Template:Short description Template:Good article Template:Use dmy dates Template:Use British English Template:Automatic taxobox
The Cladoniaceae are a family of lichen-forming fungi in the order Lecanorales, comprising about 560 species distributed amongst 18 genera. This family is one of the largest among lichen-forming fungi and is globally distributed, from Arctic tundra to tropical rainforests, favouring humid environments while being intolerant of arid conditions. Molecular phylogenetics has significantly advanced the understanding of their complex taxonomic history, revealing intricate evolutionary relationships and leading to a refined classification. Notable members include reindeer moss and cup lichens of the genus Cladonia, which consist of about 500 species and forms a significant part of the diet for large mammals in taiga and tundra ecosystems.
A distinctive feature of many Cladoniaceae species is their dimorphic thallus: a scaly or crust-like Template:Lichengloss form and a Template:Lichengloss (shrub-like) secondary form known as a podetium or Template:Lichengloss. These lichens typically grow on soil, decaying wood, or tree trunks, with a few species found on rocks. They form symbiotic associations with green algae, usually from the genus Asterochloris. The family is known for its diverse secondary metabolites—over 70 have been identified—which play roles in species identification and ecological functions such as protection against UV radiation and herbivore deterrence. Genomic studies have uncovered significant variation in mitochondrial DNA among Cladoniaceae species, contributing to the understanding of their evolution and diversity.
Some Cladoniaceae species have economic value, particularly in decorative uses such as floral arrangements and model-making due to their unique structures. Six species are included in the International Union for Conservation of Nature's Red List of Threatened Species, facing threats from habitat loss, climate change, and human activities. Conservation efforts are ongoing to protect these vulnerable species.
SystematicsEdit
Historical taxonomyEdit
Before the term 'lichen' was widely adopted, one of the earliest classification systems for these organisms was developed by the German botanist Johann Jacob Dillenius. In his 1741 system, Cladonia species were placed within the genus Coralloides.Template:Sfn In his Species Plantarum, Carl Linnaeus formally described several species that are now classified within the Cladoniaceae. Although he initially placed them in the eponymously named genus Lichen, a dozen of these species are recognised as belonging to the genus Cladonia.<ref name="Jørgensen 1994"/> Among these was Cladonia pyxidata, a representative of the "pixie cup" or "trumpet" lichens—so named for their distinctive shape,Template:Sfn as well as some well-known and widespread Cladonia species: C. coccifera, C. cornuta, C. deformis, C. digitata, C. fimbriata, C. gracilis, C. portentosa, C. rangiferina, C. stellaris, C. subulata, and C. uncialis.Template:Sfn These 12 species represent about 14% of the 80 Lichen species Linnaeus described in his seminal 1753 work.<ref name="Jørgensen 1994"/>
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The German naturalist Jonathan Carl Zenker formally introduced the Cladoniaceae to science in 1827, with his work appearing in a publication edited by Karl Goebel.<ref name="Goebel 1827"/> Zenker's initial concept of the family included genera such as Baeomyces, Icmadophila, and Stereocaulon, which have since been reclassified into separate families due to advances in taxonomic understanding.Template:Sfn William Nylander included 53 Cladonia species worldwide in his 1860 work Synopsis lichenum.<ref name="Nylander 1860"/> When Edvard August Vainio published his three-volume monograph on the Cladoniaceae (Monographia Cladoniarum universalis, 1887,<ref name="Vainio 1887"/> 1894,<ref name="Vainio 1894"/> and 1897<ref name="Vainio 1897"/>), he included 134 species and subspecies. In his circumscription of the family, the genera Pycnothelia, Cladia, and Cladina were included in the genus Cladonia.Template:Sfn In recent history, Teuvo Ahti's extensive research, including comprehensive monographs and revisions, has significantly advanced the understanding of Cladoniaceae taxonomy and biogeography.<ref name="Coppins 2002"/>
Cladoniaceae is now one of the largest families of lichen-forming fungi,<ref name="Lücking et al. 2017"/> with about 560 species distributed amongst 18 genera. The type genus is Cladonia, circumscribed by the Irish physician and botanist Patrick Browne in 1756. He included eight species in his new genus. Of their occurrence, he wrote: "All these species are found in great abundance in the mountains of Liguanea: they grow mostly on the ground, among other sorts of moss, but a few ... species chiefly are found upon the decaying trunks of trees."<ref name="Browne 1756"/>
Etymology and namingEdit
As is standard practice in botanical nomenclature,<ref name="Hawksworth 1974"/> the name Cladoniaceae is based on the name of the type genus, Cladonia, with the ending Template:Nowrap indicating the rank of family. The genus name comprises the Greek word: {{#invoke:Lang|lang}} (klādos), meaning "branch", "bud", or "shoot"; and the Latin -ia, a suffix commonly used in Latin to form nouns, particularly in taxonomy to denote genera.<ref name="Ulloa & Aguirre-Acosta 2020"/>
It is well known that reindeer feed on lichens, which has led to the widespread but misleading name "reindeer moss".Template:Sfn This common name, along with "reindeer lichen" and "caribou lichen", is typically applied to the ground-dwelling, mat-forming species that were previously classified in the genus Cladina.Template:Sfn Cladonia species with cup-shaped structures borne at the tips of vertical stalks (podetia) are often known as "pixie cups". Examples include the "boreal pixie cup" (C. borealis),Template:Sfn the "finger pixie cup" (C. digitata),Template:Sfn and the "red-fruited pixie cup" (C. pleurota) Template:Sfn Additional names alluding to these characteristic structures include the "powdered funnel lichen" (C. cenotea),Template:Sfn and the "trumpet lichen" (C. fimbriata).Template:Sfn Some names reference the reddish hue of their fruiting structures, such as "British soldiers" (C. cristatella),Template:Sfn the "jester lichen" (C. leporina),Template:Sfn and the "lipstick powderhorn" (C. macilenta).Template:Sfn
PhylogeneticsEdit
Template:Cladogram Molecular phylogenetics studies have significantly advanced the scientific understanding of relationships within the Cladoniaceae, particularly in the large and diverse genus Cladonia. Early studies in the early 2000s began to reveal the complexity of relationships within the family, challenging traditional morphology-based classifications. More recent comprehensive analyses have identified 13 major clades within Cladonia, providing a framework for understanding the genus's evolution and diversity. These clades, while generally well-supported by molecular data, often lack clear morphological synapomorphies (shared physical characteristics inherited from a common ancestor), highlighting the challenges in Cladonia taxonomy. Some clades, such as clade Erythrocarpae (characterised by red apothecia) and clade Ochroleucae (with pale ochraceous apothecia), do share distinctive features. However, most clades encompass a wide range of morphological and chemical variation.<ref name="Stenroos et al. 2019a"/>
Within these clades, several species complexes have been identified, such as the Cladonia gracilis group and the Cladonia humilis group. These complexes often include morphologically similar species that are difficult to distinguish based on traditional taxonomic characters. Molecular studies have revealed that many of these complexes contain cryptic diversity, with genetically distinct lineages that are not easily recognisable morphologically.<ref name="Stenroos et al. 2019a"/>
Focused molecular studies have further refined the understanding of specific groups within Cladoniaceae. For instance, detailed analyses of the Cladonia furcata complex have revealed high levels of homoplasy (the occurrence of similar traits due to convergent evolution rather than shared ancestry) in the morphological characters traditionally used for species delimitation. Similarly, studies on the Cladonia cariosa group and the Cladonia pyxidata group have uncovered previously unrecognised diversity and highlighted the need for integrative approaches combining molecular, morphological, and chemical data in species delimitation. These phylogenetic studies have also shed light on biogeographic patterns within Cladoniaceae. For example, some clades show distinct geographic distributions, such as a group of predominantly African species within clade Perviae, while others have more cosmopolitan distributions. Morphologically distinct genera like Carassea, Pycnothelia, and Metus form a sister clade to Cladonia. These genera share some morphological and chemical traits, such as dimorphic thalli and the production of atranorin. However, their geographic distributions vary, with Carassea being endemic to Brazil, while Pycnothelia has a bipolar distribution (i.e., found in the high latitudes of both hemispheres) and Metus is found primarily in Australasia.<ref name="Stenroos et al. 2019a"/>
GenomicsEdit
Genomic studies have revealed significant variation in the size and structure of mitochondrial DNA in Cladoniaceae, uncovering significant variation in genome size and structure. Within the genus Cladonia, mitochondrial genomes span from approximately 45,000 to 66,000 base pairs, consistently containing respiratory genes and ribosomal RNA regions across all examined species. Crustose lichens tend to have smaller mitochondrial genomes compared to their fruticose and foliose counterparts. The genomes often harbour homing endonuclease genes, which may influence genomic evolution. Notably, substantial intraspecific variation has been observed, particularly in widespread species such as C. rangiferina and C. submitis. Unlike some other symbiotic organisms, Cladoniaceae do not exhibit mitochondrial genome reduction, suggesting complex evolutionary dynamics.<ref name="Hoffman et al. 2023"/>
SynonymyEdit
Several phylogenetic studies have shown that Cladoniaceae is a member of the order Lecanorales, and is closely related to the family Stereocaulaceae.<ref name="Wedin et al. 2000"/><ref name="Stenroos et al. 2002"/><ref name="Arup et al. 2007"/><ref name="Ekman et al. 2008"/><ref name="Miadlikowska et al. 2014"/> The family Cetradoniaceae, which was created in 2002 to contain the endangered species Cetradonia linearis,<ref name="Wei & Ahti 2002"/> was folded into the Cladoniaceae in 2006.<ref name="Zhou et al. 2006"/>
In 2018, Ekaphan Kraichak and colleagues used a technique called temporal banding to reorganise the Lecanoromycetes, proposing a revised system of classification based on correlating taxonomic rank with geological (evolutionary) age. They synonymised the families Squamarinaceae and Stereocaulaceae with the Cladoniaceae, resulting in a large increase in the number of genera and species.<ref name="Kraichak et al. 2018"/> The Squamarinaceae had already been included in the Cladoniaceae by previous authors.<ref name="Lücking et al. 2017"/> Although this reorganisation has been used in some later publications,<ref name="Wijayawardene et al. 2020"/> the folding of the Stereocaulaceae into the Cladoniaceae was not accepted in a recent analysis. Robert Lücking highlighted that merging the two families under the name Cladoniaceae is not permissible without a formal conservation proposal because Stereocaulaceae, established in 1826, predates Cladoniaceae, which was established in 1827. According to the rules of botanical nomenclature, the earliest validly published name has priority and must be used when two families are combined unless an exception is granted. This means that if the families were merged without a conservation proposal, the combined family would have to be named Stereocaulaceae due to its earlier establishment.<ref name="Lücking 2019"/> In a 2021 treatment of the British and Irish Cladoniaceae, the authors also keep these families separate, noting "both families are monophyletic and easily distinguishable on both morphological and molecular terms".<ref name="Pino-Bodas et al. 2021"/>
DescriptionEdit
Template:Multiple image The thallus (body) of Cladoniaceae lichens often have a unique structure known as Template:Lichengloss growth, where two distinct forms develop simultaneously within the same organism.<ref name="Ahti 1982"/> The Template:Lichengloss, which can be short-lived (Template:Lichengloss) or long-lasting, grows close to the surface and may appear crusty, leafy, or scaly. From this base, a Template:Lichengloss typically grows upright, bearing the reproductive structures (ascomata).<ref name="Frey 2016"/> This secondary growth can range from a few millimetres to over 25 centimetres (10 inches) in height.<ref name="Pino-Bodas et al. 2021"/> Due to this dual structure, the overall appearance of these lichens can be either fruticose (bushy) or foliose (leafy). However, some species in this family do not develop either the primary thallus or the upright structures, showing variations within the group.<ref name="Stenroos et al. 2019a"/> As for vegetative propagules, isidia occur rarely in this family, whereas soredia are common.<ref name="Pino-Bodas et al. 2021"/>
The ascomata are in the form of an apothecium, and are Template:Lichengloss, meaning they are of the Template:Lichengloss type – light in colour and soft in consistency. They often have a reduced margin.<ref name="Frey 2016"/> Their colour is typically dark brown (sometimes pale brown), red, ochraceous, or black.<ref name="Stenroos et al. 2019a"/> The Template:Lichengloss (referring to all hyphae between the asci in the hymenium) consists of sparsely branched paraphyses, and is amyloid, indicating that stains blue to blue-black with iodine-based reagents. The asci (spore-bearing cells) are somewhat Template:Lichengloss, meaning they have two layers that separate during ascus dehiscence. The ascus structure consists of an Template:Lichengloss and a tube (both of which are amyloid), which is cylindrical to Template:Lichengloss (club-shaped). Ascospores number eight per ascus, and they are usually non-septate (lacking internal partitions), ellipsoid to more or less spherical in shape, hyaline (translucent), and non-amyloid.<ref name="Frey 2016"/> Except for a few genera that produce septate ascospores (Calathaspis, Pycnothelia and Pilophorus), the hymenium does not generally have Template:Lichengloss that are useful in taxonomy.<ref name="Stenroos et al. 2019a"/> The conidiomata (asexual fruiting bodies) are in the form of pycnidia; the conidia (asexual spores) are non-septate, usually Template:Lichengloss (thread-like), and hyaline.<ref name="Frey 2016"/>
ChemistryEdit
In the Cladoniaceae, over 70 different secondary metabolites (lichen products), primarily polyphenols, have been identified. These substances crucial roles in species identification and have ecological functions such as protection against UV radiation and deterrence of herbivores. To observe the fluorescence of certain depsides and depsidones, ultraviolet light is directly applied to the specimens. Traditional colour spot tests with reagents like KOH can be ineffective at low concentrations. Consequently, thin-layer chromatography, a laboratory technique used to separate chemical compounds, is essential for detecting and identifying lichen substances that are present in low concentrations.<ref name="Burgaz et al. 2020"/> Chemotaxonomy is an important aspect in the identification of Gray's pixie cup (Cladonia grayi): when lit by a UV light, it produces a light blue fluorescence.Template:Sfn
PhotobiontsEdit
The symbiotic algal partner (photobiont) of most Cladoniaceae taxa are unicellular green algae, usually in the genus Asterochloris, but occasionally in the genus Chlorella;<ref name="Burgaz et al. 2020"/> both of these genera are in the class Trebouxiophyceae. Eleven species of Asterochloris have found to be associated with genus Cladonia; the algal genus – one of the most common lichen symbionts – occurs in the thalli of more than 20 lichen genera.<ref name="Škaloud et al. 2015"/> The most common photobionts in this genus that associate with Cladonia are A. glomerata, A. italiana, and A. mediterranea, with some lineages showing dominance in one or several climatic regions.<ref name="Pino-Bodas & Stenroos 2020"/> In contrast, Myrmecia was shown to be the main photobiont for the Mediterranean species Cladonia subturgida.<ref name="Pino-Bodas et al. 2023"/> The algal genus Trebouxia, a common lichen photobiont, has not been recorded associating with the Cladoniaceae.<ref name="Stenroos et al. 2019a"/> Some Pilophorus species form tripartite associations, involving the fungus, green algae, and cyanobacteria within gall-like structures called cephalodia.<ref name="Burgaz et al. 2020"/> The cyanobacterial genera Nostoc and Stigonema are involved in these tripartite associations.<ref name="Stenroos et al. 2019a"/> In a study of several Cladonia lichens collected from Southern Finland, the associated microbial community, which was found to be consistent amongst the different species, consisted largely of Alphaproteobacteria and Acidobacteriota.<ref name="Shishido et al. 2021"/>
DevelopmentEdit
The development of several Cladoniaceae genera have been studied in detail,<ref name="Jahns & Beltman 2007"/><ref name="Hammer 1993"/><ref name="Hammer 1995"/><ref name="Grube & Hawksworth 2007"/> although the interpretation of results has sometimes been controversial.<ref name="Stenroos et al. 2019a"/> For example, two 1970 studies by Hans Jahns explored the development of fruiting bodies in Cladonia, significant for understanding the taxonomy and phylogeny within the Cladoniaceae. This work revealed two distinct ontogenetic types based on the formation of generative tissue and its role in developing the characteristic podetium of Cladonia species. This generative tissue, originating in the thallus horizontalis and growing vertically, is crucial for forming the podetium. The study identified variability within species, showing that different species can have more than one ontogenetic type, challenging previous assumptions about the uniformity of development patterns within the genus. This demonstrated variability had implications for the taxonomy and phylogenetic relationships within Cladoniaceae, suggesting a complex evolution of reproductive structures that did not strictly align with previously conceived taxonomic groupings.<ref name="Jahns 1970a"/><ref name="Jahns 1970b"/>
Cladoniaceae species begin development with the formation of a prothallus – a fungal layer upon which an alga-containing thallus will develop. It comprises the hyphae from the germination of an ascospore. After the protothallus contacts the alga, lichenisation begins with the development of small squamules (scale-like thallus segments) that make up the primary thallus, which is squamulose (scaly) or crustose (crustose-like). The secondary thallus consists of vertical structures that are shrubby and hollow, although they can be solid in rare cases. If these structures are made of generative tissue, they are called podetia; when they are made of vegetative tissue, they are called pseudopodetia. The morphology of these structures determines to a large part the taxonomy of the Cladoniaceae, which can range from simple to complex branching patterns.<ref name="Burgaz et al. 2020"/> Cladonia minisaxicola, found in the mountains of Bahia (Brazil) is the only species in that large genus that is completely crustose and does not develop podetia.<ref name="Aptroot & da Silva Cáceres 2018"/> Template:Multiple image The tips of the podetia have a wide range of morphology in the Cladoniaceae. They can be straight, tapering from a wide base to a point (called Template:Lichengloss), or flaring on cup-shaped Template:Lichengloss. The scyphi are sometimes closed, or have a central perforation, forming structures called funnels.<ref name="Burgaz et al. 2020"/> The podetia are slow-growing, with an annual growth rate generally ranging from 1 to 15 mm.Template:Sfn
Branching in the Cladoniaceae occurs on the podetium, driven by the growth patterns of fungal meristem tissue at its tip. There are two main branching patterns: in one, branches emerge later from a large meristem that changes shape, while in the other, smaller meristems split early but keep their shape. These growth patterns help scientists understand the evolutionary relationships within Cladoniaceae.<ref name="Hammer 2000"/> A shift from isotropous growth (uniform in all directions) to anisotropous growth (different in various directions) allows for more flexibility in development. This transition, from symmetrical to more irregular growth, may signal evolutionary adaptations. Despite these changes, the branching processes remain highly consistent even among species in the family that are not closely related.<ref name="Hammer 2001b"/>
GeneraEdit
After more than a century of discovery and research, including recent advances in understanding revealed by molecular phylogenetics studies, the Cladoniaceae encompass 18 genera and more than 500 species.<ref name="Lücking et al. 2017"/><ref name="Pino-Bodas et al. 2021"/> In terms of species diversity, the Cladoniaceae stood as the tenth-largest lichen-forming fungal family by 2017.<ref name="Lücking et al. 2017"/> This is a list of the genera contained within the Cladoniaceae, based on the Catalogue of Life; this includes taxa formerly classified in the Squamarinaceae, but does not include the Stereocaulaceae. Following the genus name is the taxonomic authority, year of publication, and the number of species: Template:Multiple image
- Calathaspis Template:Small<ref name="Lamb & Weber 1972"/> – 1 sp.
- Carassea Template:Small<ref name="Stenroos et al. 2002"/> – 1 sp.
- Cetradonia Template:Small<ref name="Wei & Ahti 2002"/> – 1 sp.
- Cladia Template:Small<ref name="Nylander 1870"/> – ca. 27 spp.
- Cladonia Template:Small<ref name="Browne 1756"/> – ca. 500 spp.
- Gymnoderma Template:Small<ref name="Nylander 1860b"/> – 3 spp.
- Heteromyces Template:Small<ref name="Müller 1889"/> – 1 sp.
- Metus Template:Small<ref name="Galloway & James 1987"/> – 3 spp.
- Muhria Template:Small<ref name="Jørgensen & Jahns 1987"/> – 1 sp.
- Notocladonia Template:Small<ref name="Hammer 2003"/> – 2 spp.
- Paralecia Template:Small<ref name="Liu et al. 2015"/> – 1 sp.
- Pilophorus Template:Small<ref name="Fries 1857"/> – 17 spp.
- Pulchrocladia Template:Small<ref name="Stenroos et al. 2019a"/> – 3 spp.
- Pycnothelia Template:Small<ref name="Dufour 1821"/> – 2 spp.
- Rexiella Template:Small<ref name="Stenroos et. al. 2019"/> – 1 sp.
- Sphaerophoropsis Template:Small<ref name="Vainio 1890"/> – 2 spp.
- Squamella Template:Small<ref name="Hammer 2001"/> – 1 sp.
- Thysanothecium Template:Small<ref name="Montagne & Berkeley 1846"/> – 3 spp.
Myelorrhiza was transferred from the Cladoniaceae to the Ramalinaceae by Sonja Kistenich and colleagues in 2018.<ref name="Kistenich et al. 2018"/> Neophyllis, originally classified in the Cladoniaceae, was transferred to Sphaerophoraceae in 1999.<ref name="Wedin & Döring 1999"/>
Habitat and distributionEdit
Cladoniaceae species have been recorded growing in many habitats and on a diversity of substrates, including soil, tree trunks, and rotten wood.<ref name="Stenroos et al. 2019a"/> In a few cases, Cladoniaceae can grow on rocks, such as Cladonia salmonea which grows on the rock faces of vertical cliffs, or Cladonia pyxidata, which can grow on thin soil on rocks.Template:Sfn Cladoniaceae species are generally absent from arid environments due to their preference for humid conditions. The range of their habitats includes boreal forests, bogs, temperate forests, the tundra of the Arctic and Antarctic, man-made habitats (e.g. roadsides), tropical highlands, and the sandy tropical lowlands of the Amazon rainforest.<ref name="Stenroos et al. 2019a"/>
In his 2000 monograph on the Cladoniaceae of the Neotropical realm, Ahti included 184 species in 4 genera, and showed that South America is a hotspot of biodiversity for genus Clanodia.<ref name="Coppins 2002"/> Bioclimatic variables significantly influence the distribution of Cladoniaceae species richness in the Neotropics, particularly under conditions of low precipitation and temperature, and high climatic variability. Areas with stable climates and higher temperatures and precipitation tend to support greater species richness.<ref name="Soto-Medina 2013"/> Twenty-six Cladoniaceae species (25 Cladonia and 1 Cladia) are known to occur in the Galápagos Islands. There, some species form mats on lava flows that have developed little soil.<ref name="Yánez et al. 2013"/> A 2013 monograph of Northern European Cladoniaceae treated 100 species (95 Cladonia, 4 Pilophorus, and the monotypic genus Pycnothelia).<ref name="Ahti et al. 2013"/> In the 2021 key to lichen species in Italy, 86 Cladoniaceae are included.<ref name="Lichens of Italy"/> In Bulgaria, 55 species in two genera were reported in 2022.<ref name="Burgaz et al. 2022"/> In a study of the lichen biodiversity in Kazakhstan's Burabay National Park, the Cladoniaceae made up about 30 percent of the species diversity.<ref name="Bukabayeva et al. 2022"/>
In western North America, the Coast Mountains of British Columbia act as a key phytogeographic barrier. This results in distinct oceanic and continental taxa groupings on either side. The research also suggests that the southern boundaries of certain species may be determined more by historical rather than purely ecological factors, indicating possible range expansions. The highest diversity of Cladonia species is found in British Columbia between 52°N and 56°N, an area that was covered by glaciers until about 10,000 to 13,000 years ago. The Cladoniaceae biodiversity in this region represents the richest assemblage of the family in western North America. Species diversity declines sharply south of 52°N, with a loss of three to five taxa for each degree of latitude.<ref name="Goward & Ahti 1997"/>
The glacial history of the region has played a crucial role in shaping the current distribution of Cladoniaceae. During the Pleistocene, most species likely survived in areas south of the Cordilleran ice sheet, with some persisting in nunataks, arctic regions, or small coastal refugia. This glacial legacy is still evident in the family's current distribution patterns. Cladoniaceae show a preference for specific habitats, with greater floristic and chemical diversity observed in humid areas and lower forested elevations compared to arid regions and alpine zones. This suggests that many species in the family are adapted to environments with relatively short periods of desiccation. The post-glacial period has seen significant changes in the distribution of Cladoniaceae. Many species that likely existed in Washington, Oregon, and California during the Pleistocene are now absent from these areas. This change is thought to be a result of climate shifts since deglaciation, particularly an increase in summer moisture deficits. While most Cladoniaceae species have reached a stable distribution, some are still in flux. Species like Cladina stellaris and C. trassii appear to be continuing their southward expansion from northern glacial refugia.<ref name="Goward & Ahti 1997"/>
ConservationEdit
Each of the six Cladoniaceae species that have been assessed by the International Union for Conservation of Nature for the global IUCN Red List face a variety of threats impacting their survival. Cetradonia linearis (vulnerable, 2015) is endangered by ecosystem changes in spruce–fir forests, specifically the balsam woolly adelgid's impact on Fraser fir, and changes in humidity regimes and cloud immersion. The species is also vulnerable to threats from logging, mining, and road building if its legal protection status is removed.<ref name="IUCN: Cetradonia linearis"/>
Cladonia appalachiensis (endangered, 2020) growing on high-elevation Anakeesta Knob rock, faces threats from visitor disruption and changes in cloud cover and humidity.<ref name="IUCN: Cladonia appalachiensis"/> The species is particularly vulnerable due to its restricted range and specific habitat requirements.<ref name="Stenroos et al. 2019a"/> The main threats to Cladonia perforata (endangered, 2003) include habitat loss, hurricanes, and improper fire management, with a single natural event potentially causing substantial subpopulation reduction.<ref name="IUCN: Cladonia perforata"/>
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Cladonia submitis (endangered, 2020) is primarily threatened by habitat loss and degradation due to land development, particularly around metropolitan areas. Climate change also poses significant risks through altered fire regimes and sea level rise, affecting its pine barren and sand dune habitats.<ref name="IUCN: Cladonia submitis"/> The species' limited distribution and specific habitat requirements make it particularly susceptible to these threats.<ref name="Stenroos et al. 2019a"/> Pilophorus fibula (endangered, 2020) is threatened by habitat loss, alteration of hydrological regimes, recreational damage, and declining water quality.<ref name="IUCN: Pilophorus fibula"/> The species is found in a limited number of locations, making it vulnerable to local extinctions.<ref name="Stenroos et al. 2019a"/>
Gymnoderma insulare (endangered, 2014), primarily found in old-growth forests in Japan and Taiwan, faces threats from natural hazards like typhoons and is affected by the decline of its tree hosts, Cryptomeria japonica and Chamaecyparis obtusa.<ref name="IUCN: Gymnoderme insulare"/> The species' dependence on specific host trees and old-growth forest conditions makes it particularly vulnerable to forest degradation and climate change impacts.<ref name="Stenroos et al. 2019a"/>
On the red list of China's macrofungi, Cladonia delavayi (vulnerable), Cladonia pseudoevansii (critically endangered), Gymnoderma coccocarpum (endangered), and Gymnoderma insulare (endangered) are the representatives of the Cladoniaceae.<ref name="Yijian et al. 2020"/>
Human interactions and usesEdit
Cladonia lichens, particularly the "reindeer lichens" such as C. stellaris, C. rangiferina, and C. arbuscula, are a critical winter food source for reindeer (caribou) in northern boreal and arctic regions.<ref name="Heggberget 2002"/> In some areas, these lichens can constitute up to 80% of reindeer winter diet.<ref name="Eriksson 1981"/> The average annual linear growth rate of these reindeer lichens is about 5 mm per year, accounting for their slow recovery rate after grazing or disturbance.<ref name="McMullin & Rapai 2020"/> Satellite-based studies have shown a significant decline in caribou lichen cover across large areas of Eastern Canada over the past three decades, likely due to factors such as climate change-induced shrub encroachment, increased wildfire frequency, and grazing pressure, which could have serious implications for caribou populations and ecosystem dynamics.<ref name="He et al. 2024"/> The abundance of lichen-rich forests has significant economic implications for reindeer husbandry, particularly for indigenous Sámi people in Fennoscandia.<ref name="Sandstrom 2016"/> However, lichen-dominated forests have declined significantly in recent decades due to factors such as intensive forestry practices, overgrazing, and fire suppression.<ref name="Sandstrom 2016"/> This decline has prompted efforts to restore lichen habitats, including experimental transplantation of lichen fragments to accelerate recovery after disturbances like forest fires.<ref name="Roturier 2017"/>
Some Cladoniaceae species are exploited in a profitable export business for decorative uses,<ref name="Cannon 2007"/> with demand reaching thousands of kilograms. In Europe, Cladonia stellaris is used ornamentally in wreaths, floral decorations and architectural models. From 1970–1975, an average of nearly 3000 metric tonnes were exported each year from Finland, Norway and Sweden; most of these exports (about 80%) went to West Germany.<ref name="Kauppi 1979"/> Fruticose Cladonia species, often dyed green and glycerol-treated for flexibility, are common in model train displays as miniature trees and shrubs.<ref name="Hale 1974"/> The product commercially sold as "ball moss" or "Icelandic moss" in hobby and craft stores is often Cladonia stellaris and other similar species, often dyed in various colours.Template:Sfn In Sweden, Cladonia lichens were used historically as a partial insulation for storm windows.<ref name="Llano 1948"/>
The complex net-like structures of the Australasian lichen Pulchrocladia retipora have been described as "of considerable beauty resembling lace or coral", and have been utilised in floral and architectural design.<ref name="nzpcn"/> This species' branches, characterised by its numerous small holes, exemplify nature's efficient use of latticework structures. This design, widely used in construction for structures such as transmission towers or bridges, allows the organism to maintain structural integrity while minimising the amount of biological material used in its construction.Template:Sfn The unique lichen architectures of five Cladoniaceae species are depicted in Ernst Haeckel's well-known and widely reproduced lichen-themed lithograph in his 1904 work Kunstformen der Nature (The art forms of nature). According to the lichenologists Robert Lücking and Toby Spribille, "the Cladonia growth form continues to be one of the most widely recognized lichen architectures, with their basal scales and erect, often trumpet-shaped podetia".Template:Sfn