Jg. Ehrenfeld, MICROSITE DIFFERENCES IN SURFACE SUBSTRATE CHARACTERISTICS IN CHAMAECYPARIS SWAMPS OF THE NEW-JERSEY PINELANDS, Wetlands, 15(2), 1995, pp. 183-189
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.