Laura Manchola Rojas | ALES Graduate Seminar

Date(s) - 19/01/2022
9:00 am - 10:00 am

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.

This is an ALES MSc Final Exam Seminar by Laura Manchola Rojas. This seminar is open to the general public to attend.

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Meeting ID: 817 4778 8589
Passcode: 930604

Thesis Topic:

Buried wood effects on nutrient supply and microbial activity in different oil sands reclamation soils in Northern Alberta

MSc with Dr. Brad Pinno

Seminar Abstract:

Buried wood is an important, yet understudied, component of natural and anthropogenic soils. Nutrient immobilization as a response to wood addition during land reclamation may be a concern. However, there are no reports about how much buried wood is added to different reclamation soils and so the potential nutrient immobilization risk is unknown. The aim of this thesis was to: 1) investigate the impacts of buried wood on the nutrient supply and microbial communities in different soils used in oil sands reclamation, and 2) determine how much buried wood is in reclamation soils and how is this linked to the soil nutrient supply in the field. A 60-day incubation study was performed with different volumes and types of buried wood (0%-50%, aspen and pine wood), and four different soils (fine and coarse forest floor-mineral mix: fFFMM and cFFMM, peat-mineral mix: PMM, and Peat) to determine the impacts on soil nutrients and microbial communities. A complementary field study was performed in a 5-year old reclamation site with FFMM and PMM in Northern Alberta where buried wood sampling was performed and soil samples were collected for nutrient supply rates analysis. In the incubation study, responses varied depending on the soil type, but buried wood caused nitrogen immobilization in three out of the four soils due to an increase in the soil C:N ratio; soils with lower C:N ratio like fFFMM and PMM were more susceptible to nitrogen immobilization; and buried wood increased the microbial activity but no significant changes in the soil metabolic profiles were noted. The field study concluded that the amount of buried wood is less than 1.5% or 34 m3/ha and it was not linked to the soil nutrient profiles. The findings in this thesis suggest that although high levels of buried wood increase the soil C:N ratio and subsequently causes nitrogen immobilization, the amount present in operational reclamation soils is not a motive of concern for operational practices.