[NatureNS] Mustard white; Cardamine pratensis; soil disturbance

From: David & Alison Webster <dwebster@glinx.com>
To: NatureNS@chebucto.ns.ca
Date: Tue, 09 Jun 2015 20:33:09 -0300
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Dear All,                            June 9, 2015
    Mustard White until recently was considered to be quite rare but, at =
least in eastern Kings Co., it has since ~2003 often locally been the =
most abundant butterfly by a wide margin. And in my experience, =
Cardamine pratensis is invariably present or nearby where Mustard White =
is seen.=20

    So as I think I have noted previously, this is an interesting =
example of a native insect which has flourished thanks to an introduced =
plant. But I have recently become aware of another twist; C. pratensis =
may need modest soil disturbance to persist on or along woodland roads.=20

    For example, it quickly became established in abundance, after horse =
logging in 2002, along a seepy portion of a woods road which I had cut =
in 2001. But with only a few truck runs per year since then it has =
gradually been crowded out by competing ground cover. But the wet period =
last summer led to some soil wash on a more frequently used road and =
this together with foot traffic on wet soil near the base of this road =
to clear multiple windfalls has led to a vigorous dense stand of =
Cardamine this year; scattered flowering plants which must have become =
established in 2014 and a carpet of 2015 seedlings.=20

    Knowing that soil formation from parent material is a very slow =
process I take great pains to reduce soil erosion or vehicle traffic on =
wet soil as much as possible so I am amused to notice that bare soil =
every decade or so may be a good thing if you are a Mustard White.

Yt, Dave Webster, Kentville
   =20

   =20

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<DIV>Dear All,&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;=20
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; =
&nbsp;&nbsp;&nbsp; June=20
9, 2015</DIV>
<DIV>&nbsp;&nbsp;&nbsp; Mustard White until recently&nbsp;was considered =
to be=20
quite rare but, at least in eastern Kings Co., it&nbsp;has since=20
~2003&nbsp;often locally been the most abundant butterfly by a wide =
margin. And=20
in my experience, <EM>Cardamine pratensis </EM>is invariably present or =
nearby=20
where Mustard White is seen. </DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;&nbsp;&nbsp; So as I think I have noted previously, this is =
an=20
interesting example of a native insect which has flourished thanks to an =

introduced plant. But I have recently become aware of another twist; =
<EM>C.=20
pratensis </EM>may need modest soil disturbance to persist on or along =
woodland=20
roads.&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;&nbsp;&nbsp; For example, it quickly&nbsp;became established =
in=20
abundance, after horse logging in 2002,&nbsp;along&nbsp;a seepy =
portion&nbsp;of=20
a woods road which I had cut in 2001. But with only a few truck =
runs&nbsp;per=20
year since then it has gradually been crowded out by competing ground =
cover. But=20
the wet period last summer&nbsp;led to some soil wash on a more =
frequently used=20
road&nbsp;and this together with&nbsp;foot traffic on wet soil near the =
base of=20
this road to clear multiple windfalls has led to a vigorous dense stand =
of=20
<EM>Cardamine</EM> this year; scattered flowering plants which must have =
become=20
established in 2014 and a carpet of 2015 seedlings. </DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;&nbsp;&nbsp; Knowing that&nbsp;soil formation from parent =
material is=20
a very slow process I take great&nbsp;pains to&nbsp;reduce soil erosion =
or=20
vehicle traffic on wet soil&nbsp;as much as possible so I am amused to =
notice=20
that bare soil every decade or so may be a good thing if you are a =
Mustard=20
White.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Yt, Dave Webster, Kentville</DIV>
<DIV>&nbsp;&nbsp;&nbsp; </DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;&nbsp;&nbsp; </DIV>
<DIV>&nbsp;</DIV></BODY></HTML>

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