Biodiversity responses to global changes

Yalcin, Semra (2018) Biodiversity responses to global changes. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Anthropogenic global changes are the main drivers of global, regional, and local biodiversity changes. Measuring and predicting accurate species range shifts in response to these anthropogenic influences is important to developing practical conservation strategies. In my thesis chapters, I first present a comprehensive literature synthesis of the most common published methods and metrics used to define species ranges and quantify species range shifts. Methods for measuring species range shifts included observation studies, grid-based mapping, convex hull, kriging, species distribution modelling, and hybrid methods. Each method is associated with a diversity of metrics that have different opportunities, assumptions, and constraints. Second, I use extensive empirical land-cover, climate and breeding bird species data in the boreal forest belt of Ontario (Canada) between the late 1980s and early 2000s to measure the relative and combined impacts of land-cover and climate change on species occupancy dynamics. I found that land-cover and climate change were top predictors of local colonization for ~ 1/3 of species considered each but that climate change was the top predictor of local extinction for ~ 2/3 of species considered. Moreover, the interspecific variations in bird responses to global changes were not well captured by species traits such as body size, migration pattern, and habitat preference. Finally, using the same empirical data as Chapter 2, I quantify the changes in local and regional bird species composition (i.e., beta diversity) over time and space and determine the influence of land-cover and climate change on changes in avian community composition. Bird communities experienced high temporal community turnover (i.e., temporal beta-diversity) and changes in their uniqueness in terms of species

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