Date of Award
Master of Science
Disturbance plays integral role in the vegetative communities and succession in northern Alberta. Fire is the most common natural disturbance, and oil industry disturbance is a rapidly increasing anthropogenic disturbance on the landscape. In situ extraction of deep oil sands is increasing across Alberta, and with it, minimum disturbance sites used for seismic exploration and natural gas extraction also increase. To determine how these sites recover after disturbance, a 21 year chronosequence was established to address the following questions: 1) How do the plant communities differ between natural bogs, recently burned bogs, and bogs disturbed by `minimum disturbance petroleum industry activities? 2) How do the environmental conditions compare between undisturbed bogs, burned bogs, and bogs disturbed by `minimum disturbance' petroleum industry activities? 3) What is the revegetation pathway of minimum disturbance sites disturbed over the 21 year period? 4) What is the revegetation pathway of the burned bogs over the 21 year disturbance span? and 5) How does the (anthropogenic) minimum disturbance revegetation pathway compare to that of the (natural) fire disturbed bogs? To answer these questions 55 stands were sampled. The plant species were identified and abundance recorded, water chemistry was analyzed, shade recorded, depth to water measured, and oldest trees aged. Bog plant communities and environmental conditions at sites surveyed are similar to one another. Burned bogs were also similar in chemistry, vegetation, and physical traits of the sites. Minimum disturbance sites were quite varied in plant species and environmental conditions studied. A minimum disturbance revegetation could not be determined due to the amount variation in plant species and abundances between minimum disturbance sites of the same age. Burned bogs showed more predictable species interactions: Polytrichum strictum establishes early and subsequently declines. Sphagnum fuscum becomes dominant between 15 and 20 years after disturbance, and Picea mariana returns to burned sites between 1 and 5 years after fire and continues to increase in density. Minimum disturbance sites do not recover in a predictable manner, and some sites become rich fens. It is not clear if these sites will return to the pre-disturbance mature bog community, but burned bogs have a community closely resembling a mature bog after 20 years of revegetation. Documentation of pre-disturbance conditions and operational protocols is recommended in order to further understand sources of cation rich waters that could yield rich fen habitats.
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