Research

impacts of mycorrhizal fungi inoculation on the establishment of quercus in a restored wetland

This study examines the impacts of inoculation with mycorrhizal fungi or a soil transfer from a reference flatwoods wetland on the survival and growth of oak saplings planted in a forested wetland restoration project. It also examines abiotic factors, including soil moisture, temperature, and electrical conductivity.

Reference Site

The restoration site has on-site mature forested flatwood wetlands that have been preserved. Samples of mycorrhizal oak roots were collected for analysis.

Mycorrhizal Fungi

An example of oak tree roots with mycorrhizal fungi mycelium. Soil, humus, and fine roots collected from the based of oak trees in the reference wetlands were included in the soil transfer treatment.

Planting Prep

The wetland restoration site is a former agricultural field that was graded, seeded with native seed, and prepped for planting using an auger to dig holes for three-gallon container trees.

Planting

Inoculated oak saplings were planted alongside other native tree species in a test plot. Randomly planted oak trees in an adjactent plot were identified as control trees and did not receive treatment.

Survival and Growth

During the following growing season, inoculated and uninoculated sapling survival and growth were recorded, and root samples were collected to analyze colonization. In addition, leaf count and soil moisture, temperature, and electric conductivity data were collected.

Year 1 Results

During the first growing season, greater survival and growth were recording in inoculated than uninoculated saplings, indicating that inoculation with mycorrhizal fungi has a positive effect on the establishment of vegetation. Tree survival and growth will be measured again during the second growing season.

Survival and Growth

During the second growing season, Year 2 survival and growth of inoculated and uninoculated saplings was recorded. Additional data including soil temperature, moisture, and electrical conductivity, and leaf count were also collected.

Year 2 Results

During the second growing season, greater survival was recorded in inoculated than uninoculated saplings. Tree growth data for Years 1 & 2 will be analyzed and biomass will be calculated. Differences in soil temperature, moisture, and electrical conductivity will be assessed as potential abiotic factors that imact tree survival and growth.

Next Steps

Soil eDNA will be used to quantify and compare the soil microbial diversity of trees treated with one of four commercial inoculums or a soil transfer with that of control trees, and samples collected in the onsite reference wetlands and onsite crop fields. Soil eDNA can be used to track changes in the microbial community over time.

Restoration

Time of planting during the dormant season, October/November 2024.

The site was formerly a monoculture corn field and supported very little biodiversity.

Year 1

First growing season, August 2025.

Ample wetland vegetation indicates that a diverse plant community has begun to form in the first year following restoration.

Year 2

Second growing season, August 2026.

Increased biodiversity of the plant community is evident in the second year following restoration.

biotic and abiotic factors influencing soil health in restored wetlands

This study examines biotic and abiotic aspects of soil health, including soil physiochemical properties, bacterial functional diversity, and fungal mycelium, as potential factors impacting the survival of oak trees and native vegetation in successful and struggling restored wetlands on former agricultural lands.

Stunted Tree Growth

Stunted tree growth, high tree mortality, low herbaceous species diversity, and invasive species plague struggling restoration projects.

Soil Sample Collection

Soil samples were collected adjacent to oak trees to assess soil physiochemical properties and bacterial functional diversity.

In-Growth Mesh Bag Burial

In-growth mesh bags were buried adjacent to oak trees to assess mycorrhizal fungal mycelium.

In-Growth Mesh Bag Collection

In-growth mesh bags were collected during the following growing season to be assessed for fungal hyphae and sand aggregation.

Soil Bacterial Functional Diversity

Soil bacterial functional diversity was measured from soil samples using Biolog EcoPlates.

Mycorrhizal Fungi Mycelium Activity

Mycorrhizal fungi mycelium activity was assessed by scoring sand particle aggregation and the presence of fungal hyphae in the in-growth mesh bags.

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