| Cladonia arbuscula | |
|---|---|
 | |
Global status: Secure (G5) | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Cladoniaceae |
| Genus: | Cladonia |
| Species: | C. arbuscula |
| Binomial name | |
| Cladonia arbuscula (Wallr.) Flot. | |
| Synonyms [1] | |
List
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Cladonia arbuscula, also referred to as shrubby cup lichen [2] or green reindeer lichen, is a species of cup lichen in the family Cladoniaceae.
The lichen is composed of two thalli; an initial primary squamulose thallus growing across bark in a scaly, flaking pattern, followed by a secondary fruticose thallus (podetium), with cup shaped podetia (4-10cm tall) bearing terminal ascocarps contained in apothecial structures. [3] [4] The coloring of C. arbuscula varies between subspecies, but is primarily white-gray, pale yellow, or bright green, with darker orange tips where ascocarps are formed. [4] [5] [6] The thallus shows negative results in typical K-tests with no color change.
The species name "arbuscula" is Latin for the word "bush" or "shrub", which may be due to the fact that the lichen has branches that resemble a bush. [7]
C. arbuscula has 6 subspecies: [8]
C. arbuscula is found throughout the world, tolerating harsh conditions that many vegetative plants cannot. It is widely spread in Canada and the Northern United States (mostly Alaska), but also found in Wyoming, Idaho, and Montana. Although it is relatively uncommon in the Pacific Northwest, it can be found there. Common in Labrador and Newfoundland and found throughout England and Ireland. [5] It has been found in more southern latitudes such as Chile, Tasmania, and New Zealand as well, but is most dominant in northern latitudes. [9] The lichen is considered to be secure in terms of conservation, but in some subspecies there are areas of concern in which the species is declining. [10]
Lichens typically grow in areas of high climatic stress, where many vascular plants cannot tolerate the conditions and survive. C. arbuscula is most commonly found growing on white or black spruce, but can be found on the ground in bogs or fens as well as growing on sunny rocks. Reindeer lichens require a small amount of soil in order to stay attached to their substrate, but rarely grow directly on soil due to their ability to absorb nutrients and water from the air. Other substrates that C. arbuscula can be found on include decaying organic material, raised peat, other coniferous or hardwood trees, and rely on lakeshore rocks. [3] [11] [5] [12] The species can be found growing in association with mosses in some cases, which is thought to help with their attachment to rocks or woody debris.The species is shade intolerant, and typically cannot grow in areas with 70% canopy cover or more. With the exception of populations in the Pacific Northwest, reindeer lichen grow dominantly in cool, dry sites. They avoid areas with standing water, and in areas of high moisture will grow in the driest microbiomes. C. arbuscula is more commonly found in moist areas when compared to other species in the genus, but still prefers dry, cool habitats for ideal growth. Reindeer lichens are rarely found at high elevations, and grow dominantly at low-middle elevations.
C. arbuscula can reproduce both asexually and sexually. The asexual reproduction process can occur through fragmentation of the primary thallus in which a small portion of the thallus can regenerate a fully productive new thallus as long as the original portion contains both algal and fungal cells. Asexual spores known as conidia are produced on pycnidia borne at the edges of the podetia cups [6] [12] and are used to reproduce asexually via fragmentation. Due to the microscopic nature of these asexual reproductive elements, not many studies have been done to describe the in depth reproduction of C. arbuscula. [3]
Sexual reproduction in C. arbuscula is done through the production and release of ascospores. These sexual spores are contained in an ascus located at the tip of the podetia, and are dispersed via wind. This lichen does not disperse far from the parent organism, however, with an average dispersal distance of only around 8-10 inches in forest sites and no more than 30 inches in prairies and savannas. Lichen fragments can be dispersed from animals at longer distances, but this is not the main method used in reproduction and regeneration. [3] Lichens reproduce sexually in one of two ways, heterothally or homothally, yet the obligate lifestyle of Cladonia species and many others makes studying the sexual reproductive cycle nearly impossible in a lab, and remains unknown for this species. [13]
Most lichens are slow growing and have long life spans, particularly in the Cladonia species of reindeer lichen. Despite the overall slow process of growth, their lives can be broken down into three distinct sections of growth. The first stage of growth consists of the fastest increase in size, and is considered the growth accumulation period. The lichen grows larger in size every year without losing any parts of the podetium. This first stage typically lasts around 10 years, but depending on species and location can range from 6-25 years. [3] Especially in areas disturbed by fire regimes, growth rates are on average 4.8 mm/year, but can reach up to 12 mm/year. [14] The second period of growth is known as the renovation period, and while the podetium height continues to increase, internodes begin to decay and die at the base. This is the longest stage, lasting over 100 years in some cases. Finally, the withering period lasts around 10-20 years and consists of the decay of both the remaining internodes and the podetia. [3]
Growth periods depend heavily on a multitude of outside factors, such as habitat, climate, amount of grazing, fire regimes, and substrate material. Growth rates appear to be highest in areas with high fire disturbance and high grazing, however the overall size of lichen in areas of high grazing were on smaller on average. [3] [14]
Cladonia arbuscula is a known host species for the fungus Lichenopeltella cladoniarum . [15]
Cladonia arbuscula is a vital foodsource for caribou in the Northern hemisphere. Due to the lichen's ability to survive through cold, dry winters, they are a primary food source throughout winter for many caribou in North America. In Canada, the lichen make up around 50-90% of the caribou's diet (according to studies of caribou rumens). The fungi however can be damaged by large numbers of caribou due to overgrazing and trampling. Some small mammals such as voles and mice feed on these lichens in the winter as well. Despite the low protein levels of these lichen, especially in comparison with other vascular plants, they are the main food source for many animals, and if not protected can cause bottom-up trophic cascades with detrimental effects on caribou populations. [16] Lichens themselves are photosymbionts, and consist of intermixing fungal, cyanobacteria, and algal layers working together to survive. [17]
Thallus fragments can travel from unburned areas to freshly burned ones and easily colonize the shadeless, dry terrain. In areas of recent burns, C. arbuscula growth rates increased substantially compared to areas without fire. [3] [14] While reindeer lichens can persist in the absence of fire, the decreased canopy cover and increased groundlayer biodiversity from frequent burns can significantly help lichens grow. Fire itself does kill reindeer lichen, but leads to more favorable conditions for growth post-fire. C. arbuscula is typically found in late primary successional stages, and in early-middle secondary successional stages. Caribou grazing and trampling can affect the diversity of lichen in an area by causing early and late successional staged species to grow simultaneously.
Despite the species being considered stable and secure globally, there are many threats facing C. arbuscula across the globe. These threats include pollution, fire suppression, and mountain pine beetles. C. arbuscula is extremely sensitive to pollution, and heavy metals and acids from factories or manufacturing facilities can travel miles and harm these lichen. The toxins build up in the lichens and inhibit growth and kill many organisms each year. Mountain pine beetles indirectly affect reindeer lichen as well due to their ability to cause large scale lodgepole pine death, a commonly used substrate for the lichen. [3]
A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
Cladonia rangiferina, also known as reindeer cup lichen, reindeer lichen or grey reindeer lichen, is a light-colored fruticose, cup lichen species in the family Cladoniaceae. It grows in both hot and cold climates in well-drained, open environments. Found primarily in areas of alpine tundra, it is extremely cold-hardy.
Cladonia is a genus of moss-like lichens in the family Cladoniaceae. They are the primary food source for reindeer/caribou. Cladonia species are of economic importance to reindeer-herders, such as the Sami in Scandinavia or the Nenets in Russia. Antibiotic compounds are extracted from some species to create antibiotic cream. The light green species Cladonia stellaris is used in flower decorations.
The Cladoniaceae are a family of lichen-forming fungi in the order Lecanorales. It is one of the largest families of lichen-forming fungi, with about 560 species distributed amongst 17 genera. The reindeer moss and cup lichens (Cladonia) belong to this family. The latter genus, which comprises about 500 species, forms a major part of the diet of large mammals in taiga and tundra ecosystems. Many Cladoniaceae lichens grow on soil, but others can use decaying wood, tree trunks, and, in a few instances, rocks as their substrate. They grow in places with high humidity, and cannot tolerate aridity.
Cladonia furcata or the many-forked cup lichen is a species of cup lichen in the family Cladoniaceae. It has an intermediate to tolerant air pollution sensitivity. Extracts of this species have been shown to kill leukemia cells in vitro, and may have possible value in the treatment of cancer.
Cladonia stellaris or the star-tipped cup lichen is an ecologically important species of cup lichen that forms continuous mats over large areas of the ground in boreal and arctic regions around the circumpolar north. The species is a preferred food source of reindeer and caribou during the winter months, and it has an important role in regulating nutrient cycling and soil microbiological communities. Like many other lichens, Cladonia stellaris is used by humans directly for its chemical properties, as many of the secondary metabolites are antimicrobial, but it also has the unique distinction of being harvested and sold as 'fake trees' for model train displays. It is also used as a sound absorber in interior design. The fungal portion of Cladonia stellaris, known as a mycobiont, protects the lichen from lichenivores, superfluous solar radiation, and other kinds of stressors in their ecosystem.
Cladonia mongkolsukii is a species of fruticose lichen in the family Cladoniaceae. Described as new to science in 2011, it is found in lower-elevation montane scrub forests of northeast Thailand and in Sri Lanka. The specific epithet honors Pachara Mongolsuk, a Thai lichenologist.
Crustose lichens are lichens that form a crust which strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their growth form. This form, which is based on the appearance of vegetative part of the lichen, varies depending on the species and the environmental conditions it faces. Those who study lichens (lichenologists) have described a dozen of these forms: areolate, byssoid, calicioid, cladoniform, crustose, filamentous, foliose, fruticose, gelatinous, leprose, placoidioid and squamulose. Traditionally, crustose (flat), foliose (leafy) and fruticose (shrubby) are considered to be the three main forms. In addition to these more formalised, traditional growth types, there are a handful of informal types named for their resemblance to the lichens of specific genera. These include alectorioid, catapyrenioid, cetrarioid, hypogymnioid, parmelioid and usneoid.
Lichen morphology describes the external appearance and structures of a lichen. These can vary considerably from species to species. Lichen growth forms are used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves ; others cover the substrate like a crust, others such as the genus Ramalina adopt shrubby forms, and there are gelatinous lichens such as the genus Collema.
Cladonia subradiata is a widely distributed species of fruticose lichen in the family Cladoniaceae. It is found in Asia, Africa, Melanesia, Australia, New Zealand, and South, Central, and North America.
Pulchrocladia retipora, commonly known as the coral lichen, is a species of fruticose lichen in the family Cladoniaceae. Found predominantly in Australasia, its habitats range from the Australian Capital Territory to New Zealand's North and South Islands, and even the Pacific region of New Caledonia, where it grows in coastal and alpine heathlands. The lichen features coral-like branches and subbranches with numerous intricate, netlike perforations. It is known by multiple names, with some sources referring to it by its synonym Cladia retipora, or the common name lace lichen.
Cladonia rei, commonly known as the wand lichen, is a species of ground-dwelling, fruticose lichen in the family Cladoniaceae. It is a widely distributed species, having been reported from Africa, Asia, Australasia, Europe, and North America. It is identified by its slightly dirty-colored, rough-surfaced, slender podetia that grow up to 9 cm (3.5 in) tall. Diagnostic characters of the lichen include the continuously sorediate, green-and-brown-mottled, podetia that taper upward to a point, while chemically, it contains homosekikaic and sekikaic acids. Its reduced capacity to bioaccumulate toxic heavy metals from its surroundings, as well as its ability to switch photobiont partners, allows the lichen to colonize and survive highly polluted habitats. There are several other Cladonia species that are somewhat similar in appearance, but can be distinguished either by subtle differences in morphology, or by the secondary chemicals they contain.
Peltigera rufescens, the field dog lichen or field pelt, is a species of terricolous (ground-dwelling), foliose lichen in the family Peltigeraceae. The common and widespread species has a cosmopolitan distribution. The lichen has a surface that is densely covered with a soft, velvety layer, extending from the edges to the centre. The edges of this lichen typically curl upwards, revealing lobes that can be up to 10 millimetres wide. Beneath, it possesses a network of rhizines, which are root-like structures that merge together into a thick mat, anchoring the lichen to its substrate.
Cladonia trassii is a species of fruticose lichen in the family Cladoniaceae. It has a circumpolar distribution and is found in arctic/alpine and subarctic habitats.
Cladonia longisquama is a species of fruticose lichen in the family Cladoniaceae. It occurs in the Seychelles, where it grows on moss-covered rocks.
Schaereria bullata is a species of lichen in the family Schaereriaceae. It is found in the alpine regions of Tasmania, Australia. This lichen species is characterized by its dark brown to grey-brown thallus, which forms irregular patches over soil or bryophytes, and consists of granules that coalesce to create convex to bullate squamules. The lichen also features distinctive apothecia, which are roundish and typically superficial, and spherical spores.
Cladonia monomorpha is a species of terricolous (ground-dwelling), fruticose lichen in the family Cladoniaceae. It is part of the Cladonia pyxidata group, known for brown apothecia on cup-shaped podetia.
Cladonia cayennensis is a species of fruticose lichen in the family Cladoniaceae. It is found in French Guiana, although the authors suggest that its distribution might be more widepsread.