An Analysis of Soil Respiration in a Temperate Deciduous Forest Ecosystem
| Autor: | Daly, Katelynn |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Druh dokumentu: | Diplomová práce |
| Popis: | The production and emission of carbon dioxide (CO2) from soils, referred to as soil respiration (Rs), has a significant influence on the global carbon balance. Carbon is acquired by vegetation from the atmosphere through photosynthesis and stored on the surface and in soils as organic matter. This stored organic matter is returned to the atmosphere as CO2 through belowground decomposition of organic matter by microbial communities (heterotrophic respiration) and metabolic activity of roots and mycorrhizae (autotrophic respiration). In this study, we explore temporal and spatial dynamics of Rs in a temperate deciduous forest located in Southern Ontario and how it is influenced by climatic controls over a two year period (2014/2015). The research site is a 90-year-old managed deciduous hardwood forest (Carolinian species) and part of the Turkey Point Flux Station and global Fluxnet network. An automated soil CO2 efflux system (LI-8100A) was utilized for continuous monitoring of Rs since July 2014 at our site. To better capture the spatial variability of Rs, a portable soil CO2 efflux system (LI-6400) was also used along two 50-m transects. Comparing the two chamber systems, they both measured within one standard deviation of each other indicating that the long-term automatic chamber site is able to account for the spatial variability of the surrounding area. The coefficient of variation among automated chambers ranged from 15 to 85%. The range of Rs measured during the two study years was 0.72 to 22.74 µmol CO2 m-2s-1. Rs showed a strong soil temperature-driven seasonal trend, though soil moisture accounted for approximately 35% of the variability in Rs. Rainfall events were found to cause pulse response in Rs during and following the precipitation event, causing an 88% increase in Rs. Estimations of total CO2 emissions at the site were modeled using four different techniques, and showed that Rs can account for approximately 84% of total ecosystem respiration. The average annual temperature sensitivity (Q10 value) of the study site was found to be 2.34. The annual Q10 model was improved by the incorporation of temporal variability of Rs (by estimating the Q10 model on a monthly basis) and also through the addition of a logistic soil moisture function. This study will allow us to have a better understanding of the dynamics of Rs and how it responds to its main controlling variables, soil moisture and temperature. It will also help us to determine the impact of climate change and extreme weather events on Rs in temperate deciduous forests and help in developing vegetation ecosystem models. Thesis Master of Science (MSc) |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|