The cascade effects in spatially competitive communities

Song, Xuemeng

COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION

2026

163

Wang, RW;Zhang, F

Understanding the cascade effects triggered by perturbations in spatially competitive communities is crucial for predicting biodiversity dynamics and community stability. In this study, we extend Tilman's multispecies spatial competition-colonization model to open communities (i.e., open to the immigration of individuals) by incorporating both habitat availability and species immigration as key drivers of perturbations. Through analytical derivations and numerical simulations, we systematically examine the cascade effects triggered by global perturbations (e.g., changes in habitat availability, Delta h) and local perturbations (e.g., changes in the immigration flux of superior competitors, Delta Ii), which propagate unidirectionally downward along the competitive hierarchy. Our results demonstrate that the equilibrium abundances of species follow two quantitative rules: (i) the parity-alternating response pattern (opposite sensitivities between even-ranked and odd-ranked species); and (ii) the response-intensity attenuation rule (sensitivity magnitudes decline monotonically with increasing competitive rank). We further quantify the interactive mechanisms of multiple perturbations through synergistic superposition and antagonistic regulation, and verify that regulating the immigration flux of superior competitors can effectively buffer species extinction risks induced by habitat loss. This study establishes a comprehensive theoretical framework for predicting the separate and interactive effects of global and local perturbations in hierarchical competitive systems, providing a theoretical foundation for understanding the cascade response patterns of competitive communities under global environmental change.