Regeneration for resilience framework to support regeneration decisions for species with populations at risk of extirpation by white pine blister rust

Abstract

Natural forests are increasingly invaded by nonnative pests and pathogens that threaten host species with population extirpation and cascading ecological impacts. The regeneration for resilience (R4R) framework provides a decision structure to prioritize limited resources and utilize artificial and natural regeneration management to offer the best likelihood of success in positioning stands and landscapes to support multi-generational self-sustaining host populations in the presence of the nonnative invader by (1) increasing host population size to offset invader-caused mortality, (2) increasing the frequency of genetic resistance traits in host populations in habitats that enable their expression and durability to retard future mortality and facilitate population sustainability and recovery, and (3) maintain host genetic diversity, adaptive capacity, and population connectivity. This application is designed for conditions where the nonnative invader is expected to be a persistent threat, the host species naturally has some genetic resistance to the invasive species, and the forest host populations are integral to support valued ecosystem processes and services. The R4R framework has been developed for application in high elevation five-needle pine ecosystems of North America impacted and threatened by the nonnative pathogen Cronartium ribicola that causes the lethal disease white pine blister rust (WPBR). Several examples using the R4R framework to integrate information on current forest condition, WPBR risk or hazard, genetic resistance to WPBR, and host population dynamics and silvics to prioritize areas and design interventions are discussed. Effective management of forest regeneration dynamics can increase forest resilience and adaptive capacity to mitigate impacts of invasive species.