Author ORCID Identifier

https://orcid.org/0000-0002-4187-8982

Date of Award

Summer 2023

Document Type

Thesis (Ph.D.)

Department or Program

Ecology, Evolution, Environment and Society

First Advisor

Matthew P Ayres

Second Advisor

Mark McPeek

Third Advisor

Caitlin Hicks Pries

Abstract

To understand the downstream consequences of the extinction of a species, we must understand its role in an ecosystem. With the impending extirpation of ash (Fraxinus spp.) due to the invasive emerald ash borer (Agrilus planipennis), understanding the role of ash trees is critical to predicting whether its loss will precipitate further species declines and/or ecosystem functions. We evaluated whether subcanopy microbial, invertebrate, and floral communities under four tree species (white ash, American beech, yellow birch, sugar maple) and on two soil hydropedological types (Bh podzol and Typical podzol) varied in species richness, composition, and functional traits in a factorial study. There were frequent strong effects of tree species. White ash frequently differed from the other trees: e.g., lower cation exchange capacity and exchangeable acidity, thinner Oi layer, lower %C and C:N, and, from phospholipid fatty acids, more AM fungi and less gram+ bacteria. We found that the subcanopy vegetation under ash was unique in having more plants of more species compared to the other tree species in the study. We also found an effect of soil type on species richness with Bh podzol having greater richness. However, identity analyses of functional traits of the understory communities revealed few differences by canopy tree species, suggesting that subcanopy communities are functionally redundant under different trees. We also found that soil invertebrate abundance did not vary significantly with tree or soil type, but that a higher diversity of organisms was present under ash and beech trees compared to sugar maple and birch. Finally, we estimated invertebrate abundance and biomass per gram of basal resource (leaf-litter) to provide data to modelers of ecosystem dynamics aiming to incorporate invertebrate data into forest forecasting. Better understanding of the role of diversity and function associated with at-risk organismal communities is important for predicting changes to ecosystem services in human-altered landscapes.

Comments

To understand the downstream consequences of the extinction of a species, we must understand its role in an ecosystem. With the impending extirpation of ash (Fraxinus spp.) due to the invasive emerald ash borer (Agrilus planipennis), understanding the role of ash trees is critical to predicting whether its loss will precipitate further species declines and/or ecosystem functions. We evaluated whether subcanopy microbial, invertebrate, and floral communities under four tree species (white ash, American beech, yellow birch, sugar maple) and on two soil hydropedological types (Bh podzol and Typical podzol) varied in species richness, composition, and functional traits in a factorial study. There were frequent strong effects of tree species. White ash frequently differed from the other trees: e.g., lower cation exchange capacity and exchangeable acidity, thinner Oi layer, lower %C and C:N, and, from phospholipid fatty acids, more AM fungi and less gram+ bacteria. We found that the subcanopy vegetation under ash was unique in having more plants of more species compared to the other tree species in the study. We also found an effect of soil type on species richness with Bh podzol having greater richness. However, identity analyses of functional traits of the understory communities revealed few differences by canopy tree species, suggesting that subcanopy communities are functionally redundant under different trees. We also found that soil invertebrate abundance did not vary significantly with tree or soil type, but that a higher diversity of organisms was present under ash and beech trees compared to sugar maple and birch. Finally, we estimated invertebrate abundance and biomass per gram of basal resource (leaf-litter) to provide data to modelers of ecosystem dynamics aiming to incorporate invertebrate data into forest forecasting. Better understanding of the role of diversity and function associated with at-risk organismal communities is important for predicting changes to ecosystem services in human-altered landscapes.

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