Myxomycetes associated with monsoon lowland tropical forests in southern Vietnam
Novozhilov, Yuri K.; Erastova, Daria A.; Shchepin, Oleg N.; Schnittler, Martin; Alexandrova, Alina V.; Popov, Eugene S.; Kuznetov, Andrey N
A systematic survey for myxomycetes was carried out between 2010 and 2013 at 67 localities in lowland monsoon tropical forests of Dong Nai Biosphere Reserve (including Cat Tien National Park and Vinh Cuu Nature Reserve). In spite of a comparable effort for field collecting during four visits in the same season of subsequent years, the abundance of myxomycete fructifications varied extremely. In total, the survey included 1136 records from 371 field collections and 765 collections obtained from 953 moist chamber cultures prepared with samples taken from the bark surface of living trees and vines, ground and aerial litter, and coarse woody debris. Determinations resulted in 107 taxa (104 morphospecies and three varieties) from 27 genera and 10 families. More than half (59) of all taxa were classified as rare for the whole study area (<0.5% of all records); most of them were singletons (25) and doubletones (17). One collection of Licea could not be clearly assigned to any described species. Most of the taxa (69) were found for the first time for Vietnam; 79 were new for Cat Tien National Park; and all were new for the Vinh Cuu Nature Reserve. The Chao1 estimator calculated for individual-based species accumulation curves indicated that our sampling effort was sufficient to recover all of the more common species in the studied area. However, the completeness of the survey varies for different substrates and habitats and depends strongly on the method of data collecting. The distribution of litter-inhabiting myxomycetes in the lowland monsoon forests of southern Vietnam may be limited rather by local vegetation providing the substrate, microclimate and soil types than by seasonal monsoon rainfalls and flooding. Comparing the results for series of moist chamber cultures prepared from the samples of ground litter we found that the number of species peaks within the pH range 6.5–7.0. Among four main groups of substrates (bark, woody debris, ground and aerial litter) various trends in species richness and substrate specificity of the species were found. Myxomycete assemblages of ground litter seem to be the most diverse among all studied substrates. Among ground litter, the leafy fraction is more diverse in myxomycetes than other fractions, like twigs or fruit shells.