Understanding the impacts of anthropogenic change on the world's biodiversity is a fundamental goal of ecology. Assessing broad-scale patterns in biodiversity is especially critical for appropriately allocating limited conservation resources amid the ongoing biodiversity crisis. Recent advances in data availability and computational tools have made synthesis an increasingly powerful approach for exploring these patterns, allowing us to assess previously intractable continental and global scale questions. However, controversy over the use of synthesis methods is ongoing due to limitations in data and tools. Further, synthesis largely focuses on species-based approaches, leaving unaddressed other critical dimensions of biodiversity.

Over three chapters, I discuss the powerful opportunity synthesis represents and address the critical need for improved methodology for understanding biodiversity change. In chapter 1, I lay out a road map for overcoming limitations of biodiversity synthesis. I advocate for improved metadata for constituent studies to facilitate better inclusion of ecological context in synthesis work, adoption of best practices in code development and sharing, and more explicit statements of inference grounded in data scope. In chapter 2, I present my contribution to synthesis software, the R package `taxadb`, a tool for reconciling taxonomic discrepancies. `taxadb` uses a local database to interface with taxonomic data providers allowing quick resolution of species names to taxonomic ID's. In chapter 3, I perform the first broad-scale synthesis of temporal functional diversity trends. Bridging 1000's of assemblage time series and functional trait data, I assess general patterns of functional change. I find evidence of maintenance of functional structure across communities, regardless of taxon, climate, or realm.