robinl at NAIT.AB.CA
Mon Feb 2 16:45:04 CST 1998
Yes, there are two "indicator species" concepts, and both are valid. The
presence or absence of a particular species is often useful in used and
abused land. For example, the common mullein, Verbascum thapsus L., is a
good indicator of disturbed and often overused lands. And for lands
where the pH has changed (over-fertilized, abused, etc.), loco-weeds of
the genus Oxytropis are good indicators.
The second concept involving communities, in particular, loss of one or
more key species in a species from a defined species assemblage or
ecosystem, is useful.
> At 10:39 PM 2/1/98 +1000, you wrote:
> >It seems to me there are two very different concepts of indicator species
> >out there in the conservation literature. One is a species the presence or
> >absence of which indicates some environmental condition: metals,
> >pesticides, acidity, overclearing, compaction, temperature-shock, winter
> >frosts, etc. There are plenty of that type of indicator, both positive and
> >negative. The other is a species which indicates *biodiversity* per se:
> >ie, the presence of this species is correlated with the presence of (i)
> >lots of other, unrelated species or (ii) other species somehow judged to be
> >valuable, or endangered, or otherwise in need of some management.
> >I cannot think of any examples of the latter type of indicator, but it
> >seems that often indicators of the first type are mistaken for the second.
> >John Trueman.
> I use the latter definition of indicator plants in my field work locating
> specific medicinal plants in the Pacific Northwest. Often the "indicator"
> plant will be a very visible plant used to locate a less obvious one.
> Example: A Fern, Polystichum munitum is very visible and may indicate the
> presence of the low creeping Wild Ginger, Asarum caudatum. Valeriana
> scouleri is very visible in early spring when blooming along steep riparian
> cliffs. Later in the year, it's leaves are hidden below other taller
> species. At these times of year I can use the obvious flowers of the tall
> Boykinia elata as an possible indicator of the Valeriana. A third example I
> use is the presence of blooming Marsh Marigiold, Caltha biflora, a marsh
> growing buttercup Ranunculus sp.(the species varies in different areas),
> and the Shooting Star, Dodecatheon jeffreyi, to indicate the possibility of
> Elephant's Head, Pedicularis groenlandica, blooming in the same spots later
> in the season.
> Howie Brounstein
> howieb at teleport.com
> "It's easy to harvest wild plants, the hard part is not harvesting."
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