Plant ecophysiological responses to pyrogenic soil carbon
Fire is arguably the most important natural disturbance agent in global forests and grasslands, and plays a key ecological role in driving plant community dynamics and ecosystem processes. Under a shifting climate, both empirical evidence and predictive models indicate an increase in both the frequency and intensity of fire in the world’s ecosystems, in response to rising temperature and drought, and to human land-clearing. In turn, soil pyrogenic carbon – the recalcitrant legacy of fire, generated from the pyrolysis of plant material now represents ~15% of the soil organic carbon found in terrestrial ecosystems globally.
It is thought that soil pyrogenic carbon facilitates rapid plant regeneration following fires, by increasing the ability of soils to retain and enhance nutrient and water availability, increase soil pH, and reduce soil toxicity by sorbing inhibitory compounds (Thomas, Gale et al. 2013). As a result of these multiple benefits observed in forests (and grasslands), there has been a rapid expansion of applications of pyrogenic carbon as a soil amendment (“biochar”) into environmental management and ecosystem restoration (Thomas and Gale 2015). Physiological adaptations that enable rapid growth in early-successional pioneers (e.g. high rates of photosynthesis) should be advantageous in soils with pyrogenic carbon since plants with a capacity for expeditious resource capture can capitalize on resource pulses from leachable mineral elements. Yet how pyrogenic carbon influences the ecophysiology of plants in natural fire systems, and wild plants and trees in pyrogenic carbon-based restoration projects remains largely unknown; and is, therefore, the focus of my current Ph.D. research with Sean Thomas at the University of Toronto.
My PhD research has been instrumental in being among the first to demonstrate that pyrogenic soil carbon enhances the performance of early successional temperate old-field pioneers: increasing aboveground biomass, photosynthesis capacity (Amax), reproductive biomass, and water use efficiency, but with high species-specific variation that also includes negative responses (Gale et al. 2017). Growth enhancement is mostly due to pulses of PO4−and K+ supplied by pyrogenic carbon in the short term, while negative responses result from N immobilization and exposure to mobile organic compounds released from pyrogenic carbon (Gale et al. 2016). A census I conducted of regenerating Pinus banksiana stands in the northern extent of the boreal five years following a stand replacing fire, revealed weak correlations between soil pyrogenic carbon concentration and functional traits (In prep).
Pyrogenic carbon represents an incredibly stable pool of carbon in the soil; their use as a soil amendment is thus considered an important climate change mitigation technology that enhances overall carbon sequestration. Encouraged by the improved ecophysiology of plants observed in my work, and motivated to find real solutions to climate change, I recently led a project comparing the responses of plants to pyrogenic soil carbon applied in common land use systems in climate vulnerable Bangladesh. Pyrogenic carbon significantly improved photosynthesis and productivity of tea (Camellia sinensis) in degraded tea estates; and facilitated the growth and recruitment of canopy trees, and enhanced the photosynthesis of some understory species in a regenerating deciduous Dipterocarp forest (In prep).
It is thought that soil pyrogenic carbon facilitates rapid plant regeneration following fires, by increasing the ability of soils to retain and enhance nutrient and water availability, increase soil pH, and reduce soil toxicity by sorbing inhibitory compounds (Thomas, Gale et al. 2013). As a result of these multiple benefits observed in forests (and grasslands), there has been a rapid expansion of applications of pyrogenic carbon as a soil amendment (“biochar”) into environmental management and ecosystem restoration (Thomas and Gale 2015). Physiological adaptations that enable rapid growth in early-successional pioneers (e.g. high rates of photosynthesis) should be advantageous in soils with pyrogenic carbon since plants with a capacity for expeditious resource capture can capitalize on resource pulses from leachable mineral elements. Yet how pyrogenic carbon influences the ecophysiology of plants in natural fire systems, and wild plants and trees in pyrogenic carbon-based restoration projects remains largely unknown; and is, therefore, the focus of my current Ph.D. research with Sean Thomas at the University of Toronto.
My PhD research has been instrumental in being among the first to demonstrate that pyrogenic soil carbon enhances the performance of early successional temperate old-field pioneers: increasing aboveground biomass, photosynthesis capacity (Amax), reproductive biomass, and water use efficiency, but with high species-specific variation that also includes negative responses (Gale et al. 2017). Growth enhancement is mostly due to pulses of PO4−and K+ supplied by pyrogenic carbon in the short term, while negative responses result from N immobilization and exposure to mobile organic compounds released from pyrogenic carbon (Gale et al. 2016). A census I conducted of regenerating Pinus banksiana stands in the northern extent of the boreal five years following a stand replacing fire, revealed weak correlations between soil pyrogenic carbon concentration and functional traits (In prep).
Pyrogenic carbon represents an incredibly stable pool of carbon in the soil; their use as a soil amendment is thus considered an important climate change mitigation technology that enhances overall carbon sequestration. Encouraged by the improved ecophysiology of plants observed in my work, and motivated to find real solutions to climate change, I recently led a project comparing the responses of plants to pyrogenic soil carbon applied in common land use systems in climate vulnerable Bangladesh. Pyrogenic carbon significantly improved photosynthesis and productivity of tea (Camellia sinensis) in degraded tea estates; and facilitated the growth and recruitment of canopy trees, and enhanced the photosynthesis of some understory species in a regenerating deciduous Dipterocarp forest (In prep).
