Moisture Seasonality as a Differential Driver of Modeled Forest Distribution during the Pennsylvanian

Abstract

Environmental restriction of forest distribution may be specific to the eco-physiological limits of era-appropriate plants. Accounting for major limiting factors in deep time will improve understanding of ecosystems dominated by extinct plants, surface processes, and Earth System function. Major plant taxa associated with Earth’s penultimate icehouse (the late Paleozoic ice age [LPIA]) are thought to have been limited by moisture seasonality based on evidence from fossil and geological records. We apply recently described methodologies­—climate modeling and ecosystem-process modeling—to simulate global arboreal vegetation in the late Paleozoic ice age. We will compare the intensity of modeled moisture seasonality with plant performance of major late Paleozoic plant taxa. Using National Center for Atmospheric Research’s Community Earth System Model version 1.2 (CESM) simulations, varying pCO2, pO2, and ice extent for the Pennsylvanian, and fossil-derived leaf C:N, maximum stomatal conductance, specific conductivity, and stem physiological limitations for several major Carboniferous plant groups, we will simulate global ecosystem processes at a 2-degree resolution with Paleo-BGC. We hypothesize that moisture seasonality patterns across Pangea will interact with modeled era-appropriate taxa—based on stem hydraulic hysteresis and leaf water limitations—to impact arboreal plant growth and forest cover. The simulated function of era-appropriate stem and leaf trait combinations may provide a mechanistic link to drought-tolerance evolution in lineages like the coniferophytes that persist across global ecological upheavals.