The Effect of Belowground Biota and Soil Properties on Active Layer Depth

Soil ecosystems within the active layer may play a critical role in stabilizing permafrost in the High Arctic, yet its influence remains poorly understood. As climate change accelerates permafrost thaw, the stability of permafrost is increasingly influenced by biological drivers, including roots, fungi, and microbes that shape soil structure and hence, the thermal gradient in the soil horizon. Predicting permafrost responses to warming requires understanding how these interactions contribute to thaw susceptibility or resilience. This project will examine how vegetation types, soil structure, and microbiomes impact the active layer's insulative capacity in Svalbard. Specifically, it will examine the interactions between biotic properties and the thermal stability of the ice core beneath the active layer in a laboratory experiment. We will test the hypothesis that root traits and microbial communities influence soil structure and, consequently, the insulation of permafrost. Soil structure, fungal and microbial compositions will be studied using soil cores, with a focus on how these factors drive changes in thaw depth. We expect that variations in biological interactions will affect permafrost integrity, offering insights into permafrost thaw processes.