Log moisture capacity does not predict epixylic bryophyte growth under thinned and unthinned forest canopies

1. Coarse woody debris (CWD) serves as habitat for diverse and rare taxa in forest systems. Because the abundance of mosses appears to be correlated with log size and stage of decay, many have suggested that CWD serves as a moisture reservoir, ensuring a humid microclimate and facilitating moss growth, but no one has tested this connection. Intact forest canopies are also thought to maintain humid conditions that benefit moss growth. If microclimatic regulation is the primary mechanism contributing to high moss abundance on CWD, then epixylic moss growth should increase with the capacity of the log moisture reservoir, and the importance of the reservoir size should increase with canopy opening. 2. Three types of synthetic logs, identical in size and shape but differing in moisture capacity, and two natural substrates, well-decayed birch and Thuja logs, were used to test the effects of log moisture capacity on growth of Dicranum flagellare under thinned and intact canopies of a spruce pl...