December 2012 Number 1 - Utah Native Plant Society

Utah Native Plant Society
Figure 2. Species richness patterns based on voucher specimens (Albee et al. 1988), relative to a hexagonal grid sampling
frame (EPA 649 km 2 sampling frame). Areas highest in species richness are shown in red, with lowest species
richness shown in blue. Patterns of species richness generally correlate with elevation: the higher the richness, the
higher the elevation (Ramsey and Shultz 2004).
name, family name, growth form (tree, shrub, grass, or
forb), known elevational range within Utah, acronym
code (USDA PLANTS database), and notation as to
whether the species is native or introduced. Rare plants
are also highlighted in red on these checklists.
Analysis of biodiversity patterns. The digital version
allows reports of total species richness by ecoregion as
well as diversity within a uniform grid system (Figure
2). The layers also can be manipulated to analyze patterns
of species diversity between ecoregions. For comparisons
of ecoregions within the state, see Shultz and
others (2000).
DISCUSSION
Anyone attempting to represent the distribution of a
biological organism knows that distributions are not
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static and that maps can do no better than represent the
distribution of a species at a specified point in time.
Changing landscapes have a profound effect on the distribution
of a species. In addition, the development of
an atlas of plants contains a number of inherent problems
-- primarily regarding accurate identification and
scale. Due to the diversity of the vascular plants (with
more than 20,000 species in North America according to
the Flora of North America Editorial Committee 1992--
2006), reports of plant species generally cannot be
trusted unless accompanied by a voucher specimen.
That constraint severely limits the sample size and
skews the kind of species represented by vouchers. In
general, common species are under-represented in herbarium
collections. However, rare occurrences are usually
well-represented in herbarium collections and con-