Friday, February 7, 2014

Yosemite Rare Plants are encountered less-frequently than common plants

Accepting the assumption that a herbarium specimen is randomly gathered (a tenuous proposition), then we can determine if “rare” plants are encountered less often compared to “common” plants (rare plants defined as being on the CNPS list).

In the central Sierra Nevada region centered about Yosemite (Tuolumne, Mariposa, Madera and Mono Conties), with a total of 70,966 herbarium specimens to analyze, the results is that: yes, rare plants are collected less often as compared to common plants.

The difference is significant (using the non-parametric Kolmogorov-Smirnov two-sample test) at p=0.003.  Box plot below...

Those rare plants with the but a single specimen are:
Botrychium paradoxum
Carlquistia muirii
Cuscuta jepsonii
Potamogeton praelongus
Streptanthus gracilis
Viburnum ellipticum

The most frequently collected “rare” plants are (a.. >70 total specimens)
Agnorhiza elata
Astragalus kentrophyta var. danaus
Bolandra californica
Carex congdonii
Ceanothus fresnensis
Diplacus pulchellus
Erythranthe filicaulis
Erythranthe laciniata
Hulsea brevifolia
Lupinus spectabilis

Perhaps being infrequently collected does not diagnose rarity: there are 464 non-rare species in the Yosemite region which have been collected only once.  

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