What do We Mean by Environmental Heterogeneity? Toward A Mechanistically Explicit and Scale-Dependent Framework

Area of Science:

• Ecology
• Biodiversity Science
• Environmental Science

Background:

• Environmental heterogeneity (EH) is a recognized driver of biodiversity.
• Existing conceptual frameworks for EH lack structured definitions and operationalization.
• Inconsistencies in defining and measuring EH hinder its predictive power in biodiversity science.

Purpose of the Study:

• To evaluate how environmental heterogeneity (EH) is defined, quantified, and analyzed across scientific disciplines.
• To identify and categorize operational interpretations of EH.
• To propose an operational definition and a research roadmap for EH in biodiversity science.

Main Methods:

• A semi-systematic narrative synthesis of 360 studies from Web of Science and Scopus (2000-2025).
• Analysis of definitions, quantification methods, and reported effects of EH.
• Identification of distinct operational interpretations and their associated mechanisms.

Main Results:

• Only 10% of studies provided explicit EH definitions, which were often descriptive and lacked scale or mechanism specification.
• Over 91% of studies reported significant effects of EH across diverse taxa, regions, and disciplines.
• Four operational interpretations of EH were identified: environmental variability, habitat diversity, environmental differentiation, and structural heterogeneity.

Conclusions:

• A misalignment exists between EH definitions, measurement strategies, and hypothesized mechanisms, creating inconsistencies in the literature.
• An operational definition of EH is proposed: spatial/temporal variation in abiotic/biotic conditions influencing ecological processes.
• A Research Roadmap is presented to advance EH toward a predictive, mechanistically explicit framework in biodiversity science.