Biomass Allocation in Late Pennsylvanian Coal-Swamp Plants

Abstract

Carbon allocation to different tissues and organs of Late Pennsylvanian-aged coal-swamp plants was determined for the first time through study of coal balls from the Calhoun coal of central Illinois. Coal balls are concretions that preserve the original peat fabric of the coal seam; they occur within the coal matrix and generally are permineralized with calcium carbonate. Coalified plant cell walls are preserved within the mineral matrix of the coal ball, entombed within the calcium carbonate. Relative carbon allocation was determined by separation of the mineral matrix and organic carbon. Carbon content was determined for replicates of tissues or organs of Psaronius tree ferns, Medullosapteridosperms, the lycopsid Sigillaria approximata, the small fern Botryopteris forensis, and whole peat'. Unit volume results for tissues and organs were normalized for trunk sections 45 cm in diameter and 1 m long. Psaronius tree ferns were significantly cheaper than all other plants due to the large mantle of aerenchymatous roots that made up the bulk of the trunk. Medullosans and small ferns were most expensive, with the arborescent lycopsid in between. Relative expense of construction closely parallels the inferred ecological role of each plant within ancient coal swamps, deduced from distributional patterns and indicators of habitat conditions. Tree ferns and lycopsids are colonists, medullosans are site occupying forms.