ffiELLULARIA CALI FORNI CA ASSOCIATI ON Per cent coverage i n 10 x 10 m. Species quadrat Umbe11u1ari a ca1ifornica 100 (H. & A.) Nutt. Querous agrifo1ia Nee 10 Photinia arbutifolia 5 (Ait.) Lindl. Po1ystichum munitum 30 (Kau1f.) Presl. Figure 7. Stand representative of Umbellularia association. ' · Figure 8. Umbell ularia association as it ascends and merges \vith the chaparral. Chaparral Associ ation The chaparral association of I!Jt. Tamalpais is distributed on the higher elevated steep exposed slopes where moisture is at a minimum. The southern side of Tamal pais ridge is predominantly chaparr al except in the moist canyons. The north side chaparral i s not as wide spread. See the overlay map (Pl ates 2-6, page 27) for gener al distribution of the chaparral. Fire has been a feature of the regional environment for time periods of geological magnitude (Wel ls, 1962 ). Because of the lone dry s~mers, the vegetation is subjected to the probability of fire each year. It has become an important factor in the evolutionary development of the chaparral association. Onl y pl ants that are abl e to r ecov er or reproduce between fires have survived and become members of this peculiar association. Many of the species have t he ability to cro\'m sprout after a fire while others apparently have seeds \'lhich have fire-stimulated gerrnination. Wells, in his study of vegetation in relation to geological sub stratum and fire , as v-rell as other investigators lists several species that have been found to cro\'m sprout: Pickeringia montana, Nutt. (Chaparral Pea) ; Rhamnus ca lif arnica, Esch. (Coffee Berry) ; Garrya elliptica, Dougl. (Silk Tassel) ; Vaccinium ovatum, Pursh. (Huckleberry) ; Ouercus 50 \'lislizenii (A. DC.) var. frutescens, Engl em . (Scrub Oak ); Eriodictyon californicum (H. & A.) Gr eene (Yer ba Santo); Adenostoma fasciculatumn, H.& A. (Chami sc); Arctostaphylos gl andulosa, East\·1.; Arctostaphylos cushingiana, F... ast v1. ; and Photinia arbutifolia , (Art. } L.i ndl. (Toy on) • Many of the members of the chaparral develop fast enough to flower and fruit during the first or second season of growth follo\r.lng a fire (Holt-ro ll, 1949). Be cause of these characteristics, the chaparral association can be considered fire clL~ax veget ation. The high rate of hybridization between certain species of the e; enus Arctostaphylos, or w·i thin species of the genus Ceanothu~ and Nithin species of the genus Quercus has made it particularl y difficult to study the aspects of t he chaparr al associ ation. According to Hov1e ll, Arctostaphylos cushingiana hybridizes vri th Arctostaphylos canescens and/or Arctostaphylos glandulosa, \1hile Ceanothus r amu losus hybrid i zes \'ri th Coanothus f olio sus and/or Ccunothus jepsoni. The genus Quercus in California has been demonstrated to show hybridization in many species. Arctostaphylos cushingiana is characterized by l eaves and branchlets not being gl andu l ar hairy or bristly-hairy. Where Arctostaphylos canescens is present on the south side of East Peak, it is observed that the leaves and branchlcts of A. cushingiana are pro fusely \'lhi te hairy. Hybridization bet\'men the t\10 species 51 is apparent on East Peak. To the west of West Point, Arctostaphylos glandulosa is particularly abundant. It is characterized by sticky gl andul ar leaves and branchlets. Where Arctostaphylos cushingiana mer ges with Arctostaphylos glandulosa, individuals were observed to have combined characteristics of the two species. Eleven stands were sampled throughout the chaparral association. Each aspect of the association studied is primaril y a fire climax but some are influenced by topographical and soil differences. Chaparral Association; Arctostaphyl os cushingiana Aspect. Four stands of this aspect of the chaparral were studied. See Pl ate 7 , numbers 8 , 9 , 10, and 11 (page 28 ) for their location. The coverage and frequency data are provided in Table XI II. As can be seen , a rather haphazard distribution of t he species is evident. The random distri bution of the species comprising this aspect could be attributed to fire . It seem s unl ikel y that because one species is not present at one sit e and it i s at another , it l a cks t he ecologica l amp litude. The f ire influence could be likened to a game of musical chairs. Each fire affords a chance for reshuffl ing of species with individualistic traits which govern dispersal, establishment , dominance , or competition (We lls , 1962 ). While the Arctostaphylos 52 TABLE XIII COVERAGE AND FREQUENCY DATA FOR THE ARCTOSTAPHYLOS CUSHINGIANA ASPECT OF THE CHAPARRAL ASSOCIATION Presence Aver age % Average % i n four coverage in frequency stands plots \'Jhere in 82 plots Species present of 1 m. radius Arctostaphylos cushingiana 4 61.8 East \'1 . Quercus viislizenii A. Dc ., 4 25.5 38.1 var. frutescens Engelm. Arctostaphylos gl andulosa 2 39.2 Eastdw. Arctostaphylos senitivus 1 63 . 2 24.7 Jeps. Adenostoma fasciculatum 4 12.3 60.4 H. & A. Pickeringiana montana 1 50.0 2 Nutt. Photinia arbutifo1ia 1 31.5 2 (Ait.) Lindl. Garrya elliptica 1 33.8 2 Doug1. Ceanothus r amu1osus l 17.5 1 (Greene) McMinn Castanopsis chrysophyl1a 1 6.9 6.2 ( Dougl. ) A• DC • Rhamnus ca1ifornica 1 3.3 10.5 Esch. Xerophyl1um tenax 1 20.7 11.5 ( Pursh. ) Nutt. 53 Figure 9 . Gener al vie't'r of the Ar ctostaphylos . cushingi ana aspect of the Chaparral associati on on t he south sl ope of Mt. Tamal pais. Note the cl ump of introduced pines. cushingiana aspect of the chapar r a l is the most prevalent on Mt. Tamalpais, its species nay be entirely lacking in one area while present in another. Arctostaphylos elandulosa, Eastu., is found chiefly ":est of \Jest Point vthile to the east it is rare. This haphazard distribution '\'/Ould seem to indicate that a large element of c~ance has been involved probably at the dispersal stage. Chaparral Association; Adcnostoma fascicul atum Aspect. The pl ants of this aspect are found in patches arranged haphazardly throughout the Arctostaphylos cushing ~ aspect of the chaparral association. Adenostoma fasciculatum is the dominant shrub. Coverage and frequency are presented in Table XIV (see Pl ate 7, nUlllbers 12 and 13 , page 28, for location of stands). Particularly abundant vrl.th Adcnostoma \-Jas Ccanothus ramulosus (Greene) r~1d11inn. Thi s aspect differs from the previous one only in dominant species. Adenostoma seems to take the dominant role in this aspect while Arctostaphylos cushingiana vtas dominant in the other. \'~ ells ( 1962 ) states thD-t Adenostoma and Ceanothus , because of their comparatively light seeds, exhibit pioneer tendencies chiefly on burns vthere they freely volunteer. This behavior is correlated with fire-stimulated seed germination a ccording to Sampson (1944 ) , ~n1o stated that these tuo species are sometimes rapidly extended by fire at 55 TABLE XIV COVERA GE AND FREQUENCY DATA FOR THE ADENOSTOI4A FASCICULATUM ASPECT OF THS CHAPARRAL ASSOCIATI ON Average % Average % Presence coverage in frequency i n t't<'I O pl ots t-Jhere in 29 plots Species stands present of 1 m. radius Adenostoma fasciculatum 2 73. g 100 H.& A. Ceanothus ramulosus 2 21.5 72 (Gr eene} 1·1d 'linn Ceanothus foliosus 1 2. 6 7 Parry ArctostaEhylos cushi ngiana 2 24.5 51 Eastl,t;. Pickeringia montana 1 31.3 7 Nutt. r~imulus sp. 1 7.54 23 56 1 Fi gure 10. General aspect of t he Adenostoma aspect of the Chaparral Association. Note t he C. ramulosus in bloom. 57 the expense of the surrounding veget ation. This explains the dominant stands of Adenostoma and the high number of feanothus ramulosu.§._ pl ants present in haphazard arrangement. t hroughout the chaparral association . Chaparr a l Association; Castanopsis chrysophylla Aspect. Isol ated patches of this aspect are found distri buted over the chaparral l andscape. Cast anopsis chrysophylla (Dougl.) A. DC. does not alter the surrounding vegetation if it remains at the same height as the vegeta tion. However, Castanopsis f orms a particular aspect when it grm·rs up to tree size. One e;rove of t his aspect of the Chaparral \"tas sampl ed. The data are presented in Table XV. Lo cation of the grove is shown in Pl ate 7, number 14, page 28. The species Castanopsis chrysophyl la forms 100 per cent of the coverage and forms a very dense canopy under 'lrlhich Va ccinium ovat um is found. I n other groves observed, Vaccinium "VIas not al"t-1ays present . Dead snags of what is believed to be Arctostaphyl os cushingiana were observed under one gr ove. Probably the shade produced by the matur ing grove finally killed the shade int ol erant shrubs \"Thi ch originally were there. The random distribution of this aspect of the Chaparral associ ation 't'las probabl y due to chance at the dispersal stage. The seed of Castanopsis chrysophylla is rel ativel y l arge, which limits its dispersal to small areas. 58 TABLE XV COVERAGE DATA FOR THE CASTANOPSIS CHRYSOPHYLLA ASPECT OF THE CHAPARRAL ASSOCIATI ON Average per cent coverage Species in grove Castanopsis chrysophy11a* 100 (Doug1.) A. DC. Vaccinium ovatum 95 Pursh. Photinia arbutifo1ia 5 (Ait.} Lindl. >:' Castanopsis stem diameters r anged from 11 to 20 centimeters. 59 Chaparral Association; Arctostaphylos canescens Aspect. Thi s aspect is restricted to the steep and other~nse rather barren south-facing sandstone or shale slopes. The data for the one stand studied are presented in Table XVI (see Pl ate 7, number 15, page 2e, for l ocation) . In addition to fire, this aspect of the chaparral is also influenced in its distribution by topoedaphic factors . According to Hovm ll, Arctostaphylos canescens, Eastw. , cannot compete in dense chaparral. This dominant species appears to be the onl y speci es that can tolerate t he dry condition to any extent. Chaparral A ssoc~ation; Arctostaphylos montana Aspect. This aspect, restricted to the serpentine outcrops, is also influenced by fire. ~10 stands v1ere studied, one on the south and one on the north face of Tamal pais ridge. Both exhibited the same characteristic species. Coverage and frequency data are provided i n Tabl e XVII (see Plate 7, numbers 16 and 17, for location of stands). .. Cupressus sargentii Association Also restricted to the serpentine, this association is also influenced by fire (see Pl ate 7, number 18, for loca tion of stand). Cupressus sargentii, Jeps., the dominant species, is a well-devel oped tree \thich may grow to fifty feet tall and which is kill ed outright by fire. However, 60 TABLE XVI COVERAGE AND FREQUENCY DATA FOR THE AR CTOS TAPHYLOS CANES CENS ASPECT OF THE CHAPARRAL. ASSOCIATION Average % Average % fre6uency coverage in i n 1 plots Species plots t'lhere of 1 m. present radius Arctostaphylos canescens 70.6 100 Eastw. Adenostoma fasciculaturn . 9 37.9 H.& A. Eriodictyon californicum 1.73 19 .0 (H.& A. ) Greene Garrya elliptica 5.0 6.2 Dougl. • 61 Figure 11. Represent ative stand of Arctostaphylos canesccns aspect of the chaparral association. 'fhe rock is one foot tall. Note low growth form of Arctostaphylos canescens. 62 TABLE XVII COVERAGE AND FREQUENCY DATA FOR THE ARCTOSTAPHYLOS MONTANA ASPECT OF THE CHAPARRAL ASSOCIATION Average % Average % frequency Presence coverage i n in 35 pl ots Species in tuo plots where of 1m. stands present radi us Arctosta:Qh;y:los montana 2 39. 1 68 .8 Eastw. Quercus durata 1 32. 5 17.1 Jeps. Ceanothus je12soni 2 27. 8 31. 4 Greene Adenostoma fascicu1atum 2 25.4 54. 2 H.& A. Photinia arbutifol ia 1 31.9 25 . 4 (Ai t. ) Li ndl. Rhamnus ca1ifornica 1 fL5 14. 2 Esch. Garrya el1iptica 1 5.0 2.8 Doug1. Eriodictyon cali fornica 1 5.28 31.4 {H. &. A.) Gr eene Monardella negl ecta 2 3. 71 48.5 Greene 63 the cones remain closed until the heat of a fire opens them (Howell, 1949). The area occupi ed by this association is i ncreased a s a resul t of fire in that a grove of seedlings may devel op where only one individual tree stood before . Wells does not treat Cupressus as a member of the chaparral. For thi s reason, Cupressus sargentii a ssociation is t reated separate from t he chaparral associ ation. However, species of the chaparral typify this association so that it could be considered as an aspect of the chaparr al association. The foll owing tabl es present i n summary form t he distribution of species in the various a ssociations and t he rol e each tree species pl ays i n its respective associ ation. Tabl e XIX deals \1i t h t he tree species· as to whet her it is climax or seral in its as sociation. Tabl e XX presents all of t he non-arborescent species found in the study and indi cates in t'lhat association or associations they \'Tere found . TABLE XVIII COVERAGE AND FREQUENCY DATA FOR THE CUPRESSUS SARGENT I I ASSOCIATION Average % Average % coverage in frequency in Species plot;s where 12 plots of present 1 m. radius Cupressus sarp;entii 73. 6 S3.5 Jeps. ArctostaEhylos montana 32.1 50.0 Eastw. Quercus durata 27.5 16.6 Jeps. Adenostoma fasciculatum 2.6 16.6 H.& A. Photinia arbutifolia 5.0 8.3 ( Ai t.) Lindl. 65 Fi gure 12. Cupressus sargentii association can be seen in the background. Represent ative species of Arcto staphylos montana aspect of the chaparral association are in the foreground. Ceanothus jepsoni is lowermost , Arctostaphylos montana is on the l eft . The soil is serpentine. ''· TABLE XI X DISTRIBUTI ON AND ROLE OF TREE SPECIES OF THE T~~LPAIS STUDY AREA C'(j Cf) () ~ ..-1 ·rl S-.1 s:: Cf) •rl 0 H s:: Cf) Cf) cU rl 0 •rl Q) Q) •r-1 () Cr-1 4-l •r-1 S-.1 •ri ·r-1 •r-1 •rl CIS •r-1 +' •rf s:: Cf) •r-1 ·r-1 rl s:: ~ S-.1 s:: {j) rl ctS S-.1 0 Q) Q) 0 () j Q) Cr-1 "0 ·r-1 Cr-1 ·ri N ClS it/) ctS S-.1 rl s:: ·~I ·rl C'(j Q) ~ ;::: H ·r-! :;::$ () () s ~ c;S ell m (/) rl +' Cf) ttl~ (/) :;::$ 0 ~I 0 () :;::$ rl s:: "0 g 0 +' (.),~~ rl ro :;::$ H ;::: :;::$ Q) ~ (l) Q) +' .D ..0 (/) (/) Associations ~rith Trees :;::$ j ·r-1 k ~ I ctS j p... 0 C!l H C = dominant climax species S = major seral species s = minor seral species "' 67 TABLE XX DISTRIBUTION OF NON-ARBORESCENT SPECIES Pl ant Associations Chaparral AsJ2ects C\1 ciS § (I) r-l •rl ~ .~1 r-l § (!) C!! ~ :>. ~ .p (.) ~ (I) S-! .a •rl m (I) C!! ~ 0 ..c: r-l Q) .p Q) Ct-1 0 (I) ;:j s;:: •rt•rl\ Ii-I •rl (I) ;:j (.) @ 0 .p •rl r-l :>. (.) •rl (.) s > ctl Ii-I (.) Ii-I (.) ..c: {I) {I) {I) {I) ~ Q) (.) 0 ctl 0 0 p r-l 4-1 r-1 r-1 .~, {I) 0 •rl ..c: m ..t:: ..t:: ~ ~ {I) ~ {I) 0 {I) r-1 r- m 0 ctl C!! ;:j 0 .p .p .p .p (I) ~ Cll {I) {I) (I) {I) r-l § 0 0 0 Q) Q) .p +' ~ .p s Ii-I .0 {I) (.) Q) (.) (.) 8 ctl Ii-I "0 Ii-I Ii-I ;:j j 0 -:!! 0 :::>J < < < Number of Species stands analyzed 2 4 l l l.y 2 l 2 l Vaccinium ovatum Pursh. 1 \Jood\'mrdia fimbriata Smith 2 Po1ystieiliUm munitum (Kaulf.) Presl. 2 2 l Cory1us ca1ifornica (A. DC.) Ros 1 Photinif arbutifo1ia {Ait. Lindl. 1 1 1 1 l XerQpbYl~ tenax {Pursh. Nut1. 1 Mimu1y§ sp. l Al:ctost ~o.s ..c.wili.ing~~ Eastlt. 4 2 AI! ctostapb~Jos gJa:adulQsa East\'J. 2 Arctosta]2hy1os canescens East\'.r. 1 Arctosta]2hylos senitivus (Jepson) East't'>l. 1 6$ SillJIMARY An ecol ogical study was made of the sclerophyllous pl ants of Mt . Tamal pais, wh ich is approximatel y ei ghteen miles north of San Fr anci sco . Mt. Tamal pais i s made up of Franciscan sediments from the Jurassic and Late Cretaceous periods which include serpentine , hard grey sandst one , and dark shale. The study area r anges in el evation f r om 450 feet to 2571 feet. It i ncludes Tamal pai s r idge which lies in an east-west di rect ion and numer ous ridges which extend from it. The climate approaches t hat of t he Mediterranean climate. Essentially, precipitation occurs only during t he winter months. The summers are temper ed by the coastal fog. After a period of reconnaissance, colle ction of pl ant specimens, and mappi ng of the veget ation , t he p l ant species v1er e gr ouped i nt o five associations, t v-10 of which were found to be made up of several aspects. Discussion of each association i ncl udes coverage and frequency dat a for the characteri stic species. The foll owing associ ations v1er e determi ned and anal yzed: Seguoi a sempervirens association Lithocarpus-Umbellul ari a-Arbutus association Lithocarpus aspect Pseudotsuga aspect Umbellulari a californica association 70 Chaparral association Arctostaphyl os cushingiana aspect Adenostoma fascicul atum aspect Castanopsis chrysophylla aspect Arctostaphylos canes~~ aspect Arctostaphyl os montana a·spect Cupressus sargcntii association • Each association was determined on the basis of the dominant unions and its relati on to environmental factors. LITERATURE CITED Byers, H. R. 1953. Coast redl'TOods and fog drip. Ecology 34: 192-193. Cooper , W. S. 1917. Red'\toods , r ai nfal l and f og. Plant World 20: 179-189. Daubenmire, R. 1952. Forest vegetation of Northern Idaho and adjacent Washington, and its beari ng on concepts of vegetation cl assifica tion. Ecol. Nonog. 12 : 53-79. Jepson, W. L. 1960. A manual of t he flo\'lering plants of California. Univ. California Press, Ber keley. 1238 p. Howe ll, J. T. 1949. Marin flora. Univ. Californi a Pr ess, Ber keley . 323 p. Oosting, H. J. 1956. 'l'he study of plant communi ties. ~l . H. Freeman and Co., San Fr ancisco. 440 p. Ortman, W. T. 1964. A Washington 's birthday tradition. I ndependant Journal, Feb. 22: M4-M6 , San Rafael. Phillips, E. A. 1959 . Met hods of vegetation study. Henr y Holt and Co. 107 p . Hice , Ann , and L. Raym ond. 1957. Marin Indians. Univ. California Press, Berkel ey. 30 p . Sampson , A. W. 1944. Pl ant succession on burned chaparral burns in northern California. Univ. Cal ifornia College Agr . Bull. 685 . Tal iaferro, N. L. 1951. Geology of t he San Franci s co Bay counties, p . 117-150. In 0. P. Jenki ns , Geologic guide book of the San Franci s co Bay counties, history l andscape, geology, fossils , minerals, industry, and routes t o travel . California Dept. of Natural Re sources Bull. 154. U. S. Department of Agricult ure. 1930. Cl imatic summary of the United States, Secti on 15-Nor thwestern California. \'lashington, United States Department of Agr. 24 p. Wagner , H. H. 1941. Mt . Tamal pais State Park. U.S., V . P. A. officia l project 665-08-3-147. California State Printing Office , Sacramento. 79 p. '72 Wells, P. V. 1962. Vegetation in rel ation to geological substratum and fire in San Luis Obispo Quadrangle, California. Ecol. Monog. 32: 79-103. \'lurm, T. G., and A. C. Graves. 1954. Crookedest raihmy in the world. Acad. Li brar y Guild, Fresno , California. 209 p.