Physiological mechanisms and recovery strategies of plant responses to defoliation under environmental stresses

Defoliation caused by insect herbivory, anthropogenic disturbance, and grazing animals represents a significant challenge to plant survival and growth in forest ecosystems. This review synthesizes recent research findings on plant physiological responses to defoliation under various environmental stress conditions, including drought, low light availability, and varying plant sizes. Drawing from a series of experimental studies conducted on woody species, including Robinia pseudoacacia, Amorpha fruticosa, Quercus acutissima, and Quercus rubra, this review examines the complex interactions between defoliation and environmental factors. Key findings indicate that plants employ multiple compensatory mechanisms following defoliation, including enhanced photosynthetic rates in remaining leaves, mobilization of nonstructural carbohydrate reserves, and modifications in leaf morphological traits. The review reveals that environmental conditions significantly modulate plant recovery capacity, with drought and low light conditions generally suppressing compensatory growth responses. Furthermore, plant size emerges as a critical factor influencing recovery strategies, with larger seedlings demonstrating greater resilience through enhanced carbon reserve utilization. Native and alien species exhibit distinct response strategies, with native species investing more in chemical defenses while alien species prioritize growth recovery. These findings provide valuable insights for vegetation restoration practices and forest management strategies in the context of increasing climate variability and biotic disturbance pressures.