PRIEFER ARTICLES 
THE RELATIVE IMPORTANCE OF DIFFERENT SPECIES 
IN A MOUNTAIN GRASSLAND 
A careful study has been made by the writer through four seasons 
upon an area of dry grassland in a mountain park at Tolland, Colorado. 
The park (altitude 8889 feet) is a widened area in the valley of South 
Boulder Creek. The dry grassland covers most of those parts of the 
park that lie from 10 to 50 feet above the stream level. 
As a part of the investigation 16 quadrats, each a meter square, 
were staked off and examined from time to time through the four seasons 
of study. Most of these quadrats are on morainic material, but a few are 
on the upper creek terraces. In the quadrats 64 species of plants were 
found, while the entire dry grassland area of the park showed 62 species 
in addition. 
Estimates were made, as explained in a former paper,’ of the amount 
of bare ground in each quadrat and also the area covered by each species 
of plant. By combining the figures for the different quadrats, the rela- 
tive abundance of the various plants was determined. While the 
figures for the less frequent species are of little value, those for species 
occurring in any considerable number of quadrats show well the relation 
of these plants to the composition of the association as a whole. It is 
certain that every plant of frequent occurrence in the dry grassland of 
the park is represented in a number of quadrats. 
The data for July 1913 are gathered together in table I. These 
midsummer records have been selected for presentation as probably of 
greater interest than would be the figures for spring or autumn. In 
certain genera two or more species of similar ecological nature have 
been put together as one item, the names arranged in order of importance. 
According to the records, the two species present in the quadrats 
in greatest abundance are Artemisia frigida and Aragallus Lamberti, 
but Muhlenbergia gracilis and Carex stenophylla are almost equally 
important. Plants of the different species of Carex taken together 
cover a larger part of the area than do those of any single grass genus, 
but the grasses as a whole are of much greater importance than the 
sedges. The most abundant grasses are the species of Muhlenbergia, 
* Bot. Gaz. §7:526-528. 1914. y 
Botanical Gazette, vol. 60] [154 
