Water Relations and CO₂ Exchange of Tropical Bryophytes in a Lower Montane Rain Forest in Panama

Abstract

Abstract: For 6 tropical bryophytes, measurements of the diel courses in water status and net CO 2 exchange were made in a submontane tropical rain forest in Panama. In addition, the response of gas exchange to changes in photon flux density (PPFD) and thallus water content (WC) was studied under controlled conditions. Diel variation of WC was pronounced, and both low and high WC limited carbon gain considerably. Low PPFD, e.g. during rain storms, was less important in limiting CO 2 exchange. More than half of the mean diurnal carbon gain of 2.9 mg C per g thallus carbon was lost during the night as respiration. Assuming that the average 24‐h carbon gain was representative for the entire year, we estimated the net annual primary productivity of the mosses and liverworts to be 45% of the initial plant carbon content.