Assessment Notes

Justification

Fomitiporia nubicola is a wood-inhabiting perennial polypore that grows exclusively on Drimys (Winteraceae), likely specific on D. angustifolia, a relic plant species distributed exclusively in fragmented cloud forests of high-altitude areas in southern-southeastern Brazil. Up to now, the fungal species was found exclusively in small patches of fragmented cloud forests in three sites in Santa Catarina state. Recent targeted survey efforts (2021-2023) along its distribution model based on the host’s occurrence resulted in no additional sites, and no specimens were found in the lower altitude site, which is also the northern limit of the known species distribution.

It is well known that tropical montane cloud Forests are threatened and in decline by their highly susceptible microclimatic wrapping and by anthropic activities and climate change. Cloud forests of the Atlantic Forest domain are dependent on rare microclimatic conditions (Bruijnzeel et al. 2010, Oliveira et al. 2014), making it one of the most susceptible ecosystems to threats caused by climate change (Salazar et al. 2007, Williams et al. 2007, Goldsmith et al. 2013, Gotsch et al. 2014, Pompeu et al. 2014). Cloud forests of southern Brazil are also threatened by human activities such as cattle grazing, introduction of invasive species, anthropogenic fire and land use changes (Brooks and Balmford 1996, Tabarelli et al. 2006, Pinto et al. 2006), resulting in ongoing declines of this habitat, even in Protected Areas. In this case, the high-suitability areas for the fungal species are particularly vulnerable to anthropic pressures such as land-use changes, the introduction of alien species, fire as a management tool, and cattle grazing. Despite its more restricted distribution and population size smaller than expected, the continued expected loss of required habitat is also something that deserves special attention.

Currently, F. nubicola is known from only three sites in Santa Catarina state, but it has the potential to exist in up to 25 sites (probably with a good condition of forest maturity). Each site likely supports no more than 50 mature individuals, resulting in an inferred total population size of no more than 1,250 mature individuals, all belonging to a single subpopulation. Due to the expected loss of its crucial habitat, F. nubicola is suspected to suffer an additional reduction of 60–80% of its population size over the next 50 years (equivalent to 3 generations) (Helmer et al. 2019). This decline primarily results from habitat degradation and the impacts of climate change, particularly in a business-as-usual scenario (Leão et al. 2021, Vale et al. 2021). In the previous assessment the species was listed as Vulnerable (C2a(ii)) because of its small population size and continued decline. However, it is known to be more restricted than previously assumed with a population size also smaller than expected. Taking a precautionary approach and considering this new calculation of its population size reduction, based on the decline in area and quality of its habitat, this species is now assessed as Critically Endangered  under criterion A3ce.

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Taxonomic notes

Fomitiporia nubicola is part of the Fomitiporia apiahyna complex (Vlasák and Kout 2011, Amalfi and Decock 2013).

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Geographic range

Fomitiporia nubicola is a wood-inhabiting species, that thrives exclusively on Drimys angustifolia, a relic plant species found solely within fragmented cloud forests, primarily at altitudes exceeding 1,000 m above sea level (asl) in southern and southeastern Brazil. The distribution of F. nubicola is limited to just three known sites within Santa Catarina state, one of them without new records of the fungal species since 2016. These sites include the high Itajaí Valley (850 m asl), and the highlands of Aparados da Serra Geral, situated in São Joaquim National Park (1,500–1,720 m asl).

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Population and Trends

Fomitiporia nubicola is currently limited to only three sites in Santa Catarina state, south Brazil, found exclusively on large living and dead trunks of Drimys angustifolia. This tree species is exclusive to fragmented cloud forests across southern and southeastern Brazil within the Atlantic forest domain which has significantly diminished over time, now reduced to a mere 28% of its original extent. The remaining areas are heavily fragmented and not yet fully mature (Tabarelli et al. 2010, Rezende et al. 2018). In this context, cloud forests are a crucial part of this ecosystem, existing in small patches and relying on rare microclimatic conditions, making them highly vulnerable to the threats posed by climate change and anthropogenic actions (Salazar et al. 2007, Williams et al. 2007, Goldsmith et al. 2013, Gotsch et al. 2014, Pompeu et al. 2014). Recent data on forest coverage in Santa Catarina reveal that the mixed needle-broadleaved Araucaria forest, where most cloud forests are located, is highly fragmented, with only 21% of forest coverage remaining. Patches of 50 hectares or less account for 82% of these remaining forests (Fundação SOS Mata Atlântica 2009, Vibrans et al. 2012).

While the distribution of F. nubicola was expected to align with that of its host, recent ground truthing of its distribution model based on host occurrence failed to uncover any new sites beyond the known range. Notably, no specimens were found at the site marking the northern and lowest boundary of the known species distribution (Rodeio, Santa Catarina, 850 m asl). Surveys conducted from 2021 to 2023, under a specific project targeting this fungal species (Mohammed bin Zayed Species Conservation Fund 2023), identified areas with varying suitability for cloud forest characteristics, Drimys trees, and the presence of F. nubicola. Low-suitability areas are characterized by small (up to 0.2 km²), elevated terrains at 800–900 m asl, with infrequent Drimys trees. Medium-suitability areas consist of patches (up to 3 km²) primarily at plateau edges, at 1,300–1,500 m asl, with a moderate frequency of Drimys trees. High-suitability areas encompass a forest-grassland mosaic, including forest fragments (up to 27 km²) above 1,500 m asl, with a high frequency of Drimys trees, where Drimys plays a vital role in the canopy. After extensive sampling efforts, F. nubicola is known to inhabit mainly high-suitability areas, with 33 occurrences, and just one occurrence in low-suitability areas (without new records since 2016). The high-suitability areas are particularly vulnerable to anthropic pressures such as land-use changes, the introduction of alien species, fire as a management tool, and cattle grazing.

Currently, F. nubicola is known from only three sites in Santa Catarina state, but it has the potential to exist in up to 25 sites (probably with a good condition of forest maturity). Each one supports no more than 50 mature individuals, resulting in an inferred total population size of no more than 1,250 mature individuals, all belonging to a single subpopulation. Due to the expected loss of its crucial habitat, F. nubicola is suspected to suffer an additional reduction of 60–80% of its population size over the next 50 years (equivalent to three generations, Dahlberg and Mueller 2011) (Helmer et al. 2019). This decline results primarily from habitat degradation and the impacts of climate change, particularly in a business-as-usual scenario (Leão et al. 2021, Vale et al. 2021).

Population Trend: decreasing

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Habitat and Ecology

This species is a wood-inhabiting (facultative parasite and saprotroph), growing on large living and dead standing trunks of Drimys angustifolia, a relictual plant species of the Winteraceae family, endemic to the cloud forest fragments of high altitude areas in southern and south-eastern Brazil. The fungus is expected to occur throughout its host’s distribution.

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Threats

Fomitiporia nubicola is an endemic species of Brazil restricted to the cloud forests of the Brazilian Atlantic Forest. Cloud forests of this domain are restricted to small, fragmented patches, and are dependent on rare microclimatic conditions (Bruijnzeel et al. 2010, Oliveira et al. 2014), making it one of the most susceptible ecosystems to threats caused by climate change (Salazar et al. 2007, Williams et al. 2007, Goldsmith et al. 2013, Gotsch et al. 2014, Pompeu et al. 2014). This habitat is also threatened by human activities such as cattle grazing, introduction of invasive species, such as wild boar, pine trees, etc., anthropogenic fire, and land use changes (Brooks and Balmford 1996, Tabarelli et al. 2006, Pinto et al. 2006), resulting in a continuous decline in this habitat, even within protected areas. The loss of required habitat directly threatens this species.

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Conservation Actions

The main action to conserve this species is the protection of its habitat by the establishment, and appropriate management, of conservation units and the enforcement of public policies to recover and protect the cloud forests of southern and southeastern Brazil. Furthermore, in addition to more surveys to continuously understand the species’ distribution and species biology, urgent efforts are needed to safeguard this species’ conservation, such as ex situ conservation (mycelium culture and if needed reintroduction via inoculation), as well as in situ conservation, adding the species to the national territory planning (e.g. the Planalto Sul Territorial Action Plan, Carbonell et al. 2021) and to a national fungal red list that does not currently exist.

During a recent effort to test the potential distribution model, based on host distribution, F. nubicola was not found outside known-occurrence areas (Mohammed bin Zayed Species Conservation Fund 2023). Furthermore, new surveys to better understand the species distribution, its biology, host specificity and habitat quality requirements, are urgently needed as well as a conservation plan which includes ex situ and in situ conservation. Research is needed in order to establish a protocol to cultivate and maintain the specimen cultures of the species in a dedicated collection. For future reintroduction, studies to understand the mechanisms to do so are desired (Abrego et al. 2016).

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Use and Trade

There are no known uses of this species.

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Source and Citation

Alves-Silva, G., Kossmann, T., Titton, M., Bittencourt, F., Funez, L., Canteiro, C. & Monteiro, M. 2023. Fomitiporia nubicola. The IUCN Red List of Threatened Species 2023: e.T187001148A245516895. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T187001148A245516895.en .Accessed on 7 February 2024

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• Country occurrence