A comparison of polypore funga and species composition in forest ecosystems of China, North America, and Europe

Fang Wu, Xiaowu Man, Ablat Tohtirjap, Yucheng Dai

Institute of Microbiology, School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, 100083, China

Keywords:Basidiomycota Distribution Polypore funga Wood-decomposers

ABSTRACT

1. Introduction

Polypores (Basidiomycota, Agaricomycetes) are wood-inhabiting macrofungi with a poroid hymenophore growing on living trees, dead standing trees, fallen trunks, rotten wood, stumps, roots of trees, and even soil but closely associated with trees (Gibertoni et al., 2016; Shen et al., 2019; Wu et al., 2022). They are the major group of wood-decomposing fungi playing a key role in the wood decomposition process, releasing carbon and nutrients from woody tissues (Palviainen et al.,2010;Berglund et al.,2011;Stokland and Larsson,2011;Miettinen et al.,2016, 2018;Huang et al.,2022).

Wood-decomposing fungi have typically been classified as either causing white rot or brown rot, according to their abilities to degrade lignin,cellulose and hemicellulose:white rot fungi can decompose all the wood components, while brown rot fungi degrade cellulose and hemicellulose only(Riley et al.,2014;Chung et al.,2017;Hage et al.,2021).Besides being saprotrophic, some polypores have been observed as mycorrhizae(Alem et al.,2021).

As the earliest fungal species recorded by Linnaeus (1753), e.g.,

Coltricia perennis(L.)Murrill(≡Boletus perennis L.)and Phellinus igniarius

(L.)Qu′el.(≡Boletus igniarius L.),polypores have been extensively studied in the world,especially in China(Zhao,1989;Zhao and Zhang,1992;Daiet al.,2002,2004;Dai and Niemel¨a,2006;Dai,2012;Cui et al.,2019;Liu et al., 2021;Wu et al., 2022), North America(Lowe, 1957, 1966,1975;Gilbertson and Ryvarden, 1986, 1987; Zhou et al., 2016), and Europe(Ryvarden,1976,1978;Ryvarden and Gilbertson,1993,1994;Ryvarden and Melo,2014,2017;Runnel et al.,2019).Comprehensive checklists of Chinese and North American polypores have been published(Dai,2012;Zhou et al., 2016), and the European polypores were updated by Ryvarden and Melo(2014,2017).Previously,studies on polypore funga and diversity composition were focused on limited areas within one land mass only, for example, one mountain or several forest zones in China,Brazil, Finland, Kyrgyzstan and the USA (Sippola et al., 2005; Lindner et al., 2006; Zhou et al., 2011; Markkanen and Halme, 2012; Bian and Dai, 2015; Yuan et al., 2015; Gibertoni et al., 2016; Cho et al., 2019;Runnel et al., 2021; Wang et al., 2021). In this study, we analyze the polypore funga for large-scale of China,North America and Europe.The aim of our analysis is to better understand the funga, species diversity and composition of polypores of these three land masses.

2. Material and methods

Polypores are defined here as wood-inhabiting basidiomycetes with poroid hymenophore,previously treated in Aphyllophorales.However,they belong to 11 orders according to the current phylogeny and taxonomy.The materials used in the present study mostly according to polypore data in China(Dai,2012),North America(Zhou et al.,2016),Europe (Ryvarden and Melo, 2017), recent studies in the three land masses(D¨ammrich et al.,2017;Spirin et al.,2017;Consiglio and Setti,2018;Korhonen et al.,2018;Cui et al.,2019;Runnel et al.,2019,2021;Shen et al., 2019; Chen et al., 2020; Wu et al., 2022) with some modifications if distinct misidentifications existed, and databases of Index Fungorum and MycoBank for new polypores from the three land masses during 2012–2022.The species diversity of polypores in the three land masses is mostly verified according to current taxonomy accepted mostly in two databases, Index Fungorum (http://www.indexfung orum.org/) and MycoBank (https://www.mycobank.org/), but some species, for example Aporpium spp., Trichaptum spp., Gilbertsonia angulopora and Cyanotrama rimosa etc., their families are Incertae sedis in Index Fungorum and MycoBank.For convenient analyses we treat them in families according to the traditional taxonomy (Jülich, 1981) and some other publications(Reid,1965;Zmitrovich and Malysheva,2014;Justo et al.,2017).A compiled species list is supplied as supplementary table.

For demonstrating the species composition of polypores, genescloud tools, a free online platform for data analysis (https://www.gene scloud.cn), were used to produce the Barplot, Pieplot, Venn diagram,HeatMap and Line graph.

Fig. 1. Venn diagram of species and generic diversities of polypores in China, North America and Europe. (a) Species. (b) Genera.

The coefficient of community(CC)among the three land masses was estimated using the following equation:

where A and B are the species numbers in the two compared land masses,and C is the number of species recorded in both land masses.Values of CC range between 0 and 1.

The nutritional modes of different species are taken from previous publications (Gilbertson and Ryvarden, 1986, 1987; Dai, 2010, 2012;Yuan et al., 2015; Ryvarden and Melo, 2014, 2017) and our field observations. The three nutritional modes are white rot, brown rot and mycorrhizal. In addition, a few species whose nutritional modes are unknown are treated as uncertain.

5. Made known what his wishes were: In some versions of the story, the king s desire to marry his daughter is excused as madness resulting from his grief. Once again, the father is blameless for his actions in most versions of the story.

3. Results

3.1. Funga and species diversity of polypores

A total of 1,337 polypore species,belonging to 11 orders,43 families and 168 genera,are found in China,North America,and Europe.Of this total, 854 species belonging to 11 orders, 39 families and 146 genera occur in China,547 species belonging to 10 orders,39 families and 137 genera occur in North America,and 432 species belonging to 11 orders,38 families and 104 genera have a distribution in Europe(Table 1).China has the highest polypore diversity,followed by North America,and then Europe.

170 polypore species are shared by the three land masses (Fig. 1a).These species are members of the boreal/temperate funga and have a wide distribution in the Northern Hemisphere. In pairwise comparisons among the three land masses, North America and Europe share the greatest number of polypore species(227 species,Fig.1a)and the highest CC value (CC = 0.464), but the polypore CC value between China and Europe is slightly higher than between North America and China(CC=0.333 vs.CC=0.321)although China and Europe share 214 species and North America and China share 225 species(Fig.1a).The polypore funga and diversity in Europe are more similar to North America than to China.

Of China's 854 polypore species,585(=68.50%)are only found from China or Asia;of North America's 547 polypore species,264(=48.26%)are only found from North America or America; and of Europe's 432 polypore species,161(=37.27%)are only found from Europe.Of China's 146 polypore genera,25(=17.12%)are only found from China or Asia;of North America's 137 polypore genera,15(= 10.95%)are only found from North America or America;and of Europe's 104 polypore genera,2(=1.92%)are only found from Europe.

Fig.2. Pieplot(a)and Barplot(b)showing the species composition of all polypores in China,North America and Europe.(a)The proportions of orders(order name,percentage, and number of species). (b) Numbers of species in each family.

Fig. 3. Barplot (a) and Heatmap (b) showing the species composition of polypores in China, North America and Europe. (a) Numbers of species in each order. (b)Numbers of species in each family of poroid wood-inhabiting fungi;colors indicate species in each family. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

3.2. Species composition of polypores in China,North America and Europe

Among the 1,337 polypores found in the three land masses, Polyporales is the most prevalent order with 804 species accounting for 60.1% of all polypore species, followed by Hymenochaetales with 399 species accounting for 29.8%, and then Russulales with 70 species accounting for 5.2%(Fig.2a).The species in these three orders account for 95.1%of all polypores in the three land masses.Hymenochaetaceae is the most diverse family with 376 species accounting for 28.12% of all the polypore species,followed by Polyporaceae with 354 species accounting for 26.48%, and then Fomitopsidaceae with 106 species accounting for 7.93%. The species in these three families account for 62.53% of all polypores in the three land masses(Fig.2b).

3.3. Species composition of polypores in each of the three land masses

Polyporales is also the most prevalent order in each of the three land masses with China, North America and Europe having 506, 332 and 312 species respectively, followed by Hymenochaetales with 265,152 and 73 species respectively, and then Russulales with 46, 29 and 14 species respectively (Fig. 3a). Polyporaceae, Hymenochaetaceae and Fomitopsidaceae are also the three most diverse families in each of the three land masses and species in these three families account for 64.40%, 58.68% and 47.45% of the total polypores in China, North America and Europe, respectively (Fig. 3b, Table 1). Polyporales,Hymenochaetales, Russulales, and Hymenochaetaceae, Polyporaceae,Fomitopsidaceae are respectively the three dominant orders and families in the three land masses. The species composition of polypores in each of the three land masses also shows that China has the highest amount of diversity, North America the next highest diversity and Europe the least (Fig. 3).

Table 2 Composition of polypores causing different nutritional modes in the three land masses.

3.4. Major polypore genera in each of the three land masses

According to species of polypore genera in each of the three land masses, the major genera with more than 20 species in China are Perenniporia with 43 species, Phylloporia with 32 species, Coltricia with 30 species,Skeletocutis with 29 species,Inonotus with 28 species,Postia with 27 species, Polyporus with 27 species, Trametes with 26 species, Ganoderma with 24 species, Fuscoporia with 23 species, Antrodia with 23 species and Cyanosporus with 20 species; the major genera with more than 20 species in North America are Antrodia with 29 species,Polyporus with 20 species and Postia with 20 species;the major genera with more than 20 species in Europe are Antrodia with 39 species, Postia with 25 species and Skeletocutis with 23 species.Antrodia and Postia are two major genera in all three land masses.

3.5. Nutritional mode of polypores

Fig. 4. Line graphs showing the proportions of polypores in China, North America and Europe in the different nutritional modes.

Among the 1,337 polypores occurring in the three land masses,1,030 species cause white rot, 241 species cause brown rot, 29 species are mycorrhizal and 37 species have an unknown nutritional mode. These nutritional modes account for 77.04%,18.03%,2.17%and 2.76%of the total polypores in the three land masses,respectively(Table 2).In China the numbers of white rot, brown rot, mycorrhizal and unknown nutritional mode species are 673, 133, 16 and 32 respectively, and they account for 78.81%, 15.57%, 1.87% and 3.75% of all Chinese polypores(Table 2,Fig.4).In North America the numbers of white rot,brown rot,mycorrhizal and unknown nutritional mode species are 404,117,18 and 8 respectively,and they account for 73.86%,21.39%,3.29%and 1.46%of all North American polypores. In Europe the numbers of white rot,brown rot,mycorrhizal and unknown nutritional mode species are 293,123,11 and 5 respectively,and they account for 67.82%,28.47%,2.55%,and 1.16% of all European polypores. White rot polypores are more prevalent than brown rot polypores in the three land masses combined and in each separately.

4. Discussion

The above results are due to the different forest vegetation and climate of the three land masses. China has a diverse climate and vegetation, including temperate monsoon, subtropical monsoon, tropical monsoon, temperate continental, plateau and mountain, with boreal,temperate, warm temperate, subtropical and tropical forests. North America is dominated by boreal,temperate,warm temperate,subtropical forests,and Europe has boreal,temperate and Mediterranean vegetation types only. The diverse climate and vegetation of China provide favorable environments for polypores, especially as there is an abundance of both gymnosperm and angiosperm trees which furnish a suitable substrate for polypores.Gymnosperm trees decrease from the temperate to subtropical and tropical zones,as do the brown rot polypores,because these fungi prefer a coniferous substrate (Zhou et al., 2011; Wu et al.,2021).In the temperate zones,polypores prefer to grow in coniferous and broad-leaved mixed forests compared with pure coniferous or broad-leaved forests,and more polypore species are found in coniferous and broad-leaved mixed forests(Zhou et al.,2011;Wang and Wei,2015;Gibertoni et al.,2016).The white rot polypore proportions decrease from China to North America and Europe.There are more gymnosperm forests in North America and Europe than in China, which accounts for the brown rot polypore proportions being higher in these two land masses.In addition, Europe and North America share a similar vegetation without any tropical forest,and this is one of the reasons why the polypore funga in Europe is similar to North America, and different from China. China has tropical forests which provide environments for tropical polypores,for example, Echinochaete, Flabellophora, Lignosus and Microporus are tropical genera,with species found in China but absent from Europe and North America.Both China and North America have subtropical forests,and species of Coriolopsis, Cyclomyces, Earliella, Megasporoporia, Tinctoporellus,Wolfiporia and Wrightoporia are found in these two land masses but are absent from Europe.Neolentiporus and Podofomes are only found from Europe,but 25 and 15 genera only from China and North America,respectively, which is distinctly higher than the number of genera in Europe.

The polypore diversity patterns are also probably due to tree species diversity and the distribution patterns of angiosperm and gymnosperm trees in the three land masses, for instance, more tree species in China than those in North America and Europe (Anonymous, 1997), and this may correspond richer polypores in China than in North America and Europe.Europe is in the north of north latitude 35°without subtropical and tropical forests,North America is in the north of the Tropic of Cancer(north latitude 23.5°)with some subtropical forests,and Chinese land is up to north latitude 18°with both subtropical and tropical forests.Angiosperm tree species are dominant in subtropical and tropical forests(Anonymous,1997),which may correspond that the white rot species as a proportion of all polypores in each of the three land masses are highest in China,followed by North America and then Europe.

The species composition of polypores demonstrates that the Polyporales, Hymenochaetales, Russulales, and Hymenochaetaceae, Polyporaceae, Fomitopsidaceae are respectively the three major orders and families of the three land masses,and a similar phenomenon was found in different zones within China (Bian and Dai, 2015; Wang et al., 2021).Twelve major genera are distributed in China,compared with only three major genera in North America and Europe,demonstrating that polypore diversity is higher in China than in North America or Europe.

5. Conclusions

Significant regional differences exist in the number of species and the proportions of nutritional modes in the three land masses.China had the highest polypore diversity followed by North America,and then Europe.Polyporales,Hymenochaetales and Russulales are the three major orders,and Hymenochaetaceae, Polyporaceae and Fomitopsidaceae are the three major families for the 1,337 polypore species. White rot is the major nutritional mode of all the polypores in China,North America and Europe accounting for 77.04% of all polypore species. The white rot species as a proportion of all polypores in each of the three land masses are highest in China, followed by North America and then Europe. The brown rot polypore proportion is highest in Europe, followed by North America and China had the least.

Authors’contributions

Fang Wu and Yucheng Dai conceived the ideas and designed the study; Fang Wu, Ablat Tohtirjap, and Yucheng Dai collected and managed the data; Fang Wu and Xiaowu Man collaborated with the statistical analysis and interpretation of data;Fang Wu and Yucheng Dai wrote and revised the manuscript.All authors contributed to subsequent drafts and gave final approval for publication.

Funding

The research is supported by the National Natural Science Foundation of China(Project Nos.32161143013&32070006).

Declaration of competing interest

The authors declare that they have no competing interests.

Availability of data and materials

The datasets used during the present study are available from the corresponding author on reasonable request.

Acknowledgements

We are grateful to Dr. Genevieve Gate (Tasmania, Australia) for improving the manuscript.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://do i.org/10.1016/j.fecs.2022.100051.