How have First Nations’ past sites of habitation influenced present-day ecology on the Central Coast of British Columbia?

Date

2016-01-05

Authors

Fisher, Julia

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Abstract

Humans have transformed much of the earth’s surface through a wide range of activities of varying intensities and scales, shaping the landscape we see today. The combination of time and complex human-environment interactions within the Hakai Lúxvbálís Conservancy on the Central Coast of British Columbia has resulted in a landscape with many anthropogenically-generated modifications, such as shell middens which can be found at sites with histories of long-term habitation. Globally, shell middens (and in general, habitation sites) have been found to be factors in shaping site ecology. This thesis seeks to investigate this relationship between human activity and occupation and the landscape. The goal of this project is to examine the legacies from past land use, and subsidies from shell middens, within the present-day plant communities. I conducted an observational study to determine if species richness and overall plant communities on these habitation sites differed from sites without a history of intense occupation. To do this I selected ten habitation sites with known extensive shell middens and paired them with ten control sites with similar site conditions (but without the same site history or shell middens). I measured species abundances within 540 1 m x 1 m quadrats. I also surveyed a select group of culturally significant plant species and culturally modified trees within belt transects at each site. Data regarding the water table level and soil and foliar samples were also collected. A variety of environmental factors, along with the site history were evaluated as explanatory variables. Principal component analyses were used to describe how the gradients within the vegetation communities at three vegetation layers (ground, herb, shrub) to see if they respond differently to long-term site use. The habitation sites were found to be characterized by N-rich plant communities, which were significantly different from the plant communities on the control sites at the ground layer, herb layer, and with all layers combined, at both transect distances analysed, but the shrub layer was only significantly different when the entire transect was considered. The results show plant community composition is most strongly influenced by a combination of factors including site type, canopy cover, slope, topography, and distance from shore, with the weight of their importance depending on what vegetation layer is considered. The habitation sites had a lower average species richness at all layers, compared to the control sites, and their plant communities were shown to change differently with distance from the marine shoreline. Habitation sites also differed by having higher soil nutrient content, lower water table levels, and contained culturally important plant species that were absent on the control sites. This research highlights the influence that humans have had on landscapes in this region. This study shows how the patterns within the plant communities at the habitation sites differ from what is expected within the Coastal Western Hemlock zone. The research improves our understanding of the factors influencing vegetation patterns on the Central Coast of British Columbia with this examination of the complex intersection of historical practices and environmental changes.

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Keywords

Midden, Nutrient enrichment, Land-use legacies, Central Coast, British Columbia, Habitation sites, Calcium

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