Low Impact Development Manual for Michigan - OSEH - University ...

ule of thumb, FQIs of 20 or lower have little
ecological value, while those greater than 35 are
have ecological importance across the state. FQIs
greater than 50 represent only our highest quality
plant communities and should never be considered
for development.
The quality of a given plant community must
also be considered in comparison to other plant
communities in the state. For example, oak
openings are considerably rarer in Michigan than
dry southern forests. So, when given a choice of
development for unregulated land, the more rare
plant community should typically be avoided. A
ranking system for Michigan’s natural communities,
characterizing all communities statewide and
globally on a 1-5 scale, is available at http://web4.
msue.msu.edu/mnfi/communities/index.cfm.
2. Combine mapped natural features into a
sensitive resource areas map, prioritizing areas
to avoid development.
All sensitive resource mapping should be overlain
to produce a sensitive areas map. Randall Arendt
in Growing Greener acknowledges prioritizing
or weighting of sensitive areas by defining
them as either Primary Conservation Areas (the
most critical – avoid at all costs) or Secondary
Conservation Areas (important resources which
should be avoided when possible). Mapping the
secondary resources of the site is an important step;
the community can provide input to determine
which features are important for preservation.
Additionally, Primary and Secondary Conservation
Areas can be defined in different ways, possibly
varying with watershed context, (e.g., woodlands
in some contexts may be classified as Primary
Conservation Areas, rather than secondary). Given
the substantial variability in Michigan’s natural
resources from one ecoregion to another, this
flexibility in weighting resource types is especially
important.
3. Map potential development areas; prioritize/
weight as necessary.
The potential development area should be
delineated on the basis of protecting the primary
and secondary resources on a site. Like the
sensitive areas map, priorities and weightings
may be reflected in the potential development
area map. If sensitive areas have been prioritized,
Figure 6.4
Map of sensitive areas (top) and secondary
resources (bottom)
Source: Arndt, Randall G. 1997
LID Manual for Michigan – Chapter 6 Page 101