Elevational patterns of taxonomic groups
All taxonomic orders of ECM and root-associated fungi in the Neotropical
sites that correlated significantly with the ordination axes exhibited
highest richness in upper montane forests (e.g., Agaricales,
Archaeorhizomycetales, Eurotiales, Helotiales, Hysteriales, Russulales,
Sebacinales, and Thelephorales). In Borneo, vectors of richness for most
taxonomic orders of ECM and root-associated fungi were directed towards
the lower montane forest sites, with the exception of Sordariales and
Thelephorales with highest richness in lowland forests, and Helotiales
in upper montane forests (Fig. 2).
Vectors representing the richness of most taxonomic groups of plant
pathogens with significant correlations (e.g., in Botryosphaeriales,
Cantharellales, Diaporthales, Hypocreales, Ophiostomatales, Polyporales,
Rhizophydiales, and Xylariales) were directed mostly towards lowland
forests, whereas putatively pathogenic Helotiales were more rich in
lower montane forests (Borneo) or upper montane forests (Panama).
Orders of saprotrophic fungi that were richer in forests at lower
elevations included Agaricales, Eurotiales, Geastrales, Hypocreales,
Kickxellales, Saccharomycetales, Sporidiobolales, and Sordariales, each
with significant Pearson’s correlation values in at least two regions.
In contrast, vectors for saprotrophic Chaetothyriales, Helotiales, and
Sebacinales indicated higher richness in montane forests. Among wood
decomposers, Helotiales consistently showed highest richness in forests
at higher elevations, and Agaricales and Xylariales at lower elevations
(Fig. 2).
Overall, Archaeorhizomycetes, Leotiomycetes, Saccharomycetes, and
Sordariomycetes differed significantly in richness among the elevational
forest types in all three regions (Fig. S7). In particular, richness of
Leotiomycetes and Sordariomycetes consistently was higher and lower,
respectively, in upper montane than in lowland forests. Richness of
Archaeorhizomycetes and Saccharomycetes peaked in lower montane forests
in Borneo and Panama, but they showed contrasting patterns in Argentina
(i.e., their richness increased and decreased with elevation,
respectively). The Mortierellomycotina subphylum was always more rich in
montane forests than in the lowlands, though the difference was not
significant in Argentina. Similarly, significant differences in richness
of Agaricomycetes among the elevational forest types were only detected
in Borneo and Panama, where contrasting patterns were observed (i.e.,
higher and lower richness in lowland than in upper montane forests,
respectively) (Fig. S7).