Understanding Forest Resilience to Drought through Resilience Principles

With the intensification of climate change and anthropogenic activities, water scarcity and drought have become critical challenges around the world, threatening various ecosystems, particularly forests. Forests are social-ecological systems that provide numerous services to humans, who, in return, alter them. While it is impossible to prevent droughts, understanding the attributes of forests, particularly their resilience, may facilitate the mitigation of drought-related adverse consequences. Resilience is a multifaceted concept that has been interpreted through various lenses in the literature, with engineering resilience emphasizing system recovery, ecological resilience investigating the adaptive capacity of forests, and social-ecological resilience highlighting the interconnectedness of human and natural systems in resilience assessment.

Building on these conceptual foundations, seven principles of resilience, maintaining diversity and redundancy (P1), managing connectivity (P2), managing slow variables and feedback (P3), fostering complex adaptive system thinking (P4), encouraging learning and experimentation (P5), broadening participation (P6), and promoting polycentric governance (P7) offer a comprehensive approach to building, evaluating, and enhancing resilience. This review aims to investigate the extent to which resilience principles have been integrated into the discourse of forest resilience to drought in the literature.

Searching the Web of Science database for studies on forest resilience from 1998 to 2024 resulted in 47 papers. Among the reviewed studies, 51% investigated resilience through the lens of ecological resilience, 30% utilized the social-ecological concept, and 19% employed engineering resilience. P4 is frequently examined using tree ring data and drought severity indices (e.g., SPEI). Species richness and composition have often been considered to evaluate P1. A close examination of the methodologies of the reviewed studies revealed that 34% are evidence-based or conceptual studies aimed at understanding the mechanisms contributing to resilience, and 21% are experimental and field studies, which often involve the use of collected field data, such as tree ring width, vegetation growth rate, to explore the response of forest systems to natural or experimentally induced drought events.

The limited use of modeling, specifically landscape or ecosystem services models, in studying forest resilience to drought is evident, with only three studies conducted on this topic. Furthermore, the case studies are nearly evenly distributed across Africa, Europe, North America, and Asia, with 7, 10, 10, and 8 studies, respectively. Four studies investigated the resilience of forests in South America, and another four focused on a global scale. A closer exploration of the reviewed studies revealed that no studies have attempted to consider all seven resilience principles jointly, highlighting a significant research gap in this area and emphasizing the need for more studies to tackle the intricate relationships between ecosystems and human communities and societies.