Explore a comprehensive lecture from the ICTP-ICTS Winter School on Quantitative Systems Biology that delves into the complex relationships between non-linearity, variability, and diversity in ecological systems. Learn how biodiversity contributes to ecosystem stability and resilience through an integrative perspective that combines theoretical ecology, complex systems theory, and statistical physics. Examine cutting-edge methodologies for modeling species interactions, understanding ecosystem dynamics, and predicting critical tipping points in natural systems. Discover how multidisciplinary approaches help unravel the fundamental processes that maintain biodiversity and ecosystem function. Part of a broader winter school program that brings together international experts to address crucial questions about ecosystem stability, robustness against perturbations, and the underlying principles that govern ecological networks.