Date on Master's Thesis/Doctoral Dissertation

8-2025

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Emery, Sarah

Committee Member

Lackey, Alycia

Committee Member

Mehring, Andrew

Committee Member

Rochner, Maegen

Committee Member

Smith, Allison

Author's Keywords

ecosystem services; urban green space; biodiversity

Abstract

Accelerating urbanization poses critical challenges to urban green spaces (UGS), vital for ecological balance and human health. Rapid development often results in fragmented habitats, biodiversity loss, and diminished ecosystem service delivery. There is an urgent need to explore and evaluate novel strategies capable of enhancing urban resilience, such as implementing urban orchards, and managing existing parks and gardens in sustainable ways. This dissertation explores how different forms of urban green spaces (UGS) contribute to the provision and maintenance of critical ecosystem services that support human well-being and urban biodiversity. By analyzing UGS impact on ecosystem service provisioning and long-term sustainability, this research aims to inform effective urban green space management amidst increasing urbanization pressures. My initial study investigated plant diversity and soil health across Louisville's urban orchards, gardens, and parks. From 2021-2023, I monthly surveyed understory plant diversity at nine sites, with soil samples collected in 2023 for comprehensive analysis. I found that orchards and gardens exhibited greater plant species richness than parks. Notably, orchards displayed superior soil properties, including enhanced water v retention and earthworm populations, compared to both gardens and parks. Urban orchards and gardens support higher plant diversity than parks, with orchards showing especially strong benefits for soil health—highlighting their potential as multifunctional green spaces in cities. Next, I explored the impact of heavy metal contamination on soil microbial functional diversity in vacant lots of Louisville’s Portland neighborhood. Soil samples, collected in 2023, were analyzed alongside Pb, Cu, Cr, Cd, Zn, and Ni. Contrary to expectations, heavy metals did not significantly affect microbial community functional diversity, suggesting potential tolerance to anthropogenic stress. This finding supports the integration of tree-dominant green spaces into urban design to effectively rehabilitate soil toxicity. Lastly, I compared tree-based ecosystem services in Louisville's parks and urban orchards, focusing on oxygen production, carbon storage, pollution capture, runoff avoidance, and tree abundance. Additionally, I assessed the potential impact of the Miyawaki forestation method to enhance ecosystem services provided by one park in Louisville, Founders Square. Results indicated urban orchards significantly outperformed parks in oxygen production, carbon sequestration, tree abundance, and species richness per hectare. This suggests urban orchards are promising urban green spaces for mitigating heat island effects and other environmental challenges.

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