Fractally Sampling Diversity-Environment Relationships to Understand Plant Assemblage Health Across Spatial Scales

Humans influence the health of ecosystems and rely on healthy ecosystems to support their livelihoods and well-being. By looking at how the parts of ecosystems interact we can understand and improve ecosystem health. Ecosystem interactions change across spatial scales or different size patches of area. For example, individual organisms interact with each other at small spatial scales, while at large spatial scales, communities of organisms interact with weather conditions. However, many research studies do not look at how ecosystem interactions change across spatial scales. To address this gap in ecological research, I use a fractal sampling design which samples at the vertices of equilateral triangles nested within each other. This design allows me to investigate how spatial scale influences the relationship between plant communities and the environments they live in. I tested this design in northeast Utah rangeland where the vegetation changes depending on whether a hill faces south (more shrubs and grasses) or north (more conifer trees). In the first chapter, I look at how plant biodiversity metrics based on the tree of life (phylogenetic diversity) change across terrain and spatial scale. This analysis identifies which spatial scales influence the relationship between diversity and environment at the fieldsite. In the second chapter, I assess how the characteristics that plants have adapted to survive and thrive (functional diversity) change in response to soil temperature and water dynamics. This chapter describes the potential for plants to respond to changing conditions in the future. In the third chapter, I look at diversity-environment relationships across a larger landscape to address rangeland management concerns about an increase in undesirable species and bare ground. Overall, both phylogenetic and functional diversity changed across south- to north-facing hills. In contrast to north-facing hills, the soil temperature on south-facing hills was hotter and more variable. Plant communities on ...