The Relative Importance Of Microclimatic Heterogeneity On Plant And Animal Communities In Deserts Of Southern California, U.S.A

This dissertation examines the intricate relationships between facilitation, environmental heterogeneity, and artificial habitat constructions in arid ecosystems, focusing on plant-animal and plant-plant interactions. By leveraging ecological principles, it explores the role of foundation plant species like Ephedra californica and Larrea tridentata in fostering ecosystem resilience and biodiversity under adverse conditions due to climate change, land use, and desertification.

The study starts with an overview of facilitation theory, highlighting its importance in mitigating the negative effects of abiotic stressors in arid and semi-arid regions. It highlights the Stress Gradient Hypothesis (SGH) as a framework for understanding how competitive interactions can shift towards facilitation under harsh conditions, thus promoting the survival of diverse flora and fauna. The dissertation then delves into environmental heterogeneity, explaining its complex influence on ecosystem dynamics, species composition, and microclimatic regulation.

Chapter 2 provides a detailed analysis of camera trapping techniques, offering optimal sampling design strategies for accurately estimating vertebrate abundance and richness. Chapter 3 examines the effects of artificial canopies on microclimate regulation. This chapter evaluates various eco-friendly fabrics, such as natural burlap, cotton, and nursery seedling fabric, in buffering microclimate through lab experiments measuring understory temperature, relative humidity, and radiation.

Chapters 4 and 5 investigate how climatic variations and vegetation structure contribute to spatial and environmental heterogeneity, shaping flora and fauna diversity and abundance. A key aspect of the study is evaluating the effectiveness of artificial habitat construction as a conservation and restoration strategy in arid landscapes. Field experiments assess the microclimatic buffering capabilities of artificial shelters compared to natural vegetation in supporting vertebrate populations amid desertification in the Southwestern U.S.A.

Overall, this dissertation enhances our understanding of the complex interplay between facilitation, environmental heterogeneity, and habitat modification in arid ecosystems. By uncovering the mechanisms behind these ecological processes, it provides valuable insights for conservation, management, and restoration efforts in regions vulnerable to anthropogenic disturbances and climate change.