The Rediscovery and Status of Dissanthelium californicum (Poaceae) on Santa Catalina Island, California

2008·7.5 MB·English

by  Jenny L Mccune

Madrono, Vol. 55, No. 1, pp. 60-68, 2008
THE REDISCOVERY AND STATUS OF DISSANTHELIUM CALIFORNICUM
(POACEAE) ON SANTA CATALINA ISLAND, CALIFORNIA
Jenny L. McCune and Denise A. Knapp'
Catalina Island Conservancy, Conservation Department, P.O. Box 2739, Avalon, CA 90704
Abstract
Dissanthelium californicum (Nutt.) Benth. (Poaceae) is an annual grass known only from Santa
Catalina and San Clemente Islands, off the coast of Southern California, USA, and Guadalupe
Island, off the coast of Baja California, Mexico. It had not been recorded since Blanche Trask
collected it in 1903 on San Clemente Island, and was therefore considered to be extinct, possibly as a
result ofovergrazing by introduced goats on these islands. Duringmonitoring by the Catalina Island
ConservancyfromMarchthroughJuly2005, D. californicumwasdiscoveredgrowingin sevendiverse
andwidely spread locations on Santa Catalina Island. Therediscoverymay bea result oftheremoval
offeral goats and pigs from the island, record-breaking rainfall, and increased exploration ofremote
areas. A revised description of the species and a summary of its habitat preferences are provided.
Thorough monitoring and surveying of known and potential locations will be necessary to better
determine the conservation status ofthe species.
Resumen
Dissanthelium californicum (Nutt.) Benth. (Poaceae) es una graminea anual conocida solo de las
islas SantaCatalinay San Clemente, queseencuentrancercadelacostadel SurdeCalifornia, USAy
de la isla Guadalupe, localizada cerca de la costa de Baja California, Mexico. Esta especie no ha sido
reportada desde que Blanche Trask la colecto en 1903 en la isla San Clemente, y por lo tanto ha sido
considerada como extinta, posiblemente como resultado del sobre pastoreo de cabras introducidas a
las islas. Durante el monitoreo realizado por la organizacion Catalina Island Conservancy en los
meses de marzo ajulio del 2005, D. californicum fue redescubierto creciendo en siete diversas y muy
distantes localidades de la isla Santa Catalina. El redescubrimiento podria haberse dado debido a la
eliminacion delascabrasycerdosdela isla, a lalluvia sinprecedentesyelaumentodeexploracionen
areas remotas. Una descripcion revisada de la especie y un resumen de su preferencia en habitat son
proporcionadas. Riguroso monitoreo e inspeccion de localidades conocidas y potenciales seran
necesarios para una mejor determinacion del estado de conservacion de la especie.
KeyWords: California,Dissanthelium,extinct, GuadalupeIsland,Poaceae, rediscovery, SanClemente
Island, Santa Catalina Island.
Dissanthelium californicum, an annual grass species was an annual grass that had not yet been
first collected and described in the mid-1800s, is described, collected by William Gambel on
known from three islands off the coast of Catalina Island, off the southern coast of
southern Cahfornia and Baja CaHfornia, Mexico. CaHfornia. Nuttall placed the annual grass in a
Last collected in 1903 and subject to severe new genus named Stenochloa, and gave it the
grazing pressures on all three islands, it had been specific epithet californica (Nuttall 1848). Ben-
presumed extinct until its re-discovery in 2005 on tham later transferred it to the genus Dissanthe-
Santa Catalina Island (hereafter Catahna Island). lium, giving it the specific epithet californicum
In this paper, the history of this species is (Hooker 1881).
discussed and new population information is The genus Dissantheliumwas described byC.B.
presented, including a revised description. Cur- Trinius in 1836, and comprises approximately 20
rent conservation actions and concerns are species (Nicora 1973; Swallen and Tovar 1965;
discussed. Tovar 1985; Soreng 1998; Soreng et al. 2003).
Most species grow at high altitudes, usually
Taxonomic and Collection History —4000-5000 m, in the central Andes; one of
these species also grows on the high volcanoes of
Thomas Nuttall, in his presentation to the central Mexico (Swallen and Tovar 1965; Tovar
Academy of Natural Sciences in 1848, described 1985). Dissanthelium californicum is the only
over one hundred plant species collected in the species in the genus found north of the equator
American West (Jercinovic 2004). Among the at elevations near sea level. A recent phyloge-
netics study by RefuHo-Rodriguez has deter-
'Author forcorrespondence, e-mail: dknapp@lifesci. mined that Dissanthelium forms a clade nested
ucsb.edu within the genus Poa (Refulio-Rodriguez 2007).
2008] MCCUNE AND KNAPP: DISSANTHELIUM REDISCOVERY ON CATALINA ISLAND 61
The placement ofD. californicum in the genus 1969; Moran 1996; Ross et al. 1997). Both
was questioned by Hitchcock (1923), who wrote Eastwood (1941) and Dunkle (1950) list D.
that "this species does not appear to be closely californicum as occurring on Santa Cruz and
related to the other two [(Andean) species, the Santa Rosa Islands in addition to the three
only ones recognized at the time], but it does not southern islands, while Dunkle (1950) adds a
seem to be sufficiently different to constitute a northern mainland distribution. However, exten-
distinct genus." Oscar Tovar, an authority on the sive searches for herbarium specimens reveal that
genus, has also questioned the position of D. these reports are unsubstantiated (Wallace 1985;
californicum in the genus (personal communica- S. Junak, Santa Barbara Botanic Garden, per-
DNA
tion). Unfortunately, low sequence varia- sonal communication).
tion within the Dissanthelium clade prevents a full Despite the fact that Catalina Island, San
analysis of the relationships among its species Clemente and Guadalupe Islands have been
(Refulio-Rodriguez 2007). relatively well surveyed by botanists (e.g., East-
Dissanthelium californicum was collected only wood 1941; Millspaugh and Nuttall 1923; Moran
twice more following Gambel's collection; in 1996; Raven 1963; Thorne 1967, 1969), D.
1875 by Edward Palmer on Guadalupe Island, californicum has not been recorded since Trask's
261 km off the coast of Baja California, Mexico collection, and therefore, has been presumed
(Moran 1996), and in 1903 by Blanche Trask on extinct (e.g., CNPS 2001; Smith 1993). It has
San Clemente Island, about 34 km south of been suggested that intense herbivory by feral
Catalina Island (Jepson 1912; Raven 1963). goats {Capra hircus) was the cause of D.
There has been some uncertainty about the californicum's disappearance and the decline of
dates of the collections made by Gambel and other native plants growing on these islands
Trask. The isotype of D. californicum and other (Thorne 1967; Moran 1996). Palmer, following
specimens collected by Gambel deposited in the work on Guadalupe, wrote that it was very
Gray (GH23589, isotype) and Kew herbaria succulent and that goats were very fond of it
(Phillips personal communication) lack a date (Watson 1876). According to Moran (1996), "the
of collection. According to Millspaugh and plants were succumbing fast to the cresting goat
Nuttall (1923), Gambel visited Catalina Island population, and he [Palmer] was just in time to
in February 1847. Elsewhere, however, Gambel is findeightnatives never found on the island again:
reported to have arrived in CaUfornia in Novem- Ceanothus cuneatus, Dissanthelium californicum,
ber 1841 (McKelvey 1955; Graustein 1967), and Hesperelaea palmeri, Micropus californicus,
visited Catalina Island in 1842 (McKelvey 1955). Planta sp., Pogogyne tenuiflora, Ribes sangui-
He remained on the West Coast until 1845, when neum, and Silene antirrhina.''
he returned to Philadelphia in order to enter
medical school (Jercinovic 2004). He had sent his Rediscovery
plant specimens by whaling ship, which did not
arrive until nearly a year after he had returned. In the following description ofour rediscovery
From Philadelphia, he sent the collection to ofD. californicum, the termpopulation refers to a
Nuttall in England for identification, which distinct cluster of individual plants. An occur-
explains the delay between Gambel's collection rence, as per the CaHfornia Natural Diversity
and Nuttall's paper (Graustein 1967; Jercinovic Database (Bittman 2001), consists of all popula-
2004). Thus D. californicum was first collected tions found within 0.4 km ofeach other.
between 1841 and 1845. Biologists from the Catalina Island Conser-
In Smith's treatment ofD. californicum in The vancy (i.e., "the Conservancy") have been
Jepson Manual: Higher Plants of California, the studying and monitoring plant communities on
last known collection of the species, taken by the island in an effort to learn how they are
Trask, is said to be 1912 (Smith 1993). However, recovering from many years of overgrazing and
Raven (1963) does not mention any trips by how they may be further protected and restored.
Trask to San Clemente after 1903. We examined On March 29, 2005, during yearly monitoring of
one of Trask's specimens {Trask 324, PH recently burned Island chaparral/coastal sage
469621), and the year 1903 is penciled in on the scrub habitat near Catahna Island's airport (the
label, along with the word "common." We could "Airport Burn"), a single individual of D.
find no evidence that Trask or anyone else californicum was found growing within a large
collected D. californicum after 1903, and conclude patch of Malacothamnusfasciculatus (Torrey &
that the 1912 sighting reported by Smith (1993) is A. Gray) E. Greene (Occurrence 1, Figs. 1 and 2).
an error. In the spring of 2005, we also began a project
Dissanthelium californicum is known from characterizing the Quercus pacifica Nixon &
Catalina and San Clemente Islands off the coast C.H.Mull. communities on the island, which
of California, USA, and Guadalupe Island off brought us to many seldom-visited areas of the
the coast ofBaja CaUfornia, Mexico (Millspaugh island. During these surveys in April, we discov-
and Nuttall 1923; Raven 1963; Thorne 1967, ered three additional populations ofD. californi-
.
62 MADRONO [Vol. 55
In mid-July, we found three additional occur-
rences within Quercus pacifica plots. The first
consisted of four populations in the eastern
section of the island near the town of Avalon,
totaling 75 individuals (Occurrence 5, fig. 2). The
second consisted of one population of four
individuals, and the third consisted of one lone
individual (Occurrences 6 & 7, Fig. 2); both
occurrences are near the isthmus in the north-
western section ofthe island. These finds brought
the total to approximately 678 individuals in 17
populations and seven occurrences (Fig. 2).
Dissantheliumcalifornicumoccured onavariety
ofaspects, elevations, and slopes and had a range
of associated species (Table 2). The aspect of D.
californicum locations ranged from northerly
through easterly to south-southeasterly slopes,
and in elevation ranged from approximately
137 m to 290 m. It was found predominantly in
Island chaparral habitat, but also in areas where
oFing.fir1s.t noDteitcaiinlgoDf.tchaeliifnofrlnoirceusmceinnceOcfcruargrmeennctec1o.lPlehcotteod this habitat intergrades with coastal sage scrub.
by Jenny L. McCune.
Revised Description
cum: one of approximately 60 plants on the Dissanthelium californicum shows some plastic-
easR1aoen0suf0Udttupehalrownitnenodws-sothRi2eedo5eardsrnireoinipfdngpaiguotrverhtaiezthdti,eueioadnsnllJes.awobn(sfdyTOorc(tfachOavuoecbirucosrruiuesrtdnlCriaceosnenlcd8c,ou03ev,menmbr2Fu,yuimg,sF.bi,Nineg2ar.)n.aitc2nnh)ydge, ifhsssthtauryeasnomdimsenitf,,1ritti0aoetsnnmcicddshmsauoirstnnoauoefcraltlhoellatrreyoivesssseatcsiteabecnorsvcri.eeaegrshdaT.mtdlhiaEgesxrafhelcpieotlhmnwia,unenigrtmbneiudnhitiogevnfiiigtnds6hhut0tteaahllcelrkmesapo.a.nlvpgaeeeIInsnsn,nt
Susan Jett (Rancho Santa Ana Botanic Garden, general, the stalkswereerect, but some, especially
hcBoeolrtleaeancfitticenrgGRatSrriAdp)et,no,atnhhdeeriSesatlfeatvneedrJfuSrnBoamBkGM)(aSyacnot2nandduBcattroeb4datrhaa, ienndDsihsoasfdaeMn,tahtreeclnhiduemwdhcteaolnibfweoerdneifcicruusmmtbwoeabnsste.frlvoewderiit,nganatdtbhye
2005,duringwhichadditionalplants, populations, the beginning of May some seed was already
andoccurrenceswerediscovered. AtOccurrence 1, mature. By mid- to late- May, most florets had
we counted approximately 140 plants in the fallen, and the plants discovered after May had
vicinity ofthe first discovery (Fig. 2), within three turned tan in color with only empty glumes
populations. Columbus and colleamgues also dis- remaining. The new collections of this plant
covered a population about 500 away (just (along with inspection of previously existing
outside of the burn area), consisting of approxi- collections) have given us an opportunity to
mately 70 individuals (Occurrence 4, Fig. 2). produce a revised description, below.
Additionally, we discovered 110 individuals in Dissanthelium californicum (Nutt.) Benth.
two new populations at Occurrence 2 and two California Dissanthelium. Annual Stem
more small populations at Occurrence 3, totaling 6-46 cm. Leaf: blade flat, 6-20 cm, 1-4 mm
23 plants. Smallamountsofseedwerecollectedby wide, smooth, ligule membranous. Inflorescence
tahnedCRoSnsAe(rAvcacnecsysi(oAnccneusmsbieornsn2u1m8b9e0r-s211839347)-t1o34u0s)e f<asc1i.c6leds,m;sopmaneicolfe tnhaermrofwlotroifoerpoeuns,tboratnhcehebsasei.n
for germination testing, storage, and restoration. Spikelet florets 2(3), green to occ. reddish-purple,
We collected voucher specimens from Occur- 2.5-5 mm, equal; glumes narrow, acute, glabrous
rences 1-3 {McCune /, 2 and 3 respectively), or minutely scabrous on the keel toward the tip,
duplicates ofwhich are deposited at the Wrigley nearly equal, lower glume 3-veined, upper glume
SBoBtBanGicarlespGeacrtidveenly.onReCfautlailoi-naRoIdsrliagnude,zRScoAl,lecatnedd h1a-ivreyi,nedo;btugsleumetos a>cutef.lorOetps;enletmomfaull1.s5h-a2demmo,f
a voucher from Occurrence 4 {Refulio 238) and Island chaparral and coastal sage scrub; <500 m.:
deposited it at RSA. Searches ofGuadalupe and sChI (Santa Catalina, San Clemente Islands);!
SanClemente Islandsin2005didnotrevealanyD. Baja CA (Guadalupe Island).
californicum populations (Refulio-Rodriguez per- —
sonal communication). A summary ofall known Refs. Dissanthelium californicum (Nutt.)
herbarium specimens is presented in Table 1 Benth.
2008] MCCUNE AND KNAPP: DISSANTHELIUMREDISCOVERY ON CATALINA ISLAND 63
Fig. 2. MapshowingallsevenoccurrencesofD. californicumfoundonCatalina Islandbetween theend ofMarch
and July of2005. Numbers ofindividuals are estimates.
MADRONO
64 [Vol. 55
Table 1. FloristicDocumentationofD. Californicum. The 1912datelisted in Hickman (1993) appearsto
be an error, and is revised here as 1903.
LocaHty Voucher Date Frequency and distribution
W
USA: CA, Santa . Gambel s.n. (GH) ca. 1841-1845 Unknown
Catalina Island
iviJiA.n^vj. ouaoaiupe li. Proa1mi<m=>etr- vOoA (^iN>TVi»j 11O87/^J On warm rocky slopes m the
Island. middle ofthe island; not
Guadalupe E. Palmer 96 (GH) 1875 veryabundant;very succulent
Guadalupe E. Palmer 96 (CM #268852) 1875 and the goats are very fond
Guadalupe E. Palmer 96 (MO) 1875 ofit (Watson 1876)
San Clemente B. Trask 324 (US #469621) 1903 ''common"
Santa Catalina J. McCune 1-3 (RSA) May 2005 Infrequent. Plant found in
Santa Catalina N Refulio-Rodriguez 238 (RSA) May 2005 seven locations on the
Santa Catalina J. McCune 1-3 (SBBG) May 2005 island (17 populations.
Santa Catalina J. McCune 1-3 Wrigley Memorial May 2005 678 individuals)
Botanical Garden, Avalon, CA.
Table2. SiteCharacteristicsatD. CalifornicumLocationson Santa Catalina Island. Elevationsfor
all occurrences are approximate. Slope for Occurrence 4 is estimated.
OCC # UTM ASP. Slope Elev.(m) Habitat Substrate and associated species
1 366902E 87" 5^ 260 Island chaparral Bare ground in part shade ofMalacothamniis
3695747N fasciculatus, with Quercuspacificcu Bromus
madritensis, Polypogon interruptus,
Chenopodium californicum, Opuntia
littoralis.
2 371275E 130° 27^ 137 Island chaparral/ Leafhtter or soil with large rock outcrops in
3695273N coastal sage full or part shade of Q. pacifica or Salvia
scrub mellifera, with Bracliypodium distachyon,
Bromus madritensis, Eucrypta
chrysanthemifolia, Melica imperfecta,
Opuntia littoralis.
3 363801E 340° 34° 182 Island chaparral/ Soilornearlargerock outcropsintheopenor
3691475N coastal sage in part to full shade ofHeteromeles
scrub arbutifolia, with Salvia mellifera,
Polypodium californicum, Trifolium
willdenovii, Melica imperfecta, Bromus
madritensis, Bromus hordeaceous, Daucus
pusillus, Galium nuttallii, Rhus integrifolia,
Avena harbata, Vulpia sp.
4 367374E 157° 5^ 274 Island chaparral/ Moist soil in full or part shade ofRhus
3695702N coastal sage integrifolia, with Salvia mellifera,
scrub Malacothamnusfasciculatus. Antirrhinum
nutallianum, Phacelia cicutaria,
Gnaplialium sp., Solanum sp., Chenopodium
californicum, Opuntia littoralis, Polypogon
sp., Desmazeria rigida, Brachypodium
distachyon, Piptatherum miliaceum.
5 362599E 10° 22° 213 Island chaparral Leaflitterorsoilwith rock outcrops in full or
3700121N part shade ofQ. pacifica, Rhus integrifolia,
or Crossossoma californica, with Bronnis
madritensis, Gastridium ventricosum,
Melica imperfecta.
6 374542E 145° 32' 251 Island chaparral Moist soil, quite bare, in full shade of Q.
3691983N pacifica, Rhus integrifolia and Cercocarpus
betuloides, with Melica imperfecta.
7 362947E 0° 26' 290 Island chaparral Leaflitter in part shade of Q. pacifica, with
3700121N Opuntia littoralis, Bromus madritensis,
Brachypodium distachyon, Sonchus asper.
2008] MCCUNE AND KNAPP: DISSANTHELIUM REDISCOVERY ON CATALINA ISLAND 65
Swallen & Tovar. Phytologia 11: 361-376. 1965. Atkinson 1989; Schofield 1989; Bowen and Van
Benth. in Hook. Icon. PI. III. 4: 56. pi 1375. Vuren 1997; Oberbauer 2005). Native plants and
1881. Based on the next. animals may recover rapidly with the release of
Steiwchloa califoniica Nutt. Journ. Acad. Phila. this pressure (Wehtje 1994; Laughrin et al. 1994;
II. 1:189. 1848. Type from Santa Catalina Chess et al. 2000), depending on environmental
Island, Gaiubel. factors such as water availability (Donlan et al.
2002). On Guadalupe Island, six plant species
presumed extinct and other rare pine seedlings
DlSSCUSSION
reappeared following goat removal (Krajick
Three factors may have contributed to the 2005).
rediscovery ofD. califonncum on Catalina Island Feral goats were reported on San Clemente
after having been unrecorded for more than a and Catalina Islands by the early 1800s (Dunkle
century. First, it seems likely that D. californiciniu 1950; Raven 1963), and thrived until systematic
like many other island plants, has responded to eradication programs began in the 1970s on San
the record rainfall in 2004-2005, making it more Clemente Island (Moran 1996) and in 1990 on
abundant and conspicuous than in previous Catalina Island (Schuyler et al. 2002). Currently,
years. Second, the removal of feral goats and few or no goats remain on either island. It is
pigs has relieved grazing and rooting pressures. unknown when goats were first introduced on
Finally, the initiation of our project to charac- Guadalupe, but the goat population peaked at
terize the oak communities on Catalina Island more than 100,000 in 1870. By 1994, the
brought us to many rarely explored areas. population had been reduced to 7000 (Moran
The island received 68.1 cm of rainfall during 1996), and today, nearly all goats have been
the 2004—2005 season (averaged across Avalon, removed (Island Conservation 2007).
Middle Ranch, Airport-in-the-Sky, and Two Other introduced animals on Catalina Island
Harbors), which was significantly greater than that have posed a threat are feral pigs {Sus
the mean (Conservancy data: 29.8 cm, averaged scrofa), mule deer {Odocoileus hcmionus), and
across four to six sites from 1948 2005) and the American bison {Bison bison). Rooting distur-
highest rainfall recorded to date. This factor bance by feral pigs decreases plant productivity
likely contributed to the germination, abundance, and may disturb over 65% of the land in areas
and robustness of D. califovuicwu that year. The with high pig densities (Sweitzer and Van Vuren
response of D. califovnicuiii populations to 2002); they have contributed to the extinctions of
rainfall was further indicated by 2006 survey numerous oceanic island species (Waithman et al.
data: after below-average rainfall (24 cm from 1999). Although mule deer are primarily brows-
July 2005 through June 2006), surveys offour out ers, grasses comprise between 21% (December-
of seven of the known population sites did not January) and <1% (June-July) of their diet on
reveal any plants. Catalina Island, and their population on the
It is unclear ifD. califoruiciuu has seed that can 48,000-acre island isestimated at 2341 individuals
persist in the soil for years. Generally, grass seed (range: 1682-3259) (Manuwal and Sweitzer 2007;
does not persist as long in the soil as seeds of T. Manuwal, University of North Dakota,
forbs, but annuals are more likely than perennials unpublished data). Introduced bison on Catalina
to form a seed bank (Rice 1989 and references Island alter plant communities by grazing,
cited therein; Thompson et al. 1998). Although foraging, trampling, and wallowing, and have
many annual grasses have very short-lived seeds been found to facilitate the dispersal of non-
(i.e., 1-3 yr) (Zorner et al. 1984; Roberts 1986; native plants (Sweitzeret al. 2003; Constible et al.
Thompson 1987; Russi et al. 1992; Masin et al. 2005). Trampling by bison and deer was found to
2006), multiple species of Poa (both annual and negatively impact oak seedlings on the island
perennial) have been found to have more (Manuwal and Sweitzer 2007). Their diet is
persistent seeds (Roberts 1986; Thompson composed of approximately 84% grasses; they
1987). Results from germination trials by RSA appear to have the positive effect of reducing
suggest that D. califoriucwu seeds do not possess non-native annual grass cover, although their
physical dormancy mechanisms, as they obtained input of nutrients may also encourage annual
35% germination in 2006 by pre-treating the grass growth (Sweitzer et al. 2003).
seeds with only a 24-hour water soak (M. Wall Management ofthese introduced herbivores is
personal communication). being addressed by the Conservancy. The major-
Introduced herbivores may have greatly re- ity ofthe feral pigs were eradicated by the end of
duced the abundance and distribution of D. 2004; there are currently 14 animals estimated
caUfornicwn. Introduced ungulates have particu- remaining, and the Conservancy continues its
larly severe impacts on island ecosystems, where efforts. Bison herds are managed to between 150
endemic plants lack defenses against herbivory, and 200 individuals. Mule deer have been
and are a major cause of island extinctions (e.g., harvested almost annually on Santa Catalina
Coblentz 1978; Vitousek 1988; Adsersen 1989; Island from 1949 through the present, currently
MADRONO
66 [Vol. 55
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Acknowledgments PSW-12, U.S. Forest Service, Albany, CA.
CoTlhuembuausthaornsd wNoaunlcdy liRkeefutloio-tRhoadnrkigDure.z Jf.orTrtahveiisr Da ISnitlevraa,ctiPo.n bGe.twaenend aJ.shWr.ub,BaBractcollmorimse.pili1i9ki8r4i.s
subsp. consangitinea (Asteraceae) and an annual
enthusiasm and assistance in researching and reviewing
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