Using the functional traits of soil fungi to improve post-disturbance pine regeneration

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Novel disturbance regimes threaten the dependable forest commodity supplies that bolster provincial and national economies. The cumulative effects of successive disturbances such as wildfires, mountain pine beetle (Dendroctonus ponderosae) outbreaks, and plant invasions undermine the ability of forests to regenerate and return to pre-disturbance conditions. Regeneration of lodgepole pine (Pinus contorta) is especially critical as this is a dominant timber species in western Canada. Economic concerns and impact of cumulative disturbances may become increasingly pronounced in coming years as stress in lodgepole pine forests increases with climate change, creating conditions where biotic and abiotic disturbances are followed by wildfire and species invasions. Substantial pressure from these disturbances may exceed the forest industry's capacity to maintain sustainable forest goods and services. Improving forest regeneration methods and technologies is therefore crucial to long-term sustainability of forest resources. Our proposed research investigates how various novel disturbance scenarios alter the benefits regenerating trees receive from soil fungal communities. Tree seedlings depend on soil fungi to release usable nutrients, increase nutrient uptake, and enhance resistance to insects and pathogens. However, disturbances can adversely affect soil fungal communities, and in turn these changes may alter the benefits seedlings receive from fungi, ultimately reducing seedling health. The goals of this proposed project are to (1) determine how soil fungal communities are affected by an array of novel and cumulative forest disturbances, (2) identify the components of fungal communities that promote regeneration following disturbance, and (3) determine whether disturbances alter the functional roles of soil fungi in forest regeneration. We will combine field and greenhouse experiments to identify management practices that can prevent cumulative disturbances from collapsing soil fungal communities and forest ecosystems. New practices could include soil amendment and site preparation recommendations.