Editing Polypore (section)

==Ecology==
[[File:Trametes versicolor Bear Creek.jpg|thumb|''[[Trametes versicolor]]'' growing on a rotting log]]
Bracket fungi often grow in semi-circular shapes, looking like trees or wood.  They can be [[parasitism|parasitic]], [[saprotroph]]ic, or both.  One of the more common [[genera]], ''[[Ganoderma]]'', can grow large thick shelves that may contribute to the death of the tree, and then feed off the wood for years after.  Their hardiness means they are very resilient and can live for quite a long time, with many species even developing multi-coloured circles of colour that are actually annual growth rings.
Polypores are among the most efficient decomposers of [[lignin]] and [[cellulose]], the main components of wood. Due to this ability they dominate communities of wood-rotting organisms in land ecosystems along with [[corticioid fungi]]. Through decomposing tree trunks they recycle a major part of nutrients in forests.<ref name="Binder et al. 2013"/>

Most [[Wood-decay fungus#Brown rot|brown-rot]] fungi are polypores. Most of these species have lost their lignin degradation ability through evolution but are very efficient in degrading cellulose.<ref>{{Citation |last=Floudas |first=Dimitrios |title=Chapter Two - Evolution of lignin decomposition systems in fungi |date=2021-01-01 |work=Advances in Botanical Research |volume=99 |pages=37–76 |editor-last=Morel-Rouhier |editor-first=Mélanie |url=https://www.sciencedirect.com/science/article/abs/pii/S0065229621000537 |access-date=2025-02-17 |series=Wood Degradation and Ligninolytic Fungi |publisher=Academic Press |editor2-last=Sormani |editor2-first=Rodnay}}</ref> Brown-rot fungi are prevalent on conifer hosts and open, sun-exposed habitats. The fungal community in any single trunk may include both white-rot and brown-rot species, complementing each other's wood degradation strategies.

Polypores and other decomposer fungi are the first step in food chains that feed on decomposed plant material. A rich fauna of insects, mites and other invertebrates feed on polypore mycelium and fruiting bodies, further providing food for birds and other larger animals. Woodpeckers and other hole nesting birds typically carve their nests in softer wood decomposed by polypores.<ref name="Kraus & Krumm 2013"/>

===Threats===
Almost all polypores are dependent on trees for their survival. Deforestation and intensive forest management cause declines in polypore abundance and diversity. For many species the changes can be too much, and they start a slow slide towards extinction. Since most polypore species are relatively widespread, this process is typically slow. Regional extinctions can happen relatively quickly and have been documented (for instance ''Antrodia crassa'' in North Europe<ref>Junninen K (2009) Conservation of ''Antrodia crassa''. ''Metsähallituksen luonnonsuojelujulkaisuja, sarja A'' 182: 1–51.</ref>).

Polypores can decline for many reasons. They can be dependent on a single host or a very special habitat. For instance ''[[Echinodontium ballouii]]'' has been found only in [[Atlantic white cedar]] swamps in the Northeastern USA.<ref>Gilbertson RL, Ryvarden L (1986) ''North American polypores 1, ''Abortiporus ''to'' Lindtneria. Oslo, Fungiflora.</ref><ref>{{Cite web | url=http://www.mushroomhunter.net/ballouii.htm | title=査定の前にすべきこと – 鉄道模型の買取でBトレインショーティーの買取}}</ref> Species can be dependent on very old tree individuals like ''[[Bridgeoporus nobilissimus]]'' of the Northwestern USA.<ref name="Ledo 2007"/> Both of these species also have a rather restricted range, making them more vulnerable to extinction.

In addition to the host tree individual, the characteristics of the surrounding habitat also matter. Some species prefer closed-canopy forest with a moist, even microclimate that could be disturbed for instance by logging (e.g. ''[[Skeletocutis jelicii]]''). Others suffer from lack of open forest-fire habitat in areas where fire suppression is done (e.g. ''[[Gloeophyllum carbonarium]]'' in Nordic countries where forest fires are part of the natural forest dynamics).<ref name="Olson 2010"/>

For most declining species the main problem is lack of dead wood in the forest. When suitable tree trunks are too sparse in the landscape, not all species are able to spread to new trunks after old ones have been consumed, causing the population to decline and eventually vanish. Thus, species that are abundant in [[old-growth forests]] with abundant dead wood can be totally absent from managed forests. For instance ''[[Amylocystis lapponica]]'' and ''[[Fomitopsis rosea]]'' are dominant species in North European old-growth spruce forests from Poland to Norway, but absent in managed forests.

Climate change may cause a problem for polypores that are already dependent on a few fragments of old-growth forests and may be unable to migrate with changing vegetation.

===Indicator value===
Polypores have been used as indicator species of healthy natural forests or [[old-growth forests]] in Europe. They are good indicators of invertebrate diversity on dead wood and include many endangered species. Polypores make good indicators because they are relatively easy to find – many species produce conspicuous and long-lasting fruiting bodies – and because they can be identified in the field.<ref name="Parmasto 2001"/>

The first indicator list of polypores widely used in forest inventories and conservation work was developed in northern Sweden in 1992 ("Steget före" method).<ref>Karström M (1992) Steget före – en presentation. ''Svensk Botanisk Tidskrift'' 86: 103-114.</ref><ref>{{cite web |url=http://www.hkust.se/snf-ovik/Steget.htm |title=Steget Före-metoden |access-date=2013-04-13 |url-status=dead |archive-url=https://web.archive.org/web/20100811142826/http://www.hkust.se/snf-ovik/Steget.htm |archive-date=2010-08-11 }}</ref> "Steget före" list included six polypores in three value classes. In Finland, [[Indicator fungi in forest protection, Finland|a list of 30 species for spruce-dominated forests]] was published in 1993 and widely adopted.<ref>Kotiranta H, Niemelä T (1996) ''Uhanalaiset käävät Suomessa''. 2nd ed. Suomen ympäristökeskus, Helsinki.</ref> Later a similar list for pine-dominated forests was published. Longer lists of indicator species have since been published in Sweden.<ref>Nitare J (2000) ''Signalarter. Indikatorer på skyddsvärd skog. Flora över kryptogamer''. Skogsstyrelsen förlag, Jönköping.</ref><ref>{{cite web |url=http://www.skogsstyrelsen.se/Myndigheten/Skog-och-miljo/Biologisk-mangfald/Signalarter/ |title=Signalarter - Skogsstyrelsen |access-date=2014-10-05 |url-status=dead |archive-url=https://web.archive.org/web/20141006084033/http://www.skogsstyrelsen.se/Myndigheten/Skog-och-miljo/Biologisk-mangfald/Signalarter/ |archive-date=2014-10-06 }}</ref>

Many indicator species are [[red list|red-listed]], but not necessarily all. National red lists of fungi typically include many polypores and are used as indicator lists of conservation value in many European countries.