Island Floras Research Articles

남해안 해남군 무인도서의 하계 해조상 및 군집

한국 남해안 해남군에 위치한 무인도의 해조상과 군집조사가 1999년 6월 12일에서 29일까지 이루어졌다 조사결과 채집 동정된 해조류는 녹조류 10종, 갈조류 15종 및 흥조류 62종이었다. 우점종은 구멍갈파래와 지충이이며, 준우점종은 바위수염, 패, 톳, 불등풀가사리, 애기돌가사리이었다. 수직분포는 조간대 상부에서 하부까지 불등풀가사리, 애기가시덤불, 바위수염-참풀가사리, 애기풀가사리, 애기우뭇가사리, 구멍갈파래, 지충이-톳, 뜸부기, 진두발, 미역, 감태가 분포하였다. The marine algal flora and community of uninhabitated islands in Haenamgun, southern coast of Korea, were investigated during 12<TEX>$\~$</TEX>29, June, 1999. As the results, a total of 87 species including 10 greens, IS browns and 62 reds was identified. The dominant species were Ulva pertusa and Sargassum thunbergii and the subdominants were Myelophycus simplex, Ishige okamurae, Hizikia fusifomis, Gloiopeltis furcata and Chondracanthus intermedius. The vertical distribution pattern of intertidal marine algae represented three distinct zones; Gloiopeltis furcata, Caulacanthus okamurae, Myelophycus simplex-Gloiopeltis complanata, G. tenax, Gelidium divaricatum, Ulva pertusa, Sargassum thunbergii-Hizikia fusiformis, Pelvetia babingtonii, Chondrus ocellatus, Undaria pinnatifida, Ecklonia lava from upper to lower zones.

A barren part of the main?: the vegetation of Hunter Island, Fleurieu Group, Bass Strait

Hunter Island, visited over millennia by Aboriginal people and settled in the nineteenth century by sealers and later by a succession of grazing lessees, has preserved in its vegetation pattern the effects of a long history of firing and clearing. The vegetation also reflects the substrate and topographic features of the island with a major dichotomy between the heaths and scrub on the highly acid quartzites that underlie most of the island, and woodlands and grasslands on the highly alkaline sands that are rafted onto its western part. Eucalyptus viminalis occurs on alkaline sands on Hunter Island, in contrast to the absence of the species on calcareous coastal sands in the rest of its range in southeastern Australia. Heathlands make up 380/0 and scrub 37% of the island. Other vegetation types recorded are swamp forests, button grass moorland, exotic and native grasslands, Eucalyptus viminalis woodland, wetlands, mutton-bird rookery vegetation and lichen-fields. The flora has strong affinities with the northwestern coast of the Tasmanian mainland and a weaker affinity with Three Hummock Island, which is a granite island rather than a quartzite one. A Bassian floristic element occurs on the alkaline substrates; however, it is not as strong as that in the island flora of eastern Bass Strait. The flora and vegetation have components that are significant for nature conservation such as remnant Eucalyptus viminalisstands on the sands. The species ofconservation significance include rare and threatened species: Pterostylis cucullata, Calochilus herbaceous, Cyrtostylis robusta, Parietaria debilis, Ranunculus amphitrichus and Cotula vulgaris var. australasica.

The lichens of Marion and Prince Edward Islands

A total of 100 lichen species are listed for the islands. Six species are described as new to science: Arctomia subantarctica Øvstedal, Arthothelium evanescens Øvstedal, Coccotrema stellata Øvstedal, Ramonia subantarctica Øvstedal, Thelocarpon subantarcticum Øvstedal and Verrucaria umbilicata 0vstedal. Four new combinations are made: Amandinea subplicata (Nyl.) Øvstedal, Poeltinula cerebrinella (Nyl.) Øvstedal, Verrucaria nigra (Müll. Arg.) Øvstedal (from Cape Horn) and Verrucaria tesselata (Dodge) Øvstedal (from Heard Island), One third of the islands’ lichen species also occur in the Northern Hemisphere. Of the Southern Hemisphere species, 24 are exclusively known from areas to the east of the islands (Kerguelen Province Islands, Australia, New Zealand, contrasting to only six species recorded exclusively to the west (South Georgia, Antarctic Peninsula). This suggests a distribution against the present predominantly westerly winds. The large number of seemingly endemic species is suggested to indicate the incomplete knowledge of the lichen floras of the sub-Antarctic islands.

Polynesian plant introductions in the Southwest Pacific: initial pollen evidence from Norfolk Island

Thick organic swamp sediments, buried under land fill on Kingston Common, preserves evidence of the Norfolk Island flora and vegetation back to the middle Holocene and probably much earlier times in the Late Quaternary. These sediments provide (1) a bench mark against which the impact of humans on the flora and vegetation of a long-isolated island can be assessed and (2) a means of determining whether particular plant genera and species are introduced or native to the island. Although sediments contemporary with Polynesian occupation about 800 years ago were destroyed by European draining and cultivation of the swamp during the early nineteenth century, the pollen data indicate that New Zealand flax (Phormium tenax) was introduced to Norfolk Island by Polynesians. Other putative exotics such as Ti (Cordyline), a bull-rush (Typha orientalis) and, less certain, herbs such as the sow thistle (Sonchus oleraceus), were part of the native flora long before the earliest recorded Polynesian settlement. Wildfires have been part of the landscape ecology of Norfolk Island since at least the middle Holocene.

Darwin's Naturalization Hypothesis Revisited

In The Origin of Species, Darwin (1859) drew attention to observations by Alphonse de Candolle (1855) that floras gain by naturalization far more species belonging to new genera than species belonging to native genera. Darwin (1859, p. 86) goes on to give a specific example: “In the last edition of Dr. Asa Gray’s ‘Manual of the Flora of the United States’ ... out of the 162 naturalised genera, no less than 100 genera are not there indigenous.” Darwin used these data to support his theory of intense competition between congeners, described only a few pages earlier: “As the species of the same genus usually have, though by no means invariably, much similarity in habits and constitution, and always in structure, the struggle will generally be more severe between them” (1859, p. 60). Darwin’s intriguing observations have recently attracted renewed interest, as comprehensive lists of naturalized plants have become available for various regions of the world. Two studies (Mack 1996; Rejmanek 1996, 1998) have concluded that naturalized floras provide some support for Darwin’s hypothesis, but only one of these studies used statistical tests. Analyses of additional floras are needed to test the generality of Darwin’s naturalization hypothesis. Mack (1996) tabulated data from six regional floras within the United States and noted that naturalized species more often belong to alien genera than native genera, with the curious exception of one region (New York). In addition to the possibility of strong competition between native and introduced congeners, Mack (1996) proposed that specialist native herbivores, or pathogens, may be

Mutualism as a constraint on invasion success for legumes and rhizobia

AbstractBecause hereditary symbiont transmission is normally absent in the mutualism of legume plants and root‐nodule bacteria (rhizobia), dispersing plants may often arrive at new habitats where mutualist partners are too rare to provide full benefits. Factors governing invasion success were explored by analysing a system of two coupled pairwise competition models: a legume invader competing with a resident non‐mutualistic plant, and a rhizobial population competing with a resident population of nonsymbiotic bacteria. The non‐linear dependence of benefits on partner abundance in this mutualism creates the possibility of two alternative population size equilibria, so that a threshold density can exist for invasion. If legumes and rhizobia exceed a critical population size, both species achieve rapid population growth, while if initial densities of both species are below their respective thresholds, they remain rare and are thus vulnerable to extinction in the presence of competitors. Overall, the results indicate that legumes may often fail at colonization attempts within habitats where mutualist partners are scarce. Data on legume prevalence in island floras and rates of geographical spread by legume weeds are consistent with this inference. Predictive insights about invasiveness may emerge from comparative research on key traits identified by the model, especially the shape of the function determining the number of nodules formed at low rhizobial density.

Significance of gametophyte form in long-distance colonization by tropical, epiphytic ferns

Gametophyte morphology of tropical epiphytic ferns may confer an advantage for establishment on islands. Most tropical, epiphytic ferns belong to five families: Hymenophyllaceae, Grammitidaceae, Vittariaceae, Polypodiaceae, and Elaphoglossaceae. Gametophytes of these families are long-lived and clone-forming. In addition, most Hymenophyllaceae, Grammitidaceae, and Vittariaceae produce dispersible gemmae. Each of these characteristics increases opportunity for outbreeding, and when island floras are statistically compared with floras of adjacent mainlands, island floras are found to be rich in epiphytic species possessing gemmae (Hymenophyllaceae, Grammitidaceae, and Vittariaceae), and depauperate in epiphytic species lacking gemmae (Polypodiaceae and Elaphoglossaceae). We propose that gametophytic gemmae significantly aid long-distance colonization of outbreeding species because gemmae 1) allow gametophytes to exploit available niches through dispersal of gemmae, and through clonal expansion and persistence of the resulting gametophyte, and 2) facilitate sexual reproduction by providing the opportunity for sperm and antheridiogen transfer when gametophytes are distant, and by providing a new source of tissue for antheridia formation.

Breeding System and pollination of selected plants endemic to Juan Fernández Islands

We conducted field studies on the Juan Fernández Islands flora on the breeding system of 25 endemic species from 17 families. We recorded data on flower features, pollen and ovule number, pollen/ovule ratio, pollen size, self-compatibility, floral visitors, and pollination. Flowers are mostly hermaphrodite, inconspicuous, small, and green. Six species are dioecious. Over 80% of the cosexual species are self compatible. However, many species are dichogamous (mostly protandrous); thus, even the self-compatible species may require pollen transfer. Selfing through geitonogamy seems to be the most common system, and several species express mixed breeding systems. Floral visitors are uncommon to rare, except for two hummingbird species (one native and one endemic) that visit five species we studied. In more than 300 h of observation of flowers over three field seasons, we detected only 23 native insect visits representing ten species (Diptera, Lepidoptera, and Coleoptera). One species each of an introduced ant and an introduced bee were also observed on some flowers, all near the single human settlement of San Juan Bautista. Wind directly moving pollen, or indirectly via shaking the flowers, is the most important pollen distribution mechanism. The majority of the wind-pollinated species bear some typical anemophilous features, but also others not characteristic of wind pollination, that presumably represent the condition of their biotically pollinated ancestors. Floral features often reflect ancestral reproductive systems, so floral biology studies of oceanic islands in particular must be done with cognizance of presumed ancestral forms, because the observed characters can be misleading.

Plants Used in Urinary Pathologies in the Canary Islands

A field study of medicinal plants of the Canary Islands flora used for the treatment of kidney and urinary diseases revealed that 63 plants, belonging to 32 families, about 34% of which are endemic, are used as diuretic, antiseptic or calculolytic agents. This wide range of ethnomedicinal uses involves approximately 10% of the total medicinal flora of the Canaries, indirectly indicating the high incidence of these pathologies in the insular population. The botanical family and vernacular names are given along with data on plant parts used, methods of preparation and administration, frequency of use and medicinal application of each species.

The flora of the South Sandwich Islands, with particular reference to the influence of geothermal heating

AbstractAim To carry out as comprehensive a survey as practicable of the flora (higher plants, mosses, liverworts, lichens, basidiomycete fungi and diatoms) of the isolated, volcanically active, South Sandwich Islands archipelago in the southern South Atlantic. To relate the components of this flora to (1) the influence of local geothermal heating and (2) wider regional floras.Location South Sandwich Islands, southern South Atlantic Ocean, maritime Antarctic (56–60° S, 26–28° W).Methods Ice‐free accessible sites on all 11 of the major islands in the archipelago were visited by helicopter in January 1997. During each visit, voucher specimens of each floral group were collected. The comprehensiveness of collections obtained at each site varied with the duration of each visit (a function of tight logistic constraints) and extent of site. Visit duration varied from 1 to 9 h at most sites, with longer periods spent on Bellingshausen Island (2 days) and Leskov Island (1 day). Candlemas Island was examined in greater detail over a 4‐week period in February 1997. At all sites, particular attention was given to areas influenced by geothermal heating.Results Data obtained in 1997 are combined with updated records from the only previous survey (in 1964) to provide a baseline description of the flora of the archipelago, which currently includes 1 phanerogam, 38 mosses, 11 liverworts, 5 basidiomycete fungi, 41 lichenised fungi and 16 diatoms with, additionally, several taxa identified only to genus. Major elements of the moss and liverwort floras are composed of South American taxa (32% and 73%, respectively), with a further 45% of mosses having bipolar or cosmopolitan distributions. These two groups show low levels of Antarctic endemicity (11% and 18%, respectively). In contrast, 52% of lichens and 80% of basidiomycete fungi are endemic to the Antarctic. A further 36% of lichens are bipolar/cosmopolitan, with only 5% of South American origin.Main Conclusions The flora of the South Sandwich Islands is clearly derived from those of other Antarctic zones. The flora of unheated ground is closely related to that of the maritime Antarctic, although with a very limited number of species represented. That of heated ground contains both maritime and sub‐Antarctic elements, confirming the importance of geothermal heating for successful colonisation of the latter group. The occurrence of several maritime Antarctic species only on heated ground confirms the extreme severity of the archipelago’s climate in comparison with well‐studied sites much further south in this biogeographical zone.

Vegetation of the Wessel and English Company Islands, North-eastern Arnhem Land, Northern Territory, Australia

Vegetation patterning is described for two neighbouring continental island chains off Arnhem Land, Australia. A total of 684 species was recorded from 57 islands, with reasonably comprehensive lists for 36 of these islands. Almost 90% of the deviance in plant species richness was associated with island size. The richness of plants dispersed by sea and/or vertebrates was proportionally greater on small islands; that of relatively poor dispersers was greater on larger islands. Twelve vegetation communities were defined by classification of plant species composition in 226 50 × 50-m quadrats. There was no relationship between island size and species richness at the quadrat level, at least for the most extensive vegetation types. The vegetation of the islands is now composed of two main elements—an original set of communities (mostly of heath, tussock grassland and eucalypt open forest) whose species have poor inter-island dispersal, and a set of more recent colonists (mostly of strand, mangrove and coastal thicket communities). The former group is allied to the sandstone flora of western Arnhem Land, but is species-poor in comparison, as the islands lack the deep gorges which drive much of the species richness of western Arnhem Land. The latter group comprises many species with a broad geographic range across tropical coastal areas, including many species which have been shown elsewhere to be highly vagile. Many species of the former set appear to have been lost from the smaller islands. The island flora has been influenced by three sets of human managers. Aboriginal use of the islands has been long-standing and probably resulted in a fire regime which may have accentuated environmental patchiness. Centuries of wet-season use of some islands by Macassan trepang-harvesters, ending early this century, has apparently left few effects other than the persistence of occasional small populations of an introduced food tree. In contrast, European use of these islands has been minimal and fleeting, but is associated with the introduction of most weeds.

Relative risk of extinction of passerine birds on continents and islands

Greater numbers and higher proportions of recent species extinctions have been on islands rather than on continents. In contrast, predictions of massive future extinctions stem from the current clearing of continental, tropical forests1. For instance, since 1600, 97 out of 108 bird extinctions have been on islands2. However, 452 of the total 1,111 species currently considered to be threatened are continental3. Island flora and fauna are uniquely vulnerable to the human introduction of previously absent predators, diseases and other menaces4, whereas species on continents are not so ecologically naive. So could predictions of future continental extinctions based on island histories be exaggerated1? Most threatened species have small geographic ranges5, and the ranges of island species are inevitably smaller than those of continental species. For a given range size, how do the proportions of threatened island and continental species compare? Here we compile the ranges of thepasserine (perching) birds of the Americas. Corrected for range size, continental species are more—not less—likely to be threatened. We use this unexpected vulnerability of continental species with small ranges to produce a map showing where species losses might occur in the long term.

Plant Communities and Flora of Robins Island (Long Island), New York

have not been reported in other natural circumstances. The island's other communities were similar to descriptions of other regional plant communities, although Robins Island's communities were relatively depauperate. Based upon a detrended correspondence analysis, variability among each community's transects ranged from high to low; this variability was associated with the random sampling design, inherent heterogeneity, physiographic characteristics, and edge effects. The island's flora consisted of 215 species of vascular plants representing 151 genera and 60 families; seven species were rare or endangered in New York State and 30% of the flora was non-native and naturalized. The flora showed a greater similarity to neighboring Shelter Island (S0rensen's similarity index [SSI] = 55%) than to the adjacent north and south forks of eastern Long Island (SSI = 36 and 38%).

Contribution to the study of the Greek flora: Flora and vegetation of the E Aegean islands Agathonisi and Pharmakonisi

Panitsa, M. & Tzanoudakis, D.: Contribution to the study of the Greek flora: Flora and vegetation of the E Aegean islands Agathonisi and Pharmakonisi. — Willdenowia 28: 95–116. 1998. — ISSN 0511-9618.The flora and vegetation of the north-easternmost islands of the prefecture of Dodekanisos, Agathonisi and Pharmakonisi, which remained floristically almost unexplored until recently, have been investigated. Included are also the flora and vegetation of the seven islets around Agathonisi. Altogether, 402 species and infraspecific taxa of higher plants belonging to 131 genera and 52 families have been found. The analysis of the flora and the classification of the taxa into three main chorological units and five life form types shows that the Mediterranean elements and the therophytes predominate. A comparison of the individual floras of the two islands and seven islets revealed very low values of Sørensen's similarity coefficient, indicating a remarkable floristic independence. This floristic independence is also expressed by the fact that the nine islands and islets have not one taxon in common, whereas 130 taxa occur only on one island or islet each. Three vegetation zones (littoral, epilittoral and interior) are distinguished and described. The vegetation physiognomy differs from islet to islet due to different dominant species. Human activities such as agriculture, grazing, fires, etc. likewise affect the local floristic composition and vegetation physiognomy.

Persistence, extinction and different species pools within the flora of lake islands in western Ireland

The vascular flora on twenty‐nine lake islands in Lough Corrib, western Ireland was surveyed in 1992–93. Thirteen of these islands had been surveyed by the author in 1974 (Roden, 1979). Data on species–area curves and species turnover between 1974 and 1992 are presented. Species numbers on each island did not change greatly in the 18‐year interval and extinctions were most common on smaller islands. It is known that six of the islands surveyed are less than 150 years old and their flora must have immigrated over open water during that period. It is shown that this group of species has a different log species/log area regression than the remaining flora, with a much shallower slope (low Z value). The proportion of less widespread species was greatest on islands nearest to the mainland. The implication of different slopes in different species groups and the restriction of turnover to rare species is discussed with reference to the island Theory of Biogeography.

Rat management for endangered species protection in the U.S. Virgin Islands

Author(s): Witmer, Gary W.; Campbell, Earl W., III; Boyd, Frank | Abstract: Introduced roof rats (Rattus rattus) pose a substantial threat to the fauna and flora of many tropical islands. In the Caribbean, there is concern about rat impacts to several endangered species, including the Atlantic hawksbill sea turtle (Eretmochelys imbricata) and the least tern (Sterna antillarum). The authors surveyed the rat population on Buck Island, Buck Island Reef National Monument, U.S. Virgin Islands in February 1998. Based on three nights of trapping, rats were of low to moderate abundance during the sampling period when compared to results from other Caribbean islands. The impact of rats on native vegetation was evident over the entire island. A rat management program was proposed using anticoagulant rodenticide baits in bait boxes in and around the two picnic areas on the island. Once an appropriate rodenticide registration is obtained, the baiting program can be extended to include the rest of the island. The eventual eradication of rats from Buck Island will not only provide relief for several endangered species nesting on the island, but will set the stage for the reintroduction of the endangered St. Croix ground lizard (Ameiva polops).

Distyly and heteromorphic incompatibility in oceanic island species ofErythroxylum (Erythroxylaceae)

Surveys of oceanic island floras have shown that heterostyly is usually absent in such regions, probably because this floral polymorphism is often associated with a self-incompatibility system. In this context we describe the floral biology of three species ofErythroxylum on La Reunion island and examine the compatibility relationships of one of these species,E. laurifolium. All three species are distylous but differ in relative stigma-anther separation in the different morphs. In general, short-styled flowers have greater stigma-anther separation than long-styled flowers, which are often homostylous in appearance. This lack of stigma-anther separation in long-styled flowers is due to style twisting which improves reciprocity at the high organ level. The reduced stigma-anther separation does not appear to be associated with the evolution of selfing asErythroxylum laurifolium shows heteromorphic self-incompatibility. The presence of heteromorphic incompatibility in a group of species that have colonized an oceanic island is discussed.

Insular Endemic Plants Lack Defenses Against Herbivores

Islands are of special conservation importance because island ecosystems typically support unique biotic communities rich in endemic taxa (Mueller-Dombois 1981). Species endemic to islands, however, have suffered a disproportionate share of extinctions worldwide since 1600 (Atkinson 1989; Olson 1989; Reid & Miller 1989; Case et al. 1992). Exotic predators and herbivores introduced by humans are believed to be a major cause of extinctions on islands; herbivorous mammals in particular cause severe damage when introduced to island ecosystems (Vitousek 1988; Atkinson 1989). Insular endemic plants are believed to be vulnerable to introductions of herbivores because mammalian herbivores were absent from most islands until the arrival of humans (Atkinson 1989). Most plants have defenses against herbivory (Marquis 1991). Plants evolve defenses in direct proportion to the risk of herbivory (Rhoades 1979; Marquis 1991); because defenses are costly, production decreases when herbivores are absent (Rhoades 1979). Consequently, insular endemic plants that evolved in the absence of large mammalian herbivores may lack defenses against herbivory (Thorne 1969; Carlquist 1974; Coblentz 1978). This hypothesis, although widely accepted (Vitousek 1988; Atkinson 1989; Primack 1993; Paulay 1994), has never been tested. Santa Cruz Island (249 km2), 30 km from mainland southern California, is the largest of the eight California Channel Islands. Santa Cruz supports 650 plant taxa organized into 10 or more communities (Junak et al. 1995). Overall, the Santa Cruz Island flora is similar to nearby species and communities on the mainland. Fortyfive island taxa, however, are endemic to the Channel Islands and eight are endemic to Santa Cruz Island (Junak et al. 1995). Endemic plants on Santa Cruz exhibit both

The rebuilding of an isolated rain forestassemblage: how disharmonicis the flora of Krakatau?

The compositional balance of the flora of the Krakatau Islands, Indonesia, is examined in order to identify taxonomic and/or ecological groups which are under-represented in this recovering island ecosystem in relation to regional analogues and potential source areas in the Sunda Strait (Ujung Kulon and Sebesi Island). Interpretations are conditioned by the limited availability of comparative data, the uncertainty surrounding dispersal classifications, the problem of determining habitat suitability for missing elements, and thus the unsuitability of a formal statistical approach. Analysis by dispersal syndrome supports predictions that species with large, winged, wind-scattered propagules, or those with no particular dispersal potential, are under-sampled. However, some species with winged propagules have colonized, in most cases probably by thalassochory (sea-dispersal). Although zoochorous (animal-dispersed) trees and shrubs are well represented on Krakatau, those large-seeded species which are primarily dependent on dispersal by animals other than birds are under-represented. Large-seeded zoochores are probably highly dependent on two species of Ducula (large fruit-pigeons) for transport to Krakatau and their colonization has been relatively slow. Comparison with Christmas and Jarak Islands yields differing degrees of overlap for thalassochorous, zoochorous, and anemochorous (wind-dispersed) spermatophytes and for pteridophytes, interpretable in terms of dispersability and size of the respective species pools. Particular families and genera can be identified which are seemingly under-sampled on Krakatau, as can some which are over-represented in relation to the principal comparative site, the Ujung Kulon peninsular, West Java. The latter are mostly very small-seeded wind-dispersed epiphytic herbs (especially orchids). Ferns are also very well represented in relation to the West Javan source pool. It is concluded that the flora of Krakatau remains disharmonic, in a predictable fashion, although it is certainly becoming less so. The data provide empirical evidence for the abilities of particular functional guilds of rain forest plants to disperse across significant barriers: the implications of these findings are discussed in relation to current concerns with forest fragmentation in the tropics.

Diatom flora of Oahu and Hawaii Islands in the Hawaii-islands.

Diatom flora of Oahu and Hawaii Islands in the Hawaii-islands.