Date of Graduation

12-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Naithani, Kusum J.

Committee Member

Cothren, Jackson D.

Second Committee Member

Huang, Xiao

Third Committee Member

Roberts, Caleb P.

Keywords

canopy complexity; carbon sequestration; diversity; ecosystem function; multitrophic; terrain complexity

Abstract

Forests play a pivotal role in sustaining global biodiversity and mitigating the global climate, as they serve as the primary refuge for terrestrial biodiversity and effectively capture and store atmospheric carbon dioxide. However, changing climate and land use are altering the geographic distribution, physical structure, and productivity of forested ecosystems that can have profound impacts on biodiversity conservation, forest productivity, and global climate. This dissertation contributes to our understanding of multifaceted interactions between the physical and biological structural complexity and ecosystem functions in forested landscapes across the United states by using openly available data from two national networks: the National Ecological Observatory Network (NEON) and Ameriflux. The first chapter provides a critical review and synthesis of historical and contemporary approaches for quantifying biodiversity, assessing their relevance and constraints, and emphasizing the necessity for new methods to monitor biodiversity on a landscape scale. Alongside a comprehensive review and synthesis of existing literature, this chapter introduces an innovative method for computing a multi-trophic diversity (MDI) index that offers a comprehensive assessment of diversity across multiple trophic levels, encompassing plants, beetles, and birds. This index holds promise for streamlining biodiversity monitoring on a landscape scale by employing remotely sensed data and has broad applications in forest management. The second chapter introduces a new method to calculate a combined terrain and canopy structural complexity metric using widely-available LiDAR data, enabling the prediction of MDI– a combined diversity metric that integrates diversity across trophic levels; developed in chapter one. Specifically, this chapter investigates how structural complexity of terrain and forest canopy influence the diversity of primary producers (plants), herbivores (beetles), and omnivores (birds). This chapter underscores the importance of considering both structural complexity and forest type in addition to climate and geographical factors when making land management decisions to promote biodiversity and ecosystem health. The third chapter explores the links between complexity (biological and structural) and ecosystem functions, specifically focusing on key ecosystem processes like net ecosystem exchange (NEE), ecosystem respiration (Reco), and gross primary productivity (GPP). The findings of this chapter highlight the importance of including complexity (structural and biological) in predicting ecosystems functions including carbon sequestration potential of a landscape.

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