howieb at TELEPORT.COM
Mon Feb 2 12:38:49 CST 1998
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.
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.
howieb at teleport.com
"It's easy to harvest wild plants, the hard part is not harvesting."
More information about the Taxacom