Water-borne hyphomycetes in tree canopies of Kaiga (Western Ghats), India

Abstract

The canopy samples such as trapped leaf litter, trapped sediment (during summer), stemflow and throughfall (during monsoon) from five common riparian tree species (<em>Artocarpus heterophyllus, Cassia fistula, Ficus recemosa, Syzygium caryophyllatum</em> and <em>Xylia xylocarpa</em>) in Kaiga forest stand of the Western Ghats of southwest India were evaluated for the occurrence of water-borne hyphomycetes. Partially decomposed trapped leaf litter was incubated in bubble chambers followed by filtration to assess conidial output. Sediments accumulated in tree holes or junction of branches were shaken with sterile leaf disks in distilled water followed by incubation of leaf disks in bubble chamber and filtration to find out colonized fungi. Stemflow and throughfall samples were filtered directly to collect free conidia. From five canopy niches, a total of 29 water-borne hyphomycetes were recovered. The species richness was higher in stemflow and throughfall than trapped leaf litter and sediments (14-16 vs. 6-10 species). Although sediments of <em>Syzygium caryophyllatum</em> were acidic (5.1), the conidial output was higher than other tree species. Stemflow and throughfall of <em>Xylea xylocarpa</em> even though alkaline (8.5-8.7) showed higher species richness (6-12 species) as well as conidial load than rest of the tree species. <em>Flagellospora curvula</em> and <em>Triscelophorus acuminatus</em> were common in trapped leaf litter and sediments respectively, while conidia of <em>Anguillospora crassa</em> and A. longissima were frequent in stemflow and throughfall. Diversity of water-borne hyphomycetes was highest in throughfall of <em>Xylea xylocarpa</em> followed by throughfall of <em>Ficus recemosa</em>. Our study reconfirms the occurrence and survival of diverse water-borne hyphomycetes in different niches of riparian tree canopies of the Western Ghats during wet and dry regimes and predicts their possible role in canopy as saprophytes, endophytes and alternation of life cycle between canopy and aquatic habitats.

Beyond the water column: aquatic hyphomycetes outside their preferred habitat

“…During heavy rains, the biotope in such tree holes may correspond to a flow chamber, and resemble a running water habitat. G€ oncz€ ol (1976) found large numbers of spores in the water, many belonging to Alatospora Live leaves India, Japan, Hungary, Poland Ando and Kawamoto, 1986;Tubaki, 1984a, 1984b;Or1owska, 1998a, 1994;R evay, 2004, 2003;G€ oncz€ ol, 1976;Karamchand and Sridhar, 2009;Sridhar et al, 2006;Sudheep and Sridhar, 2010 R evay, 2004G€ oncz€ ol, 1976;Sridhar, 2009, 2008;Kaufman et al, 2008;Sridhar et al, 2013 Sediment (in tree holes) India Sudheep and Sridhar, 2010 Stemflow Canada, Germany, Hungary, India, Japan, Poland Ando and Kawamoto, 1986;Ando and Tubaki, 1984b;Bandoni, 1981;Or1owska, 1999, 1994;R evay, 2006, 2004;Mackinnon, 1982;Sridhar and Karamchand, 2009;Sudheep and Sridhar, 2010 Throughfall Canada, Hungary, India, Romania, Sweden Bandoni, 1981;G€ oncz€ ol and R evay, 2006;MacKinnon, 1982;R evay and G€ oncz€ ol, 2010;Sridhar and Karamchand, 2009;Sudheep and Sridhar, 2010 Karamchand and Sridhar, 2008;Sridhar et al, 2013;Sudheep and Sridhar, 2010 acuminata, Ar. tetracladia and Camposporium pellucidum.…”

“…In a controlled study, fungal diversity, conidial production and mycelial biomass on leaves exposed in tree holes and in a stream were similar (Sridhar et al, 2013), however, decay rates were considerably lower in the tree holes. Finally, sediment and leaves trapped on five common riparian tree species yielded a total of 29 species (Sudheep and Sridhar, 2010). Epiphytic ferns often trap leaf litter and water, which again provide a fungal habitat Sridhar et al, 2006).…”

“…This records fungi that are potentially reproductive. Sudheep and Sridhar (2010) introduced an intermediate step by incubating sediment with sterile leaves that were subsequently checked for the presence of aquatic hyphomycetes. This potentially captures fungi that are unable to reproduce before additional growth .…”

Aquatic hyphomycetes associated with leaves, leaf detritus and crown humus in palm canopies.

“…Species belonging to the genera Anguillospora, Flagellospora, Lunulospora and Triscelophorus were consistently well represented in streams, tree holes, epiphytic ferns and drain water from canopies (Sridhar & Kaveriappa 1984, 1989, 2013, Karamchand & Sridhar 2008, 2009, Sudheep & Sridhar 2010. These genera are ubiquitous in warm climates and also dominant as root endophytes in the Sampaje and Virajpet-Badaga streams of the Western Ghats (Ghate & Sridhar 2016).…”

“…Interestingly, these fungi have expanded their habitats beyond detritus decomposition in streams, as they are common in canopies (Sokolski et al 2006, Sridhar 2009, Sridhar et al 2013. There seems to be scanty information on the occurrence of aquatic hyphomycetes in detritus (autochthonous and allochthonous leaf litter) and crown humus in canopies (Sridhar et al 2006, Karamchand & Sridhar 2008, Sudheep & Sridhar 2010. Studies on the occurrence of aquatic hyphomycetes in palm canopies are also lacking, although these are very common in the southwestern part of India.…”