- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Soil Tolerances
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Environmental Impact
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Campylopus introflexus (Hedwig) Bridel, 1819
Other Scientific Names
- Dicranum introflexum Hedwig 1801
International Common Names
- English: Campylopus moss; heath star moss; heath star-moss
Local Common Names
- Denmark: stjerne bredribbe; vestlig bredribbe
- Germany: einwärtsgebogenes krummstielmoos; haartragendes krummstielmoos; heidepest; kaktusmoos; langhaariges krummstielmoos
- Iceland: hæruburst
- Latvia: jautrioji raštuote
- Lithuania: parasta liklape
- Netherlands: cactusmos; duinpest; grijs kronkelsteeltje; tankmos
- Norway: ribbesåtemose
- Poland: krzywoszczec przywloka
- Sweden: hårkvastmossa
Summary of InvasivenessTop of page
The rapid spread of the moss, C. introflexus within its newly colonized continents (Europe in 1941, North America in 1975) is attributed to its high dispersal capacity, locally by fragmentation and over longer distances by small spores. It can quickly and effectively establish on acidic open sites with low competition from other plants and often benefits from disturbances (burning, trampling and digging by animals, wind erosion). C. introflexus can form extensive carpets that have impact on habitat conditions and on the native flora and fauna. Van der Meulen et al. (1987) first pointed out the negative impact of the moss invasion on the Netherlands coastal dunes. Today (2009), the species is listed as an environmental weed on the “Global Compendium of Weeds” (http://www.hear.org/gcw).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Streptophyta
- Class: Bryopsida
- Order: Dicranales
- Family: Dicranaceae
- Genus: Campylopus
- Species: Campylopus introflexus
Notes on Taxonomy and NomenclatureTop of page
The species was first described as Dicranum introflexum by Hedwig in 1801 (Spec. Musc. Frond.: 147). Previously the name Campylopus introflexus was also used for Campylopus pilifer Brid. (Campylopus polytrichoides De Not.) and therefore considered as an almost cosmopolitan species until Giacomini (1955) showed that two different species were present. References for C. introflexus in Europe older than 1941 have to be referred to C. pilifer. References for C. introflexus in North America older than 1975 have to be referred to C. pilifer, Campylopus surinamensis or Campylopus oerstedianus (Frahm, 2007). Old records of C. introflexus generally have to be treated carefully, as there have been numerous revisions, e.g. Frahm (1985b) revised “C. introflexus” in the Hawaiian Islands to Campylopus aureus, which was later changed to Campylopus schmidii by Staples et al. (2004). For a list of synonyms see Frahm (1975), Greene (1986), and Streimann and Klazenga (2002), for example.
DescriptionTop of page
C. introflexus is an acrocarpous, perennial moss forming dense cushions or mats. Plants are 0.5 to 5 cm high with yellow to olive-green leaves, 2.5 to 6.5 mm long, excurrent in a hyaline hair tip, particularly in sunny stands. When plants are dry these hair tips are strongly reflexed and form a white star, when seen from above (see Pictures). The seta is 7 to 12 mm long, yellowish when young and brownish when older. Capsules are 1 to 1.5 mm long. They are rare in drier areas, and frequent to abundant in wetter regions. Spores are 10 to 15 µm in diameter (Smith, 2004).
Plant TypeTop of page Perennial
DistributionTop of page
C. introflexus is considered native in the southern hemisphere where it is common in temperate and sub-Antarctic regions, between 22 and 57°S (Gradstein and Sipman, 1978; Ochyra et al., 2008). The most northwards locality is on the island of Réunion at approximately 21°S (Frahm, 1985a). Records are known from southern South America (Argentina, Brazil, Chile, Paraguay, and Uruguay), southern Africa (Botswana, Lesotho, Namibia, and South Africa), Australia, New Zealand, and many islands throughout the southern oceans (e.g. South Sandwich Islands, Kerguelen Islands, Juan Fernández Islands, and Saint Helena). This species invaded the northern hemisphere, where it was first recorded in 1941 in Europe and 1975 in North America. At present, it ranges between approximately 35°N (California; Norris and Shevock, 2004) and 66°N (Iceland; Weidema, 2006).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Atlantic, Antarctic||Absent, invalid record||Lewis Smith, 1988; Ochyra et al., 2008||The Lewis Smith (1988) record for Deception Island (South Shetland Islands) was later discarded by Ochyra et al. (2008)|
|Indian Ocean, Antarctic||Present||Native||Frahm, 1985a; Tixier, 1980||Kerguelen Islands|
|Pacific, Southwest||Present||Native||Streimann and Klazenga, 2002||Macquarie Island|
|Turkey||Present||Introduced||2004||Tonguç Yayintas, 2009||First found in Thrace Region: Istranca Mountains, 350 m.a.s.l.|
|Botswana||Present||Native||Perold and Rooy, 1993|
|Cameroon||Absent, invalid record||Schultze-Motel, 1975; O'Shea, 1999||The Schultze-Motel (1975) record was later discarded by O'Shea (1999) who corrected the species to Campylopus pilifer|
|Chad||Absent, unreliable record||O'Shea, 1999||The record from O'Shea (1999) was possibly a misidentification|
|Crozet Islands||Present||Native||Hebrard, 1970|
|Lesotho||Present||Native||Perold and Rooy, 1993|
|Mauritius||Absent, invalid record||O'Shea, 1999; Frahm et al., 2009||Frahm et al. (2009) did not list C. introflexus in 'The Moss Flora of Mauritius'|
|Namibia||Present||Native||Perold and Rooy, 1993|
|Saint Helena||Present||Native||Frahm, 1985a|
|-Tristan Da Cunha||Present||Native||Dixon, 1960; Wace and Dickson, 1965; Streimann, 2002|
|Sierra Leone||Absent, invalid record||Schultze-Motel, 1975; O'Shea, 1999||The Schultze-Motel (1975) record was later discarded by O'Shea (1999) who corrected the species to Campylopus pilifer|
|South Africa||Present||Native||Frahm, 1985a; Zanten, 1971; O'Shea, 1999; Streimann, 2002|
|Canada||Present||Present based on regional distribution.|
|-British Columbia||Present||Introduced||1994||Taylor, 1997; Frahm, 2007|
|USA||Present||Present based on regional distribution.|
|-California||Present||Introduced||1975||Frahm, 1980; Norris and Shevock, 2004; Frahm, 2007|
|-Hawaii||Absent, invalid record||Frahm, 1985b; Hoe, 1974; Staples et al., 2004||C. introflexus mentioned in Hoe (1974) was later corrected to Campylopus schmidii by Staples et al. (2004)|
|-Oregon||Present||Introduced||Schofield, 1997; Frahm, 2007|
|Argentina||Present||Native||Gradstein and Sipman, 1978|
|-Rio Grande do Sul||Present||Native||Frahm, 1975|
|-Santa Catarina||Present||Native||Frahm, 1991|
|-Sao Paulo||Present||Native||Frahm, 1991|
|Chile||Present||Native||Frahm, 1975; Gradstein and Sipman, 1978|
|Falkland Islands||Present||Native||Hassel and Söderström, 2005|
|Paraguay||Present||Native||Stech and Dohrmann, 2004|
|South Georgia and the South Sandwich Islands||Present||Native||Longton and Holdgate, 1979; Ochyra et al., 2002|
|Uruguay||Present||Native||Gradstein and Sipman, 1978|
|Austria||Present||Introduced||1985||Grims et al., 1999|
|Belgium||Present||Introduced||1966||Jacques and Lambinon, 1968; Stieperaere and Jacques, 1995|
|Czech Republic||Present||Introduced||1988||Novotny, 1990; Mikulásková, 2006||Shows distribution map for Czech Republic|
|Denmark||Present||Introduced||1968||Frahm, 1971; Weidema, 2006|
|Faroe Islands||Present||Introduced||1973||Boesen et al., 1975|
|Germany||Present||Invasive||Neu, 1968; Hübschmann, 1970; Benkert, 1971; Biermann, 1999|
|Hungary||Present||Introduced||2006||Szücs and Erzberger, 2007||First found in Komárom-Esztergom County: northern foothills of Gerecse Mountains, c. 175 m.a.s.l.|
|Iceland||Present||Introduced||1983||Weidema, 2006||1983 in northern Iceland, 2001 in southwestern Iceland. Locally invasive|
|Italy||Present||Introduced||Aleffi et al., 2008|
|Latvia||Present, few occurrences||Introduced||2000||Abolina and Reriha, 2004|
|Liechtenstein||Present, few occurrences||Introduced||1991||Senn, 2000|
|Lithuania||Present, few occurrences||Introduced||1996||Jukoniene, 2003|
|Luxembourg||Present||Introduced||1979||Werner, 1981||First found in heath on schist along the path at 380 m.a.s.l. (Oesling)|
|Netherlands||Present||Introduced||1961||Sipman, 1977; Meulen et al., 1987||First found in Noordoostpolder|
|Poland||Present||Introduced||1986||Lisowski and Urbanski, 1989; Fudali et al., 2009||Shows distribution map for Poland|
|Portugal||Present||Introduced||1996||Sérgio, 1997; Sérgio et al., 2003||Shows distribution map for Portugal|
|-Madeira||Present, few occurrences||Introduced||1989||Nieuwkoop and Arts, 1995||First found on a loamy path along a levada at 1000 m.a.s.l.|
|Russian Federation||Present||Introduced||2000||Razgulyaeva et al., 2001||Found in Kaliningrad Province (Curonian spit)|
|Slovakia||Present||Introduced||Holotová and Šoltés, 1997|
|Spain||Present||Introduced||1980||Frahm, 1981; Casas et al., 1988||First found in northern Spain|
|-Balearic Islands||Present, few occurrences||Introduced||1993-1996||Sáez et al., 1998||Mallorca|
|Switzerland||Present||Introduced||1980||Bisang et al., 1998||First found in Kt. Solothurn|
|UK||Present||Introduced||1941||Richards, 1963||Locally invasive|
|-Channel Islands||Present||Introduced||Hill et al., 1992||Jersey|
|Australia||Present||Present based on regional distribution.|
|-Australian Northern Territory||Absent, invalid record||Scott and Stone, 1976; Streimann and Klazenga, 2002||Scott and Stone (1976) record discarded by Streimann and Klazenga (2002)|
|-Lord Howe Is.||Present||Native||Streimann and Klazenga, 2002|
|-New South Wales||Present||Native||Streimann and Klazenga, 2002|
|-Queensland||Present||Native||Streimann and Klazenga, 2002|
|-South Australia||Present||Native||Streimann and Klazenga, 2002|
|-Tasmania||Present||Native||Streimann and Klazenga, 2002|
|-Victoria||Present||Native||Streimann and Klazenga, 2002|
|-Western Australia||Present||Native||Streimann and Klazenga, 2002|
|French Polynesia||Absent, unreliable record||Miller et al., 1978; Streimann, 2002||The records from Miller et al. (1978) and Streimann (2002) were possibly misidentifications|
|New Caledonia||Present||Native||Gradstein and Sipman, 1978|
|New Zealand||Present||Native||Vitt, 1974; Vitt, 1979; Streimann, 2002||North Island, South Island, Steward Island, Auckland Island, Campbell Island, Chatham Islands, Kermadec Islands|
|Norfolk Island||Present||Native||Streimann, 2002|
History of Introduction and SpreadTop of page
This species was first discovered outside its natural area in Europe in 1941 in Washington, Sussex, UK (Richards, 1963) where it arrived probably by human activities (van der Meulen et al., 1987). The source area of the European population in the southern hemisphere could not be localized (Stech and Wagner, 2005) because only low intraspecific variation was revealed by a phylogenetic survey (Stech and Dohrmann, 2004).
In 1942 this species was found in Ireland, in 1954 it was reported from France (the first confirmation in Europe at that time because prior ones were detected later by surveying herbarium specimens), in 1961 from the Netherlands, 1966 from Belgium, 1967 from Germany, and 1968 from Denmark. Today (2009), it has expanded its European distribution towards the north to Iceland, towards the south to Portugal and eastwards as far as Latvia, Russia (Kaliningrad) and eastern Poland, Hungary and even Turkey. It also invaded islands such as the Azores, Madeira, the Faeroes and the Balearics.
IntroductionsTop of page
Risk of IntroductionTop of page
Presently (2009), there is no evidence that the spread of C. introflexus has stopped and more records will probably emerge. No measures are known to counteract this spread, which probably originates from the dispersal of tiny spores dispersed by the wind over long distances. The number of sites where the species is considered to be invasive is also still increasing.
HabitatTop of page
C. introflexus is most widespread in low elevations of up to a few hundred metres, but occurs up to 1000 m.a.s.l. (e.g. Equihua and Usher, 1993; Nieuwkoop and Arts, 1995; Bisang et al., 1998). In southern Africa it was found above 3000 m (Germishuizen and Meyer, 2003). It prefers temporarily dry to humid, non-calcareous, nutrient-poor, humus or mineral soil or peat in fairly open situations; it is also found on bases of trees, rotten wood, and gravel on roofs and rarely on rocks (Gradstein and Sipman, 1978; Stieperaere and Jacques, 1995; Smith, 2004). Roadside banks, open sites and trails in poor shrub and forest, sparse grassy ground, swamps and fire sites are typical habitats. In the subarctic and subantarctic region (Iceland, South Sandwich Islands) this species is confined to geothermal ground where the soil is warmed up. A common factor of all these habitats is that they are, to some degree, exposed to natural or man-made disturbance and that competition from higher plants is low.
In Europe, C. introflexus is recorded as most invasive in stands of the grass Corynephorus canescens on stabilized and decalcified sand dunes on the coast (van der Meulen et al., 1987; Biermann, 1999; Ketner-Oostra and Sýkora, 2004) and inland (Biermann and Daniëls, 1997). It also invades heathlands (Stiperaere and Jacques, 1995), light forests and pine plantations, and raised and blanket bogs where it prevails on bare peat (Equihua and Usher, 1993; Lambdon, 2009). Furthermore, it can cover large areas of recently exposed and abandoned sandy ground in post-mining land.
In North America, the moss occupies similar habitats and is very abundant in sand dunes along the coast, for example (Frahm, 2007).
In Europe, C. introflexus performs best in the oceanic and suboceanic regions where precipitation is above 700 mm/year. It tolerates precipitation as low as approximately 500 mm/year. Microclimatic conditions can sometimes outrank macroclimate as the occurrences on geothermal ground show. In dune areas, C. introflexus is reported as having difficulties in dominating south-facing slopes most exposed to the sun (Ketner-Oostra et al., 2006). However, C. introflexus is still rather drought-resistant. Robbins (1952) showed that moss carpets can recover after a period of drought of 25-28 weeks maximum. In periods of drought, the leaves of the moss twist around the stems to impede evaporation. The hyaline hair tips reflect irradiation and thus keep the temperature within the carpets relatively moderate (van der Meulen et al., 1987).
The pH value of the substrate ranges from 3.5 to 7.0 with a peak at about 4.5 (e.g. Biermann, 1999; Hasse, 2005; Isermann, 2005). Values above 6.5 are reported only from fen peat (Equihua and Usher, 1993). In addition to the Soil Tolerances list, special soil tolerances for C. introflexus include organic substrates such as peat, rotten wood, and tree bases.
With reference to the Habitat List, the harm caused by C. introflexus in managed forests, plantations and orchards; disturbed areas; natural forests; wetlands (raised and blanket bogs); and cold lands/tundra (referring to geothermal warmed ground only), is evaluated to be local and not as severe as in coastal dunes.
Habitat ListTop of page
|Terrestrial – Managed||Managed forests, plantations and orchards||Principal habitat||Harmful (pest or invasive)|
|Managed forests, plantations and orchards||Principal habitat||Natural|
|Managed grasslands (grazing systems)||Secondary/tolerated habitat||Natural|
|Disturbed areas||Principal habitat||Harmful (pest or invasive)|
|Disturbed areas||Principal habitat||Natural|
|Rail / roadsides||Principal habitat||Natural|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Principal habitat||Harmful (pest or invasive)|
|Natural forests||Principal habitat||Natural|
|Wetlands||Principal habitat||Harmful (pest or invasive)|
|Cold lands / tundra||Present, no further details||Harmful (pest or invasive)|
|Cold lands / tundra||Present, no further details||Natural|
|Rocky areas / lava flows||Present, no further details||Natural|
|Scrub / shrublands||Principal habitat||Natural|
|Coastal dunes||Principal habitat||Harmful (pest or invasive)|
|Coastal dunes||Principal habitat||Natural|
Hosts/Species AffectedTop of page
In the northern hemisphere, C. introflexus is not a weed of agricultural land, but occurs on low-productive soils. In the southern hemisphere, the moss also occurs in pasture (Robbins, 1952), but is not mentioned to have major impact there.
Biology and EcologyTop of page
Stech and Dohrmann (2004) resolved that C. introflexus is monophyletic. It is unknown to what extent hybridization plays a role. However, molecular relationships (Stech and Dohrmann, 2004) and morphological characteristics (Gradstein and Sipman, 1978) of C. introflexus and Campylopus pilifer might indicate hybridization between both species. Chromosome numbers (n = 12) of specimens from Australia (Ramsay, 1974) and Poland (Ochyra and Kuta, 1990) were checked.
C. introflexus is dioecious. In favourable habitats, the moss produces numerous tiny spores (10-15 µm). These are distributed by the wind over long distances and are therefore presumably primarily responsible for the rapid range expansion of the species within Europe and North America (Hassel and Söderström, 2005; Frahm, 2008).
Vegetative propagation by shoot tips plays an important role in local dispersal and the forming of invasive stands (Hallingbäck et al., 1985; Söderström, 1992). The abundance of these deciduous leafy buds shed from the upper leaves is highest in the young moss carpets, only a few millimetres high (Biermann, 1999). They are dispersed by the wind or animals and enable a very efficient and rapid occupation of gaps, a strategy which is often superior to strategies of native pioneer mosses.
Another advantage for colonizing new habitats is the ability of fragments of the moss carpets to survive for years after being detached and displaced, and to give rise to new individuals if conditions are suitable (Robbins, 1952; van der Meulen et al., 1987; Hasse, 2007). Animals frequently disperse them and thus assist the local spread of the moss.
C. introflexus is perennial. Under adequate conditions the moss can form carpets of 2-10 cm thickness. These barely allow other plants to colonize once they are established and therefore often form monotonous stands of up to several hundred square metres. These carpets persist over several years before being succeeded by other plants (Daniëls et al., 2008) or being rejuvenated with new individuals of the moss, often due to disturbance. The dry moss carpets are often observed to fragment and break loose from the ground, due to birds in search for food or trampling and digging or scraping animals. Alternate wetting and drying of moss carpets leads to the forming of polygon-shaped cracks and thus facilitates fragmentation.
ClimateTop of page
|BS - Steppe climate||Preferred||> 430mm and < 860mm annual precipitation|
|BW - Desert climate||Tolerated||< 430mm annual precipitation|
|Cf - Warm temperate climate, wet all year||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cw - Warm temperate climate with dry winter||Tolerated||Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)|
|Ds - Continental climate with dry summer||Tolerated||Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)|
|ET - Tundra climate||Tolerated||Tundra climate (Average temp. of warmest month < 10°C and > 0°C)|
Soil TolerancesTop of page
- very acid
Special soil tolerances
Notes on Natural EnemiesTop of page
C. introflexus may be grazed to some extent by typical moss herbivores such as slugs or pill beetles (Bhyrridae) (Lambdon, 2009).
Means of Movement and DispersalTop of page
The pathway taken by C. introflexus to invade Europe and North America is unknown and theories about it are based on speculation. It is possible that the species was introduced accidentally by human activities (van der Meulen et al., 1987). Possibilities include plants or spores imported as stowaway with trading goods, attached to imported exotic plants, and/or dispersed by military activities or travelling tourists. It is less likely that the species invaded the northern hemisphere without human interference, either by long-distance transport of spores by air currents (cf. Frahm, 2008) or by migrating birds. Previous molecular studies of C. introflexus did not reveal the origin of the European population and therefore could not explain the pathways involved (Stech and Wagner, 2005).
Self-dispersal by spores might be the most prominent pathway of expansion within Europe and North America after the species has reached the new continents (Hassel and Söderström, 2005), but other factors might also have been involved. In the case of Madeira, Nieuwkoop and Arts (1995) supposed that tourists might have introduced the species accidentally, because the first record was from a popular tourist walk. Razgulyaeva et al. (2001) argue migrating birds as possible agents of introduction to Russia. Some people supposed that tanks during World War II spread the species throughout the Netherlands and they therefore gave the moss the name “tank moss”. However, the first report of the species in the Netherlands dates from 1961. Again, molecular studies could not elucidate the pathways for the European expansion (Stech et al., 2007). It is nearly impossible to differentiate clearly if a new occurrence derived from introduction (human activity) or not.
Locally, vegetative propagation presumably plays the more important role in the spread and the impressive dominance that the moss can gain (Hallingbäck et al., 1985). Shoot tips can be dispersed by wind or animals when stuck to their fur. Tufts of moss carpets can be dispersed by animals, trampling, scraping or tearing the carpet apart in search for food.
Natural Dispersal (Non-Biotic)
Spores are dispersed by the wind over long distances. Vegetative propagation by shoot tips may occur over short distances in strong winds.
Vector Transmission (Biotic)
Wild animals (e.g. game, boar, and rabbit) and humans may disperse fragments of moss carpets over short distances by trampling or scraping. Birds such as thrush or pheasant are observed to pick the moss carpets into pieces in search of food. These tufts can re-establish at new sites if conditions are suitable. Shoot tips may stick to animal fur and be transported locally.
There are no recorded cases of introductions that could be clearly identified as accidental. However, most introductions are probably accidental because bryophytes are rarely deliberately introduced (Söderström, 1992).
There are no recorded cases of intentional introduction.
Pathway CausesTop of page
Pathway VectorsTop of page
Impact SummaryTop of page
Environmental ImpactTop of page
Extensive stands of C. introflexus alter the appearance of the invaded biotopes (see Pictures), habitat conditions and species composition. C. introflexus also invades rare habitats and locally threatens rare species. Impact on Habitats Like other pioneer species, C. introflexus covers open substrate rapidly. In open dune areas, when sand dynamics begin to cease, this process can be accelerated by the massive expansion of this moss. As well as being an effective colonizer of open substrate, the moss can also out-compete other species (Biermann and Daniëls, 1997). Once fully established, these moss carpets without gaps impede the germination of herbs, grasses and dwarf-shrubs (van der Meulen et al., 1987; Equihua and Usher, 1993) and therefore impede vegetation succession. When emerging shrubs or trees increase shading and humidity or when the moss carpets become senescent, they may be succeeded by other species (e.g. Hasse, 2007; Daniëls et al., 2008). In a long-term study in the Netherlands, a succession from dominance by C. introflexus to native lichen-dominated vegetation on sun-exposed drift sand was observed on inland dunes during a period of 15 to 20 years (Daniëls et al., 2008). However, periodic disturbances may lead to periodic rejuvenation and thus continuous predominance of these moss carpets. Impact on Biodiversity The encroachment by C. introflexus reduces the dominance of other plants. Other pioneer mosses that are capable of forming carpets, such as Polytrichum piliferum, Polytrichum juniperinum, Dicranum scoparium, and Racomitrium canescens (cf. Weidema, 2006), as well as lichens (Biermann and Daniëls, 1997; Ketner-Oostra and Sýkora, 2004) and phanerogams (Equihua and Usher, 1993) are affected. The risk of extinction for other species due to moss encroachment is difficult to assess and depends on the specific situation of the affected site. Hasse (2007) and Daniëls et al. (2008) argue that in an inland dune complex in the Netherlands, the encroachment is locally temporal and native species return after they persevered in adjacent habitats, whereas Weidema (2006) reports a negative impact on some rare moss species in a small-sized geothermal area in Iceland. The following conditions/factors might regulate the risk of extinction: - The availability of adjacent habitats that are little or unaffected by the moss encroachment and suitable for persistence of the species. - The time span of the moss dominance. - The species’ capability to re-colonize the invaded site after the moss carpets cease in dominance. - The species’ ability to persist or rejuvenate within the moss carpets. Van Turnhout (2005) supposed that moss encroachment may have contributed to the extinction of the Tawny Pipit (Anthus campestris) (a breeding bird in the Netherlands) due to the decreased abundance of arthropods and thus food availability for the bird on the extensive carpets.
Impact on Habitats
Like other pioneer species, C. introflexus covers open substrate rapidly. In open dune areas, when sand dynamics begin to cease, this process can be accelerated by the massive expansion of this moss. As well as being an effective colonizer of open substrate, the moss can also out-compete other species (Biermann and Daniëls, 1997).
Once fully established, these moss carpets without gaps impede the germination of herbs, grasses and dwarf-shrubs (van der Meulen et al., 1987; Equihua and Usher, 1993) and therefore impede vegetation succession. When emerging shrubs or trees increase shading and humidity or when the moss carpets become senescent, they may be succeeded by other species (e.g. Hasse, 2007; Daniëls et al., 2008). In a long-term study in the Netherlands, a succession from dominance by C. introflexus to native lichen-dominated vegetation on sun-exposed drift sand was observed on inland dunes during a period of 15 to 20 years (Daniëls et al., 2008). However, periodic disturbances may lead to periodic rejuvenation and thus continuous predominance of these moss carpets.
Impact on Biodiversity
The encroachment by C. introflexus reduces the dominance of other plants. Other pioneer mosses that are capable of forming carpets, such as Polytrichum piliferum, Polytrichum juniperinum, Dicranum scoparium, and Racomitrium canescens (cf. Weidema, 2006), as well as lichens (Biermann and Daniëls, 1997; Ketner-Oostra and Sýkora, 2004) and phanerogams (Equihua and Usher, 1993) are affected.
The risk of extinction for other species due to moss encroachment is difficult to assess and depends on the specific situation of the affected site. Hasse (2007) and Daniëls et al. (2008) argue that in an inland dune complex in the Netherlands, the encroachment is locally temporal and native species return after they persevered in adjacent habitats, whereas Weidema (2006) reports a negative impact on some rare moss species in a small-sized geothermal area in Iceland. The following conditions/factors might regulate the risk of extinction:
- The availability of adjacent habitats that are little or unaffected by the moss encroachment and suitable for persistence of the species.
- The time span of the moss dominance.
- The species’ capability to re-colonize the invaded site after the moss carpets cease in dominance.
- The species’ ability to persist or rejuvenate within the moss carpets.
Van Turnhout (2005) supposed that moss encroachment may have contributed to the extinction of the Tawny Pipit (Anthus campestris) (a breeding bird in the Netherlands) due to the decreased abundance of arthropods and thus food availability for the bird on the extensive carpets.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Is a habitat generalist
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Tolerant of shade
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Ecosystem change/ habitat alteration
- Modification of successional patterns
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Competition - monopolizing resources
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
- Difficult/costly to control
UsesTop of page
C. introflexus may be used in moss gardens.
Uses ListTop of page
- Potted plant
Similarities to Other Species/ConditionsTop of page
If well-developed, C. introflexus is easily recognized by its typical strongly reflexed hair tips. These hair tips are sometimes poorly developed, especially in semi-shady habitats, and confusion with other Campylopus species in the field is possible. It is most difficult to separate C. introflexus from Campylopus pilifer. Characteristics for the separation of both species were discussed by Richards (1963), Frahm (1974) and Gradstein and Sipman (1978), but they are still subject to discussion. Frahm and Stech (2006) put the hitherto known characteristics into perspective by describing intermediate forms between both species from France. In the southern hemisphere both species are even less clearly separated by morphological characteristics than in Europe (Gradstein and Sipman, 1978). C. introflexus can best be distinguished from its near relative C. pilifer with a transverse section of the leaf nerve. C. introflexus’ dorsal lamellae are composed of 1 (to 2) cell rows whereas C. pilifer has (1 to) 2 to 4 (to 6) cell rows (Frahm and Stech, 2006). Furthermore, the seta is longer (ca. 4 mm for C. pilifer) and spores are smaller (12 to 19 mm for C. pilifer; Gradstein and Sipman, 1978).
C. introflexus can best be distinguished from its near relative C. pilifer with a transverse section of the leaf nerve. C. introflexus’ dorsal lamellae are composed of 1 (to 2) cell rows whereas C. pilifer has (1 to) 2 to 4 (to 6) cell rows (Frahm and Stech, 2006). Furthermore, the seta is longer (ca. 4 mm for C. pilifer) and spores are smaller (12 to 19 mm for C. pilifer; Gradstein and Sipman, 1978).
Prevention and ControlTop of page
Invasive Species Management
Disturbance is a key factor in many ecosystems invaded by C. introflexus. It is essential to maintain different successional phases that contribute to overall species richness, as many native species in these ecosystems rely on the creation of open habitats. There are several natural sources of disturbance (e.g. wind and water erosion, animals, fire) and management practices often target for the same factor. These open habitats are prone to invasion by C. introflexus.
Management measures such as the removal of pine plantations to restore heathland (Wilton-Jones and Ausden, 2005), and natural disturbances such as wild fire (Ketner-Oostra et al., 2006) were reported to result in an increased emergence of the alien moss.
No prevention methods have been described for C. introflexus. It seems impossible to prevent its dispersal because it is very fertile and the tiny spores are distributed by the wind over long distances.
Management options to control moss encroachment can be categorized into direct interference with the moss plants or the control of habitat conditions to the disadvantage of the moss as an indirect measure. However, all management options have been of limited success.
The use of the herbicide asulam (Asulox), tested in experiments with different mosses, showed little impact on C. introflexus (Rowntree et al., 2003). Sod-cutting of a 200 m² plot did not successfully remove C. introflexus long-term, and the moss reclaimed dominance 3 years later (Ketner-Oostra and Sýkora, 2000).
This moss does not tolerate burial in calcareous sand (van der Meulen et al., 1987; van Boxel et al., 1997; Ketner-Oostra and Sýkora, 2000; 2004), thus stimulating sand drift from the first foredunes and the beach could be a protective measure against moss invasion on the coast. Burial under a thin layer of decalcified sand was tolerated by C. introflexus (Hasse and Daniëls, 2006).
ReferencesTop of page
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Hasse T, 2005. Characterisation of the successional stages in the Spergulo-Corynephoretum (Corynephorus grasslands) with particular emphasis on lichens. (Charakterisierung der Sukzessionsstadien im Spergulo-Corynephoretum (Silbergrasfluren) unter besonderer Berücksichtigung der Flechten) Tuexenia, 25:407-424.
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Lambdon PW, 2009. Campylopus introflexus (Hedw.) Brid., heath star moss (Dicranaceae, Bryophyta). In: Handbook of Alien Species in Europe. Invading nature: Springer series in invasion ecology 3 Dordrecht, Netherlands: Springer, 344.
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Meulen F der van; Hagen H der van; Kruijsen B, 1987. Campylopus introflexus. Invasion of a moss in Dutch coastal dunes. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, Series C - Biological and Medical Sciences, 90:73-80.
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Söderström L, 1992. Invasions and range expansions and contractions of bryophytes. In: Bryophytes and lichens in a changing environment [ed. by Bates JW, Farmer AM] Oxford, UK: Clarendon Press, 131-158.
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Zanten BO van, 1971. Musci. In: Marion and Prince Edward Islands: report on the South African biological and geological expedition 1965-1966 [ed. by Zinderen Bakker EMvan , Winterbottom JM, Dyer RA] Cape Town, South Africa: A.A. Balkema, 173-227.
ContributorsTop of page
24/07/09 Original text by:
T Hasse, Consultant, Germany
Distribution MapsTop of page
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