Bryophyte mass to stem length ratio: A potential metric for eco-physiological response to land use

Abstract

<p align="justify"> <span style="font-family:'Arial','sans-serif';font-size:10pt;"><span style="font-family:Verdana;font-size:12px;">Methods of analysis are needed that quantitatively characterize the response of organisms to anthropogenic disturbance. Herein a method is presented that characterizes bryophyte morphological variability in response to timber harvest treatments (clearcut and partial cut). Samples (n = 6196) of the semi-aquatic bryophyte </span><i><span style="font-family:Verdana;font-size:12px;">Brachythecium frigidum</span></i><span style="font-family:Verdana;font-size:12px;"> were collected from clearcut, partial cut and full forest stream reaches between August 2003 and October 2005 and analyzed to obtain mass to stem length ratios (M:SL). Results show that relative to a full forest (i.e. full canopy cover condition), average M:SL ratios were reduced approximately 18% in the partial cut and 37% in the clearcut, indicating a decrease in biomass per unit stem length with increasing harvest intensities. Increased light intensities and higher air temperatures resulting from decreased canopy cover in the harvest treatments corresponded to lower M:SL ratios (0.31 and 0.24 for the partial cut and clearcut, respectively). Results quantify the morphological response of </span><i><span style="font-family:Verdana;font-size:12px;">B. frigidum</span></i><span style="font-family:Verdana;font-size:12px;"> to habitat perturbation, thereby validating the method as a useful assessment of anthropogenic disturbance in post-timber harvest environments. Additional work should be conducted to test the method in other physiographic regions and to isolate bryophyte response to alterations of distinct environmental variables.</span></span> </p