Insights on Oak Community Assembly by Connecting Spectral Biology of Leaves to Belowground Processes

Jeannine Cavender-Bares

Published May 2026 in International Oaks No. 37: 183–194

Abstract

The ecological processes that shape diversification, community assembly, and coexistence among oak species (genus Quercus) remain an active area of discussion, particularly in North American oak-dominated forests, where distantly related lineages co-occur more often than expected by chance. I ponder the mechanisms that enable these lineages – particularly Red Oaks (section Lobatae) and White Oaks (section Quercus) – to live together, and whether their interactions minimize competition or facilitate growth and survival. Central to this question is the role of leaves as drivers of ecosystem function. Oak leaves are critical to forest productivity, capturing carbon through photosynthesis and regulating nutrient cycling through their chemistry and nutrient dynamics. Variation among species in leaf longevity, nutrient resorption, and structural compounds such as cellulose and lignin influences decomposition rates and soil nutrient availability. Species that resorb nutrients less efficiently may contribute more to soil fertility through litter, potentially benefiting neighbors. Differences in litter chemistry also shape microbial activity and interactions with ectomycorrhizal fungi and pathogens. Coexistence among oak lineages may be mediated by shared beneficial mycorrhizal networks alongside contrasting susceptibility to lethal pathogens such as oak wilt. Faster-growing, nutrient-efficient Red Oaks may benefit from soils enriched by more stress-tolerant, pathogen-resistant White Oaks, while differences in disease vulnerability may prevent competitive exclusion. Advances in spectral biology allow rapid prediction of leaf chemical traits, revealing lineage-level differences in structural compounds. The chemical patterns that emerge surely influence belowground processes and long-term forest dynamics. Together, leaf chemistry, microbial interactions, and evolutionary history will help tell the story of how oak diversity contributes to ecosystem stability and function.

Keywords

oak diversity, species coexistence, leaf chemistry, nutrient resorption, litter decomposition nutrient cycling, plant-microbe interactions, ecosystem function

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