Forest Cover Influences the Predictions Made by Species Distribution Models: A Case Study of American hazelnut (Corylus americana)

Cramb, Nicholas

Forest Cover Influences the Predictions Made by Species Distribution Models: A Case Study of American hazelnut (Corylus americana)

dc.contributor.advisor	Vamosi, Jana
dc.contributor.advisor	Dawson, Andria
dc.contributor.author	Cramb, Nicholas
dc.contributor.committeemember	Galpern, Paul
dc.contributor.committeemember	Yeaman, Samuel
dc.date	2025-05
dc.date.accessioned	2024-10-18T17:16:41Z
dc.date.available	2024-10-18T17:16:41Z
dc.date.issued	2024-10-11
dc.description.abstract	Species distribution models can be used to predict climate impacts on biodiversity and guide conservation efforts. However, they may not fully represent biological reality when they entirely rely on climate variables alone and neglect biological interactions. My research objective is to test if including forest cover as a quantitative proxy for shrub-canopy interactions improves the predictive ability of species distribution models. My work focuses on American hazelnut (Corylus americana) as a case-study to test this framework. American hazelnut is a good candidate species because it is widely distributed throughout the eastern temperate and northern forests of North America and is likely to interact with the full gradient of 0 to 100% forest cover. The species remains understudied regarding the determinants of its distribution, despite an excellent fossil pollen record. This project used the hazelnut fossil pollen record to model the influence of canopy cover on distribution through time and to test whether hazelnut niche has been stable over time. For distribution models of American hazelnut, I found no difference in model performance when land cover variables are included at a continental extent. However, at a regional extent I found significant increases in model performance when forest cover was included. These findings suggest that land cover can more precisely define where species habitat exists at a local level compared to climate variables alone. Distribution models developed using fossil pollen occurrences and climate simulations indicate that hazelnut has maintained a consistent niche space over the past 11,000 years before present. However, the limitations of fossil pollen data created less certainty in these results. Future work involves testing this framework on additional species to determine if these patterns are consistent across woody taxa, as well as testing if land cover datasets that are more categorically resolved and include human impacts are able to improve distribution models.
dc.identifier.citation	Cramb, N. (2024). Forest cover influences the predictions made by species distribution models: A case study of American hazelnut (Corylus americana) (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/119978
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	American Hazelnut
dc.subject	Species Distribution Modeling
dc.subject	Fossil Pollen
dc.subject	Remote Sensing
dc.subject	Forest Cover
dc.subject	Ensemble modeling
dc.subject.classification	Ecology
dc.subject.classification	Biostatistics
dc.title	Forest Cover Influences the Predictions Made by Species Distribution Models: A Case Study of American hazelnut (Corylus americana)
dc.type	master thesis
thesis.degree.discipline	Biological Sciences
thesis.degree.grantor	University of Calgary
thesis.degree.name	Master of Science (MSc)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.