Plant Ecophysiological Responses to Soil Pyrogenic Carbon
Gale, N. V.. 2024.
Abstract
Pyrogenic carbon (PyC), produced by wildfires and engineered biochars, significantly influences
soil fertility and plant ecophysiology. This thesis investigates the interactions between PyC and
plants, elucidating the mechanisms underlying the variable responses of plants to PyC across
different ecosystems. Through controlled greenhouse experiments and a field study, this research
addresses critical knowledge gaps in understanding the effects of PyC on plant growth,
physiology, and reproduction. In a first experiment, I demonstrate that mobile organic
compounds in biochars can cause phytotoxicity, which can be mitigated by leaching and heating
treatments. A second experiment reveals species-specific responses of early-successional
pioneers to biochar amendments, emphasizing the importance of plant functional diversity in
biochar applications for ecosystem restoration. A third experiment establishes dose-response
relationships between biochar application rates and plant ecophysiological traits, highlighting the
need for optimizing biochar dosages based on soil conditions and plant species. A final field
study examines spatial heterogeneity of PyC in post-fire boreal forests and its impact on tree
growth and physiology, underscoring the ecological implications of PyC in fire-affected
landscapes. This thesis advances our understanding of plant-PyC interactions by emphasizing the
roles of species-specific responses, dose-dependency, and spatial heterogeneity in shaping the
ecological effects of PyC. Novel contributions include identifying phytotoxic compounds in
biochars, characterizing dose-response relationships for plant ecophysiology, and quantifying
fine-scale spatial heterogeneity in PyC distribution following wildfire. The findings have
important implications for the sustainable application of biochar in agroecological systems,
ecological restoration, and post-fire management. By bridging controlled experiments and field
studies, this thesis provides a foundation for future research aimed at promoting sustainable land
management and ecosystem resilience in a changing world.
