Effects of
Treethrow Microtopography on the Characteristics
and Genesis of
Spodosols, Michigan, USA
R.
J. Schaetzl
This study examined the pedogenic
effects of pit and mound microtopography, formed by tree uprooting, in a
Spodosol (Haplorthods) landscape. Most
soils in treethrow pits were Entic Haplorthods or Spodic Upidsamments whereas
mound soils usually classified as Typic Udipsamments, suggesting that degree of
profile development is: Undisturbed Pit > Mounds. Given that pit and mound soils are substantially younger than
pedons on undisturbed sites, rates of pedogenesis are thought to be: Pit > Undisturbed > Mound. Strong pedogenesis in pits was explained by
:
1.
greater
water contents in the upper sola, which may facilitate weathering processes,
2.
thicker
O horizons, which may lead to increased production of organic acids, and
3.
greater
insulation by thick litter and snow cover, which reduces the incidence of soil
freezing.
In winter, mound soils may develop impermeable layers of concrete soil frost that impede infiltration of snowmelt waters, whereas pit soils remain unfrozen or acquire only a porous, granular frost layer. Thus, saturated flow of snowmelt within pits is relatively unrestricted, resulting in maximal leaching and profile differentiation.