Pattern of Substrate Preferences of Free Living Protists (Myxomycetes) on Decaying Wood

Abstract

We have studied the influence of the stage of decomposition and acidity of wood, as well as the illumination of the microhabitat on the species composition, abundance, and occurrence of slime molds (Myxomycetes) of the xylobiontic (inhabitants of the wood) substrate complex of forest communities in Siberia (Altai krai, Altai Republic, and Novosibirsk oblast). This work is based on a study of 1777 samples of fruit bodies (sporophores) of myxomycetes. In the analysis of data for communities of Myxomycetes of the xylobiontic substrate complex, we recognize a successional series which clearly correlates with the stage of wood decomposition. The study of the distribution of the species composition of the slime mold on wood of various stages of decomposition shows that the maximum number of species is observed on dead trunks where the wood is of medium density and the bark can easily be separated (W3). The lowest specificity and diversity of species composition is observed on the fallen trunks of trees with very dense wood and dense bark (W1). These dead trees have low water-retaining capacity, tight bark, and almost intact wood containing large amounts of lignin, preventing the invasion of plasmodia and myxamoebae of Myxomycetes into the trunk. A study of the location of slime-mold colonies in relation to the illumination level shows that the greatest number of species is found on the front, side, and bottom parts of dead trunks of woody plants. The least specificity and the least variety of Myxomycetes species are found on apical parts of dead tree trunks facing the sun. The exception are species with large fruit bodies such as Fuligo septica and Reticularia splendens, which are most often observed on the upper parts of the sun facing trunks of woody plants. In the research area, the complex of species typical for wood of coniferous trees is described. It is noted that acidophilic slime molds of the genera Comatricha and Cribraria can be traced in xylobiontic and epiphytic–corticuloid substrate complexes.