Fig 1.
Species richness and abundance of all of the macrofungi identified to the genus level (113 species; 54 genera).
Highest species richness was observed in the family Agaricaceae (25.3%) followed by Polyporaceae (15.31%) and Marasmiaceae (10.8%). Agaricaceae (21.2%) also had the highest % relative abundance followed by Polyporaceae and Psathyrellaceae with a contribution of 14.5% each.
Table 1.
% Species richness and relative abundance of various families over this study region calculated on the basis of the Berger-Parker dominance index.
The dominance index was calculated for two categories: (i) for the samples observed (exact observations, nobs)–‘dobs’ and (ii) for the observations simulated 50 times incorporating the bootstrapping technique (resampled simulations, nres)–‘dres’. Based on this index, the observed families were classified into three major categories: (i) dominant (D), (ii) general (G), and (iii) rare (R). The dominant, general and rare species differed significantly for the observed species, whereas all of the simulated observations of the macrofungal species were general in the study region. Please refer to the main text for more details related to the methodology of obtaining the relative dominance index.
Table 2.
Diversity indices calculated for the ground-dwelling and tree-dwelling macrofungi.
Tree-dwelling species were found to be more diverse and even in both the categories of ‘observed’ and ‘simulated/resampled (res)’ data.
Fig 2.
Distribution of macrofungi in different regions of India belonging to the families Agaricaceae, Marasmiaceae, Pluteaceae, Polyporaceae and ‘other families’.
Chennai was compared with Karnataka, West Bengal, Kerala and Maharashtra.
Table 3.
Paired t-test performed for the actual and simulated observations.
The p-values for the pairs varied between the actual and the simulated observations; however, the conclusions drawn remained the same.
Fig 3.
Scanning electron microscopic images of some the selected macrofungal species belonging to Ascomycota and Basidiomycota.
a- Agaricus hondensis, b—Agaricus moelleri, c—Chlorophyllum nothorachodes, d—Conocybe mandschurica, e—Coprinellus aureogranulatus, f -Coprinellus radians,g—Gymnopilus purpureosquamulosus, h—Hymenagaricus taiwanensis,i—Leucoagaricus atrodisca, j—Micropsalliota globocystis, k—Pholiota spumosa, l—Psathyrella candolleana (young spores),m—Psathyrella candolleana (mature spores), n—Psathyrella gracilis, o—Volvariella taylorii, p—Ceriporia lacerate, q—Ganoderma lucidum, r—Phellinus repandus, s—Geastrum pectinatum, t—Geastrum striatum, u—Daldinia eschscholzii, v—Cosmospora viliuscula and w—Xylaria cirrata. Spores were observed in varying size and shapes. Scale is varying for each panel and is shown respectively.
Fig 4.
Source vs. Ambient spore morphological similarities.
Panel of figures (Sa–Sc) at the top show manually extracted fungal spores identified to the species level. Panel of figures (Aa–Ac) at the bottom show the fungal spores collected from the ambient air on a polycarbonate filter paper as reported by Valsan et al., 2015 [41]. It is to be noted that the ambient fungal spores reported and depicted here were mainly observed during the NE monsoon season, the season with the fungal bloom. Both of the studies are from the same study region, IIT Madras and from same season of October–January (monsoon and winter in southern India, Chennai). Kindly refer Valsan et al., 2015 [41] for further details regarding the bioaerosols SEM study.
Fig 5.
Fungal spore presence and the concentration distribution predicted at a height of 10m from the source using the Gaussian plume model.
Spore concentrations were highest near the source. Gradients are also large near the source but gradually become less steep with the increasing downwind distance (x, m). Color shading indicates the spores/m3 of air for a stability class A. Release (Cinitial) was 540 × 104 spores/m2/s and the ambient wind speed was 1.79 m/s; Presence of spores could also be seen at a location of (100, 100, 10) m from the source.
Fig 6.
Incidence (%) of macrofungal species incidence during the sampling period (Oct–Feb 2015) comprising the winter season with rainfall (Oct–Jan 2015) and summer (Feb 2015).
Macrofungal incidence is correlated with cumulative rainfall (mm) that occurred, % relative humidity (RH) and the temperature (°C). Incidence of macrofungi was found to be the maximum during November; the rainfall of October and highest % RH (80%) seemed conducive for the increased incidence of macrofungi during November. Again the rainfall during December further supported its growth and persistence throughout the months December and January. The decrease in the macrofungi incidence from December to February can be associated with the decrease in rainfall and increase in temperature.
Fig 7.
Conceptual spore movement framework in the study region.
Macrofungi source is at a height of 10m from the ground. Spore release and dispersal viewed at a height (z) of 10 m, downwind distance (x) of 10–100 m and at a crosswind distance (y) of 10 to 100 m (crosswind not depicted). Spores released through convective currents had an Ug of 0.06 m/s and the wind velocity that existed (ambient) was U = 1.79 m/s. Spores released from the macrofungi can act as a potential bioaerosol as proven by GPM. DNA analysis of PM10 measurements done during the same period (not a part of this study), confirmed the presence of Agaricaceae and Polyporaceae found at the source.