Microsite differences in surface substrate characteristics inChamaecyparis swamps of the New Jersey Pinelands

Abstract

Atlantic white cedar wetlands have pronounced hummock-hollow microtopography, in which the hummocks may be covered by Sphagnum spp. or may have only a layer of needle and leaf litter present. I tested the hypotheses that characteristics of the hummock peat, including moisture content, bulk density, redox potential and fiber content, would vary linearly with elevation above the water table, and that these relationships would not vary between moss-and litter-covered surfaces. These hypotheses underlie the frequent use ofmicrosite elevation as an indicator of habitat differentiation in wetlands. I found that moisture and redox potential varied with elevation, but balk density and fiber content were independent of elevation.Furthermore, moisture and redox status on Sphagnum-covered microsites had a weaker relationship to elevation (lower slope coefficient and lower r 2) than on litter-covered microsites. Principal components analyses showed that Sphagnum-covered microsites were differentiated primarily on the basis of the relative content 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. Environmental disturbances that reduce

The role of microtopography and substrate in survival and growth of Atlantic white-cedar seedlings

“…This is consistent with other studies that demonstrated complex microtopographic gradients in AWC wetlands (Ehrenfeld, 1995a;Mylecraine and Zimmermann, 2000). According to Ehrenfeld (1995b), elevation may be considered the 'master variable' informing the variation in physical and chemical conditions encountered by wetland plant species.…”

“…This finding is also consistent with other studies (Ehrenfeld, 1995b;Mylecraine and Zimmermann, 2000). It has been suggested that microtopography, especially as it affects moisture availability, may be an important factor explaining AWC seedling distribution on hummocks (Korstian and Brush, 1931;Little, 1950;Ehrenfeld, 1995aEhrenfeld, , 1995b. Seedling recruitment may be unsuccessful at the top of hummocks and at the lowest elevations in the hollows because of drought and prolonged flooding, respectively (Ehrenfeld, 1995b;Kuser and Zimmermann, 1995).…”

Forest Resource Islands in a Sub-tropical Marsh: Soil–Site Relationships in Everglades Hardwood Hammocks

“…In wetlands, vegetation patterning may also be organized around slight discontinuities in surface topography (Huenneke and Sharitz 1986;Titus 1990), though these variations do not always translate into edaphic differences (Ehrenfeld 1995). Ecological theory suggests that environmental heterogeneity may also structure emergent properties of the plant community such as species diversity (Tilman 1988;Huston 1994;Rosenzweig 1995).…”

Morphological plasticity of Primula nutans to hummock-and-hollow microsites in an alpine wetland

“…Depending on the history of development, the hummocks and hollows can (Ivanov 1981;Glaser 1992via Weltzin et al 2001). These differences are influenced by various physical and biological factors (Ehrenfeld 1995;Karofeld 1998;Nungesser 2003). For example, the change of ground water level is the major environmental driver of the "growth" of hummocks (Couwenberg 2005), while soil characteristics, frozen degree and the accumulation of peat can all result in the formation of hummocks (Mark 1994;Tallis and Livett 1994;Tallis 1994;Karofeld 1998).…”