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Dear All,
Some of you may remember that for a number of years I recorded the=20
flowering, fruiting and grazing damage of about 100 numbered Common Lady=20
Slipper plants in one relatively small area of woodland.
After one strange winter (2008-2009 ??) when soil under snow cover=20
.was sheathed with ~3 cm of ice they nearly all died (I am not sure in=20
which year I found this to be so without plowing through a stack of=20
notes but I think it was a year or more after 2009).
I do not recall now to what I attributed their death but am now=20
reasonably sure it was oxygen deprivation. Soil respiration continues=20
year round until temperature is near zero. So a soil profile, sealed in=20
by a layer of surface ice would quickly become anaerobic and Lady=20
Slippers, not being swamp plants, would be unlikely to tolerate lack of=20
Oxygen.
This condition of ice over soil was true in many locations this=20
winter and frost in soil was likely more than 3' deep. The lawn out back=20
has previously been well drained but this year hydraulic conductivity=20
has approached zero; the slightest rain leads to immediate ponding and=20
eventually to runoff with apparently little or no infiltration.
I suspect this change was due to deep frost, followed much later by=
=20
slow thawing from the surface downward often aided by rain,
so that the topsoil aggregates became seriously slaked. This not only=20
slows infiltration of water to near zero but impedes the movement of=20
Oxygen into the soil. I had not anticipated that a wetland soil could be=20
generated in one winter but that seems to have happened. Is Anhydrite=20
still available in the Windsor area ?
YT, DW, Kentville
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<body>Dear All,<div>=C2=A0 =C2=A0 Some of you may remember that for a numbe=
r of years I recorded the flowering, fruiting and grazing damage of about 1=
00 numbered Common Lady Slipper plants in one relatively small area of wood=
land.</div><div>=C2=A0=C2=A0=C2=A0=C2=A0After one strange winter (2008-2009 =
??) when soil under snow cover .was sheathed with ~3 cm of ice they nearly =
all died (I am not sure in which year I found this to be so without plowin=
g through a stack of notes but I think it was a year or more after 2009).=
=C2=A0</div><div>=C2=A0=C2=A0=C2=A0=C2=A0I do not recall now to what I attr=
ibuted their death but am now reasonably sure it was oxygen deprivation. So=
il respiration continues year round until temperature is near zero. So a so=
il profile, sealed in by a layer of surface ice would quickly become anaero=
bic and Lady Slippers, not being swamp plants, would be unlikely to tolerat=
e lack of Oxygen.</div><div>=C2=A0 =C2=A0=C2=A0<span class=3D"Apple-tab-spa=
n" style=3D"font-size: 12pt; white-space: pre;"> </span>This condition of i=
ce over soil was true in many locations this winter and frost in soil was l=
ikely more than 3' deep. The lawn out back has previously been well drained =
but this year hydraulic conductivity has approached zero; the slightest ra=
in leads to immediate ponding and eventually to runoff with apparently litt=
le or no infiltration.</div><div>=C2=A0 =C2=A0=C2=A0=C2=A0I suspect this ch=
ange was due to deep frost, followed much later by slow thawing from the su=
rface downward often aided by rain, =C2=A0</div><div>so that the topsoil ag=
gregates became seriously slaked. =C2=A0This not only slows infiltration of =
water to near zero but impedes the movement of Oxygen into the soil. I had =
not anticipated that a wetland soil could be generated in one winter but t=
hat seems to have happened. Is Anhydrite still available in the Windsor are=
a ?</div><div>YT, DW, Kentville</div></body></html>
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