Study area

The actual study was carried out in seven sites distributed in six ejidos of Madera municipality, Chihuahua, located in area No. 12 of the state (Table 1; Figure 1). Pinus spp. constitute 88 % of the vegetal communities (^{Rzedowski, 2006}) and, in the portion corresponding to the municipality, they are located at various altitudes on the Western Sierra Madre; the mean annual precipitation is 400 to 1 200 mm, with a temperature of 8 to 22 °C (^{Inegi, 2017}).

Figure 1 Location of the study area. 

Collection method and taxonomic classification

The data were collected in July and August, 2016, according to the procedures of ^{Lodge et al. (2004)}; a 100 m × 100 m plot was established for each sampling site and was georeferenced with the aid of an eTrex 10 Gramim^TM satellite navigator, Furthermore, it was divided into four 50 m x 50 m quadrants; the central point of each quadrant was marked in order to establish a 20 m × 20 m square, which was in turn divided into 2 m × 2 m squares. The fungal species were counted, and the number of the square and the number of sporomes were recorded for each specimen. The macroscopic characteristics in fresh ―shape, color, texture, size, diameter, and life habit― were registered in writing; a photographic support of the species was also made, using a Samsung^TM ST888 camera.

Both the macroscopic and the microscopic characteristics were considered, and several specialized works (^{Largent et al., 1977}; ^{Gilbetson y Ryvarden, 1986}; ^{Singer, 1986}; ^{Phillips, 1991}) were consulted for purposes of taxonomic determination. In order to corroborate the scientific names, the ^{Index Fungorum (2018)} and the norm NOM-059-SEMARNAT-2010 (^{Semarnat, 2010}) were consulted in order to verify whether any of the registered species is classified in it as being at risk.

Ecological parameters

The total species richness was determined for each sampling site and according to the abundance of sporomes. The alpha diversity was estimated using Margalef’s index (D_MG) and the Shannon index (Hˈ) with the abundance for each taxon. The sampling intensity was evaluated using the Chao 1 diversity estimator, based on the number of taxa. Jaccard’s similarity index was utilized for assessing the species composition per site. The data were analyzed using PAST 3 statistical software, 1.0 version (^{Hammer et al., 2001}).

Margalef’s diversity index was determined using the following equation:

Where:

D _Mg =Margalef’s diversity index

S= Number of species present

N=Total number of sporomes

The Shannon-Wiener diversity index was determined using the following equation:

Where:

Hˈ=Shannon-Wiener diversity index

S = Number of species

Pi =Proportion of sporomes of species i

The higher the value of Hˈ, the greater the diversity of species is considered to be.

Taxonomic description and habits

A richness of 69 species of macromycetes, Basidiomycetes were represented by 68 species, and Ascomycetes, by one; these species belong to 27 families and 46 genera. The saprobic life habit had the best representation, with 37 taxa (53.62 %), mainly belonging to the families Agaricaceae, Mycenaceae, Omphalotaceae, and Polyporaceae. The ejidos with the largest wealth of saprobe species were Socorro Rivera (14), Nicolás Bravo (El Pedregoso site) (10), La Norteña (8) and Madera (6). The presence of these species indicates that this area has high amounts of organic matter, in whose recycling the fungi intervene. Cebadillas de Dolores and El Oso, La Avena and neighboring areas exhibited the lowest richness, with only one taxon per ejido.

The best represented genera were Gymnopus and Lycoperdon, with four taxa (Table 2), among which L. perlatum Pers., L. echinatum Pers. and L. curtisii Pers., stand out as edible species. The study by ^{Díaz-Moreno et al. (2009)} records 83 species of the saprobe group. The results of this research are consistent with this study in that the family Polyporaceae has the highest species richness. The record of 37 species for Madera municipality is significant, as it is a large figure, compared to those cited by the above authors, who provide a value that includes more than one municipality of Chihuahua.

The state has large forested areas, which are kept balanced thanks to various interactions, including the mycorrhizal associations that participate in the conservation of forest ecosystems. 30 taxa of mycorrhizal fungi were identified; the ejidos with the greatest species richness were Madera (10) and Socorro Rivera (10), followed by Nicolás Bravo (Mesa del Venado site) (7), El Oso, La Avena and neighboring areas (7), and La Norteña (5). The lowest values were for Nicolás Bravo (El Pedregoso site) (3) and Cebadilla de Dolores (2). The genera with the greatest species richness were: Amanita (6), with A. cochiseana, A. citrina Pers., A. muscaria var. flavivolvata (Cantante) DT, A. novinupta Tulloss & J. Lindgr., A. phalloides (Vaill. ex Fr.) Link and A. rubescens, of which A. cochiseana and A. rubescens are edible; A. novinupta was collected in four of the study sites.

Boletus (4), with Boletus aff. edulis, B. barrowsi Thiers & AH Sm., B. rubriceps D. Arora & J. L. Frank and B. regius (Krombh.) D. Arora & J.L. Frank. The first two species are considered to be edible. Like Amanita muscaria and Hygrophorus russula (Schaeff. ex Fr.) Kauffan, B. aff. edulis is cited in the norm NOM-059-SEMARNAT-2010 as at risk or threatened (^{Semarnat, 2010}).

Inocybe (4), with I. calamistrata (Fr.) Gillet, I. geophylla (Bull.) P. Kumm. I. lacera (Fr.) Kumm. and I. rimosa (Bull.) P. Kumm. are toxic. Lactarius (3), with L. indigo (Schwein.) P., L. piperatus (L.) Pers. and L. volemus (Fr.) Fr., of which the first and the last are edible. As for the genus Russula, the registered species were R. emetica (Schaeff.) Pers, R. nigricans Pers. and R. rosea Pers., in agreement with ^{Quiñónez et al. (2009)}, who point out the same genera as those with the greatest species richness, except for Inocybe, in four ejidos of Urique municipality in the Sierra Tarahumara; they also cite most species of the genus Amanita.

The richness of mycorrhizal species for the Madera municipality is considered to be high, compared to other municipalities like Bocoyna, where ^{Quiñónez et al. (2008)} document 39 species; of these, A. muscaria var. flavivolvata and R. emetica were the most representative. They register others, like Astraeus hygrometricus (Pers.) Morgan, in most of their sampling sites; a similar situation occurs in the Madera municipality, where four ejidos were registered (Table 2).

Edible macromycetes have been scarcely studied in northern Mexico even though they have a great ethnomycological importance; 20 of these were identified (28.98 %). The ejidos with the largest number of species were Madera (8) and Socorro Rivera, Nicolás Bravo (El Pedregoso site) and La Norteña, with four taxa each. The family Agaricaceae and the genus Lycoperdon stand out for having most edible species; other identified edible species were A. cochiseana, A. rubescens, H. russula, H. lactifluorum, L. indigo, and Laccaria laccata (Scop.) Cooke, equally cited by ^{Quiñónez et al. (2010)} in the forests of Bocoyna and Urique, Chihuahua. According to ^{Quiñones-Martínez et al. (2014)}, the most widely consumed taxa among the inhabitants of the Sierra Tarahumara are A. rubescens, Agaricus campestris L., Ustilago maydis (DC) Corda, H. lactifluorum and A. cochiseana, Boletus edulis and B. pinophilus. H. lactifluorum was the only species in the Ascomycetes group registered in this study, and it has a high nutritional value for the inhabitants of the area (Table 2).

Ecological parameters

Alpha diversity

Socorro Rivera ejido had the greatest species richness, with 21 taxa, followed by Madera, Nicolás Bravo (El Pedregoso site) and La Norteña, with 17, 16 and 13 taxa, respectively. The ejidos with the lowest values were Nicolás Bravo (Mesa del Venado site), and El Oso, La Avena and neighboring areas, both with eight taxa. Socorro Rivera had the highest diversity (H’=2.44 and D_MG=3.58), while Cebadilla de Dolores (H’=1.15 and D_MG =0.75) had the lowest (Table 3).

A total of 1 606 sporomes were registered. Nicolás Bravo ejido (El Pedregoso site) was the most abundant (38.91 %), and El Oso, La Avena and neighboring areas, the least abundant, with a mere 1.93 %.

The most abundant species, with over 100 sporomes, were Astraeus hygrometricus, present in Madera, Socorro Rivera, and El Oso, La Avena ejidos and neighboring areas, amounting to 14.82 % of the total sporomes; Stereum gausapatum (Fr.) P., with 12.20 %; Auricularia mesentérica (Sw.) Birkebak, (Dicks) Pers. (with 8.96 %), collected in Nicolás Bravo (El Pedregoso site) and Socorro Rivera; Stereum ostrea (Blume and T. Nees), with 8.34 %, and H. lactifluorum, with 7.34 %. This last species was registered for Nicolás Bravo (El Pedregoso site) and Madera; the rest of the species included 1 to 69 sporomes, distributed among the various study sites.

The results of Chao 1 for Cebadilla de Dolores, Madera, Socorro Rivera, Nicolás Bravo (Mesa del Venado site), and El Oso, La Avena and neighboring areas, indicate that the record of species met the expected number of taxa; a diversity of 19 and 16 species is estimated to exist in the localities of Nicolás Bravo (El Pedregoso site) and La Norteña (Table 3). More long-term diversity studies on this group are necessary in order to achieve greater knowledge of the species distributed in the area and at a national level (^{Aguirre-Acosta et al., 2014}).

Jaccard’s similarity

The highest percentage of similarity occurred in Madera and Nicolás Bravo ejidos (El Pedregoso site), with 18 %; the species identified in the two sites were A. novinupta, Auricularia mesenterica, Cortinarius violaceus (L.) Gray, H. lactifluorum and L. piperatus. El Oso, La Avena and neighboring areas registered a value of 14 %, like Madera and Nicolás Bravo (Mesa del Venado site). Shared taxa were A. novinupta, A. hygrometricus and R. nigricans (tables 2 and 4).