Influence of bark pH on the occurrence and distribution of tree canopy myxomycete species

Abstract

This study compares the occurrence and distribution of myxomycete species in the canopy of living trees and neighboring grapevines. Corticolous myxomycetes of three temperate forests in southeastern USA were studied on six tree species (30 trees) and grapevines (30 vines) to determine distribution and occurrence of myxomycete species relating to geographic location, host species, and bark pH. The double-rope climbing technique was used to access the canopy and sample bark up to 16.5 m. Bark samples were examined in 580 moist chamber cultures and 44 myxomycete species were identified representing 21 genera, averaging 3.0 +/- 2.1 species per sample site. Jaccard's coefficient determined community similarity between five individuals of six tree species, Acer saccharum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Platanus occidentalis and Tsuga canadensis, and neighboring grapevines, Vitis aestivalis and V. vulpina. Vertical variation in species richness was significantly different only for Platanus occidentalis and might be attributable to flaking of bark with increasing height in the canopy. Tsuga canadensis and neighboring grapevines had greatest community similarity. Cribraria violacea was observed on all tree and grapevine species except T. canadensis and neighboring grapevines. Occurrence and species assemblages of myxomycetes were associated with bark pH, not geographic location. Bark of V. aestivalis (pH 4.5) was more acidic than neighboring T. canadensis (pH 4.1), compared to grapevines of the same species neighboring other tree species. Results indicated that most species are not regionally restricted, and although some myxomycetes are associated with a certain pH range, others develop on any substratum. Future research protocols for corticolous myxomycetes should emphasize sampling adequate amounts of substrata in a local region from different host species that have a wide range of bark pH, ensuring a representative sample of species for an entire region.

Ecological assemblages of corticulous myxomycetes in forest communities of the North-East Ukraine

“…However, we should note the fact that the Physarales were best represented in the taxonomic spectrum of the consortia of F. excelsior and A. platanoides, but were completely absent on P. sylvestris. This agrees with the earlier published data (Everhart et al, 2008;Novozhilov et al, 2017a) that the distribution of Physarales is limited by acidity of the substrate, because sporocarps of this group contain limey deposits. Since рН of the bark of P. sylvestris (4.3) was the lowest among the compared species, and the highest values (5.9) is typical for F. excelsior and A. platanoides (Leontyev, 2006a), this observation may be explained by the difference between the substrate-forming plants according to this parameter.…”

“…Species that were represented by the highest number of observations may be characterized as the commonest, i.e. such that occur most often and are characterized by broad ecological optimum, particularly concerning the type of substrate and the parameters dependent on it, as pH (Romanenko, 2002;Everhart et al, 2008), hygroscopy (Romanenko, 2002Schnittler et al, 2016), age of the plants and sampling height (Ing, 1994;Schnittler et al, 2016). Unlike the previous parameter, the number of sporocarps characterizes not the distribution, but the intensity of the development in favourable conditions (which may occur in the territory relatively seldom).…”

“…Texture of the bark, hygroscopicity, pH, the age of the tree and epiphyte load on its trunk have a significant effect on the species composition of corticulous myxomycetes. Similar peculiarities of substrate-forming plants are less important to litter, xylophilous and nivicolous species (Everhart et al, 2008;Schnittler, 2016).…”

Distribution of Myxomycetes on Varied Leaf Litter Types in a Mixed Forest in Warm-Temperate Western Japan

“…It is well known that myxomycetes inhabiting tree bark are remarkably responsive to bark pH (e.g., Everhart et al, 2008). Myxomycetes use bacteria and organic matter as nutrient resources (Madelin, 1984); thus, the cellulolytic activity of microorganisms associated with the decomposition of leaf litter was expected to promote the presence of myxomycetes.…”

“…Physarum plasmodium formation occurs in a vegetative phase that is influenced by the incubation pH (Collins & Tang, 1973). Furthermore, myxomycetes that occur mostly on the bark surface of living trees, shrubs, woody vines, and prairie and desert plants are divided into four pH groups along a broad spectrum of pH 3.5 -7.5 (Everhart et al, 2008).…”