Summer 2018 Forestry Plots: Leaf Habit versus Mycorrhizal Fungi Association: A Framework for Predicting Temperate Tree Species Effects on Soil

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Tree species affect the biogeochemistry of soil differently. Understanding these effects provides not only insight into current forest function, but also better informs predictions of how shifting forest composition will influence soils in the future. Our objective was to assess if a tree species’ phylogenetic leaf habit or mycorrhizal fungi association is a better predictor of soil biogeochemistry in temperate forests. This study took place in single-species forestry plots throughout the Morton Arboretum (DuPage County, IL). Plots varied by leaf habit (evergreen or deciduous) and known mycorrhizal fungi association (ectomycorrhizal or arbuscular). We collected a composite sample of four cores per plot in June 2018 from both the forest floor (0-5 cm) and mineral soil (5-15 cm) layers. The soil layers were analyzed separately using a two-way ANOVA (P < 0.05, DF=1). We found that both leaf habit and mycorrhizal fungi association can predict a tree’s effects upon soil, and that which factor is the better predictor depends on the nutrient process being measured. In both soil layers, leaf habit predicts percent organic matter (P= 0.0128) and carbon mineralization (P= 0.0095). A linear regression suggested that carbon mineralization is driven by percent organic matter (R² = 0.7482, P= 5.079 e -12). Both leaf habit and type of mycorrhizal fungi association predict C:N ratio in the forest floor layer (Leaf P= 0.0263, Fungi P= 0.0005). Type of mycorrhizal association predicted differences in forest floor pH (P= 0.0001). A linear regression suggested that 30% of differences in pH were driven by exchangeable calcium (Ca2+) (R² = 0.3038, P= 0.0004943). As arbuscular associating trees (usually deciduous) become more dominant in the Chicago region, a trait based framework for predicting soil nutrient changes could aid in the management and mitigation of nutrient cycling and overall ecosystem productivity.

Related Entities
Midgley, Meghan G. (is local contact/expert)
Sims, Rachel (is local contact/expert)
Catania, Michelle (is local contact/expert)
Spatial Coverage
East and West sides of the Morton Arboretum, forestry plots with a single species of tree