Ecological Restoration - Theses, Dissertations, and other Required Graduate Degree Essays

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The effect of vegetation structure and abiotic variables on oviposition-site selection by amphibians

Author: 
Date created: 
2018-04-20
Abstract: 

Assessing restoration success for pond-breeding amphibians frequently focuses on hydrology, water quality and vegetation, while neglecting the requirements of amphibians that use the restored areas for breeding. Both biotic and abiotic conditions can influence oviposition-site selection of amphibians that do not provide parental care. This study examines how vegetation structure and abiotic variables affect oviposition-site selection by amphibians. The goal of my study was to better understand the requirements of pond-breeding amphibians. In 2017, I surveyed egg masses in four ponds at the Sunshine Coast Botanical Garden in Sechelt, B.C. I identified 667 egg masses of four native amphibian species that varied in abundance and species richness among ponds. I recorded five biotic variables (i.e., vegetation cover, vegetation type, stem density, stem diameter, and canopy closure) and two abiotic variables (i.e., water depth and solar radiation) at egg-mass sites and random sites where no egg masses were detected. Logistic regression analysis with backward elimination revealed that stem count (p = 0.008) and water depth (p = 0.0001) significantly influenced oviposition-site selection. The results also showed that higher stem density and shallower water depth increased the likelihood of egg masses being present. My study indicated that quantifying stems in the water column characterized vegetation density better than estimating percent cover of vegetation. Shallow areas that have structurally complex vegetation might provide an advantage for the offspring by increasing refuge, food resources, and favourable thermal conditions for egg development. Hence, restoration projects could incorporate vegetation structure and shallow areas in their pond designs to potentially increase the abundance and diversity of amphibian communities, thereby contributing to successful restoration projects.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Scott Harrison
Department: 
Environment: Ecological Restoration
Thesis type: 
(Project) M.Sc.

The effect of mowing and hand removal on the regrowth rate of Himalayan blackberry (Rubus armeniacus)

Author: 
Date created: 
2018-04-19
Abstract: 

Himalayan blackberry (Rubus armeniacus Focke) is an invasive species in the Pacific Northwest. Mowing and hand removal are two of the common treatments used for controlling Himalayan blackberry. I examined the effectiveness of mowing, hand removal, and control treatments by measuring the mean number of stem and mean stem length during a growing season. Treatments were applied on March 2017. Bi-weekly sampling was from April to August 2017. Data were analyzed with a two-factor split-plot Analysis of Variance (ANOVA) test. The overall trend showed no statistically significant difference between mowing and hand removal treatments in one growing season. Integrated treatments (e.g. mowing + hand removal + planting) are recommended to be used to effectively reduce Himalayan blackberry cover because one removal treatment showed to be insufficient to eliminate Himalayan blackberry.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Scott Harrison
Department: 
Environment:
Thesis type: 
(Project) M.Sc.

Investigating the Role Of Elevated Salinity in the Recession of a Large Brackish Marsh in the Fraser River Estuary

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-04
Abstract: 

At least 160 ha of the Sturgeon Bank low marsh in the Fraser River delta died off between 1989 and 2011. Humans have heavily modified the Fraser River estuary since the late 1800’s, including installing a series of jetties throughout the leading edge of the delta to train the course of the river. I established a reciprocal transplant experiment to determine the role of elevated salinity in the marsh recession and generate information needed to eventually revegetate areas of receded marsh as part of an intergovernmental collaboration to investigate the causes of this marsh recession. I propose specific actions to better monitor, maintain, and restore the Fraser River delta foreshore brackish marshes in response to ongoing ecological degradation of the estuary. The predicted effects of climate change and sea-level rise may cause us to rethink options for restoring the Sturgeon Bank marsh.

 

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Ken Ashley
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.

The Effects of Canopy Closure on Precipitation Throughfall: Ecological Restoration Considerations for Spanish Bank Creek

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-04
Abstract: 

Since the 1860s the watershed of Spanish Bank Creek has experienced many ecological disturbances due to extensive old-growth logging and urban development. Most notably, these disturbances have altered the vegetative composition and hydrology throughout the watershed. The historic old-growth forest has been replaced by species typical of earlier seral stages, as well as invasive species such as English ivy (Hedera helix). This disturbed vegetation mosaic is characterized by an arrested ecological trajectory that perpetuates degraded conditions. Urban development has eliminated over a third of the historic length of Spanish Bank Creek and storm drains were installed to direct residential drainage into the stream. The combination of a disturbed forest and degraded hydrology intensifies runoff and associated sediment transport, and decreases the hydraulic retention time of the watershed. This has led to a significant decline in abundance of chum, coho, and cutthroat salmonids in Spanish Bank Creek.

 

Previous research has established how trees partition precipitation into throughfall, stemflow, and interception, however there are few studies examining the effects of canopy closure on throughfall within the context of ecological restoration. Thus, the objective of this paper is to determine if increasing canopy closure can be used as a restoration model to decrease throughfall, and consequently increase the hydraulic retention time of the watershed. Results indicated that greater canopy closure was associated with decreased precipitation throughfall.

 

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Ken Ashley
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.

Evaluating Stream Degradation in Villa De Allende, Mexico: The Effect of Rural Development on the Taxonomic Richness and Relative Abundance of Benthic Macro-Invertebrates in Mexican Headwater Streams

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-05
Abstract: 

This research examines the anthropogenic effects on the water quality of headwater streams in the western mountains of the state of Mexico. Rural development has negative effects on the ecology of local streams by diverting and pumping surface and groundwater, removing riparian forests for the construction of buildings, roads, and agricultural fields, and dumping refuse in stream channels. Local development, construction, roads, and agriculture also are sources of pollution that enter the streams during rain events. These negative ecological effects are common to many streams in the watershed of the Chilesdo dam. The combined effects of human development negatively affect the quality of surface water and groundwater aquifers.

 

The issue of anthropogenic effects on the water quality of headwater streams is relevant ecologically because of likely effects on flora and fauna that depend on these streams and because of the role of headwater streams in the context of the larger watershed. Effects on upstream areas directly affect people, animals, and plants downstream. This issue is relevant economically because rural communities depend on the availability of water of suitable quality for agriculture and livestock. In addition, local water quality directly affects the cost of water purification downstream at dams that feed the Cutzamala system, a major source of Mexico City’s drinking water. This issue is relevant socially because the local community depends on this water for domestic consumption. Compromising water quality and abundance could destabilize the lives of local people because poor water quality and water contamination are a public health concern. Additionally, climate change is likely to make this resource scarcer. Projections for all major scenarios used by the International Panel on Climate Change indicate elevated year-round temperatures and decreased overall precipitation in the region (IPCC 2013).

 

The results revealed that taxonomic richness was lower in streams that had anthropogenic alterations. The results also revealed that the abundance of “sensitive” and “somewhat sensitive species” were lower and that the abundance of “pollution-tolerant species” was higher in streams with anthropogenic alterations. The stream with few anthropogenic alterations had the highest taxonomic richness and largest number of sensitive and somewhat sensitive species. These results indicate that human activities are having negative effects on water quality.

 

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Scott Harrison
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.

Geochemical and Biological Response of an Intertidal Ecosystem to Localized Restoration Efforts: Squamish East Delta

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-04
Abstract: 

Geochemical and biological attributes of three intertidal areas in the Squamish Estuary with different levels of disturbance (low, medium, and high) were assessed to determine short-­term ecosystem responses to localized restoration efforts conducted one year previously on a former log handing site. Sediment and macroinvertebrate variables were analyzed among sites to characterize the ecosystems response and provide insight on the nature and process of an assisted successional trajectory. Invertebrate composition and biomass were lowest on the site with the highest level of disturbance. The high disturbance site also contained the highest percentage of fine sand (0.0067 mm to 0.25 mm). This confirms that in the short term there are distinct site responses to disturbance and ameliorative restoration efforts – even in a highly dynamic estuarine environment. The medium site contained more invertebrates than the low disturbance site indicating that something other than localized disturbance is affecting the invertebrate community on the low site. All sites exhibited a less-­rich and less diverse invertebrate community than that of historical records (circa. 1970-­1980). Invertebrate = community in the east delta today is more typical of estuarine environments with higher salinity levels -­ which indicates more widespread levels of disturbance throughout the Estuary is affecting the study sites. This study highlights the importance of considering temporal and spatial scales when setting restoration goals, objectives and creating monitoring plans. Additional monitoring of sediment, invertebrate, and other variables on restored and reference sites is recommended to characterize typical recolonization and reassembly attributes of restoring intertidal estuaries in coastal British Columbia. This would provide evidence and rigor in determining effective restoration techniques and management strategies for a critical and increasingly threatened ecosystem.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Leah Bendell
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.

Eco-Cultural Restoration of Wetlands at Tl’chés (Chatham Islands), British Columbia, Canada

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-04
Abstract: 

This research project examined the restoration possibilities for two culturally important wetland ecosystems at Tl'chés (Chatham Islands, British Columbia, Canada). The first wetland is a sacred bathing pool and holds cultural significance, the second is a remnant silverweed and springbank clover (Potentilla anserine ssp. pacifica and Trifollium wormskjoldii) root garden. These wetlands are necessary ecosystems for the wildlife on Tl'chés as wetlands are rare, but also an integral part of Songhees' cultural practices. My work was done at the invitation from elder Súlhlima (Joan Morris) who was one of the last resident of the islands and retains hereditary rights there, and Songhees Chief Ron Sam and band council. The goal of my project was to develop a restoration plan to restore the wetlands to pre-abandonment conditions, so cultural practices can continue, and to benefit the islands native plant and animal species. The project highlights the value of combining traditional ecological knowledge (TEK) and traditional resource and environmental management (TREM) practices with ecological restoration.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Darcy Mathews
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.

Restoration of Old Forest Characteristics in a 1957 Spacing Trial in the Malcolm Knapp Research Forest, British Columbia

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-04
Abstract: 

Forest managers are interested in determining how stands that have been logged might be managed to restore features characteristic of forests in later-stages of development. Incorporating forest restoration into forest management enables the use of forest-management skills, such as silviculture and regeneration techniques, to manage individual stands for multiple objectives. Therefore, I performed a comparative analysis of large trees, very-large trees, large snags, very-large snags, and large CWD among three stand types (i.e., 60-yr-managed, 140-yr-natural, and 500-yr-natural stands). The 140-yr-natural and 500-yr-natural stands were used as reference conditions to guide the restoration of a 59-yr-managed spacing trial. All attributes differed among stand-types; however, large snags were the most similar attribute between 140-yr-natural and 500-yr-natural stands. Large trees were the fastest attribute to recover in 60-yr-managed stands, however mean values among stand-types still differed. This study highlights the potential of restoring old-natural attributes in younger-managed stands to increase ecological resiliency.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Dr. Doug Ransome
Department: 
Environment: Ecological Restoration Program
Thesis type: 
(Project) M.Sc.