Introduced and native plants of the Hastings Reservation, central coastal California: A comparison

Biological Conservation 71 (1995) 115-123 Elsevier Science Limited Printed in Great Britain. ELSEVIER

0006-3207(94)00008-5

INTRODUCED A N D NATIVE PLANTS OF THE HASTINGS RESERVATION, CENTRAL COASTAL CALIFORNIA: A COMPARISON Johannes M. H. Knops* Department of Botany. Arizona State University, Tempe, Arizona 85287, USA

James R. Griffin Hastings Natural History Reservation, 38601 East Carmel Valley Road, Carmel Valley, California 93924, USA and Museum of Vertebrate Zoology, University qf California. Berkeley, CaliJbrnia 94720, USA

&

Anne C. Royalty* 1022 West 9th Street, Tempe, Arizona 85281, USA

(Received 26 February 1993; revised version received and accepted 18 November 1993)

Abstract Introduced plant species at the Hastings Reservation comprise 17% of the total flora, and are predominantly annual herbs and grasses. No introduced species are present in chaparral, coastal sage or rock outcrops and very few (4% of the total species number) in the mixed evergreen woodland The highest percentage of introduced species is found in disturbed areas (40%), such as roadsides and around buiMings. Introduced species have successfully invaded native grasslands (22%), oak foothill woodland (15%) and riparian areas (15%). In these vegetation types, introduced plants form an integral part, and in grasslands and the understory of oak foothill woodland, annual introduced grasses are the dominant species. The only difference found between established and recorded, but not-established, is that the latter is more recorded in disturbed areas. This reinforces anecdotal evidence that humans are the main cause of intentional or accidental dispersal into this reservation and that the most likely habitats of first establishment are the disturbed areas around houses and roads. Not all introduced species are capable of establishing a foothold in these disturbed areas and an even smaller portion is capable of intruding into grassland and oak foothill woodland. Both these vegetation types are characterized by high natural disturbance, mainly caused by pocket gophers. Vegetation types with less frequent disturbance, such as chaparral coastal sage and mixed evergreen oak woodlands are not, or much less, invasible. Finally, most of the introduced species trace their origin to a similar Mediterranean climate in Europe.

INTRODUCTION

Mediterranean climate regions are considered, next to islands, to be one of the more vulnerable ecosystems to introduced plants (Huenneke, 1988). Much attention has been given recently to biological invasions, habitats that are invaded, and the effects that invading plant species have on native plant communities (Groves & Burdon, 1986; Macdonald et al., 1986; Mooney & Drake, 1986; Drake et al., 1989; Hengeveld, 1989; Groves & Di Castri, 1991). A picture has emerged that introduced species are threatening biodiversity by direct competition with native plant species or indirectly by altering ecosystem properties (Vitousek, 1986). Relatively little attention has been given to comparing successful and unsuccessful introductions of plants at a given site, and not much attention to the smaller plant community scale in which specific vegetation types are invaded (Burgess et al., 1991). In this paper a detailed study has been done on over 50 years of accumulated herbarium specimens, field notes and three species lists (Linsdale, 1955; Griffin, 1974, 1991) of a nature reservation. All species are divided into three categories: native, introduced established, or introduced not-established. In addition, all species are divided into specific vegetation types, and these are compared on invasibility. Growth form and life-cycle categories are compared, and some generalizations about the pattern and mode of introduction are given.

STUDY AREA AND METHODS

Keywords: Mediterranean-type ecosystem, California, biological invasions, introduced species, ecosystem invasibility.

Study site

Hastings Reservation is situated in the middle of the southern coastal foothill region (Fig. 1), 42 km inland in the Carmel Valley (Monterey County), in central coastal California (36°23'N, 121°33'W). This site is

*Present address: University of California, Berkeley, Hastings Natural History Reservation, 38601 East Carmel Valley Road,

Carmel Valley, California 93924, USA. 115

116

J. M. H. Knops, J. R. Griffin, A. C. Royalty

S a n Francisco

P o i s o n Oak

Ranchland

Hill

Arnold~ Road ~ Finch 1kilometer

Fig. 1. The Hastings Natural History Reservation, showing its location in California, and a layout of the Reservation.

approximately 20 km east of the Pacific Ocean at an elevation of 500-1000 m. The upper Carmel Valley is narrow, surrounded by the Santa Lucia Range to the west (highest point: Chews Ridge) and the Sierra de Salinas in the east (highest point: Palo Escrito Ridge). Hastings covers an area of 912 ha, and has been a reserve since 1937. The first European influence was the establishment of a Mexican land grant, Rancho Los Tularcitos, directly north of the reserve in 1834. Livestock grazing, probably combined with the accidental introduction of Mediterranean weeds started in this period, and the first records of this area from 1861 record their rapid establishment: 'Thousands of acres of these lower hills are covered with wild oats, as thick as a poor oat field at home' (Brewer, 1861, unpublished

notes, cited in Griffin, 1988). The next major change was the establishment of homesteads in the 1880s, which started extensive livestock grazing, cultivating several hayfields and local wood cutting at the reserve (Griffin, 1988). The reserve was donated in 1937 to the Museum of Vertebrate Zoology (University of California, Berkeley), at which time the cultivation of the hayfields was abandoned and all livestock, except a few horses which grazed one field until 1969, was removed.

Vegetation The vegetation in central, coastal California is a patchwork of intermixed plant communities (Barbour & Major, 1977), and Hastings Natural History Reservation contains several excellent examples. Chaparral,

Introduced and native plants at a reserve

coastal sage, rock outcrops, mixed evergreen forest and riparian forest form distinct patches in a landscape dominated by oak woodlands, which vary from forest (with a closed or nearly closed canopy) to savanna (with a canopy cover of less than 25%) to open grasslands (Griffin, 1988). In addition to natural habitats, disturbed areas are present along roads and buildings.

Climate The climate of central, coastal California is characteristic of a Mediterranean area, with hot, dry summers and moderate, wet winters (James, 1966; Major, 1977). The mean annual precipitation is 538 mm, but precipitation has varied from 261 mm to 1112 mm since 1937. More than 90% of the rain falls between November and April. The mean minimum temperature varies from 1.4°C in January to 9.7°C in August, the mean maximum from 15-6°C in January to 30.4°C in July. The absolute minimum temperature is -12°C (January 1949), and the absolute maximum 44°C (August 1960). Fog occasionally reaches the study site in the spring and early summer. Flora Plants have been collected intensively since 1937, and an excellent local herbarium is presently available. All native and introduced plants, except garden plants that have not spread, are summarized in Griffin (1991), which describes vegetation types based on species dominance (Barbour & Major, 1977), and is used as the basis for this paper, most of the descriptions of habitat, abundance and life forms being obtained from it. Additional data on the origin was found elsewhere (Hitchcock, 1950: Munz & Keck, 1968; Hubbard, 1984). R E S U L T S AND D I S C U S S I O N In total, 576 plant species in 325 genera and 76 families are present at the reserve. Of these, 15% (90) of the species, 17% (55) of the genera and 4% (three) of the families are introduced. In addition to the established introduced species, another 53 were collected historically, but are not-established at present. These numbers are very similar to the total flora of California, which contains 173 families, 1222 genera, and 5862 species, of which 1023 (17%) are naturalized aliens (Hickman, 1993).

Growth forms and vegetation types The main growth forms of the introduced plants are annual herbs and grasses (Table 1). Most of the introduced plants have been recorded in disturbed areas, 40% of the established species and 60% of the total recorded introduced plants (Table 2). Among the natural plant communities, four are invaded by introduced plants: grasslands with 22%, foothill oak woodland and riparian forests both with 15%, and mixed evergreen oak woodland with 4%. No introduced plants have been recorded in the chaparral, coastal sage and rock outcrops. This is in

117

Table 1. Introduced and native plants by life form and vegetation type Growth-form

Introduced established

% of total

Native

% of total

Disturbed areas Grass Herb Shrub

9 25 1

26 71 3

46 6

88 12

Total

35

100

52

100 4 2 1 7 81 3 2

Grasslands Bulb Fern Rush Grass Herb Shrub Vine

21 29 l 2

40 55 2 4

7 3 2 13 152 6 4

Total

53

100

187

100 4 1 3 1 8 68 9 3 3

Foothill oak woodland Bulb Epiphyte Fern Rush Grass Herb Shrub Tree Vine

14 12 1 1 1

48 41 3 3 3

7 1 5 2 14 115 16 5 5

Total

29

100

170

100

1 11 8 67 12 7 4

1 10 7 61 11 6 4

110

100

Riparian forests Fern Rush Grass Herb Shrub Tree Vine

4 14

21 74

1

5

Total

19

100

contrast to studies in more disturbed shrub habitats in southern California, where Soul6 et al. (1988) found that in some areas the natural cover of chaparral declined to as little as 5-15% due to replacement by exotic grasses, forbs and trees. Natural disturbances, such as fire, have occurred at Hastings in the last 50 years, but in contrast to other studies (Zedler & Scheid, 1988), no recruitment of exotics has occurred in chaparral and coastal sage vegetation types. It seems that introduction of a new species must coincide with an 'open invasion window' (Johnstone, 1986) and that dispersal alone does not create this window. Probably another factor, such as a fire or another major disturbance (Zedler & Scheid, 1988), has to create a 'temporary open invasion window' during the dispersal of seeds into these vegetation types. Johnstone (1986) argues that invasions are caused by the removal of a barrier that has previously excluded a plant species from a site and that these barriers are time-dependent. Thus, classified by time, invasions may not occur (default window); may occur on a first-arrival basis after a

118

J. M. H. Knops, J. R. Griffin, A. C. Royalty

Table 2. The distribution of non-established, established and native plant species over the different vegetation types, and the importance of the different vegetation types

Vegetation type

Introduced notestablished

Introduced established

Native

% introduced established

Relative importance a

Mixed evergreen woodland Foothill oak woodland Grassland Chaparral Coastal sage Riparian Rocky outcrops Disturbed areas

0 1 2 l 0 7 0 44

5 29 53 0 0 19 0 35

113 170 187 84 16 110 33 52

4 15 22 0 0 15 0 40

*** *** *** *** * ** * *

Total

53

90

486

16

~***, widespread and important; **, less widespread but locally common; *, minor. window opens (temporary window); may be permanently possible for selected species once a specific barrier is removed (stable window): and may be possible for selected species in the future (future window) (Johnstone, 1986). Foothill oak woodland introductions are similar to grasslands, probably as a result of the similarity of these two vegetation types. Tree cover comprises from as low as 5% up to 80%, and the difference between the low tree cover savanna type of vegetation and grassland is minimal. Mixed evergreen woodland, in contrast, is much denser, and often occupies the slightly wetter north slopes. Here, the lack of invasion is probably a combination of low light availability and a lack of disturbed substrate, similar to conditions found to inhibit invasions in other studies in forest vegetations (Brothers & Spingarn, 1992). However, Fiedler and Leidy (1987) reported that the mixed broadleaf evergreen forest of a preserve in the San Francisco area contained 21% non-native species and also the grasslands contained a much higher number of introduced species (44%, versus 22% in this study). It is not clear if this difference is caused by longer or more intense disturbance (this preserve was established in 1983), the higher amount of rainfall (710 mm), the much shorter collection period, or the smaller size of the preserve (148 ha) which limits the number of non-common species found. It is, however, not likely that there has been a marked decrease in the number of alien plants in these communities at Hastings, since intensive collecting took place immediately after its establishment, and subsequently hardly any change has been recorded in the grasslands (Stromberg & Griffin, in press). It is well known that plant invasions are promoted by disturbance (Elton, 1958; Forcella & Harvey, 1983; Mooney & Drake, 1986; Hobbs & Huenneke, 1992), and the situation at Hastings is no different. A large portion of the introduced plants is established in disturbed areas, and most of the not-established species have been recorded in these areas (Table 2). Hastings has been a reserve since 1937 and disturbed areas are restricted to the areas around the houses and along the roads. This is in contrast to most studies of introduced

plants, which are based on larger floras, including much more disturbed habitats. Three factors may play a role in the invasibility of disturbed areas. The first is disturbed soil, with frequent breaks in plant cover and high light intensity (Forcella & Harvey, 1983; Baker, 1986). Second, these are the areas most in contact with humans (Schmidt, 1989; Tyser & Worley, 1992), which are the dominant means of dispersal for invading species. Finally, introduced and native plants might have differential responses to trampling: resistance and recovery. Resistant species tend to be specialized with low growth rates. |n contrast, species with fast growth rates appear to use a recovery strategy (Sun & Liddle, 1991; Sun, 1992). Introduced grasses are often characterized by high growth rates (Baker & Stebbins, 1965; Bazzaz, 1986), and probably use more of a recovery strategy as compared with plants specialized to trampling. In contrast to most other studies (Mooney & Drake, 1986), the disturbed areas at Hastings have not been impacted by cattle grazing and cultivation since 1937. There seems to be no positive relationship between the diversity of the natural vegetation type and the number of introduced plants, as has been argued in the literature (Elton, 1958; Moulton & Pimm, 1986). In contrast, most introduced species are present in species-rich plant communities, and the least in species-poor plant communities (Fig. 2). This supports the view of Richardson and Couling (1992), that resource availability influences invasibility, and that resource availability is unrelated to species diversity. Among habitats, introduced plants are well established in communities dominated by herbs: foothill oak woodland, grasslands and disturbed areas (Table 1). Plant communities dominated by shrubs - - coastal sage, chaparral, and mixed evergreen woodland - - do not have any, or only a minor number of, introduced plants. One exception is the riparian areas. This vegetation type is present along seasonal creeks, and therefore has an extensive border in common with grasslands, oak foothill woodlands and mixed evergreen forest. In contrast to the mixed evergreen forest, the riparian forest is much more open, and in contrast to the oak foothill woodland, the water availability is much higher.

Introduced and native plants at a reserve 4O

• "~

119

disturbed areas

35 '~ 30 e~

25 "0

2O "0

S 15

,~_

IO 5 •

•

•

"

I

•

50

0

t

I

1 O0

150

I

200

Number of Native Species

Fig. 2. Percent introduced versus the number of native species in the vegetation types. Disturbed areas are excluded from the analysis. A regression is significant with t = 0.0103 and an Adjusted R 2 of 0"7142. The predominant life-form of both the introduced and the native species is herbaceous: 60% of the introduced and 69% of the native plants (Table 3). A major difference between introduced and native growth forms is seen in grasses; these represent only 6% of the native species but 31% of the introduced species. Herbs and grasses strongly dominate the species list of introduced plants. In contrast, the native flora has a much broader spectrum of life-forms. This is also found in the lifecycle categories of these species. The majority of the introduced plants are annuals, 71% of the established

species and 83% of the c o m m o n species, but annuals represent only 47% of the native plant species (Table 4). Only one of the introduced species (Cynodon dactylon) spreads with rhizomes, as compared with 16 native species (including four grasses). However, this does not imply a significant difference, since vegetative spread occurs more commonly in perennial species, and a larger part of the native flora is perennial. Introductions

The origin of the introduced flora of Hastings (Table 5)

Table 3. Life forms of native versus introduced plant species

Growthform Bulb Epiphyte Fern Moss Rush Grass Herb Shrub Tree Vine Total

Introduced total

% of total

Introduced established

% of total

Native

% of total 2 0 2 0 3 6 69 12 3 3 100

41 93 2 5 2

29 65 1 3 1

28 54 1 5 2

31 60 1 6 2

11 1 12 1 13 30 334 56 15 13

143

100

90

100

486

Table 4. The life-cycle category of introduced and native plants

Introduced all

Introduced established

Native all

Introduced common

Native common

Introduced grass

Native grass

Annual Biennial Perennial

105 2 36

64 2 24

228 11 247

29 0 6

97 8 93

20 0 8

4 1 25

Total

143

90

486

35

198

28

30

73 1 25

71 2 27

47 2 51

83 0 17

49 4 47

71 0 29

13 3 83

% annual % biennial % perennial

J. M. H. Knops, J. R. Griffin, A. C. Royalty

120

Table 5. The origin of the introduced plants Origin

Introduced

% of total

Introduced established

'7,, of total

Africa America Australia Asia Eurasia Europe

1 19 l 2 l0 109

1 13 1 1 7 77

1 9 1 0 8 71

1 10 1 0 9 79

Total

142

100

90

100

closely reflects the pattern throughout California (Raven, 1977), where the majority of the introduced plants have their origin in Europe, mostly from the Mediterranean region. Some species have a Eurasian distribution and a substantial number have their origin in America, mostly from other areas of North America, and from tropical America. Species from other non-European Mediterranean ecosystems are virtually absent; Africa, and Australia have only one representative each. California was first settled by the Spaniards in the mid-18th Century, and they brought animals and plants from their native land both directly and indirectly overland through Mexico (Heady, 1977; Raven, 1977). These plants found a very similar climate to which they were adapted, and therefore established themselves readily, Plant collecting at Hastings started in 1937, long after most of these plants were introduced. It is therefore difficult to establish the time-frame in which they became established and how they arrived. Parsons (1992) compared the introduced species list of the flora at a research site in Arizona (Burgess et al., 1991) to that of a similar climate in Australia, and found that (aside from escapes of cultivation) 19 out of 20 species established in Arizona were also present in Australia. Ten of the same list are established at Hastings (an additional three are recorded, but not-established) which has a markedly different climate from these other two areas (Appendices I and 2). Of the 10 established species, eight are naturalized in natural vegetation types, five in the grassland, and three in the riparian forest, and only two are restricted to disturbed areas. It seems that part of the introduced species at Hastings are capable of successfully invading native vegetation in very different climates. In most cases we do not understand the dispersal mechanisms of species that invade and the influence of exotics on major ecosystem properties, such as nutrient cycling. Most grasses and herbs have been present since the Mexican invasion in the mid-18th Century (Heady, 1977). Therefore, relatively little is known of the timeframe and mode of introduction. The following information is available about all of the more recently established species. Bromus tectorum is attributed to its use as a bird-trapping bait in the mid-1970s. Of the not-established grasses, three were introduced in the ranching years, before the reservation was established - - Arena sativa (oat fields, disappeared from 1944 on),

Agropyron desertorum (planted pastures, last collection in 1938), and Hordeum vulgare (cattle food, disappeared after cattle were no longer kept). Four were introduced in recent years - - Poa pratensis (planted lawns around the buildings), Panicum mileaceum (bird-trapping bait, recorded once in 1972), Lolium multiflorum (seeded in the adjacent Los Padres forest after a fire in 1977, occasionally along creeks and disturbed areas), and Briza maxima (accidental along a road). Of the established herbs, four have been recorded in historic times; two invaded without an obvious cause (Draba verna in the mid-1960s and Erodium botrys in the mid-1940s), whereas Lamium amplexicaule was introduced in the mid-1940s as a chicken food contaminant by reservation residents, and Asparagus offi'ciale which persisted, but did not spread from an abandoned garden. Of the not-established herbs, three were found on disturbed soil - - Foeniculum vulgare (1979, all plants intentionally destroyed), Xanthium spinosum (1939, 1969, 1979), and Anagallis linf/blia (1956). The rest were associated with an abandoned garden (Papaver somniflerum), an abandoned experiment transplant field (Plantago insularis), and a disturbed area around a house (Centaurea solstitialis 1992 destroyed on purpose). One species invaded without an apparent cause (Tribulus terrestris 1944, destroyed on purpose). Of the introduced trees and shrubs, six out of seven species were planted around buildings (Cytisus monspessulanus, Cupressus macrocarpa, Robinia pseudo-acacia, Juglans hindsii, Pinus radiata and Juglans regia), and spread from there: Robinia pseudo-acacia spread vegetatively, Cytisus mon,spessulanus both vegetatively and through seed, and all other species through seed. One not established recorded species in a disturbed area was probably brought there by road equipment (Nicotiana glauca). All of these were introduced in historic times. In general, the most important factor causing the presence of these species at Hastings is the deliberate or accidental introduction by humans. Very few species, even though many more are well established in California, appear capable of dispersing into Hastings by natural means, such as birds. The most striking influence of introduced plant species has been on the grassland, and oak foothill woodlands. Here the introduced annual grasses have replaced native species as the dominant herb layer. This is clearly reflected in the species number (Table 1). This conversion took place a long time before records were kept, not only at Hastings, but throughout California. Of the species introduced in recent times, the majority are associated with a disturbance or transport mode associated with humans. The origin of these has mostly been from Europe and other areas in America. At present few species have been introduced from the other three Mediterranean climatic regions: South America, Africa and Australia. This is probably caused from lack of mass movement of humans to California from these areas (Kruger et al., 1989). Most of the recent introduced plant species are annual grasses and herbs from the Mediterranean region in Europe. These plants have evolved in the same climate as California, and in

Introduced and native plants at a reserve

addition are more adapted to livestock grazing (Naveh, 1967). There is also no obvious change in the composition of all the vegetation types, and even 50 years after the abolition of grazing formerly grazed fields show no succession to a vegetation dominated by perennial native species (Stromberg & Griffin, in press). It is not clear if this is caused by a change in climate during the last 200 years, the longer evolution time in the Mediterranean resulting in plants better adapted to human disturbance (Naveh, 1967), or by fundamental changes in ecosystem properties, after the introduction of these species (Vitousek, 1986). The annual grasslands and foothill oak woodlands are, even in the absence of grazing, characterized by heavy disturbance, predominantly caused by pocket gophers Thomomys bottae (Hobbs & Mooney, 1985, 1991; Koide et al., 1987), so it is difficult to determine if there have been any substantial alterations in ecosystem properties in those vegetation types where introduced species are important (Vitousek, 1986; Vitousek et al., 1987). However, in the grasslands and foothill oak woodland, the character of the vegetation has changed markedly from a perennial to an annual type (Heady, 1977). The seed weight of introduced species has been reported to be higher than the native species (Baker, 1972). This might be one reason why introduced annuals are capable of dominating the grasslands year after year, even in the absence of grazing, since the growth rate of plants is often strongly influenced by the initial plant size which is often closely related to the seed weight (Harper, 1977). CONCLUSION Most introduced species at Hastings are herbs and grasses, and most of these have invaded those vegetation types that were already dominated by grasses and herbs. Very few of the introduced species are shrubs and trees, and those that are introduced are almost all accidental ones, species not specifically adapted for a Mediterranean climate. The only exception here is Cytisus monspessulanus, which has been successfully suppressed for the last 20 years. However, even now, occasional seedlings are found (W. Koenig, pers. comm.). In more disturbed habitats in southern California, shrub species such as Shinus and Eucalyptus (Alberts, cited in Soul6 et al., 1992) have invaded chaparral and coastal sage vegetation types, and on Santa Cruz island Foeniculum vulgate has invaded coastal sage (Beatty & Licari, 1992). In addition, it has been reported that in South Africa introduced Acacia (Witkowski, 1991a, b), Hakea (Richardson & Cowling, 1992) and Banksia (Honig et al., 1992) species from Australia, and Pinus species (Richardson et al., 1990) from California and the Mediterranean region, are successfully invading native vegetation types and altering nutrient availability. These species have not yet been introduced at Hastings but they might be capable of invading vegetation types dominated by shrubs and trees, subsequently altering their ecosystem properties (Vitousek, 1990). This evidence supports the view that humans are

121

presently the main mode of dispersal of exotics into Hastings, unlike in other areas of the US where birds can play a major role (White & Stiles, 1992; Sallabanks, 1993). In addition, since disturbed areas have the highest contact with humans, it is not surprising that the highest number of introduced plant species, and an even higher number of the not-established ones, are found in these areas. It seems that these areas are the first 'filter' that new species encounter, once they reach Hastings. Not all of the introduced species are capable of establishing a foothold in these disturbed zones, and an even smaller number are capable of intruding into riparian forest, grassland, and oak foothill woodland. The latter two vegetation types are characterized by a high frequency of natural disturbance, mainly caused by pocket gophers, a low plant cover and a high light regime. The riparian forests are also characterized by a high natural disturbance caused by seasonal creeks. Denser vegetation types with less frequent disturbance and a higher plant cover, such as chaparral, coastal sage and mixed evergreen oak woodlands, are not, or much less, invasible. ACKNOWLEDGEMENTS We wish to thank all the people who contributed over the last 55 years to the Hastings herbarium, Mark Stromberg, Bill Schlesinger, Walt Koenig, John Barthell and two anonymous reviewers for reviewing this paper, and J. B. for Fig. 1 and a discussion on 'careless researchers and bird-feeding wildlife sympathizers'. We are grateful for the continuing support of the Hastings/ Arnold family to the Hastings Reservation; this work would not have been possible without it.

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Introduced and native plants at a reserve

123

Appendix 1. Introduced, established plant species at the Hastings Reservation Aira caryophyllea Asparagus officinalis Brassiea campestris Bromus mollis Bromus tectorum Centaurea melitensis" Cirsium vulgare Cupres:s'us maerocarpa Cl'tisus monspessulanus Erodium hotrvs Erodium mosehatum Galium aparine Gastridium ventrieosum Holeus lanatus Hordeum leporinum Juglans regia Lamium amplexicaule Lolium temulentum Marrubium vulgare Melilotus indicus" Phalaris' tuberosa Poa annua Polypogon monspeliensis ~ Rorippa nasturtium Rumex crispus Silybum marianum Sonchus oleraceus Streptanthus glandulosa Urtica urens Vicia das'ycarpa

Anagallis arvensis Avena barbata Brassica nigra Bromus rigidus Capsella bursa-pastoris Cerastium glomeratum Conium maculatum Cynodon dactylon" Daetylis glomerata Erodium brachycarpum Festuca arundinaceae Galium murale Geranium dissectum Hordeum glaucum Itypoehoeris glabra Lactuca serriola ~ Lepidium strictum Madia sativa Medicago poO,morpha Mentha spicata Pinus radiata Polygonum aviculare Portulaca oleracea Rumex acetosella Senecio vulgaris Sisymbrium officinale Spergularia bocconii Torilis nodosa Veronica persiea Vulpia bromoides

Anthriscus scandicina A vena fatua" Bromus arenarius Bromus ruben,s~ Catapodium rigidum Chrysanthemum parthenium Convolvulus arvensis" Cynosurus eehinatus Draba verna Erodium cicutarium ~ Filago gallica Galium parisiense Geranium molle Hordeum hystrix Juglans hindsii Lamarkia aurea Lolium perenne Malva parviflora" Melilotus albus Paspalum dilatatum Plantago lanceolata Polypogon australis Robinia pseudo-acacia Rumex conglomeratus Silene galliea Sonchus asper" Stellaria media Trifolium hirtum Vicia angust~dia Vulpia myuros

"Species also recorded by Parsons (1992) in Australia.

Appendix 2. Introduced, not-established plant species at the Hastings Reservation a Abutilon theophrasti Amaranthus blitoides Anthemis cotula Brassica kaber Centaurea solstitialis b Conyza bonariensis Deseurania sophia Foeniculum vulgare b Hypochoeris radicata Medicago sativa Papaver somn(ferum Pisum sativum Plantago major Rumex pulcher Schismus barbatus" Spergularia rubra Trifolium dubium Vicia villosa

~Species also recorded by Parsons (1992) in Australia. bActively eradicated.

Agropyron desertorum Amaranthus retroflexus A vena sativa Briza maxima Chenopodium album Datura meteloides Echinoehloa crusgalli Gnaphalium luteo-album Lepidium perfoliatum Nicotiana glauca Phalaris minor~ Plantago indica Poa pratensis Sagina apetala Sisymbrium altissimum Taraxaeum officinale Triticum aestivum Xanthium spinosum

Amaranthus albus Anagallis linifolia Brassica geniculata Bri=a minor Chenopodium murale" Datura stramonium Euphorbia peplus Hordeum vulgare Lolium multiflorum Panicum mileaceum Phalaris paradoxa Plantago insularis Raphanus sativus Sanguisorba minor Solanum sarrachoides Tribulus terrestris ;~ Vicia sativa