INVASIVE EUROPEAN ANNUAL PLANTS IMPACT A RARE ENDEMIC SUNFLOWER

2011·7.8 MB·English

by  Jolene R Moroney

31
VOLUME 58, NUMBER 2 APRIL-JUNE 201
1
H
1^3
>
Bc>T
/ J "•vv >'
jm s ' I t
I
Invasive EuropeanAnnual Plants Impact a Rare Endemic
Sunflower
JoleneR. Moroney, PaulaM. Schiffman, and ChristyA. Brigham 69
Pollen Siring Success in the CaliforniaWildflower Clarkia
UNGUICULATA (ONAGRACEAE)
NancyL. Smith-Huerta andFrank C. Vasek 78
Smaller Olea europaea Fruits have More Potential Dispersers:
Implications for Olive Invasiveness in California
Clare E. Aslan andMarcelRejmanek 86
Systematics, Phylogeny, and Evolution ofPapaver californicum
and Stylomeconheterophylla (Papaveraceae)
Joachim W. KadereitandBruce G. Baldwin 92
Morphological Comparisons ofWhite Fir and Red Fir Dwarf
Mistletoes in the Sierra Nevada and Southern Cascade
Mountains
RobertL. Mathiasen 101
Is Cylindropuntia xfosbergii(Cactaceae) a Hybrid?
MichaelS. Mayer, Anastasia Gromova, Kristen Hasenstab-Lehman,
MollyLippitt, Mia Barnett, andJon P. Rebman 106
GabbroSoilsandPlantDistributionson Them
EarlB. Alexander
1 1
FurtherFloristics on LateTertiary Lacustrine Deposits in the
SouthernArizona Deserts
John L. Anderson 123
Erratum 129
———
2
Madrono(ISSN0024-9637)ispublishedquarterlybytheCaliforniaBotanicalSociety,Inc.,andisissuedfromthe
officeoftheSociety,Herbaria,LifeSciencesBuilding,UniversityofCalifornia,Berkeley,CA94720.Subscription
informationoninsidebackcover.Established1916.PeriodicalspostagepaidatBerkeley,CA,andadditionalmailing
offices.Returnrequested.Postmaster: SendaddresschangestoMadrono,KimKersh,MembershipChair,Uni-
versityandJepsonHerbarium,UniversityofCalifornia,Berkeley,[email protected].
— —
CorrespondingEditor TimothyLowrey CopyEditor RichardWhitkus
M—useumofSouthwesternBiology DepartmentofBiology
MSC032020 SonomaStateUniversity
UniversityofNewMexico 1801 E.CotatiAvenue
Albuquerque,NM87131-0001 RohnertPark,CA94928-3609
[email protected] [email protected]
—
BookEdi—tor JonE.Keeley
NoteworthyCollectionsEditors DieterWilken,MargrietWetherwax
BoardofEditors
Classof:
2011 JamieKneitel,CaliforniaStateUniversity,Sacramento,CA
KevinRice,UniversityofCalifornia,Davis,CA
2012 GretchenLeBuhn,SanFranciscoStateUniversity,CA
RobertPatterson,SanFranciscoStateUniversity,CA
2013 EricRoalson,WashingtonStateUniversity,WA
KristinaSchierenbeck,CaliforniaStateUniversity,Chico,CA
2014 BrandonPratt,CaliforniaStateUniversity,Bakersfield,CA
TomWendt,UniversityofTexas,Austin,TX
CALIFORNIABOTANICALSOCIETY,INC.
Officersfor2011-201
President: V.ThomasParker,DepartmentofBiology, SanFranciscoStateUniversity, SanFrancisco,CA94132,
[email protected]
FirstVicePresident: AndrewDoran,UniversityandJepsonHerbaria,UniversityofCalifornia,Berkeley,CA94720,
[email protected]
SecondVicePresident:MarcLosHuertos,DivisionofScience&EnvironmentalPolicy,CaliforniaStateUniversity,
MontereyBay,Seaside,CA93955,[email protected]
Recording Secretary. Mike Vasey, Department ofBiology, San Francisco State University, San Francisco, CA
94132,[email protected]
CorrespondingSecretary. HeatherDriscoll,UniversityHerbarium,UniversityofCalifornia,Berkeley,CA94720,
[email protected]
Treasurer: ThomasSchweich,CaliforniaBotanicalSociety,JepsonHerbarium,UniversityofCalifornia,Berkeley,
CA94720,[email protected]
TheCounciloftheCaliforniaBotanicalSocietycomprisestheofficerslistedaboveplustheimmediatePastPresident,
DeanKelch,JepsonHerbarium,UniversityofCalifornia,Berkeley,CA94720,[email protected];theMembership
Chair,KimKersh,UniversityandJepsonHerbaria,UniversityofCalifornia,Berkeley,CA94720,kersh@berkeley.
edu;theEditorofMadrono;andthreeelectedCouncilMembers:ChelseaSpecht,DepartmentofPlantandMicrobial
Biology,UniversityofCalifornia,Berkeley,CA94720-2465,[email protected];EllenSimms,Department
ofIntergrativeBiology, 3060ValleyLife Sciences Bldg., #3140, University ofCalifornia, Berkeley, CA94720,
[email protected]. Staci Markos, University and Jepson Herbaria, University ofCalifornia, Berkeley, CA
94720,[email protected]:BenCarter,DepartmentofIntegrativeBiology
andUniversityHerbarium,UniversityofCalifornia,Berkeley,CA94720,[email protected]:Susan
Bainbridge,JepsonHerbarium,UniversityofCalifornia,Berkeley,CA94720-2465,[email protected].
®
This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).
Madrono, Vol. 58, No. 2, pp. 69-77, 2011
INVASIVE EUROPEAN ANNUAL PLANTS IMPACT A RARE
ENDEMIC SUNFLOWER
JOLENE R. MORONEY1 AND PAULA M. SCHIFFMAN
Department of Biology, California State University, 18111 Nordhoff Street,
CA
Northridge, 91330-8303
[email protected]
Christy A. Brigham
Santa Monica Mountains National Recreation Area, 401 West Hillcrest Drive,
Thousand Oaks, CA 91360
Abstract
Pentachaeta lyonii A. Gray is a state- and federally-listed endangered species, endemic to heavily
invaded southern California grasslands. Recent population extirpations resulting in a decrease in
range size have prompted investigation into the effects ofinvasive annual plants on this species. The
goals ofthis studywere(1) toexaminetheimpacts ofcompetitionfromnon-nativespeciesfromthree
different functional groups (annual grasses, early-season forbs, and late-season forbs) on P. lyonii
success in the field and in pots, (2) to determine which non-native species/functional groups have the
greatest competitive effect on P. lyonii, and (3) to evaluate the environmental conditions that
contribute to the displacement ofP. lyonii by non-native plants. In the field, at two sites over two
years, control plots were paired with plots in which non-native competitors were clipped at the soil
surface. In pots, individual P. lyoniiplants were grown in competition with all three groups ofnon-
nativecompetitorsatbothhighandlowdensity. Inboththefield andinthepots, allthreenon-native
plant groups had negative effects on P. lyonii reproductive potential, with Centaurea melitensis L.
havingthegreatesteffect. Theeffects on P. lyoniiheightwerevariable amongnon-nativecompetitors
and between years. Comparisons made of environmental features ofsites where P. lyonii has been
extirpated to those where it persists suggested that the presence ofannual grass is associated with P.
lyonii extirpation. Management of P. lyonii presents a challenge considering the tendency of this
species to coexist with non-native annual plants due to their common disturbance-dependence, and
the ubiquity ofEuropean annuals in P. lyoniihabitat.
KeyWords: Californiagrassland, competition, conservation, endangered species, non-nativeinvasive
plants, Pentachaeta lyonii rare plants, restoration.
,
Pentachaeta lyonii A. Gray (Asteraceae) is a In the case of a rare endemic such as P. lyonii,
state and federally listed endangered species which has already lost at least 45% of its
endemic to southern California grasslands populations in recent decades, and with the
(Fotheringham and Keeley 1998). Following its remaining populations geographically isolated
extirpation at sites in the southern part of its by fragmentation, competitive pressures could
range, P. lyonii became restricted to 21 popula- contribute to local declines and possibly to its
tions in the Santa Monica Mountains and Simi ultimate extinction.
Hills, persisting entirely within the increasingly Annual surveys done by the National Park
suburban northern Los Angeles and southern Service of both P. lyonii numbers and the
Ventura counties. Historically, P. lyonii had a presence of invasive species have indicated a
wider distribution in the Los Angeles basin, possible relationship between invasion and de-
Santa Catalina Island, and San Diego (Hickman clines, but no competition studies have been done
1993), but as many as 15 populations have been previous to the present work. Invasive species do
extirpatedwithin recent decades, andmany ofthe play an important role in native species diversity
remaining populations appear to be in decline declines (Hobbs and Mooney 1998; Simberloff
(Brigham 2007). The U.S. Fish and Wildlife 2005). Impacts include the alteration of ecosys-
Service (1999) recovery plan for P. lyonii tem functioning (Evans et al. 2001), altered
identifies competition from invasive non-native disturbance regimes (Brooks et al. 2004) and
plants as a possible cause ofthe species’ decline. competition for resources (Dyer and Rice 1997;
Eliason and Allen 1997; Brooks 2000). Rare
native plants can be particularly vulnerable to
1Present address: Department of Ecology and Evo- competition from invasive plants (Huenneke and
lutionary Biology, University of California, Los An- Thomson 1995; Walck et al. 1999; Miller and
geles, 621 Charles E. Young Drive South, Los Angeles, Duncan 2003; Kingston et al. 2004; Thomson
CA 90095-1606. 2005; Corbin et al. 2007), especially those species
MADRONO
72 [Vol. 58
LO
-CQD
E
ZC3
CO
o
E
0) CO _
CE I
Grass Erodium Centaurea
COMPETITOR
Fig. 1. Differences in number ofinflorescences on P. lyoniiplants between paired field plots. Pairs consisted of
non-native competitors removed, and competitors present. Results are shown fortwo different seasons. Boxplots
arecenteredatthemedian,andwhiskersindicatetheoctiles. Pairedt-testsshowedsignificantdifferencesinallcases
(P < 0.01).
Centaurea and grasses, (P < 0.05), but not taller than those in plots with competitors
significant between Centaurea and Erodium (P removed (P < 0.01, Fig. 2). In 2004, P. lyonii
= 0.5688). Grasses and Erodium did not differ plants growing without competition from Cen-
significantly in their competitive effects on P. taurea were marginally taller than those in
lyonii inflorescence number (P = 0.1426). control plots (P = 0.064, Fig. 2). Annual grasses
Effects from competition on height ofP. lyonii had a greatereffect on P. lyoniiheight in the field
differed among the non-native functional groups than Centaurea or Erodium (P < 0.05).
and between years (Fig. 2). In four of the six
cases, differences in height were not significant Pot Competition Experiment
for competition vs. no-competition plants. Sig-
nificant differences were found between treat- Under the more controlled research conditions
ments in Erodium plots in 2004, where those ofthe pot experiment, competition from all non-
released from competition grew taller than those native groups had a negative effect on P. lyonii
in control plots (P = 0.01, Fig. 2). In contrast, in reproductive potential. Pentachaeta lyonii plants
2005, plants competing with annual grasses grew produced significantly fewer inflorescences when
Grass Erodium Centaurea
COMPETITOR
Fig. 2. Differences in height (mm) ofP. lyonii plants between paired field plots. Pairs consisted ofnon-native
competitorsremoved, andcompetitorspresent. Resultsareshownfortwodifferentseasons. Boxplotsarecentered
at themedian, and whiskers indicate the octiles. Asterisks indicatecases inwhichpaired t-tests showed significant
differences between treatments.
2011] MORONEY ET AL.: EUROPEAN ANNUALS IMPACT A RARE ENDEMIC 73
a
I
Control Grass Erodium Centaurea
COMPETITOR
Fig. 3. NumbersofinflorescencesonP. lyoniiplantsgrowninpotswithdifferentnon-nativecompetitorsgrowing
atbothhighandlowdensity,comparedwithP. lyoniiplantsgrowninpotswithoutcompetitors(control). Boxplots
are centered at the median, and whiskers indicate the octiles. Different letters above the plots indicate significant
differences (Tukey HSD).
grown in pots with non-native competitors at were good predictors ofP. lyoniiextirpation (P <
both low and high densities compared with 0.05 in all cases, Fig. 5). Nonmetric multidimen-
control plants grown without competition (P < sional scaling yielded a final stress2 of 0.33747.
O.001, Fig. 3). Pentachaeta lyonii plants grown All of the environmental variables that were
with Erodium or Centaurea at low density had correlated with whether the population at a site
more inflorescences than those growing with was extant or extirpated had r2 > 0.2 except for
Erodium or Centaurea at high density, or those volumetric water content and percent cover of
growing with annual grasses (Fig. 3). Similarly, Centaurea. Therewas a clear separation ofextant
P. lyonii plants growing without competition from extirpated sites (along the horizontal axis).
(control) were significantly taller than plants The factors that were most positively correlated
growing in competition with all three non-native with sites supporting extant populations of P.
species groups, both at high and low densities lyonii were percent cover of Erodium PAR and
(P < 0.001, Fig. 4). With all three invasive com- percentbareground. Amount oflitter,and annual
petitors, P. lyoniiplants competingin low-density grasses were the most negatively correlated with
pots were taller than those in high-density pots; sites with extant populations (Fig. 6).
however, thesedifferenceswere onlysignificantin
the Erodium group (Fig. 4). Discussion
Comparison ofExtant Versus Extirpated Sites This study addressed the direct effects of
competition from three different functional
The logistic regressions suggested that high groups of non-native plants on P. lyonii and
,
cover of litter, annual grasses, and non-native the factors possibly contributing to its extirpa-
plants other than those in our target groups, as tion. Competition from all three groups of non-
well as low cover of Erodium and bare ground native plants reduced the reproductive potential
I I Highdensity
T I I Lowdensily
^E o- s
E
Control
COMPETITOR
Fig. 4. Heights ofP. lyoniiplants grown in pots with different non-native competitors grown at both high and
lowdensity,comparedwithP. lyoniiplantsgrowinginpotswithoutcompetitors(control). Boxplotsarecenteredat
the median, and whiskers indicate the octiles. Different letters above the plots indicate significant differences
(Tukey HSD).
MADRONO
74 [Vol. 58
Fig. 5. Comparison ofthe composition ofsites where P. lyonii is extant and sites where it is extirpated.
of P. lyonii and the presence of annual grasses difference between years in available soil mois-
,
not only resulted in direct competitive interac- ture. 2004—2005 was an exceptionally wet year
tions, but also was implicated as an indirect (56 cm above average), with four times more
factor contributing to P. lyonii extirpation. rainfallthan in 2003-2004. Evenwith anexcess of
a potentially limiting resource, competitive inter-
Direct Effects ofCompetition ference from non-native plants significantly
reduced the reproductive output of P. lyonii.
The competitor removal experiment took place This indicated that these invasive plants have a
over two field seasons with very different superior ability to capture other important
environmental conditions (2003-2004 and 2004— limiting resources (perhaps nutrients, space,
2005), and examined two possible indicators of and/or light). These results were corroborated in
competitive effects on P. lyonii number of the pot competition study, where growing condi-
:
inflorescences produced and plant height. Effects tions were more controlled, and water was
of competition on the number of inflorescences generously provided. The reduction in number
remainedconsistent overbothfield seasonsforall of inflorescences across the board indicated that
three invasive plant groups, despite the large at least three non-native plant groups that
Axis1
Fig. 6. Nonmetric multidimensional scaling ofenvironmental variables. Ordination rotated so Axis 1 correlates
maximallywithextant (unfilled triangles) versusextirpated (filledtriangles) sites. The lengths anddirections ofthe
vectors indicate the strengths and directions ofthe correlations with the axes.
2011] MORONEY ET AL.: EUROPEAN ANNUALS IMPACT A RARE ENDEMIC 75
commonly occur in P. lyonii habitat negatively ogy. The bulk oftheir reproductive efforts occur
impact fecundity, potentially reducing time to as, or even after, annual grasses and Erodium are
extinction. completingtheirs. Two co-occurringplant species
The impacts of competition on plant height with similar phenologies and morphologies
were less clear. In both seasons P. lyonii plants would be expected to compete for, rather than
growing in the field in competition both with partition resources (Dukes 2002). Another inva-
Centaurea and Erodium were shorter than those sive species of Centaurea (C. solstitialis L.) has
in plots where competitors were removed. The been shown to increase late-season evapotrans-
opposite was true for P. lyonii plants growing in piration in the communities it has invaded
competition with grasses. This may reflect (Dukes 2001). Centaurea melitensis may, similar-
differences in root morphology between grasses ly, deplete water more efficiently than P. lyonii,
and forbs. The forbs, Pentachaeta Centaurea and resulting in reduced late-season resource avail-
Erodium possess taproots, where,as the grasses ability, when water becomes more limiting, and
have fib,rous root systems. These rooting differ- ultimately reduced reproductive capacity.
ences may cause interspecific variation in the Differences in the phenologies of annual
ability ofplants to accessbelow-ground resources grasses, Erodium, and Centaurea could subject a
and thereby affect aboveground growth and P. lyonii individual to competition early in
competitive dynamics (Gurevitch et al. 2006). development (annual grasses and Erodium) as
They may also account for the difference in well as later during flowering (Centaurea).
effects between wet and dry years. Height Depending on the species composition of the
differences were greater in the forb groups in immediate neighborhood of a P. lyonii plant,
2003-2004, when soil moisture was more limited, competitive pressure could affect an individual
than in 2004—2005 when it was more abundant. plant throughout its life cycle.
Functional group phenologymaycontribute to
differences in height response between P. lyonii Environmental Factors Associated
competing with forbs and P. lyonii competing with Extirpation
with grasses. Both Centaurea and non-native
grasses typically grow taller than P. lyonii (Hick- In the absence of outright destruction of
man 1993), and can potentially reduce available habitat, it is difficult to be certain of the causes
light. However, the grasses gain height earlier in of local extinction of this species, but compari-
the season than Centaurea which spends its first sons of sites with extant populations and sites
,
few months as a basal rosette and then matures with extirpated populations can identify environ-
later in the season. Erodium also grows rapidly mental factors correlated with extirpation. The
early in the season, but it is generally of shorter three variables that were the best predictors of
stature than P. lyonii (Hickman 1993), and likely extirpation were related. Percent cover ofannual
does not significantly reduce the light available to grasses, percent cover of litter, and low percent
P. lyonii plants. The large height difference in cover of bare ground are all associated with P.
grass plots between taller P. lyonii plants in lyoniiextirpation, and with annual grass invasion
control plots and shorter ones in plots from and dominance. The persistence oflitter in some
which competitors had been removed in 2004— annual grass species can reduce open patches of
2005 may have been due to the abundance of bare ground through the winter rainy season,
rainfall that year. Greater moisture availability when germination of P. lyonii takes place. The
likely resulted in exceptionally fast growth rates light and moisture conditions at ground level can
ofgrasses, causing P. lyonii plants to elongate to be drastically altered under a layer ofgrass litter,
compensate for early reduction in available light. possibly precluding germination ofP. lyonii. The
However, this response does not necessarily association of these three variables suggest that
indicate superior performance. Shorter P. lyonii grasses are not only important direct competitors
plants that were growing without competition with P. lyonii as indicated in the competitor
,
from grasses produced more inflorescences than removal experiment, but also cause indirect
tall plants growing with competition, indicating a competitive pressures strong enough to displace
trade-offin resource allocation. the species locally.
None of the invasive species had a greater Aside from the implication of annual grass
effect on P. lyonii reproduction or height than presence as a factor in local extirpation of P.
any of the others in the pot competition lyonii it is interesting to note the unexpected lack
,
experiment, but in the field experiment competi- of correlation of C. melitensis, and the negative
tion from Centaurea suppressed inflorescence correlation of Erodium spp. presence with P.
production more than Erodium and significantly lyonii extirpation. The percent cover of C.
more than annual grasses did. Centaurea meli- melitensis was not correlated with sites with
tensis and P. lyonii are both late-season annuals either extant or extirpated populations of P.
with basal leaf rosettes and taproots, sharing lyonii. Considering the magnitude ofthis species’
functional traits in both phenology and morphol- negative effect on P. lyonii reproduction, its co-
MADRONO
76 [Vol. 58
occurrence with P. lyoniimay not be as common systems (Keeley 1990; Schiffman 2000, 2007),
as the co-occurrence of P. lyonii with annual contributing greatly to their biodiversity (Kim-
grasses. It may be a much newer phenomenon, as ball and Schiffman 2003). In some heavily
the spread of C. melitensis in southern California invaded grasslands, native forbs have been
wildlands has been increasing in recent years excluded from fertile sites, and persist only in
(Cal-IPC 2008). If this is the case, competition marginal, relatively low-resource refugia, where
from C. melitensis has the potential to pose an non-native plants cannot invade (Seabloom et al.
even greater threat to P. lyoniipopulations in the 2003). The resulting fragmentation ofnative forb
future. The unexpected negative correlation of populations and reduction ofpopulation size can
Erodium with P. lyonii extirpation suggested that potentially contribute to local extinction (Lande
it, like Pentachaeta, favors sites without extensive 1993). In order to preserve biodiversity in
annual grass presence. California grassland ecosystems, conservation
research efforts must include annual forbs.
Management Implications Although much work remains ahead for the
conservation of P. lyonii this study provides a
,
Conservation biology is a crisis discipline foundation for the design of a sound conserva-
(Primack 2010). Because of the unprecedented tion strategy for this endangered species, and
rate of species extinctions, often managers are serves as a starting point for further research.
forced to take actions to attempt to preserve More broadly, the information gained here may
endangered species without thorough prior in- be relevant to the conservation of other rare
vestigations into their ecological relationships. In annual plants in other Mediterranean-type grass-
the case of P. lyonii little is known about its land ecosystems, which are under increasing
ecology. The disturbe,d grassland areas where P. pressure from the same non-native invaders.
lyonii occurs exhibit characteristics that promote
Acknowledgments
invasion by non-native species, and non-native
plants have dominated many of the sites with We thank Paul Wilson, California State University,
extant P. lyoniipopulations over a long period of Northridge, for his generous assistance and input on
time. In this study, non-native plants were this project. Funding for this research was contributed
removed individually by hand. These methods bytheNationalParkService, SantaMonica Mountains
would be extremely labor-intensive and expensive NationalRecreationArea, andWesternNationalParks
for large-scale, long-term management of P. Association. These experiments were carried out in
compliance with the laws of the United States of
lyonii. However, they are the only methods to America.
date shown to significantly improve reproductive
potential for P. lyonii. Until alternative methods Literature Cited
have been explored, hand-weeding should be
implemented at least in the most threatened sites. Brigham, C. A. 2007. Managing rare plants at the
Alternative methods should be investigated to wildland-urban interface: an example from the
Santa Monica Mountains and Simi Hills. Pp. 109-
facilitate the feasibility of large scale, long-term 130 inD. A. Knapp(ed.), Floraand Ecologyofthe
restoration efforts. The use of monocot-specific Santa Monica Mountains: proceedings ofthe 32nd
herbicides early in the season to eliminate Annual Southern California Botanists Symposium.
competition from annual grasses may be an Southern California Botanists Special Publication
option, but effects on the native community as No. 4, Fullerton, CA.
awhole should be studiedbeforeimplementation. Brooks, M. L. 2000. Competition between alien
The use of prescribed burning may also be an annual grasses and native annual plants in the
alternative. However, P. lyonii sabilityto tolerate Mojave Desert. American Midland Naturalist
efaivnraedluiassteepaostoohrnelayleiftfuyencdtesornsotfobofoidtr,ehfarPne.dquelenyxocpnyei,riiimnaetnnetndssitityt,os GH—1o4r4ba,:bcC9se.2,,-M1M0.J8...DPE’.eAlnKlteaoenntli,eoy,a,nDdJ.. MDM...PRyDikiceTh.oamr20ad0ss4oo.n,,EfRfJ..ecBtJ.s.
associatedcommunity shouldbecarried out prior ofinvasive alien plants on fire regimes. BioScience
to consideration as a restoration tool. Moreover, 54:677-688.
large-scale removal ofinvasive species in habitats California Invasive Plant Council (Cal-IPC).
where they are established members of the 2008. Statewide risk mapping. Centaurea meli-
community can have unexpected and undesirable tensis. California Invasive Plant Coucil, Berkeley,
consequences for ecosystems (Zavaleta et al. CA. Website: http://www.cal-ipc.org/ip/mapping/
2001; Ogden and Rejmanek 2005). statewide_maps/Centaurea_melitensis.php [ac-
Conservation and restoration research in Colecemsasne,d 3H.NoMv.emabenrd2J0.08M].. Levine. 2007. Mecha-
California grassland ecosystems has focused
nisms underlying the impacts of exotic annual
primarily on the native perennial grass, Nassella grasses in a coastal California meadow. Biological
pulchra (Hitchc.) Barkworth (Stromberg et al. Invasions 9:65-71.
2007). However, annual forbs are increasingly Corbin, J. D. and C. M. D’Antonio. 2004. Compe-
recognized as a major native component ofthese tition between native perennial and exotic annual
2011] MORONEY ET AL.: EUROPEAN ANNUALS IMPACT A RARE ENDEMIC 77
grasses: implications for an historical invasion. Pacific Ocean. Biological Conservation 117:309-
Ecology 85:1273-1283. 319.
A. R. Dyer, and E. W. Seabloom. 2007. Lande, R. 1993. Risks ofpopulation extinction from
,
Competitive interactions. Pp. 156-168 in M. R. demographic and environmental stochasticity and
Stromberg, J. D. Corbin, and C. M. D’Antonio random catastrophes. American Naturalist
(eds.), California grasslands: ecology and manage- 142:911-927.
ment. UniversityofCaliforniaPress, Berkeley, CA. Miller, A. L. and R. P. Duncan. 2003. Extrinsic
Dukes, J. S. 2001. Biodiversity and invasibility in and intrinsic controls on the distribution of
g—rassland microcosms. Oecologia 126:563-568. the critically endangered cress, Ischnocarpus exilis
2002. Species composition and diversity affect (Brassicaceae). Biological Conservation 110:
gra.ssland susceptibility and response to invasion. 153-160.
Ecological Applications 12:602-617. Ogden, J. A. E. and M. Rejmanek. 2005. Recovery
Dyer, A. R. and K. J. Rice. 1997. Intraspecific and ofnative plant communities after the control ofa
diffuse competition: the response of Nassella dominant invasive plant species, Foeniculum vul-
pulchra in a California grassland. Ecological gare: implications for management. Biological
Applications 7:484=492. Conservation 125:427^139.
and 1999. Effects of competition on Primack, R. B. 2010. Essentials of conservation
resource availabi.lity and growth of a California biology. Sinauer Associates, Sunderland, MA.
bunchgrass. Ecology 80:2697-2710. Schiffman, P. M. 2000. Mammal burrowing, erratic
Eliason, S. A. and E. B. Allen. 1997. Exotic grass rainfall and the annual lifestyle in the California
competition in suppressing native shrubland re- prairie: isit time fora paradigm shift? Pp. 153-160
establishment. Restoration Ecology 5:245-255. in J. E. Keeley, M. Baer-Keeley, and C. J.
Evans, R. D., R. Rimer, L. Sperry, and J. Belnap. Fotheringham (eds.), 2nd Interface between ecolo-
2001. Exotic plant invasion alters nitrogen dynam- gy and land development in California. U.S.
Geological Survey Open-File Report 00-62. Web-
ics in an arid grassland. Ecological Applications
11:1301-1310. site: http://pubs.usgs.gov/of/2000/of00-062/ [ac-
Fotheringham, C. J. and J. E. Keeley. 1998. c—esse2d00370.JPulneiest2o0c11e]n.e and pre-European grassland
Ecology and distribution of Braunton’s milkvetch .
{Astragalus brauntonii) and Lyon’s pentachaeta ecosystems: species composition at the time offirst
{gaPnoedvn/tGFaiaclhmaeeeH,taanRldeylogneiiroi).n.aCs5a.hlxiW?feDobrosnicituaem:DeenhpttaItrpDt:=/m/e3nnr1tm5.4odffgF.[icasac.h- UEbCenaurlirgivo,feporJres.niaitnDay.sogefCrtoatCsrlasbellimiaenfnn,odtrs.an:inPadpe.cPCore.l5so2sgM-,y5.B6eaDrni’kndAelnMemt.yao,nnRaiC.goAe.Sm(teerdnos.tm).-,
Gurecveisstecdh,30J.J,unS.e M20.11]S,cheiner, and G. Fox. 2006. SeabBluorotmo,n,E.KW..,LE..CTo.tBtoirnegrh,aVm.,L.L.BoGuoclhdewra,ssRe.rS,.
TSuhnedeercloalnodg,yMoAf.plants. Sinauer Associates, Inc., W. Gram, B. E. Kendall, and F. Micheli.
2003. Competition, seed limitation, disturbance,
Heady, H. F. 1988. Valley grassland. Pp. 491-514 in and reestablishment of California native annual
M. G. Barbour and J. Major (eds.). Terrestrial forbs. Ecological Applications 13:575-592.
vegetation of California. California Native Plant SlMBERLOFF, D. 2005. Non-native species do threaten
Society, Sacramento, CA.
the natural environment! Journal of Agricultural
Hickman, J. C. (ed.) 1993, The Jepson manual: higher and Environmental Ethics 18:595-607.
plantsofCalifornia. UniversityofCaliforniaPress, Stromberg, M. R., C. M. D’Antonio, T. P. Young,
HobbBse,rkRel.eyJ,. aCAn.d H. A. Mooney. 1998. Broadening Jg.raWsisrlaknad, arensdtorPa.tiRo.n.KePpph.ar2t5.4-2208007.iCnaliMf.ornRi.a
the extinction debate: population deletions and Stromberg, J. D. Corbin, and C. M. D’Antonio
additions in California and western Australia. (eds.), California grasslands: ecology and manage-
Conservation Biology 12:271-283. ment. UniversityofCaliforniaPress, Berkeley, CA.
Hooper, D. U. and J. S. Dukes. 2010. Functional Thomson, D. 2005. Measuring the effects of invasive
composition controls invasion success in a Califor- speciesonthedemographyofarareendemicplant.
nia serpentine grassland. Journal of Ecology Biological Invasions 7:615-624.
98:764-777. United States Fish and Wildlife Service. 1999.
Huenneke, L. F. andJ. K. Thomson. 1995. Potential Recovery plan for six plants from the mountains
interference between a threatened endemic thistle surrounding the Los Angeles Basin. U.S. Depart-
and an invasive nonnative plant. Conservation ment of the Interior, Fish and Wildlife Service,
Biology 9:416-425. Region 1, Portland, OR. Website: http://www.fws.
Keeley, J. E. 1990. The California valley grassland. gov/ecos/ajax/docs/recovery_plan/990930a.pdf [ac-
Pp. 2-23 in A. Schoenherr (ed.), Endangered plant cessed 30 June 2011].
communities of southern California. Southern Walck, J. L., J. M. Baskin, and C. C. Baskin. 1999.
California Botanists, Claremont, CA. Effects of competition from introduced plants on
Kimball, S. and P. M. Schiffman. 2003. Differing establishment, survival, growth and reproduction
effects ofcattle grazing on native and alien plants. of the rare plant Solidago shortii (Asteraceae).
Conservation Biology 17:1681-1693. Biological Conservation 88:213-219.
Kingston, N., S. Waldren, and N. Smyth. 2004. Zavaleta, E. S., R. J. Hobbs, and H. A. Mooney.
Conservation genetics and ecology of Angiopteris 2001. Viewing invasive species removal in a whole-
chauliodonta Copel. (Marattiaceae), a critically ecosystemcontext. Trends in Ecology & Evolution
endangeredfernfromPitcairnIsland, southcentral 16:454=4-59.