FLORA OF A VERNAL POOL COMPLEX IN THE MAYACMAS MOUNTAINS OF SOUTHEASTERN MENDOCINO COUNTY, CALIFORNIA

8 Pages·1999·4 MB·English

by  Kerry L Heise

Madrono, Vol. 46, No. 1, pp. 38-45, 1999
FLORA OF A VERNAL POOL COMPLEX IN THE MAYACMAS
MOUNTAINS OF SOUTHEASTERN MENDOCINO COUNTY, CALIFORNIA
Kerry L. Heise
University of California, Hopland Research and Extension Center,
Hopland, CA 95449
Adina M. Merenlender
Environmental Science, Policy, and Management, University of California,
Berkeley, CA 94720-3110
Abstract
Vernal pools in the Mayacmas Mountains of southeastern Mendocino County, CA typically occupy
topographic depressions related to landslide dams and fissures. A group ofpools within a 1290 ha study
area range in size from 180 to 3069 m2, and are located at elevations between 329 and 902 m on slopes
of oak woodland and chaparral. Eryngium aristulatum Jepson var. aristulatum and Isoetes howellii En-
gelm. codominate shallow, wide-margined pools and are associated with vernal pool specialist taxa such
as Gratiola, Navarretia, Plagiobothrys, and Pogogyne. Deep, narrow-margined pools are characterized
by cosmopolitan wetland taxa such as Callitriche, Carex, Eleocharis, Juncus, and Ranunculus. Plant
surveys conducted in 1996 and 1999 indicate no significant change in species abundance orcomposition
between the two years.
The characteristic flora and fauna of California's 101 near Hopland, CA, the area includes portions
vernal pools and their distribution is well docu- of the University of California, Hopland Research
mented (Jain 1976; Holland and Jain 1987; Zedler and Extension Center (HREC) and adjacent public
1987; Keeler-Wolf et al. 1995; King et al. 1996; and private lands (Fig. 1). The area consists of
Bauder and McMillan 1998; Holland 1998). Of moderately steep, predominately southwest-facing
the16 vernal pool regions in the state described by slopes in the Mayacmas Mountains, withelevations
Keeler-Wolf et al. (1995), the Mendocino Region, ranging from 183 to 914 m. Many high gradient
which lies entirely in Mendocino County, is one of ephemeral creeks bisect this terrain creating aseries
the least known. The purpose of this study was to of parallel ridges and deep gullies. Lying approxi-
provide a description of the flora of a vernal pool mately 65 km inland from the Pacific Ocean, the
complex in the arid, mountainous portion of south- study area experiences a typical Mediterranean cli-
eastern Mendocino County based on observations mate of hot-dry summers and cool-wet winters.
from 2 years. These interior cismontane vernal Rainfall for the winters of 1995-1996 and 1998-
pools occur on relatively unstable soils that are de- 1999 totaled 1074 mm and 880 mm respectively;
rived from marine sedimentary rocks. A number of the 35-year average is 947 mm (Table 1).
floristic studies have been completed in the area The 12 vernal pools in this study range in ele-
and the occurrence of vernal pools has been men- vation from 329 m to 902 m and are situated on
tioned (Neilson and McQuaid 1981; Murphy and benches originating from old landslides and soil
Heady 1983; De Nevers 1985; Smith and Wheeler slips. The soils are predominately fractured sand-
1991, 1992; Baad 1998), but ourknowledge ofver- stones and shales (Sutherlin Series) or glaucophane
nal pool floristics remains poorly understood. schist andrelated metamorphic rocks (Yorkville Se-
Study area and methods. The 1290 ha study area ries) of the Franciscan Formation (Gowans 1958),
is located in the interior north coast ranges of which are especially prone to landslipping. The
southeastern Mendocino County. Lyingjust east of pool basins are underlain with a moderately com-
the Russian River and 6 km northeast ofU.S. Hwy pact clay hardpan. Mixed oak woodland and savan-
Table 1. Monthly Rainfall (mm) for Winters of 1995-1996 and 1998-1999 at the University of California
Hopland Research and Extension Center, Mendocino County, CA. Elevation = 244 m. 35 year average =
947 mm.
Year Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Tot
1995-1996 5 350 214 244 88 88 64 21 1074
1997-1998 22 17 41 215 92 325 502 150 71 111 1546
1998-1999 24 184 74 101 287 149 57 4 880
1999] HEISE AND MERENLENDER: MAYACMAS VERNAL POOLS
A
aLoncdaEtxitoennosfioHnopCleantnedrResearch 0•.5 Vernal0Pools 0.5 onoo ^> cooonion^oocMoirnriiorc)o
inCalifornia 'Contours(50mintervals) CM fN
HoplandResearchandExtensionCenterBoundary
mooooooooo
fN
rH .>H rH *0
Tj- fN
O»0O00»nOir)
On
O
t~- rH rH rH rH
co
2 <u -nOOOooOOm
CON ^>h ^ rn CN
ON CO
OCNOOOOOOm
t3 c3 OCM >.h 00 CO fN fN
ON rH
Fpaiongod.lE1ixs.tleoLncosacitaoetndio5Cneknotmfervn,eorrMnteahlnwdeposoctoliosnfoaHtoCtohguenpHtooyopl,.laCTnAod.wnRTsewhsieinapirnc1g3h 3°l3 TICTO)f.>HoCoMoo—oooNo^otor^ocooororo
North, Range 11 West.
o>nOOOOOfN
na dominate the lower elevations, whereas chapar- UW Oonn Uoo ££o IT) >kh oroH vo ^ rH
ral and patches of closed cone forest are common
above 675 m (Murphy and Heady 1983). Some
dpoouogllsasairei sHhoaodke.d&byAmma.t,urQe.QluoebractausNesep,p.Q(.Qugearrcruas- OIrTJN-Z.rfTjoN"oirHOnoorHooiinnicnocionrcoo
yana Hook., Q. agrifolia Nee), but otherwise are
surrounded by annual grassland or chamise chap-
aarrreaal.sAupgprorotuppeorfesnangiaplonwdestljaunstdotuatxsaidseuocfhthaessStcuidry- K 5 Js wG0O3 Oirn-n >.h oOn mCM -cho O O rH TCtM
pus, Typha, and Potamogeton, which were absent GO On
from the larger vernal pools. Cattle were excluded
fcerpotmBtlhueebTiwridnianngdpRoiolleyi,na1r9e9g6;raazleldotbhyershpeoeopl.s, ex- rO5ot ^£*gjo Omn^>H oOcomoooomNOrH
We visited each pool in mid April, May and June
of 1996 and 1999 to inventory the vascular plants. UJ
A species list was compiled for each pool, noting »nZ_fNcofNOOOOr--
CO 1—1 CO fN
all species from pool center to upper strand line or CO NO
interface where there was an obvious change in
species composition from the adjacent upland veg- O GO
etation. The DAFOR scale (Kent and Coker 1992): OfNn ^^ NCOMfNONOr^oOfNOfNN
dominant (5), abundant (4), frequent (3), occasional CO CCMM
(2), and rare (1) was used to obtain a subjective W 03
measure of species abundance for each pool. Tree > £
canopy cover was determined from an ocular esti- c NOON N_O OONN ON
mate of noon shade over the pools in June. Since N ON ON OrN^ OONN
all pools were round in shape the mean of 4 radii y m f-
were used to determine pool area. Representative
species new to the study site were collected and VCMO CrMH »<hU <QD,
deposited into the HREC herbarium. £ £ £ £ o £
o o
Of the 90RevsasuclutlsaranpdlaDntisscausnsdioonne bryophyte U VC3',^OUB G<<OSD (3£H TO<3uhTaC3D 73 T3
f1o9u9n5d-1at99t6hea1n2dve1r9na9l8-p1oo9l9s9dusraimnpglitnhge Apperriilo-dJ,un6e3, a i W£O2Phg03 0*3 tS03 ^303
MADRONO
40 [Vol. 46
Table 3. Abundance Data for Vernal Pools at the Hopland Research and Extension Center and Adjacent
Private Land, Mendocino County, CA. Data collected April-June, 1996 and 1999. 5 = Dominant, 4 = Abundant,
3 = Frequent, 2 = Occasional, 1 = Rare. Nomenclature follows Hickman (1993).
Junc- Junc-
tion tion
Hunt- Hunt- Blue- Blue- West- West-
Species ley-96 ley-99 bird-96 bird-99 96 99
Achyrachaena mollis Schauer
Agrostis exarata Trin.
Aira caryophyllea L. 3 2 1
Allium unifolium Kellogg
Anagallis arvensis L. 2 1 ii ii
Aristidci oligcinthci Michaux
Avena barbata Link 9z ii
Briza maxima L.
Briza minor L. z9 9z 3 2
Brodiaea elegans Hoover 1 2 11 ii
Brodiaea stellaris S. Watson
Bromus diandrus Roth 1 1
Bromus hordeaceus L. 9z 9z 1 1
y^aiiiiricrie neieropriyiiu ruisii vai. uoiariaeri ^ncgciin.^ raascu 9z 9Z
Carex athrostachya Olney
Carexfeta L. Bailey
Carex subbracteata Mackenzie
Castilleja attenuata (A. Gray) Chuang & Heckard
Centunculus minimus L.
Cerastium glomeratum Thuill. J-2 9z
Ceratophyllum demersum L.
Cicendia quadrangularis (Lam.) Griseb.
Crassula aquatica L. Schonl. 9z 9Z
Cynodon dactylon (L.) Pers. 4 3
Cynosurus echinatus L.
Dactylis glomerata L.
Danthonia californica Bolander
Deschampsia danthonioides (Trin.) Munro 9z 9Z 4 4 AH J9
Deschampsia elongata (Hook.) Munro
Downingia cuspidata (E. Greene) E. Greene
Elatine californica A. Gray
Eleocharis acicularis (L.) Roemer & Schultes A /I 3 4
Eleocharis macrostachya Britton Jc /) 5 5 Z9 11
Elymus glaucus Buckley
Eremocarpus setigerus (Hook.) Benth. J J
Eryngium aristulatum Jepson var. aristulatum 9— 5 5 5 5
Festuca rubra L.
Galium aparine L. 9Z 2
Geranium bicknellii Britton
Geranium dissectum L.
Glyceria leptostachya Buckley
Gratiola ebracteata Benth. J•3 /I 4 4
Heteroeodon rariflorum Nutt.
Hordeum marinum Hudson subsp. gussoneanum (Pari.) Thell. J-} J 2 2 9Z /i
Hypochaeris glabra L.
Isoetes howellii Engelm. Jc c 2 2
Juncus bufonius L. 9 9Z
JUrlLHiS fJLltt.rltS LZ,. iVlCyCi
Juncus tenuis Willd.
Juncus xiphioides E. Meyer 3
Lasthenia californica Lindley
Lasthenia glaberrima A.DC.
Leptodictyon riparium (Hedw.) Warnst.
Lilaea scilloides (Poiret) Hauman
Lolium multiflorum Lam. 2 3 5 4
Lolium temulentum L.
Lythrum hyssopifolium L. 2 2 3 2
Madia gracilis (Smith) Keck
Menthapulegium L. 2
Microseris douglasii (DC.) Schultz-Bip.
1999] HEISE AND MERENLENDER: MAYACMAS VERNAL POOLS 41
Table 3. Extended
June- Junc-
tion tion Coon Coon Coon Coon Rifle Rifle Twin- Twin-
East- East- Riley- Riley- North-North-South-South- WS- WS- WL- WL- Hog- Hog- Range-Range- ing- ing-
99 99 96 99 96 99 96 99 96 99 96 99 96 99 96 99 96 99
2

HEISEANDMERENLENDER: MAYACMASVERNALPOOLS
Table3. AbundanceDataforVernalPools atthe Hoplan Table3. Extended
PrivateLand,MendocinoCounts',CA. DatacollectedApril-Ji
3 = Frequent,2 = Occasional, 1 = Rare.Nomenclaturefollowsi
Coon Coon Coon Coon Rifle Rifle Twin-Twin-
Blue- West- West 96 99 96 99 W9L9- Ho96g- H9o9g-Ra9n6ge-Ra9n9ge- i9n6g- i9n9g-
nifoliumKellogg
Bnntiaeue!ei;cin\ Hnnvcr
BrodiaeaslellarisS.WatS(
BmmttsJnindrusRoth
Calliincheheten>i>h\lhiPursli \ar hohuuicri (Hcgelm.)Fassett
CarexathrostachyaOlney
CurcxJemL.Bailey
CiiMillciiit .Gray)Chuang&Heckard
Cerasiiumglimu-mtumThuill.
CeratophyllumdemersumL.
Ctcendiaquadrangularis(Lam.)Griseb.
CrassulaaquaticaL.Schonl.
Cynodondactylon(L.)Pers.
CynosumsechinatusL.
D(icrxli\xiomerataL.
Duntlh'iuucalijornica Bol.mdcr
Ihwi-htiHifwitiJiinth<»u,>uie\(Tnn.lMunro
Deschampsiaelongala(Hook.)Munro
DiiwmnxHicuspnlata(H.Greene)E. Greene
ElatinecalifornicaA.Gray
Eleocharisacivulans(L.)Roemer& Schultes
EleocharismacrastachyaBritton
ElytnusflattensBuckley
Eremocarpussctigerus(Hook.)Benth.
i.ryngiumaristttUitumJepbonvar.aristulatum
FeslucarubraL.
GaliumaparineL.
GeraniumbicknelliiBritton
GeraniumdissectumL.
GlycerinleproslnchvaBuckley
GratiolaebracteataBenth.
HelerocodonrariflorumNutt.
HordeummarinumHudsonsubsp.gussoneanum(Pari.)Thell.
HypoeluiehsglabraL.
IsoeieshoweliiiEngelm.
JuncushufoniusL.
JuncuspatensE.Meyer
JuncustenuisWilld.
JuncusxiphioidesE.Meyer
LastheniacalifornicaLindley
LastbeniaglaberrimaA.DC.
f.cpit'Jictyi'iiripur/ttmiHedu.)Wanisi
Lilaeascilloides(Poiret)Hauman
L<>liuniinuhijlorumLam.
LoliumtemulentumL.
LythrumhyssoptfoHumL.
Madiagracilis(Smiihi Kcxk
MenthapulegiumL.
edouglasii(DC.)Schultz-BiD.
MADRONO
42 [Vol. 46
Table 3. Continued
June- Junc-
tion tion
Hunt- Hunt- Blue- Blue- West- West-
Species ley-96 ley-99 bird-96 bird-99 96 99
iviirriuius guiiuiuj ljk^. 9z 2 2 3
IVIIruUlUS pilOSUS ^DCIHIl.^ o. VValsUIl
Montiafontanel L.
Navarretia intertexta (Benth.) Hook. j 3 z ii
Phalaris aauatica L.
Plagiobothrys bracteatus (T. J. Howell) I. M. Johnston j 2 J"5 Jc
J3/)/; 1//// I Z 1
Poa secunda J. S. Presl
Pogogyne zizyphoroid.es Benth. z 1 z 1I
l uiypugufi iriicirlApiuci rvuiim 11 1
Polypogon monspeliensis (L.) Desf. J 3 3 1
Potamogetonfoliosus Raf.
Psilocarphus tenellus Nutt.
Ranunculus aauatilus L.
Ifx?tsilyfilLulyrii/L'HlLJl1t11iSv IInLlflUhUtllii (\-\\f*VY\\ /AA. CV~J\vi5&\\yI 2 1
2 2 2
O\it11c//>l1t1/;> g(iC/i1l1l1l1C/C/i1 TJ_*.
Sisvrinchium bellum S. Watson
Spiranthespovnifolia Lindley 1 3
optr(Jticiu puiy11m^u. \y^-) ocniciucii z 1
O\ltsc>llllt/llvf~iIfCll fvfyttsctCsliliCsii \(L\~i.J\ \V/il1l1l^idtl"aC
Taeniatherum caput-medusae (L.) Nevski 1
Trichostema laxum A. Gray
Trifolium dubium Sibth.
Trifolium variegatum Nutt. 3 3 2 3
Trisetum canescens Buckley
Triteleia hyacinthina (Lindley) E. Greene 2
Veronicaperegrina L. subsp. xalapensis (Kunth) Pennell 2 1 2 3 1 1
Vulpia bromoides (L.) S. F. Gray 2 2 3 1
Vulpia myuros (L.) C. Gmelin
Zigandenus micranthus Eastw.
Total number ofspecies 29 27 24 24 15 15
(70%) were native species (Appendix 1). Species band and extending toward the pool centers, Er-
richness ranged from 12 at Coon North pool to 45 yngium aristulatum var. aristulatum, Eleocharis
at Hog pool (Table 2). Centunculus minimus L., macrostachya, and Isoetes howellii were common
Crassula aquatica (L.) Schonl, Deschampsia dan- and usually the dominant species (Table 3). Of 27
thonioides (Trin.) Munro, Downingia cuspidata (E. exotic species, Briza minor L., Hordeum marinum
Greene) E. Greene, Elatine californica A. Gray, ssp. gussoneanum, Lolium multiflorum Lam., and
Eryngium aristulatum Jepson var. aristulatum, Gra- Polypogon monspeliensis (L.) Desf. were the most
tiola ebracteata Benth., Isoetes howellii Engelm., abundant, commonly encroaching into the pools
Plagiobothrys bracteatus (T. J. Howell) I. M. John- from the outer margin. Exotic species were rare to-
ston, Pogogyne zizyphoroides Benth., and Ranun- ward the pool centers.
culus lobbii (Hiern) A. Gray, were restricted to ver- There were no significant changes observed in
nal pools in the study area, but absent from other species composition and abundance between the
nearby wetland types. Of these species, Hog pool two sampling periods of 1995-1996 and 1998-
had the highest number (7) compared to Riley and 1999 (Table 3). Although the two winters fell close
Coon North pools, which had none. Eleocharis aci- to the 35 year rainfall average of 947 mm, a wet
cularis (L.) Roemer & Schultes, E. macrostachya late spring and early summer in 1996 lengthened
Britton, Eryngium aristulatum var. aristulatum, the period of inundation by several weeks over
Gratiola ebracteata, Hordeum marinum Hudson those in 1999. Surprisingly, the pool phase was
subsp. gussoneanum (Pari.) Thell., and Plagioboth- shorter after the El Nino winter of 1997-1998,
mm
rys bracteatus had the highest constancies, occur- which produced 1546 ofrainfall (Table 1). Re-
ring in 8 out of 12 pools. Species richness was sults from cover estimates taken in September of
highest in a band approximately 1 meter below the 1997 are shown in Table 4 and reflect the summer
high strand line where a mix of introduced annuals pool vegetation.
and native wetland species occurred. Below this The variables that seem to influence differences
1999] HEISE AND MERENLENDER: MAYACMAS VERNAL POOLS 43
Table 3. Extended Continued
June- Junc-
tion tion Coon Coon Coon Coon Rifle Rifle Twin- Twin-
East- East- Riley- Riley- North-North-South-South- WS- WS- WL- WL- Hog- Hog- Range-Range- ing- ing-
99 99 96 99 96 99 96 99 96 99 96 99 96 99 96 99 96 99
2
2
1
2 1
19 24 29 28 1 1 12 27 30 22 24 15 20 43 40 15 35 32
between pools in this study are pool depth and pro- deepest (115 cm) vernal pool but has a very shal-
file, length of inundation phase, degree of shade, low profile, thus supporting a diverse mix of pe-
and management. Deep pools such as Riley, Coon rennial wetland and vernal pool specialist taxa.
South, Coon North, and Hog experience longer pe- Huntley, Bluebird, Junction West, Junction East,
riods of inundation and often support taxa more Weather Small, Weather Large, Rifle Range, and
typical ofperennial wetlands such as Juncus, Eleo- Twining pools are relatively shallow with wide
charis, and Carex. Riley and Coon South pools are margins and little orno tree canopy. Eryngiumaris-
also steep-profiled with narrow margins, a topog- tulatum var. arisulatum was a dominant species in
raphy that did not support vernal pool specialist both Junction West and Junction East, which lie
plants common on shallow-profiled pools withwide adjacent to each other. Junction East was the deeper
margins. Coon South was the only vernal pool un- ofthe two with /. howellii as a codominant, where-
derlain with a dense mat of the aquatic moss Lep- as Lolium multiflorum codominated in Junction
todictyon riparium. Although Coon North and West. Weather Large and Weather Small, paired
Riley pools are both deep, densely shaded, steep- pools similar in many respects, were both codom-
profile pools, they had little in common floristically. inated by E. aristulatum var. aristulatum and /.
Coon North, which receives heavy sheep use, was howellii. Huntley and Bluebird pools lie within 500
m
essentially devoid of herbaceous vegetation, while of each other at similar elevations and are both
Riley, protected from livestock use since 1956, had codominated by E. macrostachya and E. aristula-
a dense band of Carex subbracteata Mackenzie, tum var. aristulatum. Rifle Range pool was origi-
Eleocharis macrostachya, and Agrostis exarata nally a shallow profile vernal pool with an area of
Trin around its upper perimeter. Both pools lack ca. 1200 m2. Excavation of the fragmented shales
Eryngium aristulatum var. aristulatum and Isoetes that overlay the surface resulted in the creation of
howellii which were characteristic of many of the several small, deep pools, which are dominated by
othervernal pools. Hog is the largest (3069 m2) and E. aristulatum var. aristulatum in the basins and