Date of Graduation

5-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Cell & Molecular Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Steven L. Stephenson

Committee Member

Frederick W. Spiegel

Second Committee Member

Mary C. Savin

Third Committee Member

Burton H. Bluhm

Keywords

Biodiversity, Ion Torrent, Metabardocing, litter microhabitats, foraging mycelia, fungal taxonomy and community, prescribed burning impact, macrofungal, community structure, Bioinformatics

Abstract

Fungi are taxonomically the most species-rich group of organisms on the earth, ecologically occupy distinctive niches and interact with diverse other organisms throughout their biogeographic distributions and functionally play key roles through their various lifestyles. Plant litter, in particular, is a keystone component in ecosystems and provides heterogeneous microhabitats for the often overlooked litter-decomposing fungi and other organisms on the floor of temperate deciduous forests. Litter fungi involve indirect interactions with the plant, soil and whole food web network. However, the community structure and functions of litter-associated fungi as well as patterns of species richness distributed across various litter microhabitats have been largely neglected and potentially threatened by forest management activities. This is because of the primary focus on fungi with direct interactions with plants or soils and methodological limitations. In this project, fruiting body inventories, incubation chambers and Sanger sequencing and DNA-metabarcoding techniques were applied to document and compare the hidden diversity and productivity of the fungi associated with litter microhabitats on the forest floor in the temperate deciduous forests of northwest Arkansas. Using traditional methods (inventories and incubation chambers), a total of 126 taxa, likely with many new species, were recorded, the majority of which were associated with dead leaves in the Pea Ridge National Military (PR) Park and Devil’s Den State (DD) Park. Functionally, saprotrophs were dominant and appeared to shape the community structure of other overlapping guilds present. On each site, diverse macrofungal species inhabited multiple microhabitats of this heterogeneous substrate. The taxonomic and functional diversity of community assemblages were significantly distributed over the forest floor litter and clustered across the twenty plots on the investigated study sites. The rDNA- metabarcoding of the fungal ITS2 region generated a more meaningful data body once direct sampling of leaf litter as the main component of litter forest floor in these deciduous forests as opposed to traditional methods. There were 415 OTUs including 349 macrofungal OTUs and 66 OTUs with new macrofungal sequences recorded for the first time across both investigated sites. The deep sequencing presented more diverse and overlap functional groups inhabiting leaf litter without significant differences in richness of the dominant saprotrophs, while the variations recorded for the richness of the ectomycorrhizas, parasites, and members of other uncertain functional groups in both sites. Molecular identification for the DNA macrofungi through direct samplings of leaf litter identified distinctive communities and indicator species. The results of both methods revealed that several abiotic and biotic factors were apparent, but other complex factors not considered in the present study may be important for characterizing the litter-associated macrofungi of forests in the Ozark Mountains. The effect of prescribed burning practices on the litter macrofungi was assessed and it was concluded that as a result of prescribed burning, neither total species richness nor total macrofungal productivity were substantially different between the compared sites. Nevertheless, prescribed burning shaped the composition of the fungal assemblage on various litter microhabitats, resulting in a decline in the species richness and numbers of fruiting bodies inhabiting the various microhabitats, and reduced the indicator species in PR sites. The data presented herein provide an unprecedented insight into the macrofungal diversity taxonomically, functionally and compositionally in the litter microhabitat of the Ozark forests aiding in future fungal investigation and forest management decisions.

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