MICROSITE DIFFERENCES IN SURFACE SUBSTRATE CHARACTERISTICS IN CHAMAECYPARIS SWAMPS OF THE NEW-JERSEY PINELANDS

Atlantic white cedar wetlands have pronounced hummock-hollow microtopo graphy, in which the hummocks may be covered by Sphagnum spp. or may h ave only a layer of needle and leaf litter present. I tested the hypot heses that characteristics of the hummock peat, including moisture con tent, bulk density, redox potential and fiber content, would vary line arly with elevation above the water table, and that these relationship s would not vary between moss- and litter-covered surfaces. These hypo theses underlie the frequent use of microsite elevation as an indicato r of habitat differentiation in wetlands. I found that moisture and re dox potential varied with elevation, but bulk density and fiber conten t were independent of elevation. Furthermore, moisture and redox statu s on Sphagnum-covered microsites had a weaker relationship to elevatio n (lower slope coefficient and lower r(2)) than on litter-covered micr osites. Principal components analyses showed that Sphagnum-covered mic rosites were differentiated primarily on the basis of the relative con tent of undecomposed and decomposed fibers, while litter-covered sites were differentiated primarily on the basis of moisture and elevation. These results suggest that environmental gradients on hummock-hollow systems are complex and not a simple reflection of elevation. Environm ental disturbances that reduce Sphagnum cover may affect vegetation by creating more drought-prone microsites on the tops of the hummocks, a nd this may be important for management of cedar regeneration.