Abstract: Tsuga canadensis (hemlock) is an ectomycorrhizal (ECM) foundation tree in the Northern Forest critical for maintaining biodiversity, ecosystem functioning, and forest health. However, Adelges tsugae (Hemlock Woolly Adelgid; HWA) is an invasive insect that is moving further into the region, threatening both hemlock and the ecological integrity of the Northern Forest. The plight of hemlock is also part of a greater decline in economically important ECM trees and increase in arbuscular mycorrhizal (AM) trees, resulting in reduced functional diversity and carbon storage capacity of the Northern Forest. Evidence suggests that silvicultural treatments that manipulate the size and number of canopy gaps can enhance hemlock resilience to HWA. However, it is unclear how gap size specifically influences microclimate and the performance of hemlock across all demographic stages. Additionally, it is unknown how soil biogeochemistry and understory plant and ECM fungal communities influence hemlock resilience while serving as indicators of forest health. We propose to take advantage of a planned commercial timber harvest and silvicultural study of hemlock release and resilience to HWA in the Adirondack Mountains of NY, 16 km from the current HWA invasion front. We will study hemlock response, understory and belowground communities, biogeochemistry, and changes in abiotic conditions in response to these treatments before and potentially after HWA invasion. Identifying a silvicultural prescription that maximizes belowground processes and provides the ideal microclimate that best enhances hemlock resilience can foster sustainable hemlock ecosystem management among landowners and managers and enhance ecosystem functioning and health of the Northern Forest.